Glossary of Video Terms and Acronyms - Isotest

Glossary of Video Terms and 

Acronyms 

G l o s s a r y o f T e r m s

This Glossary of Video Terms and Acronyms is a compilation of material gathered over time from numerous 

sources. It is provided "as-is" and in good faith, without any warranty as to the accuracy or currency 

of any definition or other information contained herein. Please contact Tektronix if you believe that any of 

the included material violates any proprietary rights of other parties.

1/4" Phone – A connector used in audio production that is characterized 

by its single shaft with locking tip. 

1/8th Mini – A small audio connector used frequently in consumer electronics. 

1 CBPS – 1 Coded Bit Per Symbol. 

1:1 – Either a perfectly square (9:9) aspect ratio or the field:frame ratio of 

progressive scanning. 

100 Field Per Second – Field rate of some European proposals for a 

world standard for ATV (Advanced Television). 

12.5T Sine-Squared Pulse with 3.579545 MHz Modulation – 

Conventional chrominance-to-luminance gain and delay measurements are 

based on analysis of the baseline of a modulated 12.5T pulse. This pulse is 

made up of a sine-squared luminance pulse and a chrominance packet 

with a sine-squared envelope as shown in the figure below. This waveform 

has many advantages. First it allows for the evaluation of both gain and 

delay differences with a single signal. It also eliminates the need to separately 

establish a low-frequency amplitude reference with a white bar. 

Since a low-frequency reference pulse is present along with the highfrequency 

information, the amplitude of the pulse itself can be normalized. 

The HAD of 12.5T was chosen in order to occupy the chrominance bandwidth 

of NTSC as fully as possible and to produce a pulse with sufficient 

sensitivity to delay distortion. 

0.5 

0 

0.5 

-0.5 

1-9 

0 

LUMINANCE 

COMPONENT 

CHROMINANCE 

COMPONENT 

3.12 µs 

125M – See SMPTE 125M. 

1410 NTSC Test Signal Generator – Discontinued analog circuit based 

Tektronix test signal generator that is used to generate full field composite 

analog test signals. Replaced by the Tektronix TSG-170A. 

1450 Demodulator – Tektronix high quality demodulator that provides 

envelope and synchronous demodulation. 

1480 Waveform Monitor – Discontinued Tektronix waveform monitor. 

Replaced by the 1780R. 

16 VSB – Vestigial sideband modulation with 16 discrete amplitude levels. 

BOTH COMPONENTS ADDED 

A 

3.12 µs 

HAD 

1.56 µs 

MOD 12.5T PULSE 

1 

0 

Video Terms and Acronyms 

Glossary 

16 QAM – 16 Quadrature Amplitude Modulation. 

16x9 – A widescreen television format in which the aspect ratio of the 

screen is 16 units wide by 9 high as opposed to the 4x3 of normal TV. 

1780R Waveform Monitor/Vectorscope – Tektronix microprocessor controlled 

combination waveform monitor and vectorscope. 

1910 Digital Generator/Inserter – Tektronix VITS test signal generator. 

2-1/2D (Two and One-Half Dimensions) – This term refers to the kind 

of dimensionality (i.e., 2D, 3D) that can be created using multiplane animation. 

Since a layer in such animation can lie in front of one cel (or plane), 

or in back of another layer, the resulting effect is of a three dimensional 

world. This is a limited 3D world, however, because the layers are fixed in 

relation to each other. For this reason, multiplane animation is referred to 

as 2-1/2 dimensions. It is a very useful technique, however, even for computer 

graphics, because by ordering the layers in the way a painter does, 

you can save the computer the need to compare objects that are in different 

layers (that is, compare them for purposes of hidden surface removal). 

2 CBPS – 2 Coded Bits Per Symbol. 

2:1 – Either an aspect ratio twice as wide as it is high (18:9) or the 

field:frame ratio of interlaced scanning. 

24 Frames Per Second – International standard for motion picture film 

shooting and projection, though film shot for television in 625 scanningline 

countries is usually shot at 25 frames per second (even if not, it is 

transferred to television at 25 frames per second). There are moves afoot 

in the U.S. to increase the film frame rate to 30 for improved temporal resolution. 

The ImageVision HDEP system and other electronic cinematography 

systems use 24 frames per second. RCA once proposed an electronic cinematography 

system with 2625 scanning lines (2475 active), a 2:33:1 

aspect ratio, and a frame rate of 23.976023 frames/sec. 

25 Frames Per Second – Frame rate of television in all countries not 

conforming to CCIR system M (NTSC). Also the frame rate of film shot for 

television in those countries. 

25 Hz HDTV Bitstream – A bitstream which contains only Main Profile, 

High Level (or simpler) video at 25 Hz or 50 Hz frame rates. 

25 HZ HDTV IRD – An IRD (Integrated Receiver Decoder) that is capable of 

decoding and displaying pictures based on a nominal video frame rate of 

25 Hz or 50 Hz from MPEG-2 Main Profile, High Level bitstreams, in addition 

to providing the functionality of a 25 Hz SDTV IRD. 

25 Hz SDTV Bitstream – A bitstream which contains only Main Profile, 

Main Level video at 25 Hz frame rate. 

25 Hz SDTV IRD – An IRD (Integrated Receiver Decoder) which is capable 

of decoding and displaying pictures based on a nominal video frame rate of 

25 Hz from MPEG-2 Main Profile, Main Level bitstreams. 

29.97 Frames Per Second – Frame rate of NTSC color television, 

changed from 30 so that the color subcarrier could be interleaved between 

both the horizontal line frequency and the sound carrier. 

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2K – A film image scanned into a computer file at a resolution of 2048 

horizontal pixels per line. 

2T Pulse – See the discussion on Sine-Squared Pulses. 

3-Perf – A concept for saving money on film stock by shooting each 

35 mm frame in an area covered by three perforations rather than four. 

The savings is more than enough to compensate for switching from 24 

frames per second to 30. Three-perf naturally accommodates a 1.78:1 

(16:9) aspect ratio and can be easily masked to the 1.85:1 common in 

U.S. movie theaters. It changes the shoot-and-protect concept of using 

theatrical film on television, however, from one in which the protected area 

is extended vertically to one in which the shooting area is reduced 

horizontally. 

3.579545 MHz – The frequency of the NTSC color subcarrier. 

3:2 Pull Down – a) The technique used to convert 24 frames per second 

film to 30 frames per second video. Every other film frame is held for three 

video fields resulting in a sequence of 3 fields, 2 fields, 3 fields, 2 fields, 

etc. b) A frame cadence found in video that has been telecined or converted 

from film to video. This cadence is produced because the frame rates 

for film and video are different. During the process of compression, some 

compression hardware recognizes this cadence and can further compress 

video because of it. Material which is video to start with gains no extra 

compression advantage. Material edited after being telecined may not gain 

a compression advantage. 

30 Hz HDTV Bitstream – A bitstream which contains only Main Profile, 

High Level (or simpler) video at 24000/1001, 24, 30000/1001, 30, 

60/1001 or 60 Hz frame rates. 

30 Hz HDTV IRD – An IRD (Integrated Receiver Decoder) that is capable of 

decoding and displaying pictures based on nominal video frame rates of 

24000/1001, 24, 30000/1001, 30, 60/1001 or 60 Hz from MPEG-2 Main 

Profile, High Level bitstreams, in addition to providing the functionality of a 

30 Hz SDTV IRD. 

30 Hz SDTV Bitstream – A bitstream which contains only Main Profile, 

Main Level video at 24000/1001, 24, 30000/1001 or 30 Hz frame rate. 

30 Hz SDTV IRD – An IRD (Integrated Receiver Decoder) which is capable 

of decoding and displaying pictures based on a nominal video frame rate of 

24000/1001 (approximately 23,98), 24, 3000/1001 (approximately 29,97) 

or 30 Hz from MPEG-2 Main Profile at Main Level bitstreams. 

30 Frames Per Second – Frame rate of NTSC prior to color. Frame rate of 

the ATSC/SMPTE HDEP standard. A potential new film standard. 

3D (Three Dimensional) – Either as in stereoscopic television (NHK has 

suggested alternating 3DTV transmissions with HDTV), or more often, when 

referring to ATV, relating to the three dimensions of the spatio-temporal 

spectrum: horizontal, vertical, and time. 

3D Axis (Menu) – The 3D function that moves the image away from the 

center of rotation. The image can be moved along, or off any of the three 

axes. 

3D Space – Three dimensional space is easily imagined by looking at a 

corner of a rectangular room. The corner is called the origin. Each edge 

leaving from the origin (there are three of them) is called an axis. Each axis 

extends infinitely in two directions (up/down, left/right, and front/back). 

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Imagine laying long measuring sticks on each axis. These are used to 

locate specific points in space. On the Cubicomp, or any other graphics 

systems, the yardsticks are not infinitely long, and 3D space on these 

devices is not infinite; it is more like an aquarium. 

3XNTSC – A Zenith proposal for an HDEP scheme that would use three 

times as many scanning lines as NTSC (1575), but would otherwise retain 

NTS characteristics. It is said to allow easy standards conversion to 525or 

625-scanning line systems and to accept material shot in 1125 scanning 

lines in a 16:9 aspect ratio without difficulty. 3XNTSC would have 

1449 active scanning lines, 2:1 interlace, a 4:3 aspect ratio, and a bandwidth 

of 37.8 MHz. 

4:1:1 – 4:1:1 indicates that Y' has been sampled at 13.5 MHz, while Cb 

and Cr were each sampled at 3.375 MHz. Thus, for every four samples of 

Y', there is one sample each of Cb and Cr. 

4:2:0 – A sampling system used to digitize the luminance and color difference 

components (Y, R-Y, B-Y) of a video signal. The four represents the 

13.5 MHz sampling frequency of Y, while the R-Y and B-Y are sampled at 

6.75 MHz – effectively between every other line only. 

4:2:2 – a) A commonly used term for a component digital video format. 

The details of the format are specified in the CCIR-601 standard document. 

The numerals 4:2:2 denote the ratio of the sampling frequencies of 

the single luminance channel to the two color difference channels. For 

every four luminance samples, there are two samples of each color difference 

channel. b) ITU-R BT.601 digital component waveform sampling standard 

where the luminance signal is sampled at the rate of 13.5 MHz, and 

each of the color difference signals, (Cr and Cb) are sampled at the rate of 

6.25 MHz each. This results in four samples of the luminance signal for 

each two samples of the color difference signals. See ITU-R BT.601-2. 

10 Bit 

Y Sample 

10 Bit 

C r Sample 

10 Bit 

Y Sample 

10 Bit 

C b Sample 

10 Bit 

Y Sample 

10 Bit 

C r Sample 

10 Bit 

Y Sample 

10 Bit 

C b Sample 

4:2:2p (Professional Profile) – 4:2:2p refers to a higher quality, higher 

bitrate encoding designed for professional video usage. It allows multiple 

encodings/decodings before transmission or distribution. 

4:2:2:4 – Same as 4:2:2 with the addition of a key channel sampled at the 

same frequency as the luminance. 

4:4:4 – A sampling ratio that has equal amounts of the luminance and 

both chrominance channels. 

4:4:4:4 – Same as 4:2:2 with the addition of a key channel, and all channels 

are sampled at the same frequency as the luminance. 

45 Mbps – Nominal data rate of the third level of the hierarchy of ISDN in 

North America. See also DS3. 

4fsc – Composite digital video as used in D2 and D3 VTRs. Stands for four 

times the frequency of subcarrier, which is the sampling rate used. In 

NTSC, 4FSC is 14.3 MHz and in PAL it is 17.7 MHz. 

4K – A film image scanned into a computer file at a resolution of 4096 

horizontal pixels per line. 4K is considered to be a full-resolution scan of 

35 mm film.

5-Step Staircase – This signal is commonly used to check luminance 

gain linearity. 

5.1 Channel Audio – An arrangement of five audio channels (left, center, 

right, left-surround, and right-surround) and one subwoofer channel. 

50 Fields Per Second – Field rate of 25 frame-per-second interlaced television. 

520A Vectorscope – Discontinued Tektronix vectorscope. It has been 

replaced by the 1780R. 

59.94 Fields Per Second – Field rate of NTSC color television. 

60 Fields Per Second – Field rate of the ATSC/SMPTE HDEP standard. 

60 Frames Per Second – Frame rate of Showscan and some progressively 

scanned ATV schemes. 



601 – See ITU-R BT.601-2. 

75%/100% Bars – See Vectorscopes. 

8 mm – A compact videocassette record/playback tape format which uses 

eight millimeter wide magnetic tape. A worldwide standard established in 

1983 allowing high quality video and audio recording. Flexibility, lightweight 

cameras, and reduced tape storage requirements are among the format’s 

advantages. 

8 PSK (8 Phase Shift Keying) – A variant of QPSK used for satellite links 

to provide greater data capacity under low-noise conditions. 

8 VSB – Vestigial sideband modulation with eight discrete amplitude levels, 

used in the ATSC digital television transmission standard. 




A–Advanced. 

A and B Rolls, Tape – Separation of material into two groups of reels (A 

rolls and B rolls), with alternate scenes on each reel pair (A reel and B reel) 

to allow transitions between reels. 

A Bus – The top row of the two rows of video source select buttons associated 

with a given M/E. 

A Bus Keyer – A keyer that appears only on top of an “A” bus background 

video on an M/E. 

A/A (A/X/A) Roll Editing – Editing from a single source using effects to 

transition from the source to itself (source “A” to “A”) using a picture freeze 

at the end of one scene to transition the start of the next scene. 

A/B Roll – Creating fades, wipes and other transitions from one video 

source to another. 

A/B Roll Editing – Editing from two source VCRs (“A” and “B”) to a third 

(recording) VCR. Typically a switcher or mixer, such as the Digital Video 

Mixer, is used to provide transition effects between sources. Control over 

the machines and process can be done manually or automatically using an 

edit controller. 

A/D – See A-to-D Converter. 

A/V – Audio/Video. 

A/V Edit – An edit that records new audio and video tracks. Also called 

Straight Cut. 

A/V Mixer – See Audio/Video Mixer. 

A:B:C Notation – The a:b:c notation for sampling ratios, as found in the 

ITU-R BT.601 specifications, has the following meaning: a) 4:2:2 means 

2:1 horizontal downsampling, no vertical downsampling. Think four Y samples 

for every two Cb and 2 Cr samples in a scan line. b) 4:1:1 ought to 

mean 4:1 horizontal downsampling, no vertical. Think four Y samples for 

every one Cb and one Cr samples in a scan line. It is often misused to 

mean the same as 4:2:0. c) 4:2:0 means 2:1 horizontal and 2:1 vertical 

downsampling. Think four Y samples for every Cb and Cr samples in a scan 

line. Not only is this notation not internally consistent, but it is incapable of 

being extended to represent any unusual sampling ratios, that is different 

ratios for the Cb and Cr channels. 

AAL – ATM Adaptive Layer. 

AAL5 – ATM Adaptation Layer 5. 

AAU (Audio Access Unit) – See Access Unit. 

A-B Rolls – Duplicate rolls of videotape information having identical time 

code; required to achieve effects of dissolves. 

ABC – Television network financially supporting development of ACTV and 

pioneering the use of digital video transmission. 

ABKW – See Audio Breakaway. 

Abort – Halts the program and returns control to the operator or operating 

system. 

4 

A 

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Absolute Time Code – Absolute time code (ATC) is generally recorded in 

the subcode or control track region of any digital tape. This is the code that 

digital tape machines use to locate specific points on a tape for autolocation 

or other functions. In some machines, it is even used to synchronize 

the tape to other equipment. ATC is precisely accurate and usually conforms 

to the IEC standard which is easily converted to the more commercially 

used SMPTE time code. Unlike SMPTE, ATC always begins at zero at 

the beginning of a digital tape and increments one frame at a time until 

recording stops. Some DAT machines have the ability to function without 

ATC on a tape while others simply will not play a tape without it. These 

days, almost all machines record it automatically so it will always be on 

every tape. 

Absorption – In acoustics, the opposite of reflection. Sound waves are 

“absorbed” or soaked up by soft materials they encounter. Studio designers 

put this fact to work to control the problem of reflections coming back to 

the engineer’s ear and interfering with the primary audio coming from the 

monitors. The absorptive capabilities of various materials are rated with an 

“Absorption Coefficient.” 

Absorption Coefficient – a) A measurement of the absorptive characteristics 

of a material in comparison to air. b) A measure of the relative 

amount of sound energy absorbed by the material when a sound strikes its 

surface. 

ABU – Asia-Pacific Broadcasting Union. 

AC Bias – The alternating current, usually of frequency several times higher 

than the highest signal frequency, that is fed to a record head in addition 

to the signal current. AC bias serves to linearize the recoding process 

and is universally used in analog recording. Generally, a large AC bias is 

necessary to achieve maximum long-wavelength output and linearity, but a 

lower value of bias is required to obtain maximum short-wavelength output. 

The mechanism of AC bias can best be explained in terms of anhysteresis. 

AC Coefficient – Any DCT coefficient for which the frequency in one or 

both dimensions is non-zero. 

AC Coupled – a) AC coupling is a method of inputting a video signal to a 

circuit to remove any DC offset, or the overall voltage level that the video 

signal “rides” on. One way to find the signal is to remove the DC offset by 

AC coupling, and then do DC restoration to add a known DC offset (one 

that we selected). Another reason AC coupling is important is that it can 

remove harmful DC offsets. b) A connection that removes the constant 

voltage (DC component) on which the signal (AC component) is riding. 

Implemented by passing the signal through a capacitor. 

AC Erasure – See Erasure. 

AC-3 – Audio Coding algorithm number 3. An audio-coding technique used 

with ATSC. The audio compression scheme invented by Dolby Laboratories 

and specified for the ATSC Digital Television Standard. In the world of consumer 

equipment, it is called Dolby Digital. 

ACATS (Advisory Committee on Advanced Television Service) – A 

group comprised almost exclusively of presidents, chief executive officers,

and chairs of the boards of major broadcasting, CATV, consumer electronics, 

and entertainment production companies. It is currently supported by a 

planning subcommittee (with two advisory groups and six working parties), 

a systems subcommittee (with four working parties), and an implementation 

subcommittee (with two working parties). ACATS is an entity under the 

FCC, and is the approving body of advanced TV in the USA., ACATS recommended 

the ATSC digital TV system to the FCC in November 1995. 

ACC – See Automatic Color Correction. 

Acceleration – Graphic accelerators function like application-specific 

microprocessors whose purpose is to work in conjunction with a PC’s host 

microprocessor to display graphics. In general, graphic accelerators control 

frame memory, color processing, resolution, and display speed. With the 

advent of the high-speed local buses and higher clock rates, accelerators 

operate on 32-, 64-, and 128-bit pixel data. 

Access Time – a) The time required to receive valid data from a memory 

device following a read signal. b) This is the time it takes from when a disk 

command is sent until the disk reaches the data sector requested. Access 

time is a combination of latency, seek time, and the time it takes for the 

command to be issued. Access time is important in data intensive situations 

like hard disk recording, multimedia playback, and digital video applications. 

Lower access times are better. Keeping your drives in good shape 

with periodic de-fragging, etc. will ensure that your drive is providing the 

fastest access times it can. 

Access Unit (AU) – a) The coded data for a picture or block of sound and 

any stuffing (null values) that follows it. b) A coded representation of a 

presentation unit. In the case of audio, an access unit is the coded representation 

of an audio frame. In the case of video, an access unit includes 

all the coded data for a picture, and any stuffing that follows it, up to but 

not including the start of the next access unit. If a picture is not preceded 

by a group_start_code or a sequence_header_code, the access unit 

begins with a picture_start_code. If a picture is preceded by a 

group_start_code and/or a sequence_header_code, the access unit begins 

with the first byte of the first of these start codes. If it is the last picture 

preceding a sequence_end_code in the bit stream, all bytes between the 

last byte of the coded picture and the sequence_end_code (including the 

sequence_end_code) belong to the access unit. 

Account – See Login Account. 

Accumulator – One or more registers associated with the Arithmetic and 

Logic Unit (ALU), which temporarily store sums and other arithmetical and 

logical results of the ALU. 

Accuracy – The closeness of the indicated value to the true value. 

ACD/ACD – Application Control Data/Application Communication Data. 

Acicular – Needle-shaped, used to describe the shape of oxide particles. 

ACLE (Analog Component Link Equipment) – A form of MAC optimized 

for remote broadcasting links. 

Acoustic Echo Canceller – Full-duplex audio technology; used for the 

elimination of acoustically-coupled return echoes within a teleconference 

room. Note that all microphones connected to an AEC are active at all 

times. Consequently, as more microphones are added, the total transmitted 



noise level (caused by picking up room ambient noise) increases. See also 

Tail Time, Echo Suppresser, and Echo Return Loss Enhancement. 

Acoustic Shadow – An area in which sound waves are attenuated due to 

the presence of an acoustic absorber or reflector in the path of the sound 

waves. 

Acoustic Suspension – A type of speaker design using a sealed cabinet. 

Primarily used for low frequency enclosures, acoustic suspension designs 

use the air mass within the cabinet as a “spring” to help return the relatively 

massive speaker to the rest position. This allows heavier, longer 

throw drivers to be used, but results in a less efficient design requiring 

more amplifier power. 

ACT (Anti-Comet-Tail) – A complex technique of preventing picture highlights 

from “comet-tailing” due to lack of beam current in the camera tube. 

(The usually colored trail behind a moving, very bright light/reflection in a 

picture is called a “comet-tail” since the effect looks similar to an astronomical 

comet.) The technique involves a special tube and circuitry to drive 

it. Basically, the charge due to a very bright object is never allowed to build 

up to an unmanageable level by discharging the target above a preset level 

during horizontal retrace time when the ACT action is turned on, with an 

increased beam current. 

Active Lines – The total number of scanning lines minus those scanning 

lines devoted to the vertical blanking interval. 

Active Line Time – The duration of a scanning line minus that period 

devoted to the horizontal blanking interval. 

Active Picture – That portion of the ITU-R BT.601 digital picture signal 

between the SAV and EAV data words. 

Active Picture Area – The part of a TV picture that contains actual picture 

as opposed to sync or other data. Vertically, the active picture area is 

487 lines for NTSC and 576 lines for PAL. The inactive area is called 

blanking. 

Active Video – The part of the video waveform that is not specified to be 

blanking, burst, or sync information. Most of the active video, if not all of it, 

is visible on the display screen. 

Active Window – On a PC, the only window that recognizes input (activity) 

from the keyboard and mouse; only one window is active at a time. 

ActiveMovie – Microsoft’s architecture for the control and processing of 

streams of multimedia data and software that uses this architecture to play 

digital video and sound. It is intended to supersede Video for Windows. 

ACTV (Advanced Compatible Television) – Techniques for ATV transmission 

developed by the DSRC, with support initially from NBC and 

RCA/GE Consumer Electronics (now Thomson Consumer Electronics) and 

with later support from such organizations as ABC and HBO. There are two 

ACTVs. a) ACTV I is a channel-compatible, receiver-compatible system 

using many different techniques to add widescreen panels and increase 

horizontal and vertical resolution. Among the techniques are the filling of a 

Fukinuki hole, time compression, seam-elimination, spatio-temporal filtering, 

and quadrature modulation of the picture carrier. The last prevents 

direct compatibility with videotape recorders and with ordinary satellite 

transmission techniques. b) ACTV II is ACTV I plus an augmentation channel 

to improve resolution and sound. 




Acuity – See Visual Acuity. 

Adaptation – Visual process whereby approximate compensation is made 

for changes in the luminances and colors of stimuli, especially in the case 

of changes in illuminants. 

Adaptation Field – Ancillary program data (especially PCR) which are 

uncoded and are transmitted at least every 100 ms after the TS header of 

a data stream (PID) belonging to a program. 

Adapter – A device used to achieve compatibility between two items of 

audio/video equipment. 

Adaption Field – Ancillary program data, especially program clock reference 

(PCR), which are uncoded and are transmitted at least every 100 ms 

after the TS header of a data stream (packet information, PID) belonging to 

a program. 

Adaptive – Changing according to conditions. 

Adaptive Bit Allocation – The allocation of more bits to image areas of 

high activity which does not lend itself to all types of video compression 

techniques, especially when interframe sampling is used. 

Adaptive Differential Pulse Code Modulation – a) A compression technique 

that encodes the predictive residual instead of the original waveform 

signal so that the compression efficiency is improved by a predictive gain. 

Rather than transmitting PCM samples directly, the difference between the 

estimate of the next sample and the actual sample is transmitted. This difference 

is usually small and can thus be encoded in fewer bits than the 

sample itself. b) Differential pulse code modulation that also uses adaptive 

quantizing; an audio coding algorithm which provides a modest degree of 

compression together with good quality. c) A technique for compressing 

the transmission requirements of digital signals. ADPCM has been used by 

ABC between New York and Washington to allow NTSC transmission on a 

45 Mbps (DS3) telephone company data transmission circuit. d) A pulse 

code modulation system typically operating at a high sampling rate whereby 

coding is based on a prior knowledge of the signal to be processed (i.e., 

greater than, equal to, or less than the previous sample). The system is 

adaptive in that digital bits of code signify different sizes of signal change 

depending on the magnitude of the signal. 

Adaptive Emphasis – An ATV technique for improving detail of dark parts 

of the picture by increasing their level. If a complementary de-emphasis is 

performed at the receiver, noise can be reduced. Dolby B noise reduction 

(the form of Dolby noise reduction most common in consumer cassette 

recorders) is a classic example of complementary adaptive emphasis. 

Adaptor – A device that allows an ordinary NTSC television to receive pictures 

from a non-receiver-compatible ATV system. 

ADC – See A-to-D Converter. 

Added Calibrator – A feature of some waveform monitors which allows 

an internal 1-volt calibrator signal to be used as a reference for amplitude 

measurements. 

Adder – Device that forms, as output, the sum of two or more numbers 

presented as inputs. 

Additive – Any material in the coating of magnetic tape other than the 

oxide and the binder resins; for example, plasticizers (materials used to 


soften an otherwise hard or brittle binder), lubricants (materials used to 

lower the coefficient of friction of an otherwise high-friction binder), fungicides 

(materials used to prevent fungus growth), dispersants (to uniformly 

distribute the oxide particles), or dyes. 

Additive Color System – Color specification system in which primary colors 

are added together to create a desired color. An example is the 

red/green/blue (RGB) system. Additive systems are generally associated 

with light emitting devices (CRTs). 

Additive Mix – A mix wherein the instantaneous video output signal is 

equal to the weighted sum of the input video signals. Unless otherwise 

specified, “mix” is taken to mean “additive mix.” 

Address – Number that indicates the position of a word in the memory. 

Address Bus – Set of wires (typically 32) used to transmit addresses, 

usually from the microprocessor to a memory or I/O device. 

Address Decoding – Process of selecting a specific address or field of 

addresses to enable unique devices. 

Address Dial – See SCSI Address Dial. 

Addressing Modes – Various methods of specifying an address as part of 

an instruction. See Direct Addressing, Indirect Addressing, Immediate 

Addressing and Indexed Addressing. 

Adhesion – The degree to which the coating adheres to the base film. 

Anchorage may be checked by measuring the force required to separate 

the coating from the base film by means of a specially designed plow blade 

or, more simply, by determining whether the coating can be peeled from 

the base film by means of ordinary pressure-sensitive adhesive tape. 

Adjacent Channel – A television transmission channel immediately adjacent 

to an existing channel. For example, channel 3 is adjacent to channels 

2 and 4. There are three exceptions to what might otherwise be considered 

adjacent channels: there is a small gap between channels 4 and 5, there is 

a large gap between channels 6 and 7, and there is an enormous gap 

between channels 13 and 14. Adjacent channels figure into ATV in two 

ways. a) First, it is currently illegal to broadcast on adjacent channels in a 

single location. Some ATV proponents feel that augmentation channels 

might someday be allowed to be placed in adjacent channels. If half-size 

(3 MHz) or smaller augmentation channels are used, all current broadcasters 

could then be allowed an augmentation channel. Some proponents feel 

the use of a low-power digital augmentation channel will allow adjacent 

channels to be used without interference. b) Second, some ATV proposals 

require that the augmentation channel be adjacent to the transmission 

channel or require a larger than normal transmission channel, thus occupying 

a channel and one of its adjacent channels. 

Administrator – See System Administrator and Network Administrator. 

ADPCM – See Adaptive Differential Pulse Code Modulation. 

ADSL – See Asymmetrical Digital Subscriber Line. 

ADSR (Attack, Decay, Sustain and Release) – These are the four 

parameters found on a basic synthesizer envelope generator. An envelope 

generator is sometimes called a transient generator and is traditionally 

used to control the loudness envelope of sounds, though some modern 

designs allow for far greater flexibility. The Attack, Decay, and Release

parameters are rate or time controls. Sustain is a level control. When a key 

is pressed, the envelope generator will begin to rise to its full level at the 

rate set by the attack parameter; upon reaching peak level it will begin to 

fall at the rate set by the decay parameters to the level set by the sustain 

control. The envelope will remain at the sustain level as long a the key is 

held down. Whenever a key is released, it will return to zero at the rate set 

by the release parameters. 

ADTV (Advanced Definition Television) – A term sometimes used for 

both EDTV and HDTV. 

Advanced Encoder – A device that changes RGB or DAV into NTSE using 

some form or forms of pre-filtering to reduce or eliminate NTSC artifacts. 

Some advanced encoders also offer image enhancement, gamma correction, 

and the like. 

Advanced Television Systems Committee (ATSC) – The US-based 

organization that is defining the high definition television standard for the 

United States. A sort of NTSE for ATV. It is comprised of three technology 

groups and a number of smaller committees. T1 Group is studying receiver-compatible 

improved NTSC. T2 Group is studying non-receiver-compatible 

525 scanning line production, distribution, and display systems. T3 

Group is studying HDTV. 

Advanced TV – Although sometimes used interchangeably, advanced and 

high-definition television (HDTV) are not one and the same. Advanced television 

(ATV) would distribute wide-screen television signals with resolution 

substantially better than current systems. It requires changes to current 

emission regulations, including transmission standards. In addition, ATV 

would offer at least two-channel, CD-quality audio. 

AEA (American Electronics Association) – An organization of manufacturers 

more associated with computers and communications than is the 

EIA. The AEA has established an ATV Task Force, the members of which 

include: AT&T, Apple Computer, Hewlett-Packard, IBM, and Motorola. 

AEC – See Acoustic Echo Canceller. 

AES (Audio Engineering Society) – The official association of technical 

personnel, scientists, engineers, and executives in the audio field. Of 

potential interest in electronic production are the following: SC-2, 

Subcommittee on Digital Audio; SC-3, Subcommittee on the Preservation 

and Restoration of Audio Recording; and SC4, Subcommittee on Acoustics. 

AES/EBU – a) Informal name for a digital audio standard established jointly 

by the Audio Engineering Society and European Broadcasting Union 

organizations. b) The serial transmission format standardized for professional 

digital audio signals (AES3-1992 AES Recommended Practice for 

Digital Audio Engineering – Serial Transmission Format for Two-Channel 

Linearly Represented Digital Audio Data). c) A specification using time-division 

multiplex for data, and balanced line drivers to transmit two channels 

of digital audio data on a single twisted-pair cable using 3-pin (XLR) connectors. 

Peak-to-peak values are between 3 and 1-V with driver and cable 

impedance specified as 110 ohms. 

AES/EBU Digital Audio – Specification titled “AES recommended practice 

for digital audio engineering – Serial transmission format for two channel 

linearity represented digital audio data.” AES/EBU digital audio standard 

that is the result of cooperation between the US based AES and the 

European based EBU. 



AES3 – See AES/EBU Digital Audio. 

AF – See Adaptation Field. 

AFC – See Automatic Frequency Control. 

AFC/Direct – See Waveform Monitors. 

AFI – Authority and Format Identifier. 

AFL (After Fade Listen) – Used in mixing boards to override the normal 

monitoring path in order to monitor a specific signal at a predefined point 

in the mixer. Unlike PFL, the AFL signal definition is taken after the fader of 

a channel or group buss such that the level of the fader will affect the level 

heard in the AFL monitor circuit. AFL is sometimes also taken after the pan 

pot which also allows the engineer to monitor the signal with the pan position 

as it is in the mix. AFL is a handy way to monitor a small group of 

related instruments by themselves with all of their eq, level, and pan information 

reproduced as it is in the overall mix. An AFL circuit that includes 

pan information is often called “solo” or “solo in place” depending upon 

who builds the mixer. 

AFNOR (Association Francaise de Normalisation) – French standards 

body. 

A-Frame Edit – A video edit which starts on the first frame of the 5 video 

frame (4 film frame) sequence created when 24-frame film is transferred 

to 30 frame. The A-frame is the only frame in the sequence where a film 

frame is completely reproduced on one complete video frame. Here is the 

full sequence. (The letters correspond to the film frames.) A-frame = video 

fields 1&2, B-frame = video fields 1&2&1, C-frame = video fields 2&1, 

D-frame = video fields 2&1&2. 

Aftertouch – MIDI data sent when pressure is applied to a keyboard after 

the key has been struck, and while it is being held down or sustained. 

Aftertouch is often routed to control vibrato, volume, and other parameters. 

There are two types: the most common is Channel Aftertouch which looks 

at the keys being held, and transmits only the highest aftertouch value 

among them. Less common is Polyphonic Aftertouch, which allows each 

key being held to transmit a separate, independent aftertouch value. While 

polyphonic aftertouch can be extremely expressive, it can also be difficult 

for the unskilled to control, and can result in the transmission of a great 

deal of unnecessary MIDI data, eating bandwidth and slowing MIDI 

response time. 

AFV – See Audio Follow Video. 

AGC – See Automatic Gain Control. 

AI – Amplitude Imbalance. 

AIFF – See Audio Interchange File Format. 

Air Tally – The ability of a switcher console to indicate to an operator 

which video sources and keys are on-air at any given time. Ampex switchers 

have “true” air tally in that they sense actual presence of sources. 

ALC – See Automatic Level Control. 

Algorithm – a) A set of rules or processes for solving a problem in a finite 

number of steps. In audio, video, and data coding, the step-by-step procedure 

(often including repetition) which provides suitable compression 

and/or encryption for the specific application. When used for compression, 

this mathematical process results in a significant reduction in the number 




of bits required for transmission and may be either lossless or lossy. 

b) Step-by-step procedure for the solution to a problem. First the problem 

is stated and then an algorithm is devised for its solution. 

Alias, Aliasing – Something other that what it appears to be. Stairsteps 

on what should be a smooth diagonal line are an example of spatial alias. 

Wagon wheels appearing to move backwards are an example of temporal 

alias. Aliases are caused by sampling and can be reduced or eliminated by 

pre-filtering, which can appear to be a blurring effect. Defects in the picture 

typically caused by insufficient sampling (violation of the Nyquist sampling 

rate) in the analog-to-digital conversion process or poor filtering of 

digital video. Defects are typically seen as jaggies on diagonal lines and 

twinkling or brightening in picture detail. Examples are: Temporal Aliasing – 

such as rotating wagon wheel spokes appearing to rotate in the reverse 

direction. Raster Scan Aliasing – such as sparkling or pulsing effects in 

sharp horizontal lines. Stair-Stepping – stepped or jagged edges in diagonal 

lines or the diagonal parts of a letter. 

Alignment – Most commonly, Head Alignment, but also used to describe 

the process of adjusting a recorder’s Bias and Equalization for optimum 

results from a specific tape. 

Alpha – See Alpha Channel and Alpha Mix. 

Alpha Channel – The alpha channel is used to specify an alpha value for 

each color pixel. The alpha value is used to control the blending, on a 

pixel-by-pixel basis, of two images. Alpha typically has a normalized value 

of 0 to 1. In a computer environment, the alpha values can be stored in 

additional bit planes of frame-buffer memory. When you hear about 32-bit 

frame buffers, what this really means is that there are 24 bits of color, 8 

each for red, green, and blue, along with an 8-bit alpha channel. Also see 

Alpha Mix. 

new pixel = (alpha) (pixel A color) + 1 – alpha (pixel B color) 

Alpha Mix – A way of combining two images. How the mixing is performed 

is provided by the alpha channel. The little box that appears over 

the left-hand shoulder of a news anchor is put there by an alpha mixer. 

Wherever the pixels of the little box appear in the frame buffer, an alpha 

number of “1” is put in the alpha channel. Wherever they don’t appear, an 

alpha number of “0” is placed. When the alpha mixer sees a “1” coming 

from the alpha channel, it displays the little box. Whenever it sees a “0,” it 

displays the news anchor. Of course, it doesn’t matter if a “1” or a “0” is 

used, but you get the point. 

Alphanumeric – Set of all alphabetic and numeric characters. 

ALU – See Arithmetic and Logic Unit. 

AM – A form of modulation where the level of the baseband information 

affects the level of the carrier. See Amplitude Modulation. 

A-MAC – A MAC (Multiplexed Analog Component) with audio and data frequency 

multiplexed before modulation. See also MAC. 

Ambient Lighting – Light that emanates from no particular source, coming 

from all directions with equal intensity. 

Ambient Sound – A representative sample of background audio (such as 

a refrigerator hum or crowd murmur) particular to a shooting location. 

Ambient sound is gathered in the course of a production to aid the sound 


editor in making cuts or filling in spaces between dialog. Also called Room 

Tone. 

American Television and Communications – See ATC. 

A-Mode Edit – An editing method where the footage is assembled in the 

final scene order. Scene 1, scene 2, etc. 

Amplitude – The height of a waveform above or below the zero line. 

Amplitude Modulation – a) The process used for some radio (AM broadcast, 

in North American audio service broadcast over 535 kHz-1705 kHz) 

and television video transmission. A low-frequency (program) signal modulates 

(changes) the amplitude of a high-frequency RF carrier signal (causing 

it to deviate from its nominal base amplitude). The original program 

signal is recovered (demodulated) at the receiver. This system is extensively 

used in broadcast radio transmission because it is less prone to signal 

interference and retains most of the original signal quality. In video, FM is 

used in order to record high quality signals on videotape. b) The process 

by which the amplitude of a high-frequency carrier is varied in proportion 

to the signal of interest. In the PAL television system, AM is used to encode 

the color information and to transmit the picture. Several different forms of 

AM are differentiated by various methods of sideband filtering and carrier 

suppression. Double sideband suppressed carrier is used to encode the 

PAL color information, while the signal is transmitted with a large-carrier 

vestigial sideband scheme. 

Amplitude Non-Uniformity – A term used in connection with magnetic 

tape testing and refers to the reproduced peak-to-peak voltage and its 

variation from what was recorded. 

Amplitude Versus Frequency Response – Refer to the Frequency 

Response discussion. 

AM-VSB (Amplitude Modulation with Vestigial Sideband) – The form 

of modulation used in broadcast and cable television transmission. It is 

more efficient than dual-sideband amplitude modulation and is easier to 

implement than single-sideband amplitude modulation. 

Analog – a) A continuous electrical signal that carries information in the 

form of variable physical values, such as amplitude or frequency modulation. 

b) A signal which moves through a continuous range of settings or 

levels. c) An adjective describing any signal that varies continuously as 

opposed to a digital signal that contains discrete levels representing the 

binary digits 0 and 1. d) A signal that is an analogy of a physical process 

and is continuously variable, rather than discrete. See also Digitization. 

Analog Components – Video signals in which a continuously variable 

voltage or current (rather than a set of digital numbers) represents a pixel. 

Analog Interface – An interface between a display controller and a display 

in which pixel colors are determined by the voltage levels on three 

output lines (RGB). Theoretically, an unlimited number of colors can be supported 

by this method (24 bits per pixel allows 16,777,216 colors). The 

voltage level on any line varies between zero volts (for black) to about 700 

millivolts (for maximum brightness). 

Analog Monitor – A video monitor which accepts analog signals. Several 

types of inputs are accepted by analog monitors: composite video, RGB & 

sync, Y/C, YUV and any combination of these formats. The signals transmit-

ted to an analog monitor are usually between 0 and 1 V and use 75-ohm 

coaxial cables. 

Analog Recording – The common form of magnetic recording where the 

recorded waveform signal maintains the shape of the original waveform 

signal. 

Anamorphic Squeeze – A change in picture geometry to compress one 

direction (usually horizontal) more than the other. Anamorphic squeeze 

lenses made CinemaScope possible. Occasionally, when widescreen movies 

are transferred to video, an anamorphic squeeze will be used (usually only 

in credits) to allow the smaller aspect ratio of television to accommodate 

the larger movie aspect ratio. Some ATV proponents have suggested a gentle 

anamorphic squeeze as a technique to assist in aspect ratio accommodation. 

Anamorphic Video – Found on a large number of DVDs, anamorphic 

video squeezes a 1.78:1 picture shape into a 1.33:1 image area. If you 

view an anamorphic video image on a 1.33 set, the characters will look tall 

and thin. This format is designed for the 1.78 aspect ratio TV sets where 

the horizontal is stretched back out to the full width of the set. 

Unsqueezing an anamorphic image on a 1.33 set is accomplished by 

squeezing the vertical size. The advantage of the anamorphic video system 

is 33% more vertical information in a widescreen picture. 

Anchor Frame – A video frame that is used for prediction. I-frames and 

P-frames are generally used as anchor frames, but B-frames are never 

anchor frames. 

Anchor Point – A bit-stream location that serves as a random access 

point. MPEG I-frames are the most common anchor points. 

Anchorage – For recording tape, the degree to which the magnetic tape 

oxide coating adheres to the base film. 

Anechoic – Literally, without echoes. Anechoic refers to the absence of 

audio reflections. The closest thing to this situation in nature is the great 

outdoors, but even here there are reflections from the ground, various 

objects, etc. It is almost impossible to create a truly anechoic environment, 

as there is no such thing as a perfect sound absorber. At high frequencies, 

it is possible to create near-anechoic conditions, but the lower the frequency, 

the harder that is. 

Anechoic Chamber – A room which has totally sound absorbent walls, so 

that no reflected waves can exist and only the direct waves are heard. 

Anhysteresis – The process whereby a material is magnetized by applying 

a unidirectional field upon which is superimposed an alternating field of 

gradually decreasing amplitude. One form of this process is analogous to 

the recoding process using AC Bias. 

Animation – Animation is the process of fooling the human eye into perceiving 

a moving object by presenting the eye with a rapid succession of 

still pictures. Each still is called a frame. On the Cubicomp, animation consists 

of moving objects which, in themselves, stay unchanged. 

Animation Path – The motion of an object as it flies through space is 

called its animation or motion path. 

Anisotropy – Directional dependence of magnetic properties, leading to 

the existence of easy or preferred directions of magnetization. Anisotropy of 

a particle may be related to its shape, to its crystalline structure, or to the 



existence of strains within it. Shape anisotropy is the dominant form in acicular 

particles. 

ANRS, Super ANRS – A noise-reduction system used by JVC. ANRS operates 

on principles similar to those used by the Dolby system. Therefore, 

there is a degree of compatibility between recordings made with either 

system. 

ANSI (American National Standards Institute) – ANSI is a voluntary 

and privately funded business standards group in the USA. ANSI seeks to 

promote and to facilitate consensus standards nationally, and is internationally 

engaged as the sole US member of the ISO. The members of ANSI 

consist of about 1,300 American and international companies, 30 government 

agencies and some 250 organizations of trade, labor, professionals, 

consumers, etc. 

ANSI 4.40 – See AES/EBU Digital Audio. 

Anti-Alias Filter – A filter (typically a lowpass filter) used to bandwidthlimit 

the signal to less than half the sampling rate before sampling. 

Anti-Aliased Fonts – Computer-generated fonts that have been digitally 

rounded for smooth edges. 

Anti-Aliasing – The process of reducing aliasing effects. Aliasing occurs 

because a raster system is “discrete,” i.e., made up of pixels that have 

finite size. Representing a line with black and white pixels results in “jaggies,” 

or “aliases.” These are particularly disturbing during animation. To 

correct them, “anti-aliasing” techniques are used. These tech 

AM-VSB (Amplitude Modulation with Vestigial Sideband) – The form of 

modulation used in broadcast and cable television transmission. It is more 

efficient than dual-sideband amplitude modulation and is easier to implement 

than single-sideband amplitude modulation. 

AOE – Applications and Operational Environments. 

A-Only Edit – Audio-Only Edit. 

AP – See Active Picture. 

Aperture – a) An adjustable opening in a lens which, like the iris in the 

human eye, controls the amount of light entering a camera. The size of the 

aperture is controlled by the iris adjustment and is measured in f-stops. A 

smaller f-stop number corresponds to a larger opening that passes more 

light. b) As applied to ATV, the finite size and shape of the point of the 

electron beam in a camera or picture tube. As the beam does not come to 

an infinitesimal point, it affects the area around it, reducing resolution. 

Aperture Correction – a) Signal processing that compensates for a loss 

of detail caused by the aperture. It is a form of image enhancement adding 

artificial sharpness and has been used for many years. b) Electrical compensation 

for the distortion introduced by the (limiting) size of a scanning 

aperture. c) The properties of the camera lens, optical beam-splitting 

installation, and camera tube all contribute to a reduced signal at higher 

spatial frequencies generally falling off as an approximate (sin x)/X function. 

Additionally, it is obvious in a scanning system that the frequency 

response falls off as the effective wavelength of the detail to be resolved in 

the image approaches the dimension of the scanning aperture and 

becomes zero when the effective wavelength equals the dimension of the 

scanning aperture. Aperture correction normally introduced in all video 

cameras restores the depth of modulation to the waveform at higher fre- 




quencies with the objective of flat response to 400 TV lines (in NTSC) for a 

subjective improvement in image quality. 

Aperture Delay – In ADCs, aperture delay is the time from an edge of the 

input clock of the ADC until the time the part actually takes the sample. 

The smaller this number, the better. 

Aperture Jitter – The uncertainty in the aperture delay. This means the 

aperture delay time changes a little bit over time, and that little bit of 

change is the aperture jitter. 

Aperture, Camera – The available maximum dimensions of the optical 

image on the active surface of the photo-sensor, within which good quality 

image information is being recorded. The camera aperture determines the 

maximum usable scene information captured and introduced into the system, 

and available for subsequent processing and display. These dimensions 

are usually defined by standards. (Note: Not to be confused with lens 

aperture, which defines the luminous flux transmission of the optical path.) 

Aperture, Clean – The concept of a clean aperture in a digital system 

defines an inner picture area (within the production aperture) within which 

the picture information is subjectively uncontaminated by all edge transient 

distortions (SMPTE 260M). Filtrations for bandwidth limitation, multiple digital 

blanking, cascaded spatial filtering, etc., introduce transient disturbances 

at the picture boundaries, both horizontally and vertically. It is not 

possible to impose any bounds on the number of cascaded digital processes 

that might be encountered in the practical post-production system. 

Hence, the clean aperture is defined to represent an acceptable (and practical) 

worst-case level of production. 

Aperture, Display – The available maximum dimensions (mapped back 

into the camera aperture) for the system's ability to display good quality 

image information. The information available for display is usually cropped 

from the total captured by the cascade of tolerances that may be incorporated 

in the system, and also by intentional design features that may be 

introduced in the display. 

Aperture, Production – A production aperture for a studio digital device 

defines an active picture area produced by signal sources such as cameras, 

telecines, digital video tape recorders, and computer-generated pictures. 

It is recommended that all of this video information be carefully produced, 

stored, and properly processed by subsequent digital equipment. In 

particular, digital blanking in all studio equipment should rigorously conform 

to this specified production aperture (SMPTE 260M). The width of the 

analog active horizontal line is measured at the 50% points of the analog 

video signal. However, the analog blanking may differ from equipment to 

equipment, and the digital blanking may not always coincide with the analog 

blanking. 

Aperture, Safe Action – As defined by a test pattern, a safe action aperture 

indicates the safe action image area within which all significant action 

must take place, and the safe title image area, within which the most 

important information must be confined, to ensure visibility of the information 

on the majority of home television receivers. SMPTE RP 27.3 defines 

these areas for 35 mm and 16 mm film and for 2x2-inch slides. 

API (Application Program Interface) – a) The software used within an 

application program to activate various functions and services performed 

by the operating system. b) The Windows operating system refers to API 


functions as those which open and close windows, interpret mouse movement, 

read the keyboard, etc. These control-type functions are called 

"hooks" to the operating system. 

APL (Average Picture Level) – The average signal level (with respect to 

blanking) during active picture time, expressed as a percentage of the difference 

between the blanking and reference white levels. 

Application – An application runs in a module, communicating with the 

host, and provides facilities to the user over and above those provided 

directly by the host. An application may process the transport stream. 

Application Window – The workspace (window) available to an application. 

The size can be adjusted by the user and limited only by the size of 

the monitor's display. 

APS (Advanced Photo System) – A new photographic system conceived 

by Kodak and developed jointly with Canon, Fuji, Minolta, and Nikon. The 

APS was launched in April 1996. APS also represents the file format used 

to store data on the new film's magnetic coating. 

Apt-X100 – The apt-X100 is a proprietary audio compression algorithm 

from APT, Ltd., which features an adaptive differential PCM (ADPCM) algorithm 

in four sub-bands. The algorithm provides a fixed 4:1 compression 

with low delay and bandwidths ranging from 7.5 kHz to 22.5 kHz and output 

bit rates from 64 to 384 kbit/s, depending on the sampling rate. 

APU (Audio Presentation Unit 13818-1) – A 13818-1 audio frame. 

Architecture – Logical structure of a computer system. 

Archive – a) Off-line storage of video/audio onto backup tapes, floppy 

disks, optical disks, etc. b) A collection of several files bundled into one file 

by a program (such as ar, tar, bar, or cpio) for shipment or archiving. This 

method is very reliable and can contain large amounts of data. 

Arithmetic and Logic Unit (ALU) – One of three essential components of 

a microprocessor. The other two are the registers and the control block. 

The ALU performs various forms of addition, subtraction, and logic operations, 

such as ANDing the contents of two registers or masking the contents 

of a register. 

Arithmetic Coding – Perhaps the major drawback to each of the Huffman 

encoding techniques is their poor performance when processing texts 

where one symbol has a probability of occurrence approaching unity. 

Although the entropy associated with such symbols is extremely low, each 

symbol must still be encoded as a discrete value. Arithmetic coding 

removes this restriction by representing messages as intervals of the real 

numbers between 0 and 1. Initially, the range of values for coding a text is 

the entire interval (0, 1). As encoding proceeds, this range narrows while 

the number of bits required to represent it expands. Frequently occurring 

characters reduce the range less than characters occurring infrequently, 

and thus add fewer bits to the length of an encoded message. 

ARP – Address Resolution Protocol. 

ARS – See Automatic Route Selection. 

Artifacts – a) Artifacts can range from noise and snow, to spots. Anything 

that is visually wrong with the picture is an artifact. Artifacts however do 

not include picture errors caused by improperly adjusted displays. Artifacts 

are visual errors caused by the signal being sent to the display. b) A defect

or distortion of the image, introduced along the sequence from origination 

and image capture to final display. Artifacts may arise from the overload of 

channel capacity by excess signal bandwidth. Artifacts may also result 

from: sampling effects in temporal, spatial, or frequency domains; processing 

by the transfer functions; compromises any inadequacies in the system 

employed; cascading of minor defects; basically any other departure of the 

total system from “complete transparency.” c) Visible (or audible) consequences 

of various television processes. Artifacts are usually referred to 

only when they are considered defects. Artifact elimination is often more 

apparent than quality increases such as resolution enhancement. 

d) Interference or other unwanted “noise” in video such as flickering, 

changes in color, and macroblocking. Some artifacts, such as macroblocking, 

can be remedied in video compression and some cannot. The quality 

of the finished product is, in large part, no better than the source material. 

See also Filter Artifacts, Impairments, and NTSC Artifacts. 

ASCII (American Standard Code for Information Interchange) – 

a) Character code used for representing information as binary data in most 

computer systems. b) A standard code for transmitting data, consisting of 

128 letters, numerals, symbols, and special codes, each of which is represented 

by a unique binary number. 

ASI – Asynchronous Serial Interface. 

ASIC (Application Specific Integrated Circuit) – An integrated circuit 

designed for special, rather than general, applications. 

ASN.1 – Abstract Syntax Notation 1. 

ASPEC (Adaptive Spectral Perceptual Entrophy Coding) – An algorithm 

developed by Fraunhofer Institut, AT&T, Thomas Brandt, and the 

CNET. The ASPEC algorithm was later used for developing the MPEG audio 

Layer 3 specification. 

Aspect Ratio – The ratio of the width of the picture to the height. For 

most current TVs, this ratio is 4:3. For HDTV, the ratio will be 16:9. The 

aspect ratio, along with the number of vertical scan lines that make up the 

image, determines what sample rate should be used to digitize the video 

signal. 



:1 :9 Description 

1.0 9 Square photographic formats, including Instamatic 126 

1.33 12 Existing television, old movies, Pocket Instamatic 110 

1.44 13 IMAX film 

1.5 13.5 35mm still photographs, proposed for theatrical release 

1.61 14.5 Faroudja HDTV proposal 

1.67 15 Original NHK proposal, theatrical projection outside the U.S. 

1.78 16 ATSC/SMPTE HDEP standard, optimized for shoot and protect 

1.85 17 Theatrical projection in the U.S. 

2.0 18 Most forms of VistaVision 

2.2 20 Some widescreen movie formats 

2.35 21 CinemaScope and similar movie formats 

2.6 23 Cinerama 

2.7 24 Dimension-150, Ultra-Panavision 

2.77 25 Dynavision widescreen 3D film format 

4.0 36 Polyvision 

Aspect Ratio Accommodation – Techniques by means of which something 

shot in one aspect ratio can be presented in another. The five currently 

used or proposed techniques are compared in the following table. It 

is also possible to combine techniques. Current ATV aspect ratio debates 

concentrate on the problems of presenting widescreen images to existing 

TV sets; the same problems (in an opposite direction) will occur when current 

aspect ratio images are presented on widescreen TV sets. In movie 

theaters, these problems are usually solved with movable drapes. 

Blanking Pan and Anamorphic Shoot and 

Adjust Truncation Scan Squeeze Protect 

Maintain 

Director’s 

Intent 

Y N N N Y 

Uses Full 

Screen 

(No Burn) 

N Y Y Y Y 

Displays All 

Action 

Y N N Y Y 

Maintains 

Picture 

Geometry 

Y Y Y N Y 

Automatic 

Conversion 

Possible 

Y Y N Y Y 

Full Production Y 

Freedom 

Y Y Y N 

Asperities – Small projecting imperfections on the surface of the tape 

coating that limit and cause variations in head-to-tape contact. 

Assembled Edit – Electronic edit that replaces all previously recorded 

material with new audio and video and a new control track, starting at the 




edit point. Inserting a new control track allows for a constant speed reference 

throughout the entire tape. 

Assembler Program – Translates assembly language statements 

(mnemonics) into machine language. 

Assembly Language – Machine-oriented language. A program is normally 

written as a series of statements using mnemonic symbols that suggest 

the definition of the instruction. It is then translated into machine language 

by an assembler program. 

ASVP – Application-Specific Virtual Prototype. 

Asymmetric Compression – Compression in which the encoding and 

decoding require different processing power (the encoding is normally 

more demanding). 

Asymmetrical Digital Subscriber Line – Bellcore’s term for one-way 

T-1 to the home over the plain old, single twisted pair wiring already going 

to homes. ADSL is designed to carry video to the home. ADSL, like ISDN, 

uses adaptive digital filtering, which is a way of adjusting itself to overcome 

noise and other problems on the line. According to Northern Telecom, 

initial ADSL field trails and business cases have focused on ADSL’s potential 

for video-on-demand service, in competition with cable pay-per-view 

and neighborhood video rental stores. But ADSL offers a wide range of 

other applications, including education and health care. Once telephone 

companies are able to deliver megabits to the home, Northern Telecom 

expects an explosion in potential applications including work-at-home 

access to corporate LANs, interactive services such as home shopping and 

home banking and even multi-party video gaming, interactive travelogues, 

and remote medical diagnosis. Multimedia retrieval will also become possible, 

enabling the home user to browse through libraries of text, audio, and 

image data – or simply subscribe to CD-quality music services. In the field 

of education, ADSL could make it possible to provide a low-cost “scholar’s 

workstation” – little more than a keyboard, mouse and screen – to every 

student, providing access to unlimited computer processing resources from 

their home. For a more modern version of ADSL, see DMT, which stands for 

Discrete Multi-Tone. 

Asynchronous – a) A transmission procedure that is not synchronized by 

a clock. b) Any circuit or system that is not synchronized by a common 

clock signal. 

Asynchronous Data Streaming – Streaming of data only without any 

timing requirements. See Asynchronous Data Streaming, Synchronous Data 

Streaming. 

Asynchronous Transfer Mode (ATM) – a) A digital transmission system 

using packets of 53 bytes for transmission. ATM may be used for LANs and 

WANs. ATM is a switching/transmission technique where data is transmitted 

in small, 53-byte fixed sized cells (5-byte header, 48-byte payload). The 

cells lend themselves both to the time-division-multiplexing characteristics 

of the transmission media, and the packet switching characteristics desired 

of data networks. At each switching node, the ATM header identifies a virtual 

path or virtual circuit that the cell contains data for, enabling the 

switch to forward the cell to the correct next-hop trunk. The virtual path is 

set up through the involved switches when two endpoints wish to communicate. 

This type of switching can be implemented in hardware, almost 

essential when trunk speeds range from 45 Mb/s to 1 Gb/s. The ATM 


Forum, a worldwide organization, aimed at promoting ATM within the 

industry and the end-user community was formed in October 1991 and 

currently includes more than 500 companies representing all sectors of the 

communications and computer industries, as well as a number of government 

agencies, research organizations, and users. b) A digital signal protocol 

for efficient transport of both constant-rate and bursty information in 

broadband digital networks. 

AT&T – Consumer electronics manufacturer and long-distance telephone, 

television, and data carrier. Its Bell Labs has worked on the development of 

ATV systems. 

ATC – Adaptive Transform Coding. 

ATC (American Television and Communications) – Time Inc.’s CATV 

multiple-system operator (MSO), a co-proposer with HBO of C-HDTV and a 

supporter of ACTV. 

ATEL – Advanced Television Evaluation Laboratory) 

A-Time (Absolute Time) – Elapsed time, referenced to the program start 

(00:00:00), on a DVD. A-time is measured in minutes, seconds, and 

frames. 

ATM – See Asynchronous Transfer Mode. 

A-to-D Converter (ADC) – a) A circuit that uses digital sampling to convert 

an analog signal into a digital representation of that signal. An ADC for 

digitizing video must be capable of sampling at 10 to 150 million samples 

per second (MSPS). b) Converts analog voltages and currents to the digital 

representation used by computer systems. This enables the computer to 

sense real-world signals. 

ATRAC (Adaptive Transform Acoustic Coding) – An algorithm that 

splits an audio signal into three non-uniform sub-bands. 

ATRP – Advanced Television Research Program. 

ATSC – See Advanced Television Systems Committee. 

Attack – In audio terms, the beginning of a sound. What type of attack a 

sound has is determined by how long it takes for the volume of the sound 

to go from silence to maximum level. It is critical to consider the attack 

time of sounds when applying processing Compression, gating, and other 

types of processors as they may destroy a sound’s attack, changing the 

character and quality of the audio. Reverbs can also be affected by attack 

time; careful use of a reverb’s predelay parameter will allow you to optimize 

the reverb for different types of attacks. 

ATTC (Advanced Television Test Center) – Created by seven broadcasting 

organizations to test different broadcast ATV systems. See also Cable Labs. 

ATT-C (AT&T Communications) – The Long distance arm of AT&T. 

Attenuation – A decrease in the level of a signal is referred to as attenuation. 

In some cases, this is unintentional, as in the attenuation caused by 

using wire for signal transmission. Attenuators (circuits which attenuate a 

signal) may also be used to lower the level of a signal in an audio system 

to prevent overload and distortion. 

ATV – See Advanced TV. 

AU – See Access Unit.

Audio – a) Signals consisting of frequencies corresponding to a normally 

audible sound wave ranging between the frequencies of 20 Hz to 20 kHz. 

b) A DC signal with varying amounts of ripple. It is sometimes possible to 

see the ripple on the DC signal to convey information of widely variable 

degrees of usefulness. c) The sound portion of a program. 

Audio Bandwidth – The range of audio frequencies which directly influence 

the fidelity of the audio. The higher the audio bandwidth, the better 

the audio fidelity. The highest practical frequency the human ear can normally 

hear is 20 kHz. An audio amplifier that processes all frequencies 

equally (flat response to 20 kHz) and a reasonably high signal-to-noise 

ratio, will accurately amplify the audio signal. 

Audio Breakaway (ABKW) – The ability to independently select audio 

sources regardless of which video source is selected, even though the 

audio is normally associated with a particular video (as opposed to follow). 

Audio Coding Mode – In general, this is often used to show an audio 

coding method such as linear PCM, AC-3, or MPEG audio, etc., but in some 

contexts it refers to the channel constitution in AC-3 tracks and the speaker 

layout. 

Audio Dub – Process which allows for the replacement of an audio signal 

on a previously recorded tape without disturbing the video signal. 

Audio Editing – Portions of the audio material are combined and recorded 

onto the videotape. Examples include creating a sound track that includes 

signals such as background music, voice narration, or sound effects. 

Audio Follow Video (AFV) – Audio selections made simultaneously upon 

selection of associated video sources (as opposed to audio breakaway). 

Audio Graphic Conferencing – AGC. 

Audio Levels – The level of the audio signal in either voltage or current. 

Audio levels are measured and indicated by mechanical VU-meters or electronic 

LED bar graph meters. It is important to maintain the proper audio 

level. If the audio level is too high when recording, overload of the input 

electronics and audio distortion will result. When audio levels are low, the 

signal-to-noise ratio is compromised. 

Audio Matrix – That portion of the switcher electronics used to switch 

audio sources. Usually this matrix is controlled by AFV selections on the 

primary matrix, ABKW selections on an aux audio bus, or by an external 

editor or computer control. 

Audio Mixer – A component that combines more than one sound input for 

composite output. 

Audio Mixing – The blending of two or more audio signals to generate a 

combined signal which is often used for audio dub. During video processing, 

audio mixing may be used to insert narration or background music. 

Audio Modulation – A carrier is modified with audio information and is 

mixed with the video information for transmission. 

Audio Modulation Decoders – Converts sound carrier elements of the 

video waveform into left and right audio channels for stereo monitoring. 

Audio Modulation Monitors – Displays sound carrier elements of the 

video waveform. 

Audio On ISDN – Through use of the MPEG audio specification, the ISDN 

(Integrated Services Digital Network) may be tuned into an audio transmis- 



sion media. Data compression techniques like MPEG Layer II allow a tailored 

mix of cost and quality, and are now thought of implicitly when talking 

audio on ISDN. 

Audio Signals – XLR connectors provide dual-channel audio signals. The 

left channel can be set to click as a means of easily distinguishing the left 

channel from the right channel in audio tests. 

Audio Subcarrier – A specific frequency that is modulated with audio 

data before being mixed with the video data and transmitted. 

Audio/Video Mixer – A single electronic component that consists of an 

audio mixer and a video mixer, switcher, or special effects generator. Also 

called an A/V Mixer. 

Audio-Follow-Video – During video recording or editing, the video signal 

is usually accompanied by its associated audio signal. While editing video, 

it is sometimes necessary to separate the audio and video signals. Audiofollow-video 

mixers allow the audio to, or not to, follow the video when 

switching video signals. 

Auditory Masking – Auditory masking is used in MPEG and Dolby Digital 

compression, and is coded based on the range of frequency that human 

ears can detect. 

Augmentation Channel – A transmission channel carrying information 

that can augment that being transmitted in an ordinary transmission channel 

such that a special television set that can receive both channels can 

get a better picture than those available from the main channel alone. 

Some ATV schemes require the augmentation channel to be adjacent to the 

main channel. Others can theoretically accept a non-adjacent augmentation 

channel, though, at the time of this writing, the acceptability of non-adjacent 

channels has not been proven to everyone’s satisfaction. 

Authoring – The encoding of material from various sources, all the conversion 

processes of the encoded data, incorporating the required control 

structures and other signals for playback sequences in the DVD-video format. 

The final product of authoring is a DLT tape with DVD image files in 

DDP format. 

Authoring Platform – Computer hardware and software used to create material 

for use on a multimedia system. The video quality of the authoring platform 

has to be high enough that the playback equipment is the limiting factor. 

Auto Assembly – a) Process of assembling an edited videotape on a 

computerized editing system under the control of an edit decision list 

(EDL). A computer automatically conforms source footage into an edited 

video program under the direction of a list of preprogrammed edit instructions. 

b) An edit in which an off-line edit decision list is loaded into an online 

edit computer and all the edits are assembled automatically with little 

or no human intervention. 

Automated Measurement Set – Device that automatically performs tests 

on audio and video signals and generates pass/fail results by testing the 

signals against predetermined parameters. 

Automatic – In recorders, refers to either electrical or mechanical automatic 

bias switching devices. 

Automatic Color Correction (ACC) – A circuit found in many consumer 

viewing devices that attempts to compensate for the “Never Twice the 

Same Color” broadcast problems. This circuit can go far beyond the Auto 




Tint function in that it changes color saturation as well as type of color. In 

most cases where ACC is present, it cannot be defeated. Adjusting the 

color and tint controls, using the SMPTE Color Bar pattern and the blue filter 

will result in a gross misadjustment of color level on the set. The color 

level may have to be reduced by as much as half the value calibrated with 

the SMPTE Color Bar pattern. 

Automatic Focus – A feature on most consumer and industrial video 

cameras and camcorders that automatically makes minor focal length 

adjustments, thus freeing the videographer from focusing concerns. 

Automatic Frequency Control (AFC) – Automatic frequency control. 

Commonly used to lock onto and track a desired frequency. 

Automatic Gain Control (AGC) – a) Circuitry used to ensure that output 

signals are maintained at constant levels in the face of widely varying input 

signal levels. AGC is typically used to maintain a constant video luminance 

level by boosting weak (low light) picture signals electronically. Some equipment 

includes gain controls that are switchable between automatic and 

manual control. b) Electronic circuitry that compensates for either audio or 

video input level changes by boosting or lowering incoming signals to match 

a preset level. Using AGC, changing input levels can output at a single constant 

setting. c) A feature on most video cameras and camcorders that, 

when engaged, boosts the signal to its optimum output level. Automatic gain 

control (AGC) is available for video, and less frequently audio use. 

Automatic Iris – A feature on most video cameras and camcorders that 

automatically creates the lens aperture that allows the imaging device to 

perform under optimum conditions. 

Automatic Level Control (ALC) – Circuitry used to automatically adjust 

the audio recording level to compensate for variations in input volume. 

Some equipment includes level controls that are switchable between automatic 

and manual control. 

Automatic Picture Stop – The disc player will automatically take the program 

from the play mode to a still frame mode according to information 

programmed in the vertical interval of the disc’s video. 

Automatic Route Selection – An important part of an automatic leastcost 

routing system. 

Automatic Shut-Off – A device (usually a mechanical switch) incorporated 

into most tape recorders that automatically stops the machine when the 

tape runs out or breaks. 


Auto-Pan – A feature exclusive to AVC series switchers causing a positioned 

pattern to center itself as it grows in size. 

Autotiming – Capability of some digital video equipment to automatically 

adjust input video timing to match a reference video input. Eliminates the 

need for manual timing adjustments. 

Auto-Transition – a) The ability to electronically simulate a fader motion 

over an operator-specified duration. b) An automatic transition where the 

motion of the switcher lever arm is electronically simulated when the AUTO 

TRANS pushbutton is pressed. The duration of the transition in television 

frames or seconds is indicated by the rate display LED. 

Auxiliary Bus – A bus which has the same video sources as the switcher 

but whose crosspoints may be remotely controlled, independently of the 

switcher console. 

Auxiliary Channel (AUX) – In a video editing system, a channel reserved 

for connection to an external audio and/or video device. 

AVI (Audio Video Interleaved) – The Video for Windows file format for 

digital video and audio. An AVI (.avi) file is a RIFF file format used with 

applications that capture, edit and playback audio/video sequences. AVI 

files contain multiple streams of different types of data. Most AVI 

sequences will use both audio and video data streams. Specialized AVI 

sequences might include control track as an additional data stream. See 

Video for Windows. 

A-Vision – An ATV system proponent. 

AWGN – Additive White Gaussian Noise. 

Axis – An imaginary line through the video image used as a reference 

point for rotation and movement. The three axes are H (horizontal), Y (vertical), 

and A (depth). 

Azimuth – The angle of a tape head’s recoding gap relative to the tape. 

Azimuth Alignment – Alignment of the recoding and reproducing gaps so 

that their center lines lie parallel with each other and at right angles to the 

direction of head/tape motion. Misalignment of the gaps causes a loss in 

output at short wavelengths. For example, using a track width of 50 mils, a 

misalignment of only 0.05 degrees will cause a 3 dB loss at a wavelength 

of 0.1 mil. 

Azimuth Loss – High frequency losses caused by head misalignment.

B 

B Bus – The bottom row of the two rows of video source select buttons 

associated with a given mixed effect (M/E). 

Baby Bell – A term commonly used for one of the seven regional holding 

companies established when AT&T divested itself of its local telephone 

companies. The Baby Bells are: American, Bell Atlantic, Bell South, Nynex, 

Pacific Telesis, Southwestern Bell, and US West. 

Back Focus – A physical repositioning of the CCD, the camera element 

that translates light into electronic pulses for recording on videotape. The 

effect is to lengthen or shorten the distance between the lens and the 

CCD. 

Back Haul – Long distance digital data transport service such as Sonet, 

SDH, or Telecos. 

Back Hauler – Company that provides back haul services. 

Back Light – A switch on some camcorders used to compensate exposure 

for situations where the brightest light is coming from behind the subject. 

This term is also used to refer to a light source that illuminates a subject 

from behind, used to separate the subject from the background and give 

them depth and dimension. 

Back Porch – a) The portion of the video signal that lies between the 

trailing edge of the horizontal sync pulse and the start of the active picture 

time. Burst is located on the back porch. b) The back porch of a horizontal 

synchronizing pulse is that area from the uppermost tip of the positivegoing 

right-hand edge of a sync pulse to the start of active video. The back 

porch of a color video sync pulse includes the 8 to 9 cycles of reference 

color burst. The back porch is at blanking level. 

Back Porch Tilt – The slope of the back porch from its normal horizontal 

position. Positive or negative refer respectively to upward or downward tilt 

to the right. 

Back Time – Calculation of a tape in-point by finding the out-point and 

subtracting the duration of the edit. 

Back Up – To copy a certain set of files and directories from your hard 

disk to a tape or other non-volatile storage media. 

Backcoating – A conductive additional coating used on the reverse side 

of magnetic tape to control mechanical handling and minimize static generation. 

Background – May be thought of as the deepest layer of video in a given 

picture. This video source is generally selected on a bus row, and buses 

are frequently referred to as the background source. 

Background Generator – A video generator that produces a solid-color 

output which can be adjusted for hue, chroma, and luminance using the 

controls in the MATTE/BKGD control group. 

Background Transition – A transition between signals selected on the 

Preset Background and Program Background buses, or between an “A” bus 

and “B” bus on an M/E. 

Background Video (BGD) – a) Video that forms a background scene into 

which a key may be inserted. Background video comes from the Preset 



Background and/or Program Background bus or from an N/E “A” or “B” 

bus. b) A solid-color video output generated by the color Background generator 

within the switcher for use as background video. 

Backhaul – In television, the circuits (usually satellite or telephone) used 

to transmit or “haul” a signal back from a remote site (such as a sports 

stadium) to a network headquarters, TV station, or other central location for 

processing before being distributed. 

Backplane – The circuit board that other boards in a system plug into. 

Usually contains the system buses. Sometimes called a Motherboard. 

Back-Timing – Timing of a program from the end to the beginning. A 

reversal of clock-order so that remaining time or time left to the end of the 

program can be easily seen. 

Backup Tape – A tape that contains a copy of a set of files and directories 

that are on your hard disk. A full backup tape contains a copy of all 

files and directories, including IRIX, which are on your hard disk. 

Backward Compatibility – A new coding standard is backward compatible 

with an existing coding standard if existing decoders (designed to operate 

with the existing coding standard) are able to continue to operate by 

decoding all or part of a bit stream produced according to the new coding 

standard. 

Backward Motion Vector – A motion vector that is used for motion compensation 

from a reference picture at a later time in display order. 

Baffles – Sound absorbing panels used to prevent sound waves from 

entering or leaving a certain space. 

Balanced Line – A line using two conductors to carry the signal, neither 

of which is connected to ground. 

Bandpass Filter – Circuit that passes a selected range of frequencies. 

Bandwidth – The range of frequencies over which signal amplitude 

remains constant (within some limits) as it is passed through a system. 

More specific definitions include: a) The difference between the upper and 

lower limits of a frequency, often measured in megahertz (MHz). b) The 

complete range of frequencies over which a circuit or electronic system 

can function with less than a 3 dB signal loss. c) The information carrying 

capability of a particular television channel. d) A measure of information 

capacity in the frequency domain. The greater the bandwidth of a transmission 

channel, the more information it can carry. e) In television, bandwidth 

is usually expressed in MHz. 

Bandwidth Efficient – Phrase sometimes used to describe techniques to 

carry the maximum amount of picture information within a prescribed 

bandwidth; also, name applied to one MIT ATV proposal that would transmit 

only the spatio-temporal resolution necessary for a particular scene. For 

example, it would transmit no more than 24 frames per second when 

showing a movie shot at that rate. 

Bandwidth Limiting – A reduction in the effective bandwidth of a signal, 

usually to facilitate recording, transmission, broadcast, display, etc. The 

reduction is usually accomplished through the action of an algorithm, 




which may involve simple lowpass filtering, more complex processing such 

as interleaving or quadrature modulation, or complete resampling. The term 

bandwidth limiting is normally applied in analog systems, although it also 

has a comparable meaning in digital systems. 

Bandwidth, Monitor – Monitor bandwidth is proportional to the speed at 

which a monitor must be turned on and off to illuminate each pixel in a 

complete frame and is proportional to the total number of pixels displayed. 

For example, a monitor with a resolution of 1000 X 1000 pixels which is 

refreshed at 60 times a second, requires a minimum theoretical bandwidth 

of over 45 MHz. Once overhead is considered for scanning and small spot 

size, the bandwidth could be as much as 100 MHz. 

Barn Doors – Two- or four-leafed metal blinders mounted onto lights to 

control brightness or direction. 

Base – See Radix. 

Base Bandwidth – The amount of bandwidth required by an unmodulated 

signal, such as video or audio. In general, the higher the quality of the signal, 

the greater the base bandwidth it requires. 

Base Film – For magnetic tapes, the plastic substrate that supports the 

coating. The base film of most precision magnetic tape is made of 

polyester. 

Base Film Thickness – The thickness of the polyester material used for 

magnetic tape, varying from 0.24 mil in C120 cassette tape to 1.5 mil for 

audio mastering tape and instrumentation tape. 

Baseband – a) Refers to the composite video signal as it exists before 

modulating the picture carrier. Not modulated. Composite video distributed 

throughout a studio and used for recording is at baseband. b) Video and 

audio signals are considered to be “prime,” or baseband. Video and audio 

can be broken down into more basic elements, but those elements no 

longer constitute the desired signal as a single element. Baseband video 

and audio signals are often AM or FM modulated onto a carrier frequency, 

so that more than one set of “prime” signals can be transmitted or recorded 

at the same time. 

Baseline IRD – An IRD (Integrated Receiver Decoder) which provides the 

minimum functionality to decode transmitted bitstreams. It is not required 

to have the ability to decode Partial Transport Streams (TS) as may be 

received from a digital interface connected to a digital bitstream storage 

device such as a digital VCR. 

Baseline Restorer – An information processing unit intended to remove 

the DC and low-order frequency distortion terms that result from use of 

record/reproduce transfer function which cannot pass DC in conjunction 

with a binary code that requires low-frequency response to DC (i.e., zero 

frequency) for accurate recovery of such a code. 

Baseline Shift – A form of low-frequency distortion resulting in a shift in 

the DC level of the signal. 

BASIC – An easy-to-learn, easy-to-use language, which is available on 

most microcomputer systems. 

Basic Cable Service – Package of programming on cable systems eligible 

for regulation by local franchising authorities under 1992 Cable Act, 

including all local broadcast signals and PEG (public, educational, and government) 

access channels. 


BAT (Bouquet Association Table) – a) The BAT provides information 

regarding bouquets (collections of services marketed as a single entity). 

b) Table describing a bouquet of programs offered by a broadcaster. DVB 

only. 

Batch Capture – Combining your video capture card with deck control so 

that you can define your in and out points first, then capture only the 

footage you want. 

Baud – A unit of signaling speed equal to the number of signal events per 

second. Baud is equivalent to bit per second in cases where each signal 

event represents exactly one bit. Often the term baud rate is used informally 

to mean baud, referring to the specified maximum rate of data transmission 

along an interconnection. Typically, the baud settings of two 

devices must match if the devices are to communicate with each other. 

Baud Rate – a) The speed (calculated as bits per second) at which the 

computer sends information to a serial device, such as a modem or terminal. 

b) Measure of data flow: the number of signal elements per second. 

When each element carries one bit, the baud rate is numerically equal to 

bits per second (BPS). For example, teletypes transmit at 110 baud. Each 

character is 11 bits, and the TTY transmits 10 characters per second. 

c) The rate at which data is transmitted. The baud rates must match if two 

devices are to communicate with each other. 

BB – See Baseband. 

BBC – See British Broadcasting Corporation. 

BC – Broadcast Channel. 

BCD (Binary Coded Decimal) – A 4-bit representation of the 10 decimal 

digits “0” through “9.” Six of the sixteen possible codes are unused. Two 

BDC digits are usually packed into one byte. 

BDR – See Border. 

Bearding – An overloading condition in which highly saturated or white 

areas of a television picture appear to flow irregularly into darker areas. 

Beats – Variation in the amplitude of a mixture of two signals of close frequency 

as a result of constructive and destructive interference. 

Bel – A measure of voltage, current, or power gain. One bel is defined as a 

tenfold increase in power. If an amplifier increases a signal’s power by 10 

times, its power gain is 1 bel or 10 decibels (dB). If power is increased by 

100 times, the power gain is 2 bels or 20 decibels. 3 dB is considered a 

doubling. 

Bell Labs – Originally Bell Telephone Laboratories, the research arm of the 

Bell System. When AT&T divested itself of its regional telephone companies, 

Bell Labs was split. One division, still called Bell Labs, belongs to 

AT&T and is a proponent of a particular ATV system (SLSC). The other division, 

called Bellcore for short, belongs to the Bell regional holding companies 

(RHCs) and is, among many other R&D projects, investigating mechanisms 

for reducing the bit rate of digital video transmission, which may be 

applicable to ATV. Bellcore has formed a joint venture with NHK for HDTV 

research. 

Bellcore – See Bell Labs. 

Benchmark – Method used to measure performance of a computer in a 

well-defined situation.

BEP – Bit Error Probability. 

BER – See Bit Error Rate. 

BETACAM ® SP – A superior performance version of BETACAM‚ that uses 

metal particle tape and a wider bandwidth recording system. The interconnect 

standard is the same as BETACAM‚ and there is also limited tape 

interchangeability with standard BETACAM.. 

BETACAM ® SX – A digital tape recording format developed by Sony which 

used a constrained version of MPEG-2 compression at the 4:2:2 profile, 

Main Level (422P@ML) using 1/2-inch tape cassettes. 

BETACAM ® ‚ BETACAM ® Format – A camera/recorder system and related 

equipment originally developed by Sony, the name may also be used for 

just the recorder or for the interconnect format. BETACAM uses a version 

of the (Y, R-Y, B-Y) component set. 

BETAMAX ® – Consumer videocassette record/playback tape format using 

half-inch wide magnetic tape. Developed by Sony, BETAMAX was the first 

home VCR format. 

Bezel – The frame that covers the edge of the picture tube in some TV 

sets and can therefore hide edge information transmitted in an ATV system 

(such as ACTV) not meant for the viewer to see. See also Overscanning. 

Bézier Spline – A type of smooth curve or surface bound to its control 

points, always passing through its first and last control point. 

B-Frame (Bidirectional Frame) – The frame in an MPEG sequence created 

by comparing the difference between the current frame and the 

frames before and after it. 

BG (Also BKG and BKGND) – See Background. 

BH Loop Tracer – See BH Meter. 

BH Meter – A device for measuring the intrinsic hysteresis loop of a sample 

of magnetic material. Usually, the sample is magnetized in a 60 Hz field 

supplied by a solenoid and the intrinsic flux is detected by integrating the 

emf produced in an opposing pair of search coils, one of which surrounds 

the sample. The hysteresis loop may be displayed on an oscilloscope by 

feeding the X and Y plates with voltages proportional to the magnetizing 

coil current and the integrated search coil emf respectively. 

Bi O-L – Bi-Phase Level (Code). Also called Manchester (Code). 

Bias – A steady-state signal applied to the tape (usually by a highfrequency 

oscillation of 50 to 100,000 Hz or more) to minimize distortion 

and noise and increase frequency response and efficiency in recording. 

Every tape formulation has slightly different bias requirements. 

Bias Adj. – The control which regulates the amount of bias mixed in with 

the signal to be recorded. 

Bias Cal. – A control which calibrates the VU meter on a recorder so it 

reads 0 VU in the bias position of the output selector switch when bias is 

properly set. 

Bias Switch – Switch used on a cassette recorder to change the amount 

of bias current required for different types of tapes. 

Bidirectional – a) Indicates that signal flow may be in either direction. 

Common bidirectional buses are three-state or open collector TTL. b) In 

open reel or cassette recorders, the ability to play (and, in some cases, 



record) both stereo track pairs on a tape by reversing the tape’s direction 

of motion without removing and replacing the tape reels or cassette. 

Bidirectional Prediction – A form of compression in which the codec 

uses information not only from frames that have already been decompressed, 

but also from frames yet to come. The codec looks in two directions: 

ahead as well as back. This helps avoid large spikes in data rate 

caused by scene changes or fast movement, improving image quality. 

Compare with Unidirectional Prediction. 

Big Endian – A process which starts with the high-order byte and ends 

with the low-order byte. Motorola 68000 processors used the big endian 

format. 

Bi-Level Keyer – A keyer where two levels of hole cutting are independently 

adjustable. The top level, or insert, cuts a hole and fills with the key 

video. In a luminance key, the second level forms the border of the key; in 

a chroma key, the second level forms the shadow. The second level has 

adjustable luminance allowing borders to be varied from black to white and 

shadows to be varied in density. This is the type of keying provided on all 

Ampex switchers. 

BIM – Broadcast Interface Module. 

Binary – A base-2 numbering system using the digits 0 and 1 (as opposed 

to 10 digits, 0-9 in the decimal system). In computer systems, the binary 

digits are represented by two different voltages or currents, one corresponding 

to 0 and the other corresponding to 1. All computer programs are 

executed in binary form. Binary representation requires a greater number 

of digits than the base-10 decimal system more commonly used. For 

example, the base-10 number 254 is 11111110 in binary. The result of a 

binary multiplication contains the sum of digits of the original numbers: 

in binary: 10101111 x 11010100 = 10010000011101100 

in decimal: 175 x 212 = 37,100 

From right to left, the digits represent 1, 2, 4, 8, 16, 32, 64, 128, 256, 

512, 1024, 2048, 4096, 8192, 16384, 32768. Each digit is known as a 

bit. This example multiples two 8-bit numbers to produce a 16-bit result, a 

very common process in digital television equipment. 

Binary File – An executable file that contains a relocatable machine code 

program; in other words, a program ready to be run. 

Binary Search – Technique in which the search interval is divided by two 

at every iteration. 

Binaural Effect – The human ability to localize the direction from which a 

sound comes due to the fact that people have two ears. 

Binder – On recording tape, the binder is usually composed of organic 

resins used to bond the oxide particles to the base material. The actual 

composition of the binder is considered proprietary information by each 

magnetic tape manufacturer. The binder is required to be flexible and still 

maintain the ability to resist flaking or shedding binder material during 

extended-wear passes. 

Bi-Phase Sync – Bi-phase is an older synchronization technology used in 

the film industry. Typically, the clock was derived from a box that hung off 

of large film mag recorders. This box emitted a pulse that provided sync. 

Working with pulses alone, bi-phase sync did not provide location information, 

making it a rather limited solution. 




B-ISDN (Broadband Integrated Services Digital Network) – A mechanism 

by means of which telephone companies will be able to carry television 

signals (and, probably ATV signals) digitally, probably via optical fibers. 

ISDN systems are considered broadband if they carry at least 45 Mbps, the 

DS3 rate, currently used for delivery of broadcast television signals. If and 

when B-ISDN reaches homes it will be a powerful competitor to other delivery 

mechanisms, potentially able to perform a computer-television function. 

Bit (Binary Digit) – a) Contraction of binary digit. A single digit in a binary 

number. b) A binary representation of 1 or 0. One of the quantized levels 

of a pixel. c) An instruction in a data transmission, usually part of a word 

(byte) with high status = 1, and low status = 0. 

Bit Bucket – Any device capable of storing digital data, whether it be 

video, audio, or other types of data. 

Bit Budget – The total amount of bits available on the media being used. 

In DVD, the bit budget of a single sided/single layer DVD5 disk is actually 

4.7 GB. 

Bit Density – See Packing Density. 

Bit Depth – The number of levels that a pixel might have, such as 256 

with an 8-bit depth or 1024 with a 10-bit depth. 

Bit Error – The incorrect interpretation of a binary bit by a message processing 

unit. 

Bit Error Rate (BER) – a) This term is used in High Density Digital 

Recording (HDDR), or High Density Recording (HDR), or other such names 

and refers to the number of errors a specific magnetic tape may contain, 

and is expressed in errors per data bits, such as one in 106 or one error in 

one million data bits. b) The average probability of a digital recording system 

reproducing a bit in error. Note: IEEE 100 defines error rate as “the 

ratio of the number of characters of a message incorrectly received to the 

number of characters of the message received.” Bit error rates typical of 

current digital tape recording are: digital video tape, about 106 ; digital 

instrumentation tape, about 109 ; digital computer tape, about 1012 . 

Bit Packing Density – The number of bits recorded per track length unit, 

usually expressed in terms of kilobits per inch (KBPI) or bits per millimeter 

(BPMM). 

Bit Parallel – Byte-wise transmission of digital video down a multi-conductor 

cable where each pair of wires carries a single bit. This standard is 

covered under SMPTE125M, EBU 3267-E, and ITU-R BT.656 (CCIR 656). 

Bit Plane – Video RAM containing formatted graphics data for VGA and 

SVGA systems where four or more bit planes can be addressed in parallel. 

A bit plane is sometimes called a map. 

Bit Rate – a) The rate at which the compressed bit stream is delivered 

from the storage medium to the input of a decoder. The digital equivalent 

of bandwidth. b) The speed at which bits are transmitted, usually 

expressed in bit per second (IEEE 100). Video information, in a digitized 

image for example, is transferred, recorded, and reproduced through the 

production process at some rate (bits/s) appropriate to the nature and 

capabilities of the origination, the channel, and the receptor. c) The amount 

of data transported in a given amount of time, usually defined in Mega 

(million) bits per second (Mbps). Bit rate is one means used to define the 


amount of compression used on a video signal. Uncompressed D1 has a bit 

rate of 270 Mbps. MPEG-1 has a bit rate of 1.2 Mbps. 

Bit Rate Reduction – a) Schemes for compressing high bit rate signals 

into channels with much lower bit rates. b) A reduction in the real-time 

transmission rate in digital format, usually to facilitate recording, transmission, 

broadcast, display, etc., or even to comply with fixed limitations. 

Various algorithms appropriate for video signals may be employed from 

arbitrary resampling to more complex processing with the objective of 

reducing the transmission of redundant information in the image and possibly 

eliminating image content that will not be obvious in the final specified 

display. Bit rate reduction is also appropriate and employed in audio 

records, either associated with video or standing alone. 

Bit Rate, Real-Time – When the information is obtained from a continuously 

varying source, and the information is being transmitted continuously 

without buffering, it is exchanged at the real-time bit rate. Within the production 

sequence, it is actually only the image capture (i.e., camera and its 

recording system) that is required to be in real-time. The balance of production, 

including post-production operations, can be at a fraction of realtime 

if a more desirable result is achieved. (Subsequent to production, the 

final display must, of course, also be in real-time.) 

Bit Rate, Recording – The bit rate required of a recorder mated to a 

video camera or functioning in the origination, post-production, or distribution 

is generally greater than the concurrent bit rate, real-time because of 

the error correction designed into the recording format. This “overhead” 

may increase the bit rate, sometimes by as much as one-third, and frequently 

sets a practical limit in systems design. Examples in the following 

table are intended only to clarify the definition. They indicate the range of 

some systems currently considered and a first estimate of their challenges. 

Probable Recording Rate, Mbits/s (1, 2) 

Bits Maximum CCIR CCIR 

Per Levels Rec 601-2 (3) Rec 709 (3) 

Pixel Defined 4:2:2 4:4:4 4:2:2 4:4:4 

8 (3) 256 227 (4) 340 1290 1940 

10 1024 284 426 1610 2420 

12 4096 340 510 1940 2910 

(1) All systems postulated employ field rates of 60 or 59.94 Mbits/s, component 

encoding and 2:1 interlace. Progressive scan systems at the same 

frame rates would have double these bit rates. 

(2) Estimates for gross data recording rates assume the same ratio of overhead 

to data bits in component format recording as that in the D-1 


(3) CCIR Recommendations 601-2 and 709 document 8-bit and 10-bit sampling, 

based upon sampling frequencies that are integral multiples of 

2.25 MHz (i.e., 13.5 MHz for Rec 601-2). 

(4) The D-1 standard recording format is defined by SMPTE 224M and its 

related SMPTE Recommended Practices and Engineering Guidelines. 

Bit Serial – Bit-wise transmission of digital video down a single conductor 

such as coaxial cable. May also be sent through fiber optics. This standard 

is covered under ITU-R BT.656 (CCIR 656).

Bit Slip – The condition in a message processing unit where the bit-rate 

clock has gained (or lost) more than 180 degrees phasing with respect to 

synchronism with the binary message bits. 

Bit Slippage – a) Occurs when word flaming is lost in a serial signal so 

that the relative value of a bit is incorrect. This is generally reset at the 

next serial signal, TRS-ID for composite and EAV/SAV for component. 

b) The erroneous reading of a serial bit stream when the recovered clock 

phase drifts enough to miss a bit. c) A phenomenon which occurs in parallel 

digital data buses when one or more bits gets out of time in relation to 

the rest. The result is erroneous data. Differing cable lengths is the most 

common cause. 

Bit Stream (also Bitstream) – a) A continuous series of bits transmitted 

on a line. b) A binary signal without regard to grouping according to 

character. 

Bit Synchronizer – An information processing unit intended to extract the 

binary message and associated bit-rate clock included in a PCM signal. 

BitBLT (Bit Block Transfer) – The transfer of blocks of screen data 

(rather than a byte at a time) from one place to another in memory. The 

microprocessor tells the graphic chip what block to move and where to put 

it. The graphics chip carries out this operation, freeing the microprocessor 

to work on the next operation. 

BITC – See Burn In Time Code. 

Bitmap – a) A bitmap is the digital representation of an image in terms of 

pixel values. Storing an image as a bitmap is the most space-consumptive 

method of storing an image. b) An image consisting of an array of pixels 

that can be displayed on a computer monitor. 

Bits Per Pixel – The number of bits used to represent the color information 

of a pixel. 

Bits/s – Bits Per Second. 

Bit-Slice – Method that implements n-bits of the CPU on each of several 

chips, or slices, usually n = 4. A bit-slice processor chip implements a 

complete data path across the CPU. A 32-bit processor could be constructed 

by using eight 4-bit CPU slices. 

Black (BLK) – A black video output generated within the switcher and 

selected by the Black push-buttons on the crosspoint buses and by the 

Fade to Black push-button in the downstream mixer. 

Black A Tape – The process of recording a black-burst signal across the 

entire length of a tape. Often done before recording edited footage on the 

tape to give the tape clean, continuous video and sync and to ensure there 

is no video already on the tape. 

Black And White – Monochrome or luminance information. Monochrome 

means one color. In the color television system, the black and white portion 

of the picture has to be one “color” gray, D6500, 6500° K as defined by x 

and y values in the 1939 CIE color coordinate system. The black and white 

signal in the S or Component video path is separate from the color information. 

Black Box – A term used to describe a piece of equipment dedicated to 

one specific function, usually involving a form of digital video magic. 



Black Burst – Also called “color black,” “house sync,” or “house black.” 

Black burst is a composite video signal consisting of all horizontal and vertical 

synchronization information, burst, and usually setup. Typically used as 

the house reference synchronization signal in television facilities. 

Black Compression – a) The reduction in gain applied to a picture signal 

at those levels corresponding to dark areas in a picture with respect to the 

gain at that level corresponding to the midrange light value in the picture. 

b) Amplitude compression of the signals corresponding to the black 

regions of the picture, thus modifying the tonal gradient. 

Black Level – a) This voltage defines the picture’s black level. Video that 

dips below this level such as sync pulses are called blacker than black. 

b) Strictly interpreted, denotes the light level at which a video signal representing 

picture black is reproduced on your TV screen. In terms of light 

output from a TV set, black areas of the picture should be represented by 

an absence of light. Something that is black or below black in the video 

signal shouldn’t produce any light from the display. c) Some TV sets actually 

use Black Level as a control name. It is a far better description of the 

function than the most commonly found name for it, Brightness. 

Black Level Setup – Refer to the Setup discussion. 

Black Level, Monitor – The luminance produced on the monitor display 

by a signal at reference black level. Since the monitor brightness control 

should be adjusted to align CRT beam cutoff with reference black level signal, 

this provides zero excitation light from the CRT (only room ambient 

light reflected from the CRT faceplate). Monitor black level is normally set 

by use of a PLUGE signal to adjust CRT beam cutoff subjectively. 

Black Level, Reference – The video signal level which is intended to produce 

monitor black level in the reproduced image. In systems with a setup 

level, i.e., the 7.5 IRE setup in a 525/59.94/2:1/NTSC composite video 

documented by ANSI/EIA TIA 250-C and SMPTE 170M, reference black is 

at the setup level. In systems with no setup level, reference black is at 

blanking level. 

Black Peak – The maximum excursion of the picture signal black direction 

at the time of observation. 

Black, Absolute – a) Optical black is no light. An absolute black can only 

be produced in a scene via a light-trap, “a black hole.” b) A capped lens 

on the camera is the equivalent of an absolute scene black and should 

produce reference black level video signal from a properly adjusted studio 

camera. 

Black, Projection – The luminance level in a projected image that is correlated 

with subjective scene black has two sources: in photographic and 

other light-modulating systems there will be luminance from whatever 

transmitted light passes through the maximum modulating density representing 

scene black, additional luminance may be produced by nominateforming 

light (flare, room illumination, stray light, etc.). 

Black, Subjective, Monitor – The luminance level which produces the 

perception of black on the monitor display. This subject has not been 

explored extensively, but Bartleson and Novick present evidence that it is 

relative to the high-light or white level, such that the luminance ratio to 

produce subjective black on a monitor is higher than that in a televised 

scene. They propose a luminance ratio of 100:1 for subjective white to 




black on TV monitors in a control room “dimly lighted.” This luminance ratio 

specification has been formalized in SMPTE RP 166. 

Black, Subjective, Scene – That fraction of the high-light luminance 

required in a scene reproduced on a television display to convey the perception 

of black. The luminance of subjective black on a CRT has been 

studied by Lowry and Jarvis, who measured luminances on the original 

scenes, and compared the subjective appearance on a CRT display, as 

evaluated by viewing audiences. They found that the perception of black 

depends on a great many factors both in the reproduced scene and in the 

viewing conditions such as average scene reflection, luminance of areas 

adjacent to the display, etc. In most situation, luminance levels of 1/40 to 

1/60 of the highlight luminance produce the perception of black even 

though the scene luminance range may reach 200:1 or more. It follows, 

then, that a scene element that is perceived as black may not necessarily 

be at reference-black level in a video signal. 

Blacker-than-Black – The amplitude region of the composite video signal 

below reference-black level in the direction of the synchronizing pulses. 

Blanking – A video signal level below which no light should be emitted 

from a TV screen (the level at which the screen is blanked); also, that portion 

of the time that a video signal is transmitted when it is at or below 

blanking. These time portions can be divided into a horizontal blanking 

interval (HBI) and a vertical blanking interval (VBI). Since no picture information 

is carried in either blanking interval in an NTSC signal, various ATV 

schemes propose using them for carrying augmentation information, such 

as higher quality sound or widescreen panel information. Potentially conflicting 

with those schemes are other schemes that already use the blanking 

intervals for descrambling codes, test transmission, time code, and test 

and reference signals. Reducing the duration of the blanking intervals to 

allow more picture information to be transmitted potentially conflicts with 

the demands of the scanning circuitry of older TV sets. Sometimes this 

conflict is said to be resolved by bezel coverage and overscanning. 

Blanking (Picture) – The portion of the composite video signal whose 

instantaneous amplitude makes the vertical and horizontal retrace invisible. 

Blanking Adjustment – A technique proposed in some ATV schemes to 

increase the VBI (and, sometimes, decrease the HBI) to deal with wide 

aspect ratios. See also Burn. 

Blanking Interval – The horizontal blanking interval is the time between 

the end of one horizontal scanning line and the beginning of the next. The 

vertical blanking interval is the time between the end of one video field and 

the beginning of the next. Blanking occurs when a monitor’s electron beam 

is positioned to start a new line or a new field. The blanking interval is 

used to instantaneously reduce the beam’s amplitude so that the return 

trace is invisible. 

Blanking Level – a) Refers to the 0 IRE level which exists before and 

after horizontal sync and during the vertical interval. This voltage level 

allows the electron beam to be turned off while it is being repositioned 

(retracing) across the face of the CRT into the position needed to start 

tracing the next visible line. b) The level of the front and back porches of 

the composite video signal. c) The level of a composite picture signal 

which separates the range containing picture information from the range 


containing synchronizing information. Note: This term should be used for 

controls performing this function (IEEE 100). 

Blanking Panel – A piece of black plastic attached to the front plastic 

panel of the Indigo chassis that covers either the top or middle drive slot. 

The blanking panel is removed after installing a drive in the slot that it was 

covering. 

Blanking Processor (Sync Proc) – A circuit on the video module which 

strips blanking sync and burst from the program output of the switcher and 

replaces it with blanking and sync from a reference source. This process 

ensures that sync and blanking do not contain any unwanted timing shifts, 

and the record VPR is always receiving constant relationships of sync, 

blanking, and burst. 

Blanking Stuffing – An ATV technique that adds information to blanking 

areas that is supposed to be invisible to ordinary sets but can be used by 

an ATV set for increased resolution and/or widescreen panels. 

Blast Filter – A dense mesh screen on a microphone, which minimizes 

overload caused by loud, close sounds. 

Bleeding Whites – An overloading condition in which white areas appear 

to flow irregularly into black areas. 

Blink – A modification to a key to cause it to flash on and off. The speed 

at which a key blinks. 

Blitting – The process of using BitBLT to copy video data such as a 

bitmap from one area in memory to another. 

Block – An 8-row by 8-column matrix of pels, or 64 DCT coefficients 

(source, quantized or dequantized). A block is the entity on which the DCT 

operates. Please note, that the term “block” is used for both the actual picture 

information, and the corresponding DCT coefficients. A block represents 

luminance or chrominance information. 

Block Matching – A method of motion estimation. A search for the picture 

area that best matches a specific macro block of preceding and/or 

subsequent pictures. 

Blockiness – An artifact that refers to the tile-like appearance of a compressed 

image where the 8x8 blocks have become visible due to a (too) 

hard compression. 

Blocking – a) Occurs in a multistage routing system when a destination 

requests a source and finds that source unavailable. In a tie line system, 

this means that a destination requests a tie line and receives a tie line 

busy message, indicating that all tie lines are in use. b) Distortion of the 

received image characterized by the appearance of an underlying block 

encoding structure. 

Blooming – This effect is sometimes called whiter-than-white. Blooming 

occurs when the white voltage level is exceeded and screen objects 

become fuzzy and large. 

BLT (Block Transfer) – The process of moving blocks of data from one 

place to another rather than a byte at a time in order to save processor 

time and to expedite screen display in operations such as vertical rolling of 

video. 

Blue Aging – A tendency for blue phosphors to age more rapidly than red 

or green. See also Phosphor Aging.

Blur – A state of reduced resolution. Blur can be a picture defect, as when 

a photograph is indistinct because it was shot out of focus or the camera 

was moved during exposure. Blur can also be a picture improvement, as 

when an unnaturally jagged-edged diagonal line or jerky motion is blurred 

to smoothness. 

Blurring/Smearing – In a single frame (spatial example), reducing the 

number of pixels per horizontal line, causes a blurring or smearing effect. 

In multiple frames (temporal example), the causes become more complicated. 

They may include reduction of bandwidth, degree of image movement, 

algorithm type, and motion prediction/compensation techniques. 

B-MAC – A MAC (Multiplexed Analog Component) with audio and data time 

multiplexed before modulation, which forms the basis for the HDB-MAC 

ATV scheme, currently used for satellite transmission and scrambling in the 

United States. See also MAC. 

BMP – A bitmapped graphic file format for Windows which stores images 

as a grid of dots or pixels. The BMP file defines the size of the image, the 

number of color planes, and the palette used. 

BNC – A cable connector used extensively in television and is an abbreviation 

that has several different meanings depending on who you ask. Four 

common meanings for BNC are: Baby N Connector, Bayonet Neill 

Concelman Connector, British Naval Connector, British National Connector. 

Board – The audio console control in radio and television. 

Board Fade – A radio term, used to designate the process of gradually 

fading the volume of sound by means of a master fading control on the 

board. 

Board Tester – Product programmed to automatically stimulate the circuits 

on a PC board and check the responses. Electrical failures can be 

detected and diagnosed to facilitate board repair. 

BOC (Bell Operating Company) – A local telephone company formerly 

owned by AT&T. 

Boolean – In digital picture manipulation, a method of working on polygonal 

objects. 

Boolean Logic – Named after George Boole, who defined binary arithmetic 

and logical operations such as AND, OR, NOT, and XOR. 

Boom – A mechanical cantilevering device used to hold a microphone 

closer to a set by positioning it above the set while keeping it out of view 

of the cameras. 

Boot – To start up the system by turning on the workstation and monitor; 

the system is fully booted when you see a prompt or the login screen. 

Short for Bootstrap. 

Boot Up – To start up. Most computers contain a system operating program 

that they load into memory from disk after power up or restart. The 

process of reading and running that program is called boot up. 

Bootstrap – Program used to initialize the computer. Usually clears memory, 

sets up I/O devices, and loads the operating system. 

Border – a) The boundary between two merged video pictures, as created 

with chroma key or wipe effects. b) May be thought of as the frame which 

surrounds a given pattern or key. In the case of a key, the border is on or 

two lines side, adjustable anywhere from black to white, and may be sym- 



metrical about the key or to the right and bottom (drop shadow). An outline 

is a special key border where the insert video appears in the border area 

and the background video fills the hole where the insert would normally be. 

In the case of a pattern, the border is adjustable in width and color. A pattern 

border may be hard colored, soft colored (halo), or soft with no color. 

AVC switchers can also do half halo borders, hard on one side and soft on 

the other. 

Border (Key) – A title (caption, super) enhancement option which produces 

a black or white border or dropshadow around a key or changes the 

key into a matte filled outline in the shape of the key. The Border, 

Dropshadow, and Outline push-buttons select these optional modes. If the 

Border option is not installed, these push-buttons do not function. 

Border (Menu) – A function that uses ADO 100’s internal key to place a 

border around the image and adjust width and color (saturation, luminance, 

and hue). 

Border (Wipe) – The boundary area between the “A” video and “B” video 

when doing a wipe, to which hard, soft, halo, or 1/2 halo edges and matte 

color can be added. 

Border Luminance – The brightness of a border. 

Border Modify – A feature exclusive to AVC series switchers, allowing key 

borders to be extended to the right and bottom up to 14 lines deep. 

Several special key effects can be accomplished with this including 

delayed and decayed keys. 

Border Modify (Key) – An enhancement to the basic key border function 

allowing up to 14 lines of dropshadow or reinserted insert video in a 

decaying mode. This uses a patented circuit which increases the creative 

possibilities. 

Bottom Field – One of two fields that comprise a frame of interlaced 

video. Each line of a bottom field is spatially located immediately below the 

corresponding line of the top field. 

Bounce – a) An unnatural sudden variation in the brightness of the picture. 

b) Oscillations and noise generated when a mechanical switch is 

opened or closed. See Debounce. 

Boundary Representation Modeling – This modeling technique defines 

a world in terms of its edges. The primary components of a boundary rep 

world are vertices and polygons. PictureMaker is a boundary rep system. 

Bounding Box – A relatively simple object, usually a rectangle or box with 

the overall dimensions, or bounds, of a more complex object. A bounding is 

used in place of that exact, more complex, modeled shape to represent it 

in an animation preview, or to predict the inclusion of that object in the 

scene. This reduces the calculation/production time and expense when 

previewing computer animation sequences to check continuity, positions, 

and timing. 

Bouquet – a) A group of transport streams in which programs are identified 

by a combination of network ID and PID (part of DVB-SI). b) A collection 

of services marketed as a single entity. 

Bowtie Test Signal – The bowtie test signal actually consists of three signals, 

each being fed to a different channel of the CAV system and is used 

to evaluate the relative amplitudes and relative timing on some CAV waveform 

monitors such as the WFM300A. The figure below shows the three 




waveforms in the parade mode. The first signal is a 500 kHz sinewave 

packet which is fed to video channel 1. The other two signals are identical 

502 kHz. The three sinewave packets are generated to be precisely in 

phase at their centers. Because of their 2 kHz offset, the color difference 

channels become increasingly out of phase with the luminance channel on 

either side of center. If the three signals are properly timed, their sum 

results in the bowtie waveform shown below. 

Box House – A slang term for a mail-order business for audio and video 

components. Box houses frequently offer little or no consumer support or 

equipment repair. 

BPF – See Bandpass Filter. 


BPI – Bits per linear inch down a recorded track. 

B-Picture (Bidirectionally Predictive-Coded Picture) – An MPEG picture 

that is coded using motion compensated prediction from past and/or 

future reference pictures. Motion vectors pointing forwards and backwards 

are used, and they may point at either I-pictures or P-pictures. The B-pictures 

provide the highest compression, but demand knowledge of several 

pictures. Consequently, B-pictures give a higher delay and call for a larger 

picture memory. B-pictures are never used as a reference in a prediction. 

When B-pictures are part of a sequence, the pictures are not sent in 

chronological order owing to the fact that future P-pictures and/or 

I-pictures are needed (and therefore must be decoded) for the decoding of 

B-pictures. The P- and I-pictures have to be sent earlier than the actual 

point of time to which they relate. 

BPS – Bits Per Second. 

BPSK – Binary Phase Shift Keying. 

BR – Radiocommunication Bureau. 

BRA – Basic Rate Access. 

Branch – See Jump. 

Break Elongation – The relative elongation of a specimen of magnetic 

tape or base film at the instant of breaking when it has been stretched at a 

given rate. 

Breakdown – A written accounting of the shooting schedule and production 

resources. 

Breakpoint – a) A break in the smoothness of a curve. b) Software or 

hardware device that stops the program and saves the current machine 

status, under user-specified conditions. 

Breakup – Disturbance in the picture or sound signal caused by loss of 

sync or by videotape damage. 

Breathing – Amplitude variations similar to “bounce” but at a slow, regular 

rate. 

Breezeway – The portion of the video signal which lies between the trailing 

edge of the horizontal sync pulse and start of burst. The Breezeway is 

part of the back porch. Also refer to the Horizontal Timing discussion. 

Bridge – Bridges are devices that connect similar and dissimilar LANs at 

the data link layer (OSI layer 2), regardless of the physical layer protocols 

or media being used. Bridges require that the networks have consistent 

addressing schemes and packet frame sizes. Current introductions have 

been termed learning bridges since they are capable of updating node 

address (tracking) tables as well as overseeing the transmission of data 

between two Ethernet LANs. 

Brightness – a) Overall DC voltage level of the video signal. The brightness 

control is an adjustment of setup (black level, black reference). 

b) Attribute of a visual sensation according to which an area appears to 

emit more or less light. The subjective counterpart of objective luminance. 

c) The value of a pixel along the black-white axis. 

Brightness Signal – Same as the luminance signal (Y). This signal carries 

information about the amount of light at each point in the image.

Broad Pulses – Another name for the vertical synchronizing pulses in the 

center of the vertical interval. These pulses are long enough to be distinguished 

from all others and are the part of the signal actually detected by 

vertical sync separators. 

Broadband – a) A response that is the same over a wide range of frequencies. 

b) Capable of handling frequencies greater than those required 

for high-grade voice communications (higher than 3 to 4 kilohertz). 

Broadcast Quality – A nebulous term used to describe the output of a 

manufacturer’s product no matter how bad it looks. 

Broadcast Television – Conventional terrestrial television broadcasting, 

the most technically constrained delivery mechanism for ATV, faced with 

federal regulations and such potential problems as multipath distortion and 

co-channel interference. 

Broadcaster (Service Provider) – An organization which assembles a 

sequence of events or programs to be delivered to the viewer based upon 

a schedule. 

B-Roll – Off the shelf video sequences for various needs. 

Brouter – Brouters are bridge/router hybrid devices that offer the best 

capabilities of both devices in one unit. Brouters are actually bridges capable 

of intelligent routing and therefore are used as generic components to 

integrate workgroup networks . The bridge function filters information that 

remains internal to the network and is capable of supporting multiple 

higher-level protocols at once. The router component maps out the optimal 

paths for the movement of data from one point on the network to another. 

Since the brouter can handle the functions of both bridges and routers, as 

well as bypass the need for the translation across application protocols 

with gateways, the device offers significant cost reductions in network 

development and integration. 

Brown Stain – A non-magnetic substance that forms on that area of a 

magnetic head’s surface over which tape passes. Its origin is not well 

understood but it is known to occur primarily in the presence of low 

humidity. 

Browse – To scan a database or a list of files, either for a particular item 

or for anything that seems to be of interest. Browsing implies observing 

rather than changing information. 

Browse Station – A viewing station that provides browsing of stored 

images or video. Browse stations are internal and connected via ethernet. 

BRR – See Bit Rate Reduction. 

Bruch Blanking – A 4-field burst blanking sequence employed in PAL signals 

to ensure that burst phase is the same at the end of each vertical 

interval. 

BS – Bandwidth of the frequency slot allocated to a service. 

BSI – British Standards Institution. 

BSLBF – Bit String, Left Bit First. 

B-Spline – A type of smooth curve (or surface) bound to its control points. 

BSS – Broadcast Satellite Services. 



BTA – Japan’s Broadcast Technology Association. A national standardsmaking 

organization comprising manufacturers and broadcasters, not 

unlike SMPTE. A proponent of an ATV system. 

BTS (Broadcast Television Systems) – A joint venture of Bosch Fernseh 

and Philips established to sell television production equipment. BTS offers 

the first multi-standard HDTV camera. 

Buckling – Deformation of the circular form of a tape pack which may be 

caused by a combination of improper winding tension, adverse storage 

conditions and/or poor reel hub configuration. 

Buffer – a) An IC that is used to restore the logic drive level. b) A circuit 

or component that isolates one electrical circuit from another. c) A digital 

storage device used to compensate for a difference in the rate of flow of 

information or the time of occurrence of events when transmitting information 

from one device to another. d) In telecommunications, a protective 

material used in cabling optical fiber to cover and protect the fiber. The 

buffer material has no optical function. 

Buffer Control – The feedback algorithms used by the encoder to avoid 

overflow of the video-rate buffer. The video-rate buffer is a FIFO which 

holds the coded video prior to output into the channel. 

Bug – An error in a computer program. Eliminating errors is known as 

debugging. 

Built-In Reference Tones – Refers to adjustment tones which are available 

within the recorder for adjusting record level and bias. 

Bulk Eraser – A device used to erase an entire tape at one time. Bulk 

erasers are usually more effective than recorders’ erase heads. 

Bumping Up – Transferring a program recorded on a lower quality videotape 

to a higher quality videotape (e.g., from Hi-8 to Betacam). Bumping up 

to a higher format allows footage to be preserved on a more stable tape 

format and makes it possible to edit in a higher-end editing environment. 

Burn – An image or pattern appearing so regularly on the screen of a picture 

tube that it ages the phosphors and remains as a ghost image even 

when other images are supposed to be shown. On computer terminals, the 

areas occupied by characters are frequently burned, particularly in the 

upper left corner. In television transmission centers, color bars are sometimes 

burned onto monitors. There is some concern that some ATV 

schemes will burn a widescreen pattern on ordinary TV sets due to 

increased vertical blanking or will burn a non-widescreen pattern on ATV 

sets due to reception of non-ATV signals. In production, refers to long-term 

or permanent image retention of camera pickup tubes when subjected to 

excessive highlights. 

Burn In Time Code – A time code that is displayed on the monitor along 

with the video it pertains to. Burn In Time Code can either be Vertical 

Interval Time Code (VITC) or Longitudinal Time Code (LTC). 

Burned-In Image – An image which persists in a fixed position in the output 

signal of a camera tube after the camera has been turned to a different 

scene. 

Burned-In Time Code – Time code numbers that are superimposed on 

the picture. 




Burn-In – Component testing method used to screen out early failures by 

running the circuit for a specified length of time. 

Burst – A small reference packet of the subcarrier sine wave, typically 8 

or 9 cycles, which is sent on every line of video. Since the carrier is suppressed, 

this phase and frequency reference is required for synchronous 

demodulation of the color information in the receiver. Refer to the 

Horizontal Timing discussion. 

Burst Gate – This signal tells the receiver valid color ready for use. 

Bus – a) Any row of video crosspoints that allow selection of various 

sources to be selected, and the associated row of buttons for such selection. 

Buses are usually associated with a given M/E or the DSK although 

they may be independent as in aux buses. Also, any row of video or key 

source selections which may or may not be selected by push buttons on a 

bus row. For example, key video selections on Ampex switchers appear on 

buses which are accessed and selected by keypads. Due to the fact that 

there is no associated row of buttons, this arrangement is called a “phantom 

bus.” b) A parallel data path in a computer. 

Bus Address – A code number sent out to activate a particular device on 

a shared serial or parallel bus interface. Also, the identification number of a 

device. 

Bus Conflict – Conflict that occurs when two or more device outputs of 

opposite logic states are placed on a three-state bus at the same time. 

Bus Controller – Generates bus commands and control signals. 

Bus Driver – An IC that is added to a bus to provide sufficient drive 

between the CPU and the other devices that are tied to the bus. These are 

necessary because of capacitive loading, which slows down the data rate 

and prevents proper time sequencing of microprocessor operation and/or 

to overcome resistive loading when fan-out requirements increase. 

Bus Keyer – A keyer that does a key on top of the bus video before the 

signal gets to the M/E. On the 4100, these are packaged as “dual bus keyers” 

and are the modules between the bus rows and the M/Es. On the AVC, 

bus keyers are integral with the M/E module, with controls in a similar 

location. 

Bus Row – Any row of video source select buttons allowing immediate 

selection of switcher video sources. 

Bus Termination – Method of preventing reflections at the end of a bus. 

Necessary only in high-speed systems. 

Buss – In video switching equipment, a wire carrying line-level signals 

(anything greater than mike level). 

Button – On a mouse, a button is a switch that you press with a finger. In 

a window on your screen, a button is a labeled rectangle that you click 

using the cursor and mouse. 

BW – See Bandwidth. 


BWF (Broadcast WAV Format) – Broadcast WAV Format is an audio file 

format based on Microsoft’s WAV Format that carries PCM or MPEG encoded 

audio. BWF adds the metadata, such as a description, originator, date 

,and coding history, needed for interchange between broadcasters. 

B-Y – One of the color difference signals used in the NTSC system, 

obtained by subtracting luminance from the blue camera signal. This is the 

signal that drives the horizontal axis of a vectorscope. The human visual 

system has much less acuity for spatial variation of color than for brightness. 

Rather than conveying RGB, it is advantageous to convey luma in one 

channel, and color information that has had luma removed in the two other 

channels. In an analog system, the two color channels can have less bandwidth, 

typically one-third that of luma. In a digital system each of the two 

color channels can have considerably less data rate (or data capacity) than 

luma. Green dominates the luma channel: about 59% of the luma signal 

comprises green information. Therefore, it is sensible, and advantageous 

for signal-to-noise reasons, to base the two color channels on blue and 

red. The simplest way to remove luma from each of these is to subtract it 

to form the difference between a primary color and luma. Hence, the basic 

video color-difference pair is (B-Y), (R-Y) [pronounced “B minus Y, R minus 

Y”]. The (B-Y) signal reaches its extreme values at blue (R = 0, G = 0, 

B = 1; Y = 0.114; B-Y = +0.886) and at yellow (R = 1, G = 1, B = 0; 

Y = 0.886; B-Y = –0.886). Similarly, the extreme of (R-Y), + –0.701, 

occur at red and cyan. These are inconvenient values for both digital and 

analog systems. The color spaces YPbPr, YCbCr, Photo YCC, and YUV are 

simply scaled versions of (Y, B-Y, R-Y) that place the extreme of the color 

difference channels at more convenient values. 

Byte – a) A complete set of quantized levels containing all of the bits. 

Bytes consisting of 8 to 10 bits per sample are typical. b) Group of eight 

bits. Can be used to represent a character. Microcomputer instructions 

require one, two, or three bytes. A word can be one or more bytes. c) A 

group of adjacent binary digits operated upon as a unit, capable of holding 

one character in the local character set, and usually shorter than a computer 

word (frequently connotes a group of eight bits). Current usage within 

the context of electronic production concerns is tending to define a byte as 

eight bits to have a consistent data unit for measuring memory capacities, 

etc. d) 8 bits. The combination of 8 bits into 1 byte allows each byte to 

represent 256 possible values. See Megabyte, Gigabyte, Terabyte. 

1 byte = 8 bits = 256 discrete values (brightness, color, etc.) 

1 kilobyte = 1,024 bytes (not 1000 bytes) 

1 megabyte = 1,048,576 bytes (not one million bytes) 

1 gigabyte = 1, 073,741,824 bytes (not one billion bytes) 

1 terabyte = 1,099,511,627,776 bytes (not one trillion bytes) 

Byte Aligned – A bit in a coded bit stream is byte-aligned if its position is 

a multiple of 8-bits from the first bit in the stream.

C 

C/N – Ratio of RF or IF signal power to noise power. 

CA (Conditional Access) – Information describing, or indicating whether 

the program is scrambled. 

Cable Equalization – The process of altering the frequency response of a 

video amplifier to compensate for high-frequency losses in coaxial cable. 

Cable Television – System that transmits original programming and programming 

of broadcast television stations, to consumers over a wired 

network. 

Calibrated Delay Fixture – This fixture is another way of measuring 

Chrominance to Luminance delay. The fixture allows the delay to be incrementally 

adjusted until there is only one peak in the baseline, indicating all 

the delay errors have been dialed out. The delay value can be read from 

the fixture while the gain can be calculated from the remaining peaks. 

Call – Jump to a subroutine. A jump to a specified address is performed, 

but the contents of the program counter are saved (usually in the stack) so 

that the calling program flow can resume when the subroutine is finished. 

Camcorder – The combination of camera and video tape recorder in one 

device. Camcorders permit easy and rapid photography and recording 

simultaneously. Camcorders are available in most home video formats: 

8 mm, Hi-8, VHS, VHS-C, S-VHS, etc. 

Camera Analysis – The measurement and evaluation of the spectral sensitivities 

of the three color channels of a television camera. The camera 

and matrixing are identified and measured. 

Camera Analysis, Ideal – For optimum image quality, both objective and 

perceived, the spectral sensitivities of the three color channels of a television 

camera should be matched to the primary colors of the R, G, B color 

space. Note: Some practice still exists matching the color channels of the 

camera to the display phosphors. This reduces the color gamut and carries 

unnecessary noise penalties. The practice is deprecated. 

Camera Chain – Television camera and associated equipment, consisting 

of power supply and sync generator. 

Camera Control Unit – Remote control device for video cameras usually 

placed in the editing suite. Controls usually include video levels, color balancing, 

and iris control. 

Camera Match – Shot-to-shot picture fidelity. Improperly matched cameras 

may exhibit differences in level, balance, colorimetry, or defects that 

will cause the picture quality to change from shot to shot. These differences 

may present problems during editing, as the editor attempts to minimize 

differences. 

Camera Supply – Most video cameras use an external DC voltage supply 

which is derived either from a battery belt worn by the camera operator, 

from a battery within the video recorder itself, or from the mains power 

supply (after voltage conversion). 

Camera Tube – See Pickup Tube. 

Candlepower – The unit measure of incident light. 



Canned – In the can, old movie term still used occasionally to mean 

finished. 

Capstan – The driven spindle or shaft in a tape recorder, sometimes the 

motor shaft itself, which rotates against the tape (which is backed up by a 

rubber pressure or pinchroller), pulling it through the machine at constant 

speed during recording and playback modes of operation. 

Capstan Idler – A rubber wheel which presses the magnetic tape against 

the capstan so that the capstan can move the tape. 

Caption – See Title. 

Capture – The process of digitizing the analog video signal. See Digitize. 

Card Guides – Narrow metal tracks at the top and bottom of the chassis 

into which you slide printed circuit boards. 

Cardioid – The quasi-heart-shaped sensitivity pattern of most unidirectional 

microphones. Hypercardioid and supercardioid microphones have 

basically similar patterns, but with longer, narrower areas of sensitivity at 

the front, and slightly increased rear sensitivity. 

Carrier – A signal which is modulated with data to be transmitted. 

Carry Flag – Flag bit in the microprocessor’s status register, which is 

used to indicate the overflow of an operation by the arithmetic logic unit. 

Cartridge – A plastic container that holds tape for easy loading into a 

matching recorder or player. 

CAS – See Conditional Access System. 

Cassette – A tape cartridge in which the tape passes from one hub to 

another. 

CAT (Conditional Access Table) – Provides information on the conditional 

access systems used. Packets having PID codes of 1 and that contain 

information about the scrambling system. See ECM and EMM. 

Cathode-Ray Tube – An electron tube assembly containing an electron 

gun arranged to direct a beam upon a fluorescent screen. Scanning by the 

beam can produce light at all points in the scanned raster. 

CATV (Community Access Television) – Acronym for cable TV, derived 

from the older term, community antenna television. Also can stand for 

Community Access TV. 

CAV (Component Analog Video) – Analog video signal format in which 

the picture information is conveyed in three signals. Refer to the definition 

for Analog Components. CAV formats include: RGB; Y, R-Y, B-Y; Y, I, Q. 

CB – Scaled version of the B-Y signal. 

CBC – See Canadian Broadcasting Corporation. 

CBPS – Coded Bits Per Symbol. 

CBR – See Constant Bit Rate. 

CC – See Closed Captioning. 

CCD – See Charge Coupled Device. 




CCETT (Centre Commun d’Etudes de Telecommunications et de 

Telediffusion, France) – The CCETT is one of the three licensors of the 

MPEG Layer II coding algorithm. The audio coding technique, originally 

developed for DAB under EUREKA 147 jointly with IRT and Philips, was 

selected by ISO/MPEG as Layer II of the MPEG-1 standard. 

CCIR (Comite Consultatif Internationale des Radiocommunications) – 

International Radio Consultative Committee, an international standards 

committee that has been absorbed by the parent body, the ITU. A permanent 

organization within the ITU with the duty to study technical and operating 

questions relating specifically to radio communications and to make 

recommendations on them. The CCIR does not prepare regulations; it 

draws up recommendations and reports, produced by experts from both 

public and private entities, which provide guidance on the best operational 

methods and techniques. The CCIR is expected to base its recommendations 

upon 150 and IEC international standards, but when no relevant one 

exists, the CCIR has been known to initiate standardization. These recommendations 

and reports provide a basis for international standardization of 

telecommunications. 

CCIR-468 – Specifies the standard for weighted and unweighted noise 

measurements. The weighted standard specifies the weighting filter and 

quasi-peak detector. The unweighted standard specifies a 22 Hz to 22 kHz 

bandwidth limiting filter and RMS detector. 

CCIR-500 – Method for the Subjective Assessment of the Quality of 

Television Pictures. CCIR-500 is a detailed review of the recommendations 

for conducting subjective analysis of image quality. The problems of defining 

perceived image quality are reviewed, and the evaluation procedures 

for interval scaling, ordinal scaling, and ratio scaling are described – along 

with the applications for which each is best employed. 

CCIR-601 – See ITU-R BT.601. 

CCIR-656 – The physical parallel and serial interconnect scheme for ITU-R 

BT.601-2-601. CCIR 656 defines the parallel connector pinouts as well as 

the blanking, sync, and multiplexing schemes used in both parallel and 

serial interfaces. Reflects definitions in EBU Tech 3267 (for 625 line signals) 

and in SMPTE 125M (parallel 525) and SMPTE 259M (serial 525). 

CCIR-6601 – Consultative Committee International Radio. A standard that 

corresponds to the 4:2:2 format. 

CCIR-709 – The recommendation considers that the HDTV studio standard 

must be harmonized with those of current and developing television systems 

and with those of existing motion-picture film. In a review of current 

systems, a consensus was identified in specifications for opto/electronic 

conversion, picture characteristics, picture scanning characteristics, and 

signal format (both analog and digital representations). Work is underway in 

the editing of national and CCIR-related documents to determine whether 

these consensus values may be affirmed in the next review of the individual 

documents. The values in Rec 709 are considered interim, and CCIR 

notes that continuing work is expected to define target parameters for 

future improved image rendition. 

CCIR-801 – At present, the first results on studies related to Study 

Programme 18U/11 have been collected. It must be recognized that these 

studies must be intensified in close cooperation with such organizations as 

the IEC and ISO to take fully into account the requirements for implementa- 


tion of HDTV for media other than broadcasting, i.e., cinema, printing, 

medical applications, scientific work, and video conferencing. In addition, 

the transmission of HDTV signals via new digital transmission channels or 

networks has to be considered and taken into account. 

CCITT (Comite Consultatif Internationale Telegraphique et 

Telephonique) – A committee of the International Telecommunications 

Union responsible for making technical recommendations about telephone 

and data communication systems for PTTs and suppliers. Plenary sessions 

are held every four years to adopt new standards. 

CCITT 0.33 – Recommendation 0.33 of the CCITT Specification for 

Measuring Equipment, Volume IV, Series O Recommendations-1988. This 

defines the automatic test sequences that are used to check on the different 

parameters that are important to signal quality. Recommendation 0.33 

has defined sequences for both monaural and stereo audio testing. Also 

called EBU Recommendation R27. 

CCK – See Composite Chroma Key. 

CCTV – See Closed Circuit TV. 

CCU – See Camera Control Unit. 

CD – Committee Draft. 

CD (Compact Disc) – A 4.75" disc used to store optical, machinereadable, 

digital data that can be accessed with a laser-based reader such 

as a CD player. 

CD-DA (Compact Disc-Digital Audio) – Standard music CDs. CD-DA 

became CD-ROMs when people realized that you could store 650 Mb of 

computer data on a 12-cm optical disc. CD-ROM drives are simply another 

kind of digital storage media for computers, albeit read-only. They are 

peripherals just like hard disks and floppy drives. (Incidentally, the convention 

is that when referring to magnetic media, it is spelled disk. Optical 

media like CDs, laserdisc, and all the other formats are spelled disc.) 

CDDI (Copper Data Distributed Interface) – A high-speed data interface, 

like FDDI but using copper. See FDDI. 

CD-I – See Compact Disc Interactive. 

CD-ROM – See Compact Disc Read Only Memory. 

CDTV – See Conventional Definition Television. 

CD-XA – CD-XA is a CD-ROM extension being designed to support digital 

audio and still images. Announced in August 1988 by Microsoft, Philips, 

and Sony, the CD-ROM XA (for Extended Architecture) format incorporates 

audio from the CD-I format. It is consistent with ISO 9660, (the volume and 

the structure of CD-ROM), is an application extension. CD-XA defines 

another way of formatting sectors on a CD-ROM, including headers in the 

sectors that describe the type (audio, video, data) and some additional info 

(markers, resolution in case of a video or audio sector, file numbers, etc.). 

The data written on a CD-XA can still be in ISO9660 file system format and 

therefore be readable by MSCDEX and UNIX CD-ROM file system translators. 

A CD-I player can also read CD-XA discs even if its file system only 

resembles ISO9660 and isn’t fully compatible. However, when a disc is 

inserted in a CD-I player, the player tries to load an executable application 

from the CD-XA, normally some 68000 application in the /CDI directory. Its 

name is stored in the disc’s primary volume descriptor. CD-XA bridge discs,

like Kodak’s Photo CDs, do have such an application, ordinary CD-XA discs 

don’t. A CD-DA drive is a CD-ROM drive but with some of the compressed 

audio capabilities found in a CD-I player (called ADPCM). This allows interleaving 

of audio and other data so that an XA drive can play audio and display 

pictures (or other things) simultaneously. There is special hardware in 

an XA drive controller to handle the audio playback. This format came from 

a desire to inject some of the features of CD-I back into the professional 

market. 

CED (Capacitance Electronic Disk) – Technology used by RCA in their 

Videodisk product. 

Cel – Refers to a transparent sheet of glass or acetate on which a “layer” 

or “level” of artwork is painted. Since the sheet is clear where there is no 

artwork, several sheets can be superimposed, allowing “automatic hiddensurface 

removal,” or simply, the “painter’s algorithm.” 

Celanar – Trade name for polyester produced by Celanese. 

Cell Compression – Cell is a compression technique developed by Sun 

Microsystems. The compression algorithms, the bit stream definition, and 

the decompression algorithms are open; that is, Sun will tell anybody who 

is interested about them. Cell compression is similar to MPEG and H.261 in 

that there is a lot of room for value-add on the compressor end. Getting 

the highest quality image from a given bit count at a reasonable amount of 

computation is an art. In addition the bit-stream completely defines the 

compression format and defines what the decoder must do and there is 

less art in the decoder. There are two flavors of Cell: the original called Cell 

or CellA, and a newer flavor called CellB. 

CellB – A video coding scheme based on quadtree decomposition of each 

image. 

CELP – See Code-Excited Linear Prediction. 

CEN (Comite Europeen de Normalisation) – European committee for 

standardization. 

CENELEC (Comite Europeen de Normalisation Electrotechnique) – 

European committee for electrotechnical standardization. 

Central Processing Unit – Computer module in charge of fetching, 

decoding, and executing instructions. It incorporates a control unit, an ALU, 

and related facilities (registers, clocks, drivers). 

Centralized Network – A network where a central server controls services 

and information; the server is maintained by one or more individuals 

called network administrators. On a centralized network that uses NIS, this 

server is called the NIS master, and all other systems on the network are 

called NIS clients. See also Network Administrator, NIS, NIS Client, NIS 

Domain, and NIS Master. 

Ceramic Microphone – See Piezoelectric Microphone. 

Certified Tape – Tape that is electrically tested on a specified number of 

tracks and is certified by the supplier to have less than a certain total number 

of permanent errors. 

Certifier – Equipment that evaluates the ability of magnetic tape to record 

and reproduce. The equipment normally counts and charts each error on 

the tape, including level and duration of dropouts. In the Certify Mode, it 



stops on error to allow for visually inspecting the tape to see if the error 

cause is correctable or permanent. 

CES (Consumer Electronics Show) – A semi-annual event sponsored by 

the Consumer Electronics Group of EIA, at which IDTV and HDTV schemes 

have been demonstrated. 

CG – See Character Generator. 

Channel – a) An independent signal path. Stereo recorders have two such 

channels. Quadraphonic ones have four. b) A digital medium that stores or 

transports a digital television stream. c) A term mainly used to describe the 

configuration of audio tracks. For Dolby Digital there are six channels (left, 

center, right, left rear, right rear and low frequency effects). For linear PCM 

and MPEG audio, there are eight channels. All DVD players are required to 

have a two-channel downmix output, which is a stereo version produced 

from the intrinsic channels on the disc if there are more than two channels 

on the disc. 

Channel Code – A modulation technique that converts raw data into a signal 

that can be recorded or transmitted by radio or cable. 

Channel Coding – a) Describes the way in which the 1’s and 0’s of the 

data stream are represented on the transmission path. b) Refers to any 

processing to use a particular communication channel or medium. 

Examples are forward error correction coding and prioritization of different 

parts of the coded video bit stream. 

Channel Stuffing – Techniques for adding information to an NTSC channel 

without increasing its bandwidth or eliminating its receiver-compatibility. 

Channel-Compatible – An ATV transmission scheme that will fit within 

the confines of a standard, 6 MHz NTSC transmission channel. A higher 

level of channel-compatibility demands NTSC-like AM-VSB transmission so 

that the ATV channel will not cause any interference to other channels that 

would not otherwise be caused by an NTSC channel. Channel-compatible 

ATV schemes need not necessarily also be receiver-compatible. 

CHAP – Challenge Handshake Authentication Protocol. 

Chapter – A chapter in a video disc is a section divider. Chapters are subsets 

of the video disc. In the DVD format, a chapter is a division of a title. 

Chapter Stop – Programming that allows a viewer to jump immediately to 

a particular part of a title. A book with chapters is the common metaphor 

for a DVD. 

Character Generator (CG) – a) A computer used to electronically generate 

text and sometimes graphics for video titles or captions which can be 

superimposed over a video signal. Text is usually entered via a keyboard, 

allowing selection of various fonts, sizes, colors, styles, and background 

colors, then stored as multiple pages for retrieval. b) An electronic device 

that generates video letters for use as captions in television productions. 

The output of the character generator is often used as an external key 

input to the switcher. c) Circuit that forms the letters or numbers on a display 

or printer. 

Characteristic – An aspect or parameter of a particular television system 

that is different from another system’s, but not necessarily a defect. 

Characteristics include aspect ratio, colorimetry, resolution, and sound 

bandwidth. 




Charge Coupled Device (CCD) – a) A semiconductor device that converts 

optical images to electronic signals. CCDs are the most commonly 

found type of image sensor in consumer camcorders and video cameras. 

b) Serial storage technology that uses MOS capacitors. c) A solid-state 

image sensor that converts light energy to electricity. 

C-HDTV (Cable HDTV) – A seemingly impossible concept calling for channel-compatible 

ATV transmission of 850 lines of both static and dynamic 

horizontal and vertical resolution, among other characteristics. Its feasibility 

is being studied at ATRP. 

Check Box – Used to select from a list of related items. An “x” marks the 

selected options in the corresponding box. (Select as many items as 

desired – one, none, or all.) 

Checkerboard – Automatic assembly process where all edits from mounted 

reels are made, and edits for unmounted reels are skipped. Example: 

Reels 5, 29, and 44 are mounted on VTRs. The editing system looks at the 

list and assembles all edits that have reel numbers 5, 29, and 44 assigned 

to them, inserting these events at the exact spot on the master tape where 

they belong. 

Checksum – a) An error-detecting scheme which is the sum of the data 

values transmitted. The receiver computes the sum of the received data 

values and compares it to the transmitted sum. If they are equal, the transmission 

was error-free. b) Method used to verify the integrity of data 

loaded into the computer. c) A simple check value of a block of data, calculated 

by adding all the bytes in a block. It is easily fooled by typical 

errors in data transmission systems, so that for most applications, a more 

sophisticated system such as CRC is preferred. 

Chip – Common name for all ICs. 

Chip Chart – A black and white test chart. It contains “chips” in varying 

intensities, that make up a gray scale. It is used to check the gray scale 

taking characteristics of a camera, including the parameter of gamma. 

Chip Enable (CE) – See Chip Select. 

Chip Select (CS) – Usually enables three-state drivers on the chip’s output 

lines. Most LSI chips have one or more chip selects. The CS line is 

used to select one chip among many. 

Choose – Choose means make a choice to select an action that will take 

place, i.e., press the left mouse button to bring up a pop-up menu, move 

the cursor to highlight the command that you want to run, then release the 

button. 

Chroma – a) The depth or saturation of color. The saturation control 

adjusts the amplitude of color of the switcher’s matte and background outputs. 

b) The (M) NTSC or (B, D, G, H, I) PAL video signal contains two 

pieces that make up what you see on the screen: the black and white 

(luma) part, and the color part. Chroma is the color part. Chroma can be 

further broken down into two properties of color: hue and saturation. 

Chroma can also be described as a matrix, block, or single pel representing 

one of the two color difference signals related to the primary colors in 

the manner defined in the bit stream. The symbols used for the color difference 

signals are Cr and Cb. 

Chroma Bandpass – In an (M) NTSC or (B, D, G, H, I) PAL video signal, 

the luma (black and white) and the chroma (color) information are com- 


bined together. To decode an NTSC or PAL video signal, the luma and chroma 

must be separated. The chroma bandpass filter removes the luma from 

the video signal, leaving the chroma relatively intact. This works fairly well 

except in certain images where the luma information and chroma information 

overlap, meaning chroma and luminance information occupy the same 

frequency space. Depending on the filtering technique used, it can be difficult 

for the filter to separate the chroma from the luminance information. 

This results in some luminance information being interpreted as chroma 

and some chroma information being interpreted as luminance. The effects 

of this improper separation of luminance and chroma are especially noticeable 

when the television scene contains objects with thin, closely spaced 

black and white lines. As the camera moves across this object, a rainbow 

of colors will appear in the object indicating the improper separation of the 

luminance and chroma information. 

Chroma Burst – See Color Burst. 

Chroma Comp – A deliberate distortion of colors usually used to achieve 

unusual matching. By detecting the quadrant the color is in (by normally 

deciding whether R-Y and B-Y are positive or negative), the amplitude of R- 

Y, B-Y just for colors in that quadrant can be changed; hence, the hue and 

saturation can be changed for those colors without affecting others. 

Chroma Corrector – A device used to correct problems related to the 

chroma of the video signal, as well as color balance and color noise. 

Chroma Crawl – An NTSC artifact also sometimes referred to as moving 

dots; a crawling of the edges of saturated colors in an NTSC picture. 

Chroma Crawl is a form of cross-luminance, a result of a television set 

decoding color information as high-detail luminance information (dots). 

Most ATV schemes seek to eliminate or reduce chroma crawl, possibly 

because it is so immediately apparent. 

Chroma Demodulation – The process of removing the color video information 

from a composite video signal where chrominance information is 

modulated on a color subcarrier. The phase reference of the subcarrier, is 

color burst which is a phase-coherent sample of the color subcarrier. 

Chroma Demodulator – Refer to the NTSC Composite Receiver Model at 

the end of this glossary when studying this definition. After the (M) NTSC or 

(B, D, G, H, I) PAL video signal makes its way through the Y/C separator, by 

either the chroma bandpass, chroma trap, or comb filter method, the colors 

are then decoded by the chroma demodulator. Using the recovered color 

subcarrier, the chroma demodulators take the chroma output of the Y/C 

separator and recovers two color difference signals (typically I and Q or U 

and V). 

Chroma Flutter – A rapid coherent variation in the chroma saturation. 

Chroma Format – Defines the number of chrominance blocks in a macroblock. 

Chroma Key (CK) – a) A method of combining two video images. The 

most common example of chroma keying is the news weather person 

standing in front of a weather map. The details of the process are, a camera 

is pointed at the weather person who is standing in front of a bright 

blue or green background. The weather person and bright-blue or green 

background image is fed into a computing device along with the image of 

the weather map. Wherever the computing device sees the bright-blue or 

green background, it displays the weather map. Wherever the computing

device does not see bright blue or green, it shows the weather person. 

b) A process for controlling the overlay of one video image over another, 

the areas of overlay being defined by a specific color or chrominance in 

one of the images. More versatility is available when working in the digital 

mode than in the analog since the color to define the effective mask can 

be more precisely specified. Effective use of chroma key frequently 

required high definition in the color image and, therefore, full bandwidth R, 

G, B is preferred. Linear key provides an alternate method for control of the 

overlay. c) Chroma keying is the process of controlling the overlay of one 

video image over another. The overlay is defined by a specific color or 

chrominance in one of the images. 

Chroma Noise – Noise that manifests itself in a video picture as colored 

snow. 

Chroma Nulling – A process of generating a matte color 180 degrees out 

of phase with a background color and summing them, hence removing all 

color. 

Chroma Resolution – The amount of color detail available in a television 

system, separate from any brightness detail. In almost all television 

schemes, chroma resolution is lower than luminance resolution, matching 

visual acuity. Horizontal chroma resolution is only about 12 percent of luminance 

resolution in NTSC; in advanced schemes it is usually 50 percent. 

See also Resolution. 

Chroma Simulcast – A type of scalability (which is a subset of SNR scalability) 

where the enhancement layer(s) contain only coded refinement data 

for the DC coefficients and all the data for the AC coefficients of the chroma 

components. 

Chroma Trap – In an (M) NTSC or (B, D, G, H, I) PAL video signal, the 

luma (black and white) and the chroma (color) information are combined 

together. To decode the video signal, the luma and chroma must be separated. 

The chroma trap is a method of doing this. 

Chrominance – a) The data that represents one of the two colordifference 

signals Cr and Cb. b) Chrominance refers to the color information 

in a television picture. Chrominance can be further broken down into 

two properties of color: hue and saturation. See Chroma. 

Chrominance Frequency Response – Describes the frequency response 

of the chrominance channel. 

Chrominance Luminance Delay Inequality – When a test signal having 

defined chrominance and luminance components is applied to the sending 

end of a television facility, chrominance-luminance delay inequality appears 

(at the receiving end) as the change in relative timing of the chrominance 

component relative to the luminance component of the test signal. 

Chrominance Luminance Gain Inequality – When a test signal having 

defined chrominance and luminance components is applied to the sending 

end of a television facility, chrominance-luminance gain inequality appears 

(at the receiving end) as the change in amplitude of the color component 

relative to the luminance component (of the test signal). 

Chrominance Nonlinear Gain – This distortion is present if chrominance 

gain is affected by chrominance amplitude. Chrominance nonlinear gain 

distortion is expressed in IRE or percent. It should be measured at different 

APL (Average Picture Level) and typically the worst error is quoted. Picture 



effects include incorrect color saturation due to nonlinear gain in relatively 

high amplitude chrominance signals. The modulated pedestal test signal is 

used to test for this distortion. 

Chrominance Nonlinear Phase – This distortion is present if a signal’s 

chrominance phase is affected by chrominance amplitude. These phase 

errors are a result of the system’s inability to uniformly process all amplitudes 

of high-frequency chrominance information. Chrominance nonlinear 

phase distortion is expressed in degrees of shift of subcarrier phase. This 

parameter should be measured at different APL (Average Picture Level); the 

worst result is quoted as the amount of distortion. Chrominance nonlinear 

phase distortion will cause picture hue to shift as color saturation increases. 

A modulated pedestal signal is used to measure this distortion. The 

modulated pedestal signal consists of three chrominance packets with the 

same phase and luminance level but each chrominance packet has 

increasing amplitudes of 20, 40, and 80 IRE. 

Chrominance Signal – The high-frequency portion of the video signal 

which is obtained by quadrature amplitude modulation (QAM) of a 

4.43 MHz (PAL) or 3.579545 MHz (NTSC) subcarrier with R-Y and B-Y 

information. 

Chrominance Subsampling – Reduction of the amount of color information 

by either rejecting chrominance samples or by averaging adjacent 

chrominance samples. 

Chrominance to Burst Phase – The difference between the expected 

phase and the actual phase of the chrominance portion of the video signal 

relative to burst phase. 

Chrominance to Luminance Delay Distortion – The difference between 

the time it takes for the chrominance portion of the signal to pass through 

a system and the time it takes for the luminance portion to pass through. 

The amount of distortion is expressed in units of time, typically nanoseconds. 

The number is positive for delayed chrominance and negative for 

advanced chrominance. This distortion manifests itself in the picture as 

smearing or bleeding of the color particularly at the edges of objects in the 

picture. It may also cause poor reproduction of sharp luminance transitions. 

Any signal containing a 12.5T sine-squared pulse with 3.579545 

MHz modulation can be used to measure chrominance-to-luminance delay 

distortions. Many combination signals such as FCC Composite and NTC-7 

Composite contain this pulse. 

Chrominance to Luminance Gain Distortion – The difference between 

the gain of the chrominance components and the gain of the luminance 

components as they pass through the system. The amount of distortion can 

be expressed in IRE, percent, or dB. The number given is negative for low 

chrominance and positive for high chrominance. This distortion most commonly 

appears as attenuation or peaking of the chrominance information 

that shows up in the picture as incorrect color saturation. Any signal containing 

a 12.5T sine-squared pulse with 3.579545 MHz modulation can be 

used to measure chrominance-to-luminance gain distortions. Many combination 

signals such as FCC Composite and NTC-7 Composite contain this 

pulse. 

Chrominance to Luminance Intermodulation – This distortion is also 

known as crosstalk or cross-modulation. Splice is present when luminance 

amplitude is affect by the superimposed chrominance. The luminance 




change may be caused by clipping of high-amplitude chrominance peaks, 

quadrature distortion or crosstalk. The modulated pedestal is used to test 

for this distortion. Distortions can be expressed as: IRE with the pedestal 

level normalized to 50 IRE, as a percentage of the pedestal level, as a percentage 

of the measured white bar amplitude, as a percentage of 714 mV. 

These definitions will yield different results under some conditions so it is 

very important to standardize on a single method of making intermodulation 

measurements. Picture effects include unwarranted brightness variations 

due to color saturation changes affecting the luminance. 

Chromium Dioxide (CrO2 ) – A modern magnetic particle oxide of the high 

energy type used in magnetic recording tape. Chromium dioxide is a highly 

acicular particle with the crystal structure of rutile. Tapes made of CrO2 exhibit a coercivity of 425 to 475 oersteds. 

CI – Common Interface. 

CIE (Commission Internationale de l’Eclairage) – French acronym for 

the International Illumination Commission. An international standardization 

organization that created the chromaticity diagrams (color charts) used to 

define the colorimetry of all television systems. The CIE is concerned with 

methods of measurement plus recommended practices and standards concerning 

the properties and applications of light. 

CIE 1931 Standard Colorimetric System (XYZ) – A system for determining 

the tristimulus values of any spectral power distribution using the 

set of reference color stimuli X, Y, Z, and the three CIE color matching 

functions x(lambda), y(lambda), z(lambda), adopted by the CIE in 1931. 

CIELab Color Space – Three-dimensional, approximately uniform color 

space produced by plotting in rectangular coordinates L*, a*, b* quantities 

defined by the following equations. X, Y, Z describe the color stimulus considered, 

and Xn, Yn, Zn describe a specified white achromatic stimulus 

(i.e., white reference). Equal distances in the color space represent approximately 

equal color differences. 

L* = 116 (Y/Yn)^(1/3) – 16 Y/Yn 

a* = 500 [(X/Xn^(1/3) – (Y/Yn)^(1/3)] X/Xn > 0.008 856 ] b* = 200 {(Y/Yn)^(1/3) – (Z/Zn)^(1/3)] Z/Zn 

CIELuv Color Space – Three-dimensional, approximately uniform color 

space produced by plotting in rectangular coordinated L*, u*, v* quantities 

defined by the following equations. Y, u', v' describe the color stimulus 

considered, and Yn, u'n, v'n describe a specified white achromatic stimulus 

(white reference). The coordinates of the associated chromaticity diagram 

are u' and v'. L* is the approximate correlation of lightness, u* and v* are 

used to calculate an approximate correlate of chroma. Equal distances in 

the color space represent approximately equal color differences. 

L* = 116 (Y/Yn)^(1/3) – 16 Y/Yn > 0.008 856 

u* = 13 L * (u' – u'n) 

v* = 13 L * (v' – v'n) 

CIF – See Common Image Format, Common Interchange Format, Common 

Interface Format, or Common Intermediate Format. 

Cinching – Longitudinal slippage between the layers of tape in a tape 

pack when the roll is accelerated or decelerated. 

CinemaScope – The first modern widescreen movie format, achieving a 

2.35:1 aspect ratio through the use of a 2:1 anamorphic squeeze. 


CinePak – CinePak is a compression scheme dedicated to PC environments, 

based on a vector quantization algorithm. CinePak is a highly asymmetrical 

algorithm, i.e., the encoding takes much more processing power 

than the decoding process. The CinePak algorithm is developed by Radius, 

and is licensed by a range of companies. Both Microsoft Windows 95 

and Apple’s QuickTime have built in CinePak, for instance. 

CK – See Chroma Key. 

Clamp – a) A device which functions during the horizontal blanking or 

sync interval to fix the level of the picture signal at some predetermined 

reference level at the beginning of each scanning line. b) Also known as a 

DC-restoration circuit, or it can also refer to a switch used within the DCrestoration 

circuit. When used in the context of DC restoration, it is usually 

used as “clamping.” When used in its switch context, it is referred to as 

just “clamp.” 

Clamper – A device which functions during the horizontal blanking or sync 

interval to fix the level of the picture signal at some predetermined reference 

level at the beginning of each scanning line. 

Clamping – a) The process that establishes a fixed level for the picture 

signal at the beginning of each scanning line. b) The process whereby a 

video signal is referenced or “clamped” to a DC level to prevent pumping 

or bouncing under different picture levels. Without clamping, a dark picture 

would bounce if a white object appeared. Changes in APL would cause 

annoying pulsations in the video. Clamping is usually done at zero DC level 

on the breezeway of the back porch of horizontal sync. This is the most 

stable portion of a TV picture. 

Clean Rooms – Rooms whose cleanliness is measured by the number of 

particles of a given size per cubic foot of room volume. For example, a 

class 100,000 clean room may have no more than 100,000 particles onehalf 

micron or larger per cubic foot. Similarly, for class 10,000 and class 

100 rooms. In addition, a class 10,000 room may have no more than 65 

five-micron particles per cubic foot, while class 100,000 may have no 

more than 700.¨ 

Clear – Set a circuit to a known state, usually zero. 

Clear Channel – AM radio station allowed to dominate its frequency with 

up to 50 kW of power; their signals are generally protected for distance of 

up to 750 miles at night. 

Click – To hold the mouse still, then press and immediately release a 

mouse button. 

Click and Drag – A computer term for the user operation of clicking on 

an item and dragging it to a new location. 

Cliff Effect – An RF characteristic that causes DTV reception to change 

dramatically with a small change in power. At the fringes of reception, current 

analog TV pictures degrade by becoming “snowy.” With DTV, relatively 

small changes in received power in weak signal areas will cause the DTV 

picture to change from perfect to nothing and hence the name, cliff effect. 

Clip – a) A video file. b) In keying, the trigger point or range of a key 

source signal at which the key or insert takes place. c) The control that 

sets this action. to produce a key signal from a video signal, a clip control 

on the keyer control panel is used to set a threshold level to which the 

video signal is compared. d) In digital picture manipulators, a manual

selection that blanks portions of a manipulated image that leave one side 

of the screen and “wraps” around to enter the other side of the screen. 

e) In desktop editing, a pointer to a piece of digitized video or audio that 

serves as source material for editing. 

Clip (Insert Adjust) – To produce a key signal from a video signal, a clip 

insert control on the front panel is used to set a threshold level to which 

the video signal is compared. In luminance keying, any video (brightness) 

level above the clip level will insert the key; any level below the clip level 

will turn the key off. The clip level is adjusted to produce an optimum key 

free of noise and tearing. In the Key Invert mode, this clip relationship is 

reversed, allowing video below the clip level to be keyed in. This is used for 

keying from dark graphics on a light background. 

Clip Level – The level that determines at what luminance a key will cut its 

hole. On AVC switchers, these are the insert and border adjust controls. On 

4100 series, the corresponding controls are foreground and background. 

See Bi-Level Keyer. 

Clip Sheet – A nonlinear editing term for the location of individual 

audio/video clips (or scenes). Also known as clip bin. 

Clipping – a) An electronic limit usually imposed in cameras to avoid 

overly bright or dark signals. When improperly applied, can result in loss of 

picture information in very bright or very dark areas. Also used in switchers 

to set the cutoff point for mixing video signals. b) The electronic process of 

shearing off the peaks of either the white or black excursions of a video 

signal for limiting purposes. Sometimes, clipping is performed prior to 

modulation, and sometimes to limit the signal so it will not exceed a predetermined 

level. 

Clipping Logic – Circuitry used to prevent illegal color conversion. Some 

colors can be legal in one color space but not in another. To ensure a converted 

color is legal in one color format after being converted (transcoded) 

from another, the clipping logic clips the information until a legal color is 

represented. 

Clock – Reference timing source in a system. A clock provides regular 

pulses that trigger or synchronize events. 

Clock Doubling – Many processor chips double the frequency of the clock 

for central processing operations while maintaining the original frequency 

for other operations. This improves the computer’s processing speed without 

requiring expensive peripheral chips like high-speed DRAM. 

Clock Frequency – The master frequency of periodic pulses that are used 

to synchronize the operation of equipment. 

Clock Jitter – a) Timing uncertainty of the data cell edges in a digital signal. 

b) Undesirable random changes in clock phase. 

Clock Phase Deviation – See Clock Skew. 

Clock Recovery – The reconstruction of timing information from digital 

data. 

Clock Skew – A fixed deviation from proper clock phase that commonly 

appears in D1 digital video equipment. Some digital distribution amplifiers 

handle improperly phased clocks by reclocking the output to fall within D1 

specifications. 



Close Miking – Placing a mike close to the sound source in order to pick 

up mainly direct sound and avoid picking up reverberant sound. 

Closed Captioning – Service that provides decoded text information 

transmitted with the audio and video signal and displays it at the bottom of 

the display. See (M) NTSC EIA-608 specification. Transmitted on line 21 of 

NTSC/525 transmissions, contains subtitling information only. CC has no 

support for block graphics or multiple pages but it can support 8-colors 

and the use of an italic typeface. Frequently found on pre-recorded VHS 

cassettes and LDs, also used in broadcast. Also found on PAL/625 prerecorded 

VHS cassettes in a modified version. 

Closed Circuit – The method of transmission of programs or other material 

that limits its target audience to a specific group rather than the general 

public. 

Closed Circuit TV – A video system used in many commercial installations 

for specific purposes such as security, medical, and educational. 

Closed GOP – A group of pictures in which the last pictures do not need 

data from the next GOP for bidirectional coding. Closed GOP is used to 

make a splice point in a bit stream. 

Closed-Loop – Circuit operating with feedback, whose inputs are a function 

of its outputs. 

Closed-Loop Drive – A tape transport mechanism in which the tape’s 

speed and tension are controlled by contact with a capstan at each end of 

the head assembly. 

Closeup – A camera shot that is tightly framed, with its figure or subject 

filling the screen. Often qualified as medium closeup or extreme closeup. 

CLUT – See Color Lookup Table. 

C-MAC – A MAC (Multiplexed Analog Component) with audio and data time 

multiplexed after modulation, specified for some European DBS. See also 

MAC. 

CMTT – French acronym for the Mixed Telephone and Television 

Committee, an international standardization committee concerned with 

such issues as B-ISDN. 

CMYK – The designation for the subtractive color system used in pigment 

printers. CMYK refers to the colors that make up the system – Cyan, 

Magenta, Yellow, and black. In the CMYK subtractive color system, cyan, 

magenta, yellow, and black pigments or inks are applied to a white surface 

to filter that color light information from the white surface to create the 

final color. Black is used because cyan, magenta, and yellow cannot be 

combined to create a true black; rather it is a muddy brown. 

CMYK Color Space – A subtractive color space with cyan, magenta, and 

yellow as primary color set with an optional addition of black (K). For such 

a color set, subtractive color mixture applies. The CMYK values used represent 

the amount of colorant placed onto the background medium. They 

include the effects of dot gain. 

CNR (Carrier-to-Noise Ratio) – Indicates how far the noise level is down 

on carrier level. 

Coating – The magnetic layer of a magnetic tape, consisting of oxide particles 

held in a binder that is applied to the base film. 




Coating Resistance – The electrical resistance of the coating measured 

between two parallel electrodes spaced a known distance apart along the 

length of tape. 

Coating Thickness – The thickness of the magnetic coating applied to 

the base film of a mag tape. Modern tape coatings range in thickness from 

170 to 650 microinches. Coating thickness is normally optimized for the 

intended application. In general, thin coatings give good resolution at the 

expense of reduced output at long wavelengths; thick coatings give a high 

output at long wavelengths at the expense of degraded resolution. 

Coaxial Cable – a) A transmission line with a concentric pair of signal 

carrying conductors. There is an inner conductor and an outer conductor 

metallic sheath. The sheath aids in preventing external radiation from 

affecting the signal on the inner conductor and minimizes signal radiation 

from the transmission line. b) A large cable composed of fine foil wires 

that is used to carry high bandwidth signals such as cable TV or cable 

modem data streams. 

Cobalt Doped Oxide – A type of coating used on magnetic recording 

tape. This is normally a gamma ferric oxide particle which has been doped 

with cobalt to achieve a higher coercivity. Modern forms of this oxide are 

acicular and have been used to make tapes with coercivities in excess of 

1000 oersteds. 

Co-Channel Interference – Interference caused by two or more television 

broadcast stations using the same transmission channel in different cities. 

It is a form of interference that affects only broadcast television. 

Code – a) In computers, the machine language itself, or the process of 

converting from one language to another. b) A plan for representing each 

of a finite number of values or symbols as a particular arrangement or 

sequence of discrete conditions or events. To encode is to express given 

information by means of a code. c) A system of rules defining a one-to-one 

correspondence between information and its representation by characters, 

symbols, or signal elements. 

CODEC (Coding/Decoding) – a) The algorithm used to capture analog 

video or audio onto your hard drive. b) Used to implement the physical 

combination of the coding and decoding circuits. c) A device for converting 

signals from analog to coded digital and then back again for use in digital 

transmission schemes. Most codecs employ proprietary coding algorithms 

for data compression. See Coder-Decoder. 

Coded Order – The order in which the pictures are stored and decoded. 

This order is not necessarily the same as the display order. 

Coded Orthogonal Frequency-Division Multiplex – A modified form of 

OFDM. A modulation scheme used for digital transmission that is employed 

by the European DVB system. It uses a very large number of carriers (hundreds 

or thousands), each carrying data at a very low rate. The system is 

relatively insensitive to doppler frequency shifts, and can use multipath signals 

constructively. It is, therefore, particularly suited for mobile reception 

and for single-frequency networks. 

Coded Representation – A data element as represented in its encoded 

form. 

Code-Excited Linear Prediction – Audio encoding method for low-bit 

rate codecs. 


Coder-Decoder – Used to implement the physical combination of the coding 

and decoding circuits. 

Coding – Representing each level of a video or audio signal as a number, 

usually in binary form. 

Coding Parameters – The set of user-definable parameters that characterize 

a coded video bit stream. Bit streams are characterized by coding 

parameters. Decoders are characterized by the bit streams that they are 

capable of decoding. 

Coefficient – a) A number (often a constant) that expresses some property 

of a physical system in a quantitative way. b) A number specifying the 

amplitude of a particular frequency in a transform. 

Coefficient of Friction – The tangential force required to maintain 

(dynamic coefficient) or initiate (static coefficient) motion between two surfaces 

divided by the normal force pressing the two surfaces together. 

Coefficient of Hygroscopic Expansion – The relative increase in the linear 

dimension of a tape or base material per percent increase in relative 

humidity measured in a given humidity range. 

Coefficient of Thermal Expansion – The relative increase in the linear 

dimension of a tape or base material per degree rise in temperature (usually 

Fahrenheit) measured in a given temperature range. 

Coercivity – Measured in oersteds, the measurement of a magnetic characteristic. 

The demagnetizing force required to reduce the magnetic induction 

in a magnetic materiel to zero from its saturated condition. 

COFDM (Coded Orthogonal Frequency Domain Multiplex) – Up to 

6875 single carriers 1 kHz apart are QAM modulated with up to 64 states. 

“Coded” means that the data to be modulated has error control. 

Orthogonality means that the spectra of the individual carriers do not influence 

each other as a spectral maximum always coincides with a spectrum 

zero of the adjacent carriers. A single-frequency network is used for the 

actual transmission. 

Collision – The result of two devices trying to use a shared transmission 

medium simultaneously. The interference ruins both signals, requiring both 

devices to retransmit the data lost due to collision. 

Color Back Porch – Refer to the Horizontal Timing discussion. 

Color Background Generator – a) A circuit that generates a full-field 

solid color for use as a background in a video picture. b) A device that produces 

a full-frame color, normally used as a background for various graphics 

effects, the output of which is selectable on the last button of all 

switcher buses. 

Color Balance – Adjustment of color in the camera to meet a desired 

standard, i.e., color bar, sponsor’s product, flesh tones. Also may be 

referred to as “white balance.” 

Color Bar Test Signal – Originally designed to test early color camera 

encoders, it is commonly (albeit incorrectly) used as a standard test signal. 

The saturated color bars and luminance gray bar are usually used to check 

monitors for color accuracy. The saturated color bars are a poor test of any 

nonlinear circuit or system and at best, show video continuity. Testing a 

video system using color bars is analogous to testing an audio system 

using a simple set of monotonal frequencies. Many color TV test signals

have been developed to accurately assess video processing equipment 

such as ADCs, compressors, etc. 

Color Bars – A video test signal widely used for system and monitor 

setup. The test signal, typically containing eight basic colors: white, yellow, 

cyan, green, magenta, red, blue, and black, is used to check chrominance 

functions of color TV systems. There are two basic types of NTSC color bar 

signals in common use. The terms “75% bars” and “100% bars” are generally 

used to distinguish between the two types. While this terminology is 

widely used, there is often confusion about exactly which parameters the 

75% versus 100% notation refer to. a) RGB Amplitudes: The 75%/100% 

nomenclature specifically refers to the maximum amplitudes reached by 

the Red, Green, and Blue signals when they form the six primary and secondary 

colors required for color bars. For 75% bars, the maximum amplitude 

of the RGB signals is 75% of the peak white level. For 100% bars, the 

RGB signals can extend up to 100% of peak white. Refer to the following 

two figures. b) Saturation: Both 75% and 100% amplitude color bars are 

100% saturated. In the RGB format, colors are saturated if at least one of 

the primaries is at zero. Note: In the two associated figures that the zero 

signal level is at setup (7.5 IRE) for NTSC. c) The Composite Signal – In 

the composite signal, both chrominance and luminance amplitudes vary 

according to the 75%/100% distinction. However, the ratio between 

chrominance and luminance amplitudes remains constant in order to maintain 

100% saturation. d) White Bar Levels – Color bar signals can also 

have different white bar levels, typically either 75% or 100%. This parameter 

is completely independent of the 75%/100% amplitude distinction and 

either white level may be associated with either type of bars. e) Effects of 

Setup – Because of setup, the 75% signal level for NTSC is at 77 IRE. The 

maximum available signal amplitude is 100 – 7.5 or 92.5 IRE. 75% of 



92.5 IRE is 69.4 IRE, which when added to the 7.5 IRE pedestal yields a 

level of approximately 77 IRE. 

100% 

Red 

Signal 

7.5% 

0% 

100% 

Green 

Signal 

7.5% 

0% 

100% 

Blue 

Signal 

Red 

Signal 

Green 

Signal 

Blue 

Signal 

7.5% 

0% 

White 

Yellow 

Cyan 

Green 

100% 

77% 

7.5% 

0% 

100% 

77% 

7.5% 

0% 

100% 

77% 

7.5% 

0% 

White 

Yellow 

Cyan 

Green 

Black 

Blue 

Red 

Magenta 

Black 

Blue 

Red 

Magenta 




Color Black – A composite video signal that produces a black screen 

when viewed on a television receiver. 

Color Burst – a) The portion of a color video signal that resides on the 

backporch between the breezeway and the start of active video that contains 

a sample of the color subcarrier used to add color to a signal. It is 

used as a color synchronization signal to establish a reference for the color 

information following it and is used by a color monitor to decode the color 

portion of a video signal. The color burst acts as both amplitude and phase 

reference for color hue and intensity. The color oscillator of a color television 

receiver is phase locked to the color burst. b) A nine-cycle-NTSC 

burst of color subcarrier which is imposed on blanking after sync. Color 

burst serves as the reference for establishing the picture color. 

Color Coordinate Transformation – Computation of the tristimulus values 

of colors in terms of one set of primaries from the tristimulus values of 

the same colors in another set of primaries. Note: This computation may be 

performed electrically in a color television system. 

Color Correction – a) A process by which the coloring in a television 

image is altered or corrected electronically. Care must be taken to ensure 

that the modified video does not exceed the limits of subsequent processing 

or transmission systems. b) The adjustment of a color reproduction 

process to improve the perceived-color conformity of the reproduction to 

the original. 

Color Decoder – A device that divides a video signal into its basic color 

components. In TV and video, color decoding is used to derive signals 

required by a video monitor from the composite or Y/c.a. signals. See 

Chroma Demodulators. 

Color Demodulator – See Chroma Demodulators. 

Color Difference Signals – Signals used by color television systems to 

convey color information (not luminance) in such a way that the signals go 

to zero when there is no color in the picture. Color difference signal formats 

include: R-Y and B-Y; I and Q; U and V; PR and PB . The figure below 

shows general color difference waveforms along with the Y signal. The 

color difference signals must first be converted in their RGB form before 

they can recreate the picture. Refer to the RGB discussion to view what the 

RGB version of the color bar signal looks like. The color difference signals 

in the figure are centered around 0 volts, but this is only true for the 

SMPTE/EBU N10 standard. The NTSC and M11 color difference standards 

have the most negative portions of the color difference signals riding on a 

voltage of 0 volts or close to it. 

Color Edging – Spurious colors appearing along the edges of color pictures, 

but that do not have a color relationship to the picture. 


Y P B, B-Y, V or Q P R, R-Y, U or I 

Color Encoder – Performs the reverse function of the chroma demodulator 

in that it combines the two color difference signals into the single chroma 

signal. 

Color Frame – a) In NTSC color television, it takes four fields to complete 

a color frame. In PAL, it takes eight fields. b) Polarity of the video frame. 

Color frame must alternate polarity with each frame to keep the video signal 

in phase. 

Color Frame Timed – See the Color Framed discussion. 

Color Framed – Two signals are said to be color framed at a switcher or 

router when their field 1, line 10 events (field 1, line 7 in PAL) occur at the 

same time at the input to the switcher or router. To prevent picture distortions 

when changing signals at a switcher or router, the signals must be 

color framed. 

Color Gamut – In a system employing three color primaries to encode 

image color, each primary can be located on a CIE chromaticity diagram 

and these points connected as a plane figure. If the apexes are then connected 

with an appropriate value on the white point axis, a so) id figure is 

produced enclosing the color gamut for that system. (On the CIE chromaticity 

diagrams, the points in x, y, z space approximate an inverted tetrahedron. 

In u, v, w space, they become a somewhat irregular four-cornered 

solid.) Colors within the color gamut solid volume can be reproduced by the 

system as metameric matches. Colors outside the color gamut solid volume 

cannot be matched. Note: The area of the cross-section from the color 

gamut solid is a function of the luminance. Although it is advantageous to 

have the widest possible color gamut for the ability to provide metameric 

matches for the largest number of colors, the required transformations 

from origination colorimetry to colorimetry matched to available display primaries, 

for example, may require large matrix coefficients and, therefore, a 

signal-to-noise penalty. The choice of color gamut is a compromise 

between color rendition and signal-to-noise. 

Color Key – See Chroma Key. 

Color Killer – Circuitry which disables the receiver’s color decoder if the 

video does not contain color information. 

Color Lookup Table (CLUT) – The CLUT is a compression scheme where 

pixel values in the bitmap represent an index into a color table where the 

table colors have more bits-per-pixel than the pixel values. In a system 

where each pixel value is eight bits, there are 256 possible values in the 

lookup table. This may seem a constraint but, since multiple lookup tables 

can be referenced, there can be many tables with varying 256 color 

schemes. CLUTs work best for graphics where colors do not have to be 

natural. 

Color Map – A color map is just a numbered list of colors. Each color is 

specified in terms of its red, green, and blue components. 

Color Map Animation – In normal animation, the images representing 

separate frames are written on separate pieces of artwork. In computer 

color map animation, many images can be written into a frame buffer, each 

with a different color number. By “cycling” white, for example, through the 

color map, so that only one image at a time is visible, the illusion of animation 

can be achieved very quickly. PictureMaker’s wireframe test mode 

works this way.

Color Mapping – Color mapping is distinguished by the following: a) Each 

pixel contains a color number (or address) referring to a position in a color 

map. Each pixel has “n” bits, so there are “2 to the n” color map addresses. 

b) A hardware device called the color map defines the actual RGB values 

for each color. 

Color Masking – A method of correcting color errors which are fundamental 

in any three primary color additive reproducing system, by electrically 

changing the R, G, and B signals with a matrix or masking amplifier 

which mixes (usually subtracts) the signals in a very precise predetermined 

amount. The form is generally as follows: 

R out = R in + a(G-R) + b(R-B) a, b, c, d, e, and f are 

G out = G in + c(G-R) + d(B-G) referred to as the masking 

B out = B in + e(R-B) + f(B-G) or correction coefficients 

Color Match, Corresponding – A corresponding color is defined as the 

stimulus that, under some different condition of adaptation, evokes the 

same color appearance as another stimulus when it was seen under the 

original state of adaptation. Color match, corresponding is a subjective 

judgment. 

Color Match, Metameric – a) Color images are metameric matches 

when their spectrally different color stimuli have identical tristimulus values. 

The requirements for such a metameric match can be calculated for a 

specified viewing condition (and for viewing conditions other than those 

specified, the chromaticity will not be judged to correspond). b) The corresponding 

color chosen for the metameric match will not provide a spectrophotometric 

match. In practical applications, spectrophotometric matches 

are of only academic interest, and metameric matches are sought. 

c) Color match, metameric, resulting from calculations based upon colorimetry, 

produces a visual match as evaluated by the CIE description of 

human observers. 

Color Model – Any of several means of specifying colors according to 

their individual components. See RGB, YUV. 

Color Modulator – See Color Encoder. 

Color Palette – A component of a digital video system that provides a 

means of establishing colors (foreground and background) using a color 

lookup table to translate a limited set of pixel values into a range of displayable 

colors by converting the colors to RGB format. 

Color Phase – The phase of the chroma signal as compared to the color 

burst, is one of the factors that determines a video signal’s color balance. 

Color Plane – In planar modes, the display memory is separated into four 

independent planes of memory, with each plane dedicated to controlling 

one color component (red, green, blue, and intensify). Each pixel of the display 

occupies one bit position in each plane. In character modes and 

packed-pixel modes, the data is organized differently. 

Color Processing – A way to alter a video signal to affect the colors. The 

Video Equalizer is suited to this task. See Chroma Corrector. 

Color Purity – Describes how close a color is to the mathematical representation 

of the color. 

Color Saturation – The attribute of color perception determining the 

degree of its difference from the achromatic color perception most resem- 



bling it. An achromatic color perception is defined as one not possessing a 

hue/color. In other words, how much “color” is in an object. 

Color Space – The mathematical representation of a color. a) Regardless 

of the color space used, RGB, YIQ, YUV, a color will appear the same on the 

screen. What is different is how the color is represented in the color space. 

In the HLS color space, colors are represented based on a three-dimensional 

polar coordinate system where as in the RGB color space, colors are 

represented by a Cartesian coordinate system. b) Many ways have been 

devised to organize all of a system’s possible colors. Many of these methods 

have two things in common: a color is specified in terms of three numbers, 

and by using the numbers as axes in a 3D space of some sort, a 

color solid can be defined to represent the system. Two spaces are popular 

for computer graphics: RGB and HSV. 

Color Space, Reference – Geometric representation of colors in space, 

usually of three dimensions. There are three reference spaces recognized 

by ISO 8613: CMYK color space; CIELuv color space; and R, G, B color 

space. 

Color Subcarrier – The signal used to modulate the color information in 

the color encoder and demodulate the color information in the color 

decoder. For (M) NTSC the frequency of the color subcarrier is about 

3.579545 MHz and for (B, D, G, H, I) PAL it’s about 4.43 MHz. 

Color Temperature – Used to indicate the amount and color of light being 

given off by an object and is based on the concept of a “black body.” A 

black body is one which absorbs all incident light rays and reflects none 

(therefore, a theoretical concept only). If the black body is heated, it begins 

to emit visible light rays, first dull red, then red, then through orange to 

“white heat.” It can be likened to the heating of metal. If a metal object is 

heated enough, the metal body will emit the array of colors mentioned 

above until the object achieves a bluish-white light. The amount of light 

being emitted by the body can then be correlated to the amount of “heat” it 

would take to get the body that hot and that heat can be expressed in 

terms of degrees Kelvin. Objects that give off light equivalent to daylight 

have a Kelvin temperature of about 6,500 degrees Kelvin. Colors with a 

bluish tint, have a color temperature of about 9,000 degrees Kelvin. 

Color, Additive – Over a wide range of conditions of observation, many 

colors can be matched completely by additive mixtures in suitable amounts 

of three fixed primary colors. The choice of three primary colors, though 

very wide, is not entirely arbitrary. Any set that is such that none of the primaries 

can be matched by a mixture of the other two can be used. It follows 

that the primary color vectors so defined are linearly independent. 

Therefore, transformations of a metameric match from one color space to 

another can be predicted via a matrix calculation. The limitations of color 

gamut apply to each space. The additive color generalization forms the 

basis of most image capture, and of most self-luminous displays (i.e., 

CRTs, etc.). 

Color, Primary – a) The colors of three reference lights by whose additive 

mixture nearly all other colors may be produced. b) The primaries are chosen 

to be narrow-band areas or monochromatic points directed toward 

green, red, and blue within the Cartesian coordinates of three-dimensional 

color space, such as the CIE x, y, z color space. These primary color points 

together with the white point define the colorimetry of the standardized 

system. c) Suitable matrix transformations provide metameric conversions, 




constrained by the practical filters, sensors, phosphors, etc. employed in 

order to achieve conformance to the defined primary colors of the specified 

system. Similar matrix transformations compensate for the viewing conditions 

such as a white point of the display different from the white point of 

the original scene. d) Choosing and defining primary colors requires a balance 

between a wide color gamut reproducing the largest number of 

observable surface colors and the signal-to-noise penalties of colorimetric 

transformations requiring larger matrix coefficients as the color gamut is 

extended. e) There is no technical requirement that primary colors should 

be chosen identical with filter or phosphor dominant wavelengths. The 

matrix coefficients, however, increase in magnitude as the available display 

primaries occupy a smaller and smaller portion of the color gamut. (Thus, 

spectral color primaries, desirable for improved colorimetry, become 

impractical for CRT displays.) f) Although a number of primary color sets 

are theoretically interesting, CCIR, with international consensus, has established 

the current technology and practice internationally that is based 

(within measurement tolerances) upon the following: Red – x = 0.640, y = 

0.330; Green – x = 0.300, y = 0.600; Blue – x = 0.150, y = 0.060. 

g) SMPTE offers guidance for further studies in improving color rendition 

by extending the color gamut. With regard to color gamut, it is felt that the 

system should embrace a gamut at least as large as that represented by 

the following primaries: Red – x = 0.670, y = 0.330; Green – x = 0.210, 

y = 0.710; Blue – x = 0.150, y = 0.060. 

Color, Subjective – Subtractive colorimetry achieves metameric matching 

by removing portions of the spectrum from white light. The subtractive 

counterparts to the additive color primaries are those which when removed 

from white leave the red, green, and blue accordingly cyan, magenta, and 

yellow. Combinations of these subtractive colors in various add mixtures 

provide metameric matches to many colors. Subtractive color principles are 

employed in all hard-copy color images and in light-valve systems such as 

color transparencies, LCD panel display, motion-picture films, etc. 

Colorimetry – a) Characteristics of color reproduction including the range 

of colors that a television system can reproduce. Some ATV schemes call 

for substantially different colorimetry (with a greater range) than NTSC’s. 

b) The techniques for the measurement of color and for the interpretation 

of the results of such computations. Note: The measurement of color is 

made possible by the properties of the eye, and is based upon a set of 

conventions. 

Colorization – Special effect (also called paint) which colors a monochrome 

or color image with artificial colors. This feature is found on both 

the Digital Video Mixer and Video Equalizer. 

Color-Matching Functions – a) The tristimulus values of monochromatic 

stimuli of equal radiant power. The three values of a set of color-matching 

functions at a given wavelength are called color-coefficients. The colormatching 

functions may be used to calculate the tristimulus values of a 

color stimulus from the color stimulus function. b) The tristimulus value per 

unit wavelength interval and unit spectral radiant flux. c) A set of three 

simultaneous equations used to transform a color specification from one 

set of matching stimuli to another. Note: Color-matching functions adopted 

by the CIE are tabulated as functions of wavelength throughout the spectrum 

and are given in Section 13.5 of ANSI/IES RP16-1986. 


Comb Filter – A filter that can be used to separate luminance from 

chrominance in the NTSC or PAL composite video systems. The figure 

below shows a signal amplitude over frequency representation of the luminance 

and chrominance information that makes up the composite video 

signal. The peaks in gray are the chroma information at the color carrier 

frequency. Note how the chroma information falls between the luminance 

information that is in white. The comb filter is able to pass just energy 

found in the chroma frequency areas and not the luminance energy. This 

selective bandpass profile looks like the teeth of a comb and thus the 

name comb filter. The comb filter has superior filtering capability when 

compared to the chroma trap because the chroma trap acts more like a 

notch filter. 

Frequencies the Comb Filter 

passes as chrominance information. 

Combination Tone – A tone perceived by the ear which is equal in frequency 

to the sum or difference of the frequencies of two loud tones that 

differ by more than 50 Hz. 

Combinational Logic – Circuit arrangement in which the output state is 

determined only by the present states of two or more inputs. Also called 

Combinatorial Logic. 

Combiner – In digital picture manipulators, a device that controls the way 

in which two or more channels work together. Under software control, it 

determines the priority of channels (which picture appears in front and 

which in back) and the types of transitions that can take place between 

them. 

Combo Box – In Microsoft Windows, a combination of a text and a list 

box. You can either type the desired value or select it from the list. 

Command Buttons – In Microsoft Windows, “button-shaped” symbols 

that are “pressed” (“clicked on”/chosen) to perform the indicated action. 

Comment Field – Field within an instruction that is reserved for comments. 

Ignored by the compiler or the assembler when the program is converted 

to machine code. 

Common Carrier – Telecommunication company that provides communications 

transmission services to the public. 

Common Data Rate (CDR) – In the search for a single worldwide standard 

for HDTV, one proposal is to establish a common data rate, to be 

independent of line structure, frame rate, and sync/blanking.

Common Image Format (CIF) – The standardization of the structure of 

the samples that represent the picture information of a single frame in 

digital HDTV, independent of frame rate and sync/blank structure. The 

uncompressed bit rates for transmitting CIF at 29.97 frames/sec is 

36.45 Mbit/sec. 

Common Interchange Format (CIF) – A 352 x 240 pixel format for 

30 fps video conferencing. 

Common Interface Format (CIF) – This video format was developed to 

easily allow video phone calls between countries. The CIF format has a resolution 

of 352 x 288 active pixels and a refresh rate of 29.97 frames per 

second. 

Common Intermediate Format (CIF) – Picture format. 

Communication Protocol – A specific software-based protocol or language 

for linking several devices together. Communication protocols are 

used between computers and VCRs or edit controllers to allow bidirectional 

“conversation” between the units. See RS-232/RS-422. 

Compact Cassette – A small (4 x 2-1/2 x 1/2") tape cartridge developed 

by Philips, containing tape about 1/7" wide, running at 1-7/8 ips. 

Recordings are bidirectional, with both stereo tracks adjacent for compatibility 

with monophonic cassette recorders; whose heads scan both stereo 

tracks at once. 

Compact Disc Interactive – CD-I means Compact Disc Interactive. It is 

meant to provide a standard platform for mass consumer interactive multimedia 

applications. So it is more akin to CD-DA, in that it is a full specification 

for both the data/code and standalone playback hardware: a CD-I 

player has a CPU, RAM, ROM, OS, and audio/video/(MPEG) decoders built 

into it. Portable players add an LCD screen and speakers/phone jacks. It 

has limited motion video and still image compression capabilities. It was 

announced in 1986, and was in beta test by spring 1989. This is a consumer 

electronics format that uses the optical disc in combination with a 

computer to provide a home entertainment system that delivers music, 

graphics, text, animation, and video in the living room. Unlike a CD-ROM 

drive, a CD-I player is a standalone system that requires no external computer. 

It plugs directly into a TV and stereo system and comes with a 

remote control to allow the user to interact with software programs sold on 

discs. It looks and feels much like a CD player except that you get images 

as well as music out of it and you can actively control what happens. In 

fact, it is a CD-DA player and all of your standard music CDs will play on a 

CD-I player; there is just no video in that case. For a CD-I disk, there may 

be as few as 1 or as many as 99 data tracks. The sector size in the data 

tracks of a CD-I disk is approximately 2 kbytes. Sectors are randomly 

accessible, and, in the case of CD-I, sectors can be multiplexed in up to 16 

channels for audio and 32 channels for all other data types. For audio, 

these channels are equivalent to having 16 parallel audio data channels 

instantly accessible during the playing of a disk. Some useful references 

about CD-I are: “Discovering CD-I” available for $45 from Microware 

Systems Corp.; “Introducing CD-I” ISBN 0-201-62748-5; “The CD-I 

Production Handbook” ISBN 0-201-62750-7; “The CD-I Design Handbook” 

ISBN 0-201-62749-3. 

Compact Disc Read Only Memory – a) CD-ROM means “Compact Disc 

Read Only Memory.” A CD-ROM is physically identical to a Digital Audio 



Compact Disc used in a CD player, but the bits recorded on it are interpreted 

as computer data instead of music. You need to buy a CD-ROM Drive 

and attach it to your computer in order to use CD-ROMs. A CD-ROM has 

several advantages over other forms of data storage, and a few disadvantages. 

A CD-ROM can hold about 650 megabytes of data, the equivalent of 

thousands of floppy discs. CD-ROMs are not damaged by magnetic fields 

or the x-rays in airport scanners. The data on a CD-ROM can be accessed 

much faster than a tape, but CD-ROMs are 10 to 20 times slower than 

hard discs. b) A flat metallic disk that contains information that you can 

view and copy onto your own hard disk; you cannot change or add to its 

information. 

Companding – See Compressing-Expanding. 

Comparator – A circuit that responds to the relative amplitudes of two 

inputs, A and B, by providing a binary output, Z, that indicates A>B or A 0, then Z = 1 

If A – B < 0, then Z = 0 

Compatibility – A complex concept regarding how well ATV schemes work 

with existing television receivers, transmission channels, home video equipment, 

and professional production equipment. See also Channel- 

Compatible, Receiver-Compatible. 

A. ATV Receiver Compatibility Levels 

Level 5 – ATV signal is displayed as ATV on an NTSC TV set 

Level 4 – ATV signal appears as highest quality NTSC on an NTSC 

TV set 

Level 3 – ATV signal appears as reduced quality NTSC on an NTSC 

TV set 

Level 2 – ATV signal requires inexpensive adapter for an NTSC TV 

set 

Level 1 – ATV signal requires expensive adaptor for an NTSC TV set 

Level 0 – ATV signal cannot be displayed on an NTSC TV set 

B. Compatible ATV Transmission Schemes 

• Receiver-compatible and channel-compatible single 6 MHz 

channel 

• Receiver-compatible channel plus augmentation channel 

• Necessarily adjacent augmentation channel 

• Not necessarily adjacent augmentation channel 

• Non-receiver-compatible channel plus simulcast channel 

Compatible Video Consortium – An organization established by Cox 

Enterprises and Tribune Broadcasting, which together own 14 television 

stations, 24 CATV systems, and two production companies. The CVC, which 

is open to other organizations, was created to support ATV research and is 

currently supporting Del Ray’s HD-NTSC system. 

Compiler – Translation program that converts high-level program instructions 

into a set of binary instructions (machine code) for execution. Each 




high-level language requires a compiler or an interpreter. A compiler translates 

the complete program, which is then executed. 

Complement – Process of changing each 1 to a 0 and each 0 to a 1. 

Complex Surface – Consists of two or more simple surfaces attached or 

connected together using specific operations. 

Component – a) A matrix, block or single pel from one of the three matrices 

(luminance and two chrominance) that make up a picture. b) A television 

system in which chrominance and luminance are distributed separately; 

one of the signals of such a television system; or one of the signals that 

comprise an ATV system (e.g., the widescreen panels component). 

Component (Elementary Stream) – One or more entities which together 

make up an event, e.g., video, audio, teletext. 

Component Analog – The unencoded output of a camera, videotape 

recorder, etc., consisting of three primary color signals: red, green, and 

blue (RGB) that together convey all necessary picture information. In some 

component video formats, these three components have been translated 

into a luminance signal and two color difference signals, for example, Y, 

B-Y, R-Y. 

Component Color – Structure of a video signal wherein the R', G', and B' 

signals are kept separate from each other or wherein luminance and two 

band-limited color-difference signals are kept separate from one another. 

The separation may be achieved by separate channels, or by time-division 

multiplexing, or by a combination of both. 

Component Digital – A digital representation of a component analog signal 

set, most often Y, B-Y, R-Y. The encoding parameters are specified by 

CCIR 601. The parallel interface is specified by ITU-r BT.601-2 656 and 

SMPTE 125M (1991). 

Component Digital Post Production – A method of post production that 

records and processes video completely in the component digital domain. 

Analog sources are converted only once to the component digital format 

and then remain in that format throughout the post production process. 

Component Gain Balance – Refers to ensuring that each of the three 

signals that make up the CAV information are amplified equally. Unequal 

amplification will cause picture lightness or color distortions. 

Component Video – Video which exists in the form of three separate signals, 

all of which are required in order to completely specify the color picture 

with sound. Most home video signals consist of combined (composite) 

video signals, composed of luminance (brightness) information, chrominance 

(color) information, and sync information. To get maximum video 

quality, professional equipment (Betacam and MII) and some consumer 

equipment (S-VHS and Hi-8) keep the video components separate. 

Component video comes in several varieties: RGB (red, green, blue), YUV 

(luminance, sync, and red/blue) and Y/C (luminance and chrominance), 

used by S-Video (S-VHS and Hi-8) systems. All Videonics video products 

support the S-Video (Y/C) component format in addition to standard composite 

video. 

Composite – A television system in which chrominance and luminance are 

combined into a single signal, as they are in NTSC; any single signal comprised 

of several components. 


Composite Analog – An encoded video signal, such as NTSC or PAL 

video, that includes horizontal and vertical synchronizing information. 

Composite Blanking – The complete television blanking signal composed 

of both line rate and field rate blanking signals. See Line Blanking and 

Field Blanking. 

Composite Chroma Key – a) Also known as encoded chroma key. A 

chroma key which is developed from a composite video source, i.e., off of 

tape, rather than the components, i.e., RGB, R-Y, B-Y. b) A chroma key 

wherein the keying signal is derived from a composite video signal, as 

opposed to an RGB chroma key. See Chroma Key. 

Composite Color – Structure of a video signal wherein the luminance and 

two band-limited color-difference signals are simultaneously present in the 

channel. The format may be achieved by frequency-division multiplexing, 

quadrature modulation, etc. It is common to strive for integrity by suitable 

separation of the frequencies, or since scanned video signals are highly 

periodic, by choosing frequencies such that the chrominance information is 

interleaved within spectral regions of the luminance signal wherein a minimum 

of luminance information resides. 

Composite Color Signal – A signal consisting of combined luminance 

and chrominance information using frequency-domain multiplexing. For 

example, NTSC and PAL video signals. 

Composite Digital – A digitally encoded video signal, such as NTSC or 

PAL video, that includes horizontal and vertical synchronizing information. 

Composite Image – An image that contains elements selected from two 

or more separately originated images. 

Composite Sync – Horizontal and vertical sync pulses combined. Often 

referred to simply as “sync.” Sync is used by source and monitoring 

equipment. 

Composite Video – a) A single video signal containing all of the necessary 

information to reproduce a color picture. Created by adding quadrature 

amplitude modulated R-Y and B-Y to the luminance signal. A video 

signal that contains horizontal, vertical and color synchronizing information. 

b) A complete video including all synchronizing pulses; may have all values 

of chroma, hue and luminance; may also be many sources layered. 

Compositing – Layering multiple pictures on top of each other. A cutout or 

matte holds back the background and allows the foreground picture to 

appear to be in the original picture. Used primarily for special effects. 

Composition – Framing or makeup of a video shot. 

Compress – a) The process of converting video and audio data into a 

more compact form for storage or transmission. b) A digital picture manipulator 

effect where the picture is squeezed (made proportionally smaller). 

Compressed Serial Digital Interface (CSDI) – A way of compressing 

digital video for use on SDI-based equipment proposed by Panasonic. Now 

incorporated into Serial Digital Transport Interface. 

Compressing-Expanding – Analog compression is used at one point in 

the communications path to reduce the amplitude range of the signals, followed 

by an expander to produce a complementary increase in the amplitude 

range.

Compression – a) The process of electronically processing a digital video 

picture to make it use less storage or to allow more video to be sent down 

a transmission channel. b) The process of removing picture data to 

decrease the size of a video image. c) The reduction in the volume of data 

from any given process so that more data can be stored in a smaller 

space. There are a variety of compression schemes that can be applied to 

data of which MPEG-1 and MPEG-2 are called lossy since the data produced 

by compression is not totally recoverable. There are other compression 

schemes that are totally recoverable, but the degree of compression is 

much more limited. 

Compression (Amplitude) – a) Data Transmission – A process in 

which the effective gain applied to a signal is varied as a function of the 

signal magnitude, the effective gain being greater for small rather than for 

large signals. b) Video – The reduction in amplitude gain at one level of a 

picture signal with respect to the gain at another level of the same signal. 

Note: The gain referred to in the definition is for a signal amplitude small in 

comparison with the total peak-to-peak picture signal involved. A quantitative 

evaluation of this effect can be obtained by a measurement of differential 

gain. c) Production – A transfer function (as in gamma correction) or 

other nonlinear adjustment imposed upon signal amplitude values. 

Compression (Bit Rate) – Compression is used in the digital environment 

to describe initial digital quantization employing transforms and algorithms 

encoding data into a representation that requires fewer bits or lower data 

rates or processing of an existing digital bit stream to convey the intended 

information in fewer bits or lower data rate. Compression (bit rate) may be 

reversible compression, lossles, or it may be irreversible compression, 

lossy. 

Compression Artifacts – Compacting of a digital signal, particularly when 

a high compression ratio is used, may result in small errors in the decompressed 

signal. These errors are known as “artifacts,” or unwanted defects. 

The artifacts may resemble noise (or edge “busyness”) or may cause parts 

of the picture, particularly fast moving portions, to be displayed with the 

movement distorted or missing. 

Compression Factor – Ratio of input bit rate to output (compressed) bit 

rate. Like Compression Ratio. 

Compression Ratio – A value that indicates by what factor an image file 

has been reduced after compression. If a 1 MB image file is compressed to 

500 KB, the compression ratio would be a factor of 2. The higher the ratio 

the greater the compression. 

Compression, Lossless – Lossless compression requires that the reproduced 

reconstructed bit stream be an exact replica of the original bit 

stream. The useful algorithms recognize redundancy and inefficiencies in 

the encoding and are most effective when designed for the statistical properties 

of the bit stream. Lossless compression of image signal requires that 

the decoded images match the source images exactly. Because of differences 

in the statistical distributions in the bit streams, different techniques 

have thus been found effective for lossless compression of either arbitrary 

computer data, pictures, or sound. 

Compression, Lossy – Bit-rate reduction of an image signal by powerful 

algorithms that compress beyond what is achievable in lossless compression, 

or quasi-lossless compression. It accepts loss of information and 



introduction of artifacts which can be ignored as unimportant when viewed 

in direct comparison with the original. Advantage is taken of the subtended 

viewing angle for the intended display, the perceptual characteristics of 

human vision, the statistics of image populations, and the objectives of the 

display. The lost information cannot be regenerated from the compressed 

bit stream. 

Compression, Quasi-Lossless – Bit-rate reduction of an image signal, 

by an algorithm recognizing the high degree of correlation ascertainable in 

specific images. The reproduced image does not replicate the original 

when viewed in direct comparison, but the losses are not obvious or recognizable 

under the intended display conditions. The algorithm may apply 

transform coding, predictive techniques, and other modeling of the image 

signal, plus some form of entrophy encoding. While the image appears 

unaltered to normal human vision, it may show losses and artifacts when 

analyzed in other systems (i.e., chroma key, computerized image analysis, 

etc.). The lost information cannot be regenerated from the compressed bit 

stream. 

Compressionist – One who controls the compression process to produce 

results better than would be normally expected from an automated system. 

Compressor – An analog device that reduces the dynamic range of a signal 

by either reducing the level of loud signals or increasing the level of 

soft signals when the combined level of all the frequencies contained in the 

input is above or below a certain threshold level. 

Computer – General purpose computing system incorporating a CPU, 

memory, I/O facilities, and power supply. 

Computer Television – Name of a Time Inc. pay-TV company that predated 

HBO; also an unrealized concept created by Paul Klein, the company’s 

founder, that would allow viewers access to a vast selection of television 

programming with no temporal restrictions, in the same way that telephone 

subscribers can call any number at any time. B-ISDN might offer the 

key to the transmission problem of computer television; the random-access 

library-storage problems remain. 

Concatenation – Linking together (of systems). Although the effect on 

quality resulting from a signal passing through many systems has always 

been a concern, the use of a series of compressed digital video systems is, 

as yet, not well known. The matter is complicated by virtually all digital 

compression systems differing in some way from each other, hence the 

need to be aware of concatenation. For broadcast, the current NTSC and 

PAL analog compression systems will, more and more, operate alongside 

digital MPEG compression systems used for transmission and, possibly, in 

the studio. Even the same brand and model of encoder may encode the 

same signal in a different manner. See also Mole Technology. 

Condenser Mike – A microphone which converts sound pressure level 

variations into variations in capacitance and then into electrical voltage. 

Condition Code – Refers to a limited group of program conditions, such 

as carry, borrow, overflow, etc., that are pertinent to the execution of 

instructions. The codes are contained in a condition code register. Same as 

Flag Register. 

Conditional Access System (CA) – A system to control subscriber 

access to services, programs, and events, e.g., Videoguard, Eurocrypt. 




Conditional Jump or Call – Instruction that, when reached in a program, 

will cause the computer either to continue with the next instruction in the 

original sequence or to transfer control to another instruction, depending 

on a predetermined condition. 

Conductive Coatings – Coatings that are specially treated to reduce the 

coating resistance, and thus prevent the accumulation of static electrical 

charge. Untreated, non-conductive coatings may become highly charged, 

causing transport, noise, and dust-attraction problems. 

Confidence Test – A test to make sure a particular device (such as the 

keyboard, mouse, or a drive) is set up and working properly. 

CONFIG.SYS – A file that provides the system with information regarding 

application requirements. This information may include peripherals that are 

connected and require special drivers (such as a mouse). Other information 

that might be specified is the number of files that can be open simultaneously, 

or the number of disk drives that can be accessed. 

Configuration File – A system file that you change to customize the way 

your system behaves. Such files are sometimes referred to as customization 

files. 

Connector – Hardware at the end of a cable that lets you fasten the cable 

to an outlet, port, or another connector. 

Console Window – The window that appears each time you log in. IRIX 

reports all status and error messages to this window. 

Constant – A fixed value. 

Constant Bit Rate (CBR) – a) Operation where the bit rate is constant 

from start to finish of the compressed bit stream. b) A variety of MPEG 

video compression where the amount of compression does not change. 

c) CBR traffic requires guaranteed levels of service and throughput in 

delay-sensitive applications such as audio and video that are digitized and 

represented by a continuous bit stream. 

Constant Bit Rate Coded Video – A compressed video bit stream with a 

constant average bit rate. 

Constant Luminance Principle – A rule of composite color television 

that any change in color not accompanied by a change in brightness 

should not have any effect on the brightness of the image displayed on a 

picture tube. The constant luminance principle is generally violated by 

existing NTSC encoders and decoders. See also Gamma. 

Constant Shading – The simplest shading type is constant. The color of a 

constant shaded polygon’s interior pixels is always the same, regardless of 

the polygon’s orientation with respect to the viewer and light sources. 

Constant shading is useful for creating light sources, for example. With all 

other shading types, a polygon changes its shade as it moves. 

Constellation Diagram – Way of representing the I and Q components of 

QAM or QPSK modulation. The position of the points in the constellation 

diagram provides information about distortions in the QAM or QPSK modulator 

as well as about distortions after the transmission of digitally coded 

signals. 

Constructive Solid Geometry (CSG) – This way of modeling builds a 

world by combining “primitive” solids such as cubes, spheres, and cones. 

The operations that combine these primitives are typically union, intersec- 


tion, and difference. These are called Boolean operations. A CSG database 

is called a CSG tree. In the tree, branch points indicate the operations that 

take place on the solids that flow into the branch point. 

Content – The program content will consist of the sum total of the 

essence (video, audio, data, graphics, etc.) and the metadata. Content can 

include television programming, data, and executable software. 

Content-Based Image Coding – The analysis of an image to recognize 

the objects of the scene (e.g., a house, a person, a car, a face, ...). The 

objects, once recognized, are coded as parameters to a general object 

model (of the house, person, car, face, ...) which is then synthesized (i.e., 

rendered) by the decoder using computer graphic techniques. 

Contour Enhancement – A general term usually intended to include both 

aperture correction and edge enhancement. 

Contouring – Video picture defect due to quantizing at too coarse a level. 

The visual effect of this defect is that pictures take on a layered look 

somewhat like a geographical contoured map. 

Contrast – Contrast describes the difference between the white and black 

levels in a video waveform. If there is a large difference between the white 

and black picture levels, the image has high contrast. If there is a small 

difference between the white and black portions of the picture, the picture 

has low contrast and takes on a gray appearance. 

Contrast Ratio – a) Related to gamma law and is a measurement of the 

maximum range of light to dark objects that a television system can reproduce. 

b) The comparison of the brightest part of the screen to the darkest 

part of the screen, expressed as a ratio. The maximum contrast ratio for 

television production is 30 x 1. 

Contribution – A form of signal transmission where the destination is not 

the ultimate viewer and where processing (such as electronic matting) is 

likely to be applied to the signal before it reaches the ultimate viewer. 

Contribution demands higher signal quality than does distribution because 

of the processing. 

Contribution Quality – The level of quality of a television signal from the 

network to its affiliates. For digital television, this is approximately 45 Mbps. 

Control Block – Circuits that perform the control functions of the CPU. 

They are responsible for decoding instructions and then generating the 

internal control signals that perform the operations requested. 

Control Bus – Set of control lines in a computer system. Provides the synchronization 

and control information necessary to run the system. 

Control Menu Box – Located on the upper left corner of all application 

windows, document windows, and dialog boxes, it sizes (maximize, minimize, 

or restore) or exits the window. 

Control Processor Unit/Central Processing Unit (CPU) – a) Circuits 

used to generate or alter control signals. b) A card in the frame which controls 

overall switcher operation. 

Control Program – Sequence of instructions that guide the CPU through 

the various operations it must perform. This program is stored permanently 

in ROM where it can be accessed by the CPU during operation. Usually this 

ROM is located within the microprocessor chip. Same as Microprogram or 

Microcode.

Control Room – The enclosed room where the electronic control system 

for radio and television are located and where the director and technical 

director sit. 

Control Signal – A signal used to cause an alteration or transition of 

video signals. 

Control Track – a) The magnetized portion along the length of a videotape 

on which sync control information is placed. The control track contains 

a pulse for each video field and is used to synchronize the tape and 

the video signal. b) A synchronizing signal on the edge of the tape which 

provides a reference for tracking control and tape speed. Control tracks 

that have heavy dropouts are improperly recorded and may cause tracking 

defects or picture jumps. c) A signal recorded on video tape to allow the 

tape to play back at a precise speed in any VTR. Analogous to the sprocket 

holes on film. 

Control Track Editor – Type of editing system that uses frame pulses on 

the videotape control track for reference. 

Control-L (LANC) – Sony’s wired edit control protocol, also called LANC 

(Local Application Control), which allows two-way communication between 

a camcorder or VCR and an edit controller such as the Thumbs Up. 

Control-L allows the controller to control the deck (fast forward, play, etc.) 

and also allows the controller to read the tape position (tape counter) information 

from the deck. 

Control-M – Panasonic’s wired edit control protocol. Similar to Control-L 

in function but not compatible. Also called Panasonic 5-pin edit control. 

See Control-L. 

Control-S – Sony wired transport control protocol that duplicates a VCR’s 

infra-red remote transport control (play, stop, pause, fast forward, and 

rewind). Unlike Control-L, Control-S does not allow the controller to read 

tape counter information. 

Control-T – Similar to Control-L but allows multiple units to be controlled. 

Not used in current equipment. 

Conventional Definition Television (CDTV) – This term is used to signify 

the analog NTSC television system as defined in ITU-R Recommendation 

470. See also Standard Definition Television and ITU-R Recommendation 

1125. 

Convergence – The act of adjusting or the state of having adjusted, the 

Red, Green, and Blue color gun deflection such that the electron beams are 

all hitting the same color triad at the same time. 

Conversion, Frame-Rate – Standardized image systems now exist in the 

following frame rates per second: 24, 25, 29.97, 30, and 60. In transcoding 

from one system to another, frame rate conversion algorithms perform 

this conversion. The algorithm may be as simple as to drop or add frames 

or fields, or it may process the information to generate predictive frames 

employing information from the original sequence. In interlace systems, the 

algorithm may be applied independently to each field. 

Convolutional Coding – The data stream to be transmitted via satellite 

(DVB-S) is loaded bit by bit into shift registers. The data which is split and 

delayed as it is shifted through different registers is combined in several 

paths. This means that double the data rate (two paths) is usually obtained. 



Puncturing follows to reduce the data rate: the time sequence of the bits is 

predefined by this coding and is represented by the trellis diagram. 

Coordination System – See Reference. 

COR – Technical Corrigendum. 

CORBA – Common Object Request Broker Architecture. 

Core – Small magnetic toruses of ferrite that are used to store a bit of 

information. These can be strung on wires so that large memory arrays can 

be formed. The main advantage of core memory is that it is nonvolatile. 

Coring – A system for reducing the noise content of circuits by removing 

low-amplitude noise riding on the baseline of the signals. Both aperture 

correction and enhancement can be cored. It involves preventing any 

boosting of very low level edge transitions. The threshold point is the coring 

control. The more the coring is increased, the more the extra noise 

added by the enhanced (or aperture corrector), high frequency boosting is 

reduced. Of course, the fine detail enhancement is also reduced or eliminated. 

Too high levels of coring can cause a “plastic picture” effect. 

Co-Sited Sampling – Co-sited sampling ensures that the luminance and 

the chrominance digital information is simultaneous, minimizing 

chroma/luma delay. This sampling technique is applied to color difference 

component video signals: Y, Cr, and Cb. The color difference signals, Cr and 

Cb, are sampled at a sub-multiple of Y, the luminance frequency – 4:2:2, 

for example. With co-sited sampling, the two color difference signals are 

sampled at the same instant, as well as one of the luminance samples. 

Co-Siting – Relates to SMPTE 125M component digital video, in which the 

luminance component (Y) is sampled four times for every two samples of 

the two chrominance components (Cb and Cr). Co-siting refers to delaying 

transmission of the Cr component to occur at the same time as the second 

sample of luminance data. This produces a sampling order as follows: 

Y1/Cb1, Y2/Cr1, Y3/Cr3, Y4/Cb3, and so on. Co-siting reduces required 

bus width from 30 bits to 20 bits. 

CPE – Common Phase Error. 

CPS – Characters Per Second. 

CPU – See Central Processing Unit. 

CPU Board – The printed circuit board within a workstation chassis that 

contains the central processing unit(s). When you open the front metal 

panel of the Indigo chassis, it is the board on the left. 

CPV – A proprietary and relatively old format designed for 30 fps video 

over packet-based networks. It is still being used in closed video systems 

where 30 fps is required, such as in security applications. 

CR – Scaled version of the R-Y signal. 

Crawl – a) Titles that move slowly up the screen, mounted on a revolving 

drum. b) An appearance of motion in an image where there should be 

none. See also Chroma Crawl and Line Crawl. 

CRC – See Cyclic Redundancy Check. 

Credits – Listing of actors, singers, directors, etc., in title preceding or 

directly following the program. 

Crispening – A means of increasing picture sharpness by generating and 

applying a second time derivative of the original signal. 




Crop – Term used for the action of moving left, right, top, and bottom 

boundaries of a key. 

Cropping – A digital process which removes areas of a picture (frame) by 

replacing video pixels with opaque pixels of background colors. Cropping 

may be used to eliminate unwanted picture areas such as edges or as 

quasi-masking in preparation for keying. 

Cross Color – Spurious signals resulting from high frequency luminance 

information being interpreted as color information in decoding a composite 

signal. Typical video examples are “rainbow” on venetian blinds and striped 

shirts for example. 

Cross Luminance – Spurious signals occurring in the Y channel as a 

result of composite chroma signals being interpreted as luminance, such 

as “dot crawl” or “busy edges” on colored areas. 

Cross Modulation – See Chrominance-to-Luminance Intermodulation. 

Cross-Assembler – Assembler that runs on a processor whose assembly 

language is different from the language being assembled. 

Cross-Color – An artifact observed in composite systems employing quadrature 

modulation and frequency interleaving. Cross-color results from the 

multiplicities of line-scan harmonics in the baseband signal, which provide 

families of frequencies surrounding each of the main harmonic peaks. 

These families become even more complex if there is movement in the 

scene luminance signals between scans. Since the interstices are, therefore, 

not completely empty, some of the information on the luminance signal 

is subsequently decoded as color information. A typical visible effect is 

a moiré pattern. 

Crossfade – The audio equivalent of the video dissolve where one sound 

track is gradually faded out while a second sound track simultaneously 

replaces the original one. See Mix. 

Crosshatch – A test pattern consisting of vertical and horizontal lines 

used for converging color monitors and cameras. 

Cross-Luminance – An artifact observed in composite systems employing 

quadrature modulation and frequency interleaving. As the analog of crosscolor, 

cross-luminance results in some of the information carried by the 

chrominance signal (on color subcarrier) being subsequently interpreted as 

fine detail luminance information. A typical visible effect is chroma crawl 

and visible subcarrier. 

Crossover Network – A device which divides a signal into two or more 

frequency bands before low-frequency outputs of a crossover network. The 

level of each output at this frequency is 3 dB down from the flat section of 

the crossover’s frequency response curve. 

Cross-Play – By cross-play capability is meant the ability to record and 

reproduce on the same or a different machine; record at one speed and 

reproduce at the same or a different speed; accomplish the foregoing 

singly or in any combination without readjustment for tape or transport 

type. 

Crosspoint – a) The electronic circuit used to switch video, usually on a 

bus. b) An electronic switch, usually controlled by a push-button on the 

panel, or remotely by computer that allows video or audio to pass when the 

switch is closed. 


Cross-Sectional Modeling – This type of modeling is also a boundary 

representation method available in PictureMaker. The artist can define an 

object’s cross-section, and then extrude in the longitudinal direction after 

selecting an outline to define the cross-section changes in scale as it traverses 

the longitudinal axis. 

Crosstalk – The interference between two audio or two video signals 

caused by unwanted stray signals. a) In video, crosstalk between input 

channels can be classified into two basic categories: luminance/sync 

crosstalk; and color (chroma) crosstalk. When video crosstalk is too high, 

ghost images from one source appear over the other. b) In audio, signal 

leakage, typically between left and right channels or between different 

inputs, can be caused by poor grounding connections or improperly shielded 

cables. See Chrominance-to-Luminance Intermodulation. 

Crosstalk Noise – The signal-to-crosstalk noise ratio is the ratio, in decibels, 

of the nominal amplitude of the luminance signal (100 IRE units) to 

the peak-to-peak amplitude of the interfering waveform. 

CRT (Cathode Ray Tube) – There are three forms of display CRTs in color 

television: tri-color (a color picture tube), monochrome (black and white), 

and single color (red, green, or blue, used in projection television systems). 

Many widescreen ATV schemes would require a different shape CRT, particularly 

for direct-view systems. 

CRT Terminal – Computer terminal using a CRT display and a keyboard, 

usually connected to the computer by a serial link. 

CSA – Common Scrambling Algorithm. 

CSDI – See Compressed Serial Digital Interface. 

CSELT (Centro Studi e Laboratori Telecomunicazioni S.p.A.) – CSELT 

situated in Torino, Italy, is the research company owned by STET (Societa 

Finanziaria Telefonica per Azioni), the largest telecommunications company 

in Italy. CSELT has contributed to standards under ITU, ISO, and ETSI and 

has participated in various research programs. In order to influence the 

production of standards, CSELT participates in groups such as DAVIC, the 

ATM Forum, and in the Network Management Forum. 

CSG (Constructive Solid Geometry) – In CSG, solid objects are represented 

as Boolean combinations (union, intersection, and difference) of 

solids. 

CSPS – Constrained System Parameter Stream. 

CSS (Content Scrambling System) – A type of digital copy protection 

sanctioned by the DVD forum. 

CTA – Cordless Terminal Adapter. 

Cue – a) An editing term meaning to bring all source and record VTRs to 

the predetermined edit point plus pre-roll time. b) An audio mixer function 

that allows the user to hear an audio source (usually through headphones) 

without selecting that source for broadcast/recording; the audio counterpart 

of a preview monitor. c) The act of rewinding and/or fast-forwarding a 

video- or audiotape so that the desired section is ready for play. 

Cue Control – A switch that temporarily disables a recorder’s Tape Lifters 

during fast forward and rewind so the operator can judge what portion of 

the recording is passing the heads.

Cupping – Curvature of a tape in the lateral direction. Cupping may occur 

because of improper drying or curing of the coating or because of differences 

between the coefficients of thermal or hygroscopic expansion of 

coating and base film. 

Current – The flow of electrons. 

Current Tracer – Handheld troubleshooting tool used to detect current 

flow in logic circuits. 

Current Working Directory – The directory within the file system in 

which you are currently located when you are working in a shell window. 

Cursor – a) The small arrow on the screen that echoes the movements of 

the mouse. It changes shape depending on its location on the screen. 

b) An indicator on a screen that can be moved to highlight a particular 

function or control which is the current parameter now under adjustment or 

selected. 

Curve – A single continuous line with continuity of tangent vector and of 

curvature. It is defined by its type, degree, and rational feature. 

Cusp – Breakpoints on curves. 

Cut – a) The immediate switching from one video source to another during 

the vertical blanking interval. The visual effect is an abrupt change from 

one picture to another. b) The nearly instantaneous switch from one picture 

to another at the on-air output of the switcher. The switcher circuitry allows 

cuts only during the vertical interval of the video signal so as to prevent 

disruption of the picture. On the Vista, the Cut push-button in the Effects 

Transition control group activates an effects cut. The DSK Cut Key-In pushbutton 

cuts the downstream key on or off air. On AVCs, this is performed 

by a zero time auto transition. 

Cut-Off Frequency – That frequency beyond which no appreciable energy 

is transmitted. It may refer to either an upper or lower limit of a frequency 

band. 

Cutout – See Matte. 



Cuts Only – Transition limited to on/off or instantaneous transition-type 

edits; a basic editing process with limited capabilities. 

Cutting Head – A transducer used to convert electrical signals into hills 

and valleys in the sides of record grooves. 

CVC – Compatible Video Consortium. 

CW (Continuous Wave) – Refers to a separate subcarrier sine wave used 

for synchronization of the chrominance information. 

CX Noise Reduction – A level sensitive audio noise reduction scheme 

that involves compression, on the encode side, and expansion, on the 

decode side. It was originally developed for CBS for noise reduction on LP 

records and is a trademark of CBS, Inc. The noise reduction obtained by CX 

was to be better than Dolby B3 for tape, but remain unnoticeable in playback 

if decoding didn’t take place. A modified CX system was applied to 

the analog audio tracks for the laserdisc to compensate for interference 

between the audio and video carriers. The original CX system for LP 

records was never implemented. 

Cycle – An alternation of a waveform which begins at a point, passes 

through the zero line and ends at a point with the same value and moving 

in the same direction as the starting point. 

Cycle Per Second – A measure of frequency, equivalent to Hertz. 

Cycle Time – Total time required by a memory device to complete a read 

or write cycle and become available again. 

Cyclic Redundancy Check (CRC) – a) Binary polynomial. Used to generate 

check information on blocks of data. Similar to a checksum, but is 

harder to generate and more reliable. b) Used in data transfer to check if 

the data has been corrupted. It is a check value calculated for a data 

stream by feeding it through a shifter with feedback terms “EXORed” back 

in. A CRC can detect errors but not repair them, unlike an ECC, which is 

attached to almost any burst of data that might possibly be corrupted. 

CRCs are used on disks, ITU-R 601 data, Ethernet packets, etc. 




D 

D – Definition. 

D1 – A non-compressed component digital video recording format that 

uses data conforming to the ITU-R BT.601-2 standard. Records on highend 

19 mm (3/4") magnetic tape recorders. Systems manufactured by 

Sony and BTS. Most models can record 525, 625, ITU-R BT.601-2, and 

SMPTE 125M. The D1 designation is often used incorrectly to indicate 

component digital video. 

D16 – A format to store film resolution images on D1 format tape 

recorders. Records one film frame in the space normally used for 16 video 

frames. 

D2 – A non-compressed composite digital video recording format originally 

developed by Ampex that uses data conforming to SMPTE 244M and four 

20-bit audio channels. Records on high-end 19 mm (3/4") magnetic tape 

recorders. It uses the same tape cassette cartridge but the tape itself is 

metal particle tape like Beta SP and MII. The D2 designation is often used 

incorrectly to indicate composite digital video. 

D2-MAC – Similar to D-MAC, the form preferred by manufacturers for 

European DBS. See also MAC. 

D3 – A non-compressed composite digital video recording format that uses 

data conforming to SMPTE 244M and four 20-bit audio channels. Records 

on high-end 1/2" magnetic tape similar to M-II. The format was developed 

by Matsushita and Panasonic. 

D4 – A format designation never used due to the fact that the number four 

is considered unlucky (being synonymous with death) in some Asian languages. 

D5 – A non-compressed, 10-bit 270 Mbit/second, component or composite 

digital video recording format developed by Matsushita and Panasonic. It is 

compatible with 360 Mbit/second systems. It records on high-end 1/2" 

magnetic tape recorders. 

D6 – A digital tape format which uses a 19 mm helical-scan cassette tape 

to record uncompressed high definition television material at 1.88 GBps 

(1.2 Gbps). 

D7 – DVCPRO. Panasonic’s development of native DV component format. 

D8 – There is no D8, nor will there be. The Television Recording and 

Reproduction Technology Committee of SMPTE decided to skip D8 because 

of the possibility of confusion with similarly named digital audio and data 

recorders. 

D9 – Digital-S. A 1/2-inch digital tape format developed by JVC which 

uses a high-density metal particle tape running at 57.8 mm/s to record a 

video data rate of 50 Mbps. 

DA-88 – A Tascam-brand eight-track digital audio tape machine using the 

8 mm video format of Sony. It has become the defacto standard for audio 

post production though there are numerous other formats, ranging from 

swappable hard drives to analog tape formats and everything in between. 

DAB – See Digital Audio Broadcasting. 

DAC – Digital-to-Analog Converter. 


DAC to DAC Skew – The difference in a full scale transition between R, B, 

and B DAC outputs measured at the 50% transition point. Skew is measured 

in tenths of nanoseconds. 

Daisy Chain – Bus line that is interconnected with units so that the signal 

passes from one unit to the next in serial fashion. 

DAM – DECT Authentication Module. 

Damped Oscillation – Oscillation which, because the driving force has 

been removed, gradually dies out, each swing being smaller than the preceding 

in smooth regular decay. 

DAT (Digital Audio Tape) – a) A consumer digital audio recording and 

playback system developed by Sony, with a signal quality capability surpassing 

that of the CD. b) A magnetic tape from which you can read and to 

which you can copy audio and digital information. 

Data – General term denoting any or all facts, numbers, letters, and symbols 

or facts that refer to or describe an object, idea, condition, situation, 

or other factors. Connotes basic elements of information that can be 

processed or produced by a computer. Sometimes data is considered to be 

expressible only in numerical form, but information is not so limited. 

Data Acquisition – Collection of data from external sensors usually in 

analog form. 

Data Base – Systematic organization of data files for easy access, 

retrieval, and updating. 

Data Bus – Set of lines carrying data. The data bus is usually bidirectional 

and three-state. 

Data Carousels – The data broadcast specification for data carousels 

supports data broadcast services that require the periodic transmission of 

data modules through DVB compliant broadcast networks. The modules are 

of known sizes and may be updated, added to, or removed from the data 

carousel in time. Modules can be clustered into a group of modules if 

required by the service. Likewise, groups can in turn be clustered into 

SuperGroups. Data broadcast according to the data carousel specification 

is transmitted in a DSM-CC data carousel which is defined in MPEG-2 

DSM-CC. This specification defines additional structures and descriptors to 

be used in DV compliant networks. The method is such that no explicit references 

are made to PIDs and timing parameters enabling preparation of 

the content off-line. 

Data Compression – Application of an algorithm to reduce the bit rate of 

a digital signal, or the bandwidth of an analog signal while preserving as 

much as possible of the information usually with the objective of meeting 

the constraints in subsequent portions of the system. 

Data Domain – Analysis or display of signals in which only their digital 

value is considered and not their precise voltage or timing. A logic state 

analyzer displays information in the data domain. 

Data Element – An item of data as represented before encoding and after 

decoding.

Data Essence – Essence that is distinguished as different from video or 

audio essence. Digital data that may stand alone or may be associated with 

video or audio essence or metadata. 

Data Partitioning – A method for dividing a bit stream into two separate 

bit streams for error resilience purposes. The two bit streams have to be 

recombined before decoding. 

Data Piping – The data broadcast specification profile for data pipes supports 

data broadcast services that require a simple, asynchronous, end-toend 

delivery of data through DVB compliant broadcast networks. Data 

broadcast according to the data pipe specification is carried directly in the 

payloads of MPEG-2 TS packets. 

Data Rate – The speed at which digital information is transmitted, typically 

expressed in hertz (Hz), bits/second (b/s), or bytes/sec (B/s). The higher the 

data rate of your video capture, the lower the compression and the higher 

the video quality. The higher the data rate, the faster your hard drives must 

be. Also called throughput. 

Data Reduction – The process of reducing the number of recorded or 

transmitted digital data samples through the exclusion of redundant or 

unessential samples. Also referred to as Data Compression. 

Data Search Information (DSI) – These packets are part of the 

1.00 Mbit/s overhead in video applications. These packets contain navigation 

information for searching and seamless playback of the Video Object 

Unit (VOBU). The most important field in this packet is the sector address. 

This shows where the first reference frame of the video object begins. 

Advanced angle change and presentation timing are included to assist 

seamless playback. They are removed before entering the MPEG systems 

buffer, also known as the System Target Decoder (STD). 

Data Set – A group of two or more data essence or metadata elements 

that are predefined in the relevant data essence standard or Dynamic 

Metadata Dictionary and are grouped together under one UL Data Key. Set 

members are not guaranteed to exist or be in any order. 

Data Streaming – The data broadcast, specification profile for data 

streaming supports data broadcast services that require a streamingoriented, 

end-to-end delivery of data in either an asynchronous, synchronous, 

or synchronized way through DVB compliant broadcast networks. 

Data broadcast according to the data streaming specification is carried in 

Program Elementary Stream (PES) packets which are defined in MPEG-2 

systems. See Asynchronous Data Streaming, Synchronous Data Streaming. 

DATV (Digitally Assisted Television) – An ATV scheme first proposed in 

Britain. 

DAVIC (Digital Audio Visual Council – Facing a need to make a multitude 

of audio/visual technologies and network protocols interoperate, 

DAVIC was formed in 1993 by Dr. Leonardo Chiariglione, convenor of the 

MPEG. The purpose of DAVIC is to provide specifications of open interfaces 

and protocols to maximize interoperability in digital audio/visual applications 

and services. Thus, DAVIC operates as an extension of technology 

development centers, such as MPEG. 



dB – Abbreviation for decibels. dB is a standard unit for expressing 

changes in relative power. Variations of this formula describe power 

changes in terms of voltage or current. 

dB = 10 log10(P1/P2) 

dBm – Refer to the definition of dB. dBm is a special case of dB where P2 

in the dB formula is equal to 1 mW. 

dBFS – Decibel Full Scale. 

DBN – See Data Block Number. 

DBS – See Direct Broadcast Satellite. 

dBw – Refer to the definition of dB. dBw is a special case of dB where P2 

in the dB formula is equal to 1 watt. 

DC Coefficient – The DCT coefficient for which the frequency is zero in 

both dimensions. 

DC Coupled – A connection configured so that both the signal (AC component) 

and the constant voltage on which it is riding (DC component) are 

passed through. 

DC Erasure – See Erasure. 

DC Noise – The noise arising when reproducing a tape which has been 

non-uniformly magnetized by energizing the record head with DC, either in 

the presence or absence of bias. This noise has pronounced long wavelength 

components which can be as much as 20 dB higher than those 

obtained from a bulk erased tape. At very high values of DC, the DC noise 

approaches the saturation noise. 

DC Restore – DC restore is the process in which a video waveform has its 

sync tips or backporch set to some known DC voltage level after it has 

been AC coupled. 

DC Restorer – A circuit used in picture monitors and waveform monitors 

to clamp one point of the waveform to a fixed DC level. 

DC Servo Motor – A motor, the speed of which is determined by the DC 

voltage applied to it and has provision for sensing its own speed and 

applying correcting voltages to keep it running at a certain speed. 

DCAM – Digital Camera. 

DCC (Digital Compact Cassette) – A consumer format from Philips using 

PASC audio coding. 

DCE – Data Communication Equipment. 

DCI (Display Control Interface) – A software layer that provides direct 

control of the display system to an application or client. The display vendor 

provides information to the system (in addition to the display driver) that 

allows DCI to offer a generic interface to a client. 

DCT – See Discrete Cosine Transform. 

DCT Coefficient – The amplitude of a specific cosine basis function. 

DCT Recording Format – Proprietary recording format developed by 

Ampex that uses a 19 mm (3/4") recording cassette. Records ITU-R 

BT.601-2 and SMPTE 125M data with a 2:1 compression. 

DCT-1/IDCT – Inverse Discrete Cosine Transform. 

DD (Direct Draw) – A Windows 95 version of DCI. See DCI. 




DD2 – Data recorders that have been developed using D2 tape offer relatively 

vast storage of image or other data. Various data transfer rates are 

available for different computer interfaces. Other computer storage media 

editing is difficult and images are not directly viewable. 

DDB – Download Data Block. 

DDC – Data Download Control. 

DDC2B – A serial control interface standard used to operate control registers 

in picture monitors and video chips. The two-wire system is defined by 

data and clock signals. 

DDP (Disc Description Protocol) – A file or group of files which describe 

how to master a data image file for optical disc (DVD or CD). This is an 

ANSI industry standard developed by Doug Carson and Associates. The 

laser beam recorders use this information in the mastering process. 

DDR (Digital Disk Recorder) – See Digital Disk Recorder. 

DDS – Digital Data Service. 

Debouncing – Elimination of the bounce signals characteristic of mechanical 

switches. Debouncing can be performed by either hardware or 

software. 

Debugger – A program designed to facilitate software debugging. In general, 

it provides breakpoints, dump facilities, and the ability to examine and 

modify registers and memory. 

Decay – a) The length of time it takes for an audio signal to fall below the 

noise threshold. b) The adjustable length of time it takes for an ADO 

DigiTrail effect to complete. (The trail catches up with the primary video.) 

Decay Time – The time it takes for a signal to decrease to one-millionth 

of its original value (60 dB down from its original level). 

Decibel – One-tenth of a Bel. It is a relative measure of signal or sound 

intensity or “volume.” It expresses the ratio of one intensity to another. One 

dB is about the smallest change in sound volume that the human ear can 

detect. (Can also express voltage and power ratios logarithmically.) Used to 

define the ratio of two powers, voltages, or currents. See the definitions of 

dB, dBm, and dBw. 

Decimation – Term used to describe the process by which an image file is 

reduced by throwing away sampled points. If an image array consisted of 

100 samples on the X axis and 100 samples on the Y axis, and every other 

sample where thrown away, the image file is decimated by a factor of 2 

and the size of the file is reduced by 1/4. If only one sample out of every 

four is saved, the decimation factor is 4 and the file size is 1/16 of the 

original. Decimation is a low-cost way of compressing video files and is 

found in many low-cost systems. Decimation however introduces many 

artifacts that are unacceptable in higher-cost systems. 

Decimation Filter – The Decimation Filter is designed to provide decimation 

without the severe artifacts associated with throwing data away 

although artifacts still exist. (See the definition of Decimation.) The 

Decimation Filter process still throws data away but reduces image artifacts 

by smoothing out the voltage steps between sampled points. 

Deck, Tape – A tape recorder that does not include power amplifiers or 

speakers. 

Decode – To separate a composite video signal into its component parts. 


Decoded Stream – The decoded reconstruction of a compressed bit 

stream. 

Decoder – a) Device used to recover the component signals from a composite 

(encoded) source. Decoders are used in displays and in various processing 

hardware where component signals are required from a composite 

source such as composite chroma keying or color correction equipment. 

b) Device that changes NTSC signals into component signals; sometimes 

devices that change digital signals to analog (see DAC). All color TV sets 

must include an NTSC decoder. Because sets are so inexpensive, such 

decoders are often quite rudimentary. c) An embodiment of a decoding 

process. 

Decoder Input Buffer – The first-in first-out (FIFO) buffer specified in the 

video buffering verifier. 

Decoder Input Rate – The data rate specified in the video buffering verifier 

and encoded in the coded video bit stream. 

Decoding (Process) – The process that reads an input coded bit stream 

and produces decoded pictures or audio samples. 

Decoding Time Stamp (DTS) – A field that may be present in a PES 

packet header that indicates the time that an access unit is decoded in the 

system target decoder. 

Decompress – The process of converting video and audio data from its 

compact form back into its original form in order to play it. Compare 

Compress. 

Decrement – Programming instruction that decreases the contents of a 

storage location. 

DECT – Digital Enhanced Cordless Telecommunications. 

Dedicated – Set apart for some special use. A dedicated microprocessor 

is one that has been specially programmed for a single application such as 

weight measurement, traffic light control, etc. ROMs, by their very nature, 

are dedicated memories. 

Dedicated Keyboard – A keyboard assigned to a specific purpose. 

Deemphasis – Also known as postemphasis and post-equalization. 

Deemphasis modifies the frequency-response characteristic of the signal in 

a way that is complementary to that introduced by preemphasis. 

Deemphasis Network – Circuit that restores the preemphasized frequency 

response to its original levels. 

Deesser – A compressor which reduces sibilance by triggering compression 

when it senses the presence of high frequency signals above the compression 

threshold. 

Default – The setup condition (for example, transition rate settings, color 

of the matte gens, push-button status) existing when a device is first 

powered-up, before you make any changes. 

Default Printer – The printer to which the system directs a print request if 

you do not specify a printer when you make the request. You set the 

default printer using the Print Manager. 

Defaults – A set of behaviors specified on every system. You can later 

change these specifications which range from how your screen looks to 

what type of drive you want to use to install new software.

Defect – For tape, an imperfection in the tape leading to a variation in 

output or a dropout. The most common defects take the form of surface 

projections, consisting of oxide agglomerates, imbedded foreign matter, or 

redeposited wear products. 

Definition – The aggregate of fine details available on-screen. The higher 

the image definition, the greater the number of details that can be discerned. 

During video recording and subsequent playback, several factors 

can conspire to cause a loss of definition. Among these are the limited frequency 

response of magnetic tapes and signal losses associated with electronic 

circuitry employed in the recording process. These losses occur 

because fine details appear in the highest frequency region of a video signal 

and this portion is usually the first casualty of signal degradation. Each 

additional generation of a videotape results in fewer and fewer fine details 

as losses are accumulated. 

Degaussing – A process by which a unidirectional magnetic field is 

removed from such transport parts as heads and guides. The presence of 

such a field causes noise and a loss of high frequencies. 

Degenerate – Being simpler mathematically than the typical case. A 

degenerate edge is reduced to one point. A degenerate polygon has a null 

surface. 

Degree – An indication of the complexity of a curve. 

Del Ray Group – Proponent of the HD-NTSC ATV scheme. 

Delay – a) The time required for a signal to pass through a device or conductor. 

b) The time it takes for any circuitry or equipment to process a signal 

when referenced to the input or some fixed reference (i.e., house sync). 

Common usage is total delay through a switcher or encoder. c) The amount 

of time between input of the first pixel of a particular picture by the 

encoder and the time it exits the decoder, excluding the actual time in the 

communication channel. It is the combined processing time of the encoder 

and decoder. For face-to-face or interactive applications, the delay is crucial. 

It usually is required to be less than 200 milliseconds for one-way 

communication. 

Delay Correction – When an electronic signal travels through electronic 

circuitry or even through long coaxial cable runs, delay problems may 

occur. This is manifested as a displaced image and special electronic circuitry 

is needed to correct it. 

Delay Distortion – Distortion resulting from non-uniform speed of transmission 

of the various frequency components of a signal; i.e., the various 

frequency components of the signal have different times of travel (delay) 

between the input and the output of a circuit. 

Delay Distribution Amplifier – An amplifier that can introduce adjustable 

delay in a video signal path. 

Delete – Edit term to remove. 

Delivery – Getting television signals to a viewer. Delivery might be physical 

(e.g., cassette or disc) or electronic (e.g., broadcast, CATV, DBS, optical 

fiber). 

Delivery System – The physical medium by which one or more multiplexes 

are transmitted, e.g., satellite system, wideband coaxial cable, fiber 

optics, terrestrial channel of one emitting point. 



Delta Frame – A frame containing only the data that has changed since 

the last frame. Delta frames are an efficient means of compressing image 

data. Compare Key Frame. 

Demodulation – The process of recovering the intelligence from a modulated 

carrier. 

Demodulator – A device which recovers the original signal after it has 

been modulated with a high-frequency carrier. In television, it may refer to: 

an instrument such as the Tektronix 1450 which takes video in its transmitted 

form (modulated picture carrier) and converts it to baseband; the 

circuits which recover R-Y and B-Y from the composite signal. 

Demultiplexer (Demux) – A device used to separate two or more signals 

that were previously combined by a compatible multiplexer and transmitted 

over a single channel. 

Demultiplexing – Separating elementary streams or individual channels 

of data from a single multi-channel stream. For example, video and audio 

streams must be demultiplexed before they are decoded. This is true for 

multiplexed digital television transmissions. 

Depth Cueing – Varies the intensity of shaded surfaces as a function of 

distance from the eye. 

Depth of Field – The range of objects in front of a camera lens which are 

in focus. Smaller f-stops provide greater depth of field, i.e., more of the 

scene, near to far, will be in focus. 

Depth of Modulation – This measurement indicates whether or not video 

signal levels are properly represented in the RF signal. The NTSC modulation 

scheme yields an RF signal that reaches its maximum peak-to-peak 

amplitude at sync tip (100%). In a properly adjusted signal, blanking level 

corresponds to 75%, and peak white to 12.5%. The zero carrier reference 

level corresponds to 0%. Refer to the diagram at the right. Over modulation 

often shows up in the picture as a nonlinear distortion such as differential 

phase or differential gain. ICPM or white clipping may also result. Under 

modulation often results in degraded signal-to-noise performance. 

IRE 

Scale 

120 

100 

0 

-40 

Zero Carrier 

Reference 

Sync Tip 

Blanking 

Reference 

White 

Depth 

of Modulation 

0% 

12.5% 

75% 

100% 




Dequantization – The process of rescaling the quantized discrete cosine 

transform coefficients after their representation in the bit stream has been 

decoded and before they are presented to the inverse DCT 

Deserializer – A device that converts serial digital information to parallel. 

Desk Top Video (DTV) – Use of a desktop computer for video production. 

Detail – Refers to the most minute elements in a picture which are distinct 

and recognizable. Similar to Definition or Resolution. 

Development System – Microcomputer system with all the facilities 

required for hardware and software development for a given microprocessor. 

Generally consists of a microcomputer system, CRT display, printer, 

mass storage (usually dual floppy-disk drivers), PROM programmer, and incircuit 

emulator. 

Device Driver – Software to enable a computer to access or control a 

peripheral device, such as a printer. 

DFD (Displaced Frame Difference) – Differential picture if there is 

motion. 

D-Frame – Frame coded according to an MPEG-1 mode which uses DC 

coefficients only. 

D/I (Drop and Insert) – A point in the transmission where portions of the 

digital signal can be dropped out and/or inserted. 

DII – Download Information Indication. 

Diagnostics – A series of tests that check hardware components of a 

system. 

Diagonal Resolution – Amount of detail that can be perceived in a diagonal 

direction. Although diagonal resolution is a consequence of horizontal 

and vertical resolution, it is not automatically equivalent to them. In fact, 

ordinary television systems usually provide about 40 percent more diagonal 

resolution than horizontal or vertical. Many ATV schemes intentionally sacrifice 

diagonal resolution in favor of some other characteristics (such as 

improved horizontal or vertical resolution) on the theory that human vision 

is less sensitive to diagonal resolution than to horizontal or vertical. There 

is some evidence that diagonal resolution could be reduced to about 40 

percent less than either horizontal or vertical (overall half of its NTSC value) 

with no perceptible impairment. See also Resolution. 

Diagonal Split – An unusual quad split feature found on Ampex switchers, 

allowing diagonal or X-shaped divisions between sources, as opposed to 

the traditional horizontal and vertical divisions. 

Dialog Normalization Value – The dialog normalization value is a Dolby 

Digital parameter that describes the long-term average dialog level of the 

associated program. It may also describe the long-term average level of 

programs that do not contain dialog, such as music. This level is specified 

on an absolute scale ranging from –1 dBFS to –31 dBFS. Dolby Digital 

decoders attenuate programs based on the dialog normalization value in 

order to achieve uniform playback level. 

DIB (Device Independent Bitmap) – A file format that represents bitmap 

images in a device-independent manner. Bitmaps can be represented at 1, 

4, and 8 bits-per-pixel with a palette containing colors representing 24 

bits. Bitmaps can also be represented at 24 bits-per-pixel without a palette 

in a run-length encoded format. 


Differential Gain – a) This nonlinear distortion is often referred to as “diff 

gain” or “dG.” It is present if a signal’s chrominance gain is affected by 

luminance levels. This amplitude distortion is a result of the system’s 

inability to uniformly process the high-frequency chrominance signals at all 

luminance levels. The amount of differential gain distortion is expressed in 

percent. Since both attenuation and peaking of chrominance can occur in 

the same signal, it is important to specify whether the maximum over all 

amplitude difference or the maximum deviation from the blanking level 

amplitude is being quoted. In general, the NTSC measurement standard 

defines differential gain as the largest amplitude deviation between any two 

levels, expressed as a percent of the largest chrominance amplitude. When 

differential gain is present, color saturation has an unwarranted dependence 

on luminance level. Color saturation is often improperly reproduced at 

high luminance levels. The Modulated Ramp or Modulated Stair Step signals 

can be used to test for differential gain. b) The amplitude change, 

usually of the 3.6 MHz color subcarrier, introduced by the overall circuit, 

measured in dB or percent, as the subcarrier is varied from blanking to 

white level. 

Differential Phase – a) This nonlinear distortion is often referred to as 

“diff phase” or “dP.” It is present if a signal’s chrominance phase is affected 

by the luminance level. It occurs because of the system’s inability to 

uniformly process the high-frequency chrominance information at all luminance 

levels. Diff Phase is expressed in degrees of subcarrier phase. The 

subcarrier phase can be distorted such that the subcarrier phase is 

advanced (lead or positive) or delayed (lag or negative) in relation to its 

original position. In fact, over the period of a video line, the subcarrier 

phase can be both advanced and delayed. For this reason, it is important 

to specify whether “peak to peak diff phase” is being specified or “maximum 

deviation from 0” in one direction or another. Normally the “peak to 

peak diff phase” is given. dP distortions cause changes in hue when picture 

brightness changes. Colors may not be properly reproduced, particularly 

in high-luminance areas of the picture. b) The phase change of the 

3.6 MHz color subcarrier introduced by the overall circuit, measured in 

degrees, as the subcarrier is varied from blanking to white level. 

Differential Pulse Code Modulation – DPCM is a source coding scheme 

that was developed for encoding sources with memory. The reason for 

using the DPCM structure is that for most sources of practical interest, the 

variance of the prediction error is substantially smaller than that of the 

source. 

Differentiated Step Filter – A special filter sometimes also called a “diff 

step” filter that is used to measure luminance nonlinearity. When this filter 

is used with a luminance step waveform (see the waveform discussed in 

the Luminance Nonlinearity discussion), each step on the waveform is 

translated into a spike that is displayed on the waveform monitor. The 

height of each spike translates into the height of the step so the amount of

distortion can be determined by comparing the height of each spike. Refer 

to the figure below. 

Diffuse – Diffuse light is the light reflected by a matte surface; without 

glare or highlight. It is base on relative orientation of surface normal and 

light source positions and luminance. 

Digicipher – Digicipher is a compression and transmission technology 

from General Instrument, dedicated to Digital TV distribution via satellite. 

Digicipher video coding is based on DCT like MPEG, but does not use Bpictures. 

Instead, it uses a so-called adaptive prediction mode. Digicipher 1 

was the first incarnation and is still used today by many providers since it 

was the first commercially available digital compression scheme. 

Digicipher 2 – General Instrument’s latest distribution system and is the 

standard for 4DTV product. DC2 uses standard MPEG-2 video encoding, 

but just about everything else in this “standard” is unique to DC2. For 

example, DVB/MPEG-2 uses Musicam for audio whereas DC2 uses Dolby 

AC-3. Despite using the same video standard, DVB/MPEG-2 and DC2 signals 

are totally incompatible and no receiver can currently receive both. 

Digiloop – Patented circuitry within the Vista switcher, which allows the 

insertion of a digital effects device within the architecture of the switcher. 

This allows multi-channels of digital effects to be used on a single M/E, 

which would otherwise require 3 M/Es. 

Digimatte (Menu) – The key channel processor, providing a separate 

channel specifically for black and white key signals that processes and 

manipulates an external key signal in the same way as source video in 3D 

space. 

Digit – Sign or symbol used to convey a specific quantity of information 

either by itself or with other numbers of its set: 2, 3, 4, and 5 are digits. 

The base or radix must be specified and each digit’s value assigned. 

Digital – a) Having discrete states. Most digital logic is binary, with two 

states (on or off). b) A discontinuous electrical signal that carries information 

in binary fashion. Data is represented by a specific sequence of off-on 

electrical pulses. A method of representing data using binary numbers. An 



analog signal is converted to digital by the use of an analog-to-digital (A/D) 

converter chip by taking samples of the signal at a fixed time interval 

(sampling frequency). Assigning a binary number to these samples, this 

digital stream is then recorded onto magnetic tape. Upon playback, a 

digital-to-analog (D/A) converter chip reads the binary data and reconstructs 

the original analog signal. This process virtually eliminates generation 

loss as every digital-to-digital copy is theoretically an exact duplicate 

of the original allowing multi-generational dubs to be made without degradation. 

In actuality of course, digital systems are not perfect and specialized 

hardware/software is used to correct all but the most severe data loss. 

Digital signals are virtually immune to noise, distortion, crosstalk, and other 

quality problems. In addition, digitally based equipment often offers advantages 

in cost, features, performance, and reliability when compared to analog 

equipment. 

Digital Audio Broadcasting (DAB) – a) NRSC (National Radio Systems 

Committee) term for the next generation of digital radio equipment. 

b) Modulations for sending digital rather than analog audio signals by 

either terrestrial or satellite transmitter with audio response up to compact 

disc quality (20 kHz). c) DAB was started as EUREKA project EU 147 in 

1986. The digital audio coding process called MUSICAM was designed 

within EUREKA 147 by CCETT. The MUSICAM technique was selected by 

MPEG as the basis of the MPEG-1 audio coding, and it is the MPEG-1 

Layer II algorithm which will be used in the DAB system. The EUREKA 147 

project, in close cooperation with EBU, introduced the DAB system 

approach to the ITU-R, which subsequently has been contributing actively 

for the worldwide recognition and standardization of the DAB system. EBU, 

ETSI and EUREKA 147 set up a joint task committee with the purpose of 

defining a European Telecommunications Standard (ETS) for digital sound 

broadcasting, based on the DAB specifications. ETSI published the EUREKA 

147 system as standard ETS 300 401 in February 1995, and market adoption 

is forthcoming; the BBC, for instance, plans to have 50% transmission 

coverage in 1997 when DAB receivers are being introduced to the public. 

Digital Audio Recording – A system which converts audio signals into 

digital words which are stored on magnetic tape for later reconversion to 

audio in such a manner that dropouts, noise, distortion, and other poor 

tape qualities are eliminated. 

Digital Betacam – A development of the original analog Betacam VTR 

which records digitally on a Betacam-style cassette. A digital video tape 

format using the CCIR 601 standard to record 4:2:2 component video in 

compressed form on 12.5 mm (1/2") tape. 

Digital Borderline – A GVG option and term. A digital border type with 

fewer settings, hence less control than the analog type used on Ampex 

switchers. 

Digital Cinemas – Facing the high costs of copying, handling and distribution 

of film, an infrastructure enabling digital transport of movies to digital 

cinemas could be highly attractive. In addition, digital delivery of films 

can effectively curb piracy. The MPEG-2 syntax supports the levels of quality 

and features needed for this application. 

Digital Chroma Keying – Digital chroma keying differs from its analog 

equivalent in that it can key uniquely from any one of the 16 million colors 

represented in the component digital domain. It is then possible to key 

from relatively subdued colors, rather than relying on highly saturated col- 




ors that can cause color spill problems on the foreground. A high-quality 

digital chroma keyer examines each of the three components of the picture 

and generates a linear key for each. These are then combined into a composite 

linear key for the final keying operation. The use of three keys allows 

much greater subtlety of selection than does a chrominance-only key. 

Digital Component – Component signals in which the values for each 

pixel are represented by a set of numbers. 

Digital Component Video – Digital video using separate color components, 

such as YCbCr or RGB. See ITU-R BT.601-2. Sometimes incorrectly 

referred to as D1. 

Digital Composite Video – The digitized waveform of (M) NTSC or (B, D, 

G, H, I) PAL video signals, with specific digital values assigned to the sync, 

blank, and white levels. Sometimes incorrectly referred to as D2 or D3. 

Digital Disk Recorder (DDR) – a) A digital video recording device based 

on high-speed computer disk drives. Commonly used as a means to get 

video into and out from computers. b) A video recording device that uses a 

hard disk or optical disk drive mechanism. Disk recorders offer quick 

access to recorded material. 

Digital Effects – Special effects created using a digital video effects (DVE) 

unit. 

Digital Parallel Distribution Amplifier – A distribution amplifier 

designed to amplify and fan-out parallel digital signals. 

Digital Recording – A method of recording in which the information (usually 

audio or video) is first coded in a digital form. Most commonly, a binary 

code is used and recoding takes place in terms of two discrete values of 

residual flux. 

Digital S – A digital tape format that uses 1.25" high-density metal particle 

tape, running at 57.8 mm/s, to record a video data rate of 50 Mb/s. 

Video sampled at 4:2:2 is compressed at 3:3:1 using DCT-based intraframe 

compression. Two individually editable audio channels are recorded 

using 16-bit, 48 kHz sampling. The tape can be shuttled and searched up 

to x32 speed. Digital S includes two cue tracks and four further audio 

channels in a cassette housing with the same dimensions as VHS. 

Digital Sampling Rate – The frequency at which an analog signal is sampled 

to create a digital signal. 

Digital Storage Media – A means of storage (usually magnetic tape, disk, 

or DVD) for audio, video, or other information that is in binary form. 

Digital System – A system using devices that can be in only one of two 

possible states. 

Digital Television Communications System (DITEC) – System developed 

by Comstat Corp. for satellite links. 

Digital TV Group – A UK forum of technology and service providers created 

in August 1995 with the objective to speed up the introduction of digital 

terrestrial TV in the UK. With its focus on implementation aspects, the 

efforts of the group are seen as an extension of the work done in DVB. 

Membership is open to those DVB members who wish to participate actively 

in the introduction of digital terrestrial TV in the UK. 

Digital Versatile Disk (DVD) – DVD is the outcome of a battle between 

two formerly rivaling camps of optical data discs, each supporting the 


MMCD (Multimedia CD) and the SD (Super Density) formats. The MMDC 

and SD proposals featured different error correction, modulation, disc 

structure, etc., but targeted identical markets. Wisely, the two camps 

merged and agreed on a third format, that was a mix of the other two. The 

DVD, initially, addressed only movie player applications, but the nature of 

the medium has attracted other applications, too. In light of the increasing 

number of possible applications of the new disc format, it was therefore 

renamed to Digital Versatile Disc. The DVD consortium intends to position 

the DVD as a high-capacity, multimedia storage medium. A total of nine 

working groups in the consortium elaborate on various technology specific 

topics, such as video, ROM applications, audio-only systems, and copyprotection. 

The movie player application remains the DVD’s reason for 

being, but there’s a chance that the DVD may also take over a huge share 

of the CD-ROM market. The promoters of the format agreed in December 

1995 on a core set of specifications. The system operates at an average 

data rate of 4.69 Mbit/s and features 4.7 GB data capacity, which allows 

MPEG-2 coding of movies, or which may be used for a high-resolution 

music disc. For the PAL and NTSC specifications of the DVD, different 

audio coding has been chosen to obey market patterns. For the NTSC version, 

the Dolby AC-3 coding will be mandatory, with MPEG audio as an 

option, whereas the opposite is true for PAL and SECAM markets. 

Digital Video – A video signal represented by computer-readable binary 

numbers that describe colors and brightness levels. 

Digital Video Broadcasting (DVB) – a) A system developed in Europe 

for digital television transmission, originally for standard definition only, 

though high-definition modes have now been added to the specification. 

DVB defines a complete system for terrestrial, satellite, and cable transmission. 

Like the ATSC system, DVB uses MPEG-2 compression for video, but 

it uses MPEG audio compression and COFDM modulation for terrestrial 

transmission. b) At the end of 1991, the European Launching Group (ELG) 

was formed to spearhead the development of digital TV in Europe. During 

1993, a Memorandum of Understanding was drafted and signed by the 

ELG participants, which now included manufacturers, regulatory bodies and 

other interest groups. At the same time, the ELG became Digital Video 

Broadcasting (DVB). The TV system provided by the DVB is based on 

MPEG-2 audio and video coding, and DVB has added various elements not 

included in the MPEG specification, such as modulation, scrambling, and 

information systems. The specifications from DVB are offered to either ETSI 

or CENELEC for standardization, and to the ITU. 

Digital Video Cassette (DVC) – a) Tape width is 1/4", metal particle formula. 

The source and reconstructed video sample rate is similar to that of 

CCIR-601, but with additional chrominance subsampling (4:1:1 in the case 

of 30 Hz and 4:2:0 in the case of 25 Hz mode). For 30 frames/sec, the 

active source rate is 720 pixels/lines x 480 lines/frame x 30 frames/sec x 

1.5 samples/pixel average x 8 samples/pixel = ~124 Mbit/sec. A JPEG-like 

still image compression algorithm (with macroblock adaptive quantization) 

applied with a 5:1 reduction ratio (target bit rate of 25 Mbit/sec) averaged 

over a period of roughly 100 microseconds (100 microseconds is pretty 

small compared to MPEG’s typical 1/4 second time average!) b) A digital 

tape recording format using approximately 5:1 compression to produce 

near-Betacam quality on a very small cassette. Originated as a consumer 

product, but being used professionally as exemplified by Panasonic’s variation, 

DVC-Pro.

Digital Video Disc (DVD) – A new format for putting full-length movies on 

a 5" CD using MPEG-2 compression for “much better than VHS” quality. 

Also known as Digital Versatile Disc. 

Digital Video Interactive (DVI) – A multimedia system marketed by Intel. 

DVI is not just an image-compression scheme, but includes everything that 

is necessary to implement a multimedia playback station including chips, 

boards, and software. DVI technology brings television to the microcomputer. 

DVI’s concept is simple: information is digitized and stored on a random-access 

device such as a hard disk or a CD-ROM, and is accessed by 

a computer. DVI requires extensive compression and real-time decompression 

of images. Until recently this capability was missing. DVI enables new 

applications. For example, a DVI CD-ROM disk on twentieth-century artists 

might consist of 20 minutes of motion video; 1,000 high-res still images, 

each with a minute of audio; and 50,000 pages of text. DVI uses the YUV 

system, which is also used by the European PAL color television system. 

The Y channel encodes luminance and the U and V channels encode 

chrominance. For DVI, we subsample 4-to-1 both vertically and horizontally 

in U and V, so that each of these components requires only 1/16 the information 

of the Y component. This provides a compression from the 24-bit 

RGB space of the original to 9-bit YUV space. The DVI concept originated in 

1983 in the inventive environment of the David Sarnoff Research Center in 

Princeton, New Jersey, then also known as RCA Laboratories. The ongoing 

research and development of television since the early days of the 

Laboratories was extending into the digital domain, with work on digital 

tuners, and digital image processing algorithms that could be reduced to 

cost-effective hardware for mass-market consumer television. 

Digital Video Recording – “D1” Component, “D2” Composite. 

Digital Word – The number of bits treated as a single entity by the 

system. 

Digital Zoom – A feature found on some camcorders that electronically 

increases the lens zoom capability by selecting the center of the image and 

enlarging it digitally. 

Digitization – The process of changing an electronic signal that is an 

analogy (analog) of a physical process such as vision or hearing into a discrete 

numerical form. Digitization is subdivided into the processes of sampling 

the analog signal at a moment in time, quantizing the sample (assigning 

it a numerical level), and coding the number in binary form. The advantages 

of digitization include improved transmission; the disadvantages 

include a higher bit rate than the analog bandwidth. Bit rate reduction 

schemes work to reduce that disadvantage. 

Digitize – a) The process of turning an analog signal into digital data. 

b) To convert an image from hard copy (a photo) into digital data for display 

on a computer. 

Digitizer – A system that converts an analog input to a digital format, 

such as analog-to-digital converters (ADC), touch tablets, and mice. The 

last two, for example, take a spatial measurement and present it to a computer 

as a digital representation. 

Digitizing – The act of taking analog audio and/or video and converting it 

to digital form. In 8-bit digital video there are 256 possible steps between 

maximum white and minimum black. 



Digitizing Time – Time taken to record footage into a disk-based editing 

system, usually from a tape-based analog system, but also from newer digital 

tape formats without direct digital connections. 

DigiTrail – An enhancement of ADO effects by adding trails, smearing, 

sparkles, etc. 

DigiVision – A company with an early line-doubling ATV scheme. 

Dimmer Switch – A control used to gradually increase and decrease the 

electricity sent to a lighting fixture, thereby effecting the amount of light 

given by the lighting fixture. 

DIN (Deutsches Institut fuer Normung) – A German association that 

sets standards for the manufacture and performance of electrical and electronic 

equipment, as well as other devices. DIN connectors carry both 

audio and video signals and are common on equipment in Europe. (Also 

referred to as Deutsche Industrie Normenausschuss.) 

DIP (Dual In-Line Package) – Standard IC package with two parallel 

rows of pins. 

Dipswitch – A block of small switches formed so that they fit into an IC 

socket or into a PCB on standard IC spacing. 

Direct Access Restriction – The ability to limit a user’s capability to gain 

access to material not intended in the product structure. This is not 

parental control, but it is useful for material such as games or training 

material where such access would destroy the intent of the product. This 

type of control is usually accomplished with pre and post commands in the 

authoring process. 

Direct Addressing – Standard addressing mode, characterized by the 

ability to reach any point in main storage directly. The address is specified 

as part of the instruction. 

Direct Broadcast Satellite (DBS) – a) A distribution scheme involving 

transmission of signals directly from satellites to homes. It does not carry 

the burden of terrestrial broadcasting’s restricted bandwidth and regulations 

and so is thought by many to be an ideal mechanism for the introduction 

of high base bandwidth ATV. DBS is the most effect delivery mechanism 

for reaching most rural areas; it is relatively poor in urban areas and 

in mountainous terrain, particularly in the north. Depending on the frequency 

band used, it can be affected by factors such as rain. b) Multiple television 

channel programming service that is transmitted direct from high 

powered satellites, directly to a home receiving dish. 

Direct Color – An SVGA mode for which each pixel color value is specified 

directly by the contents of a bit field. 

Direct Draw Overlay – A feature that lets you see the video full screen 

and full motion on your computer screen while editing. Most new 3D 

graphics cards support this. If your’s does not, it simply means you will 

need an external monitor to view the video. Direct Draw Overlay has 

absolutely nothing to do with your final video quality. 

Direct Memory Access (DMA) – Method of gaining direct access to main 

storage in order to perform data transfers without involving the CPU. 

Direct Recording – A type of analog recording which records and reproduces 

data in the electrical form of its source. 




Direct Sound – The sound which reaches a mike or listener without hitting 

or bouncing off any obstacles. 

Direct to Disk – A method of recording directly to the cutting head of the 

audio disk cutter, eliminating the magnetic recorder in the sequence, typified 

by no tape hiss. 

Directional Antenna – An antenna that directs most of its signal strength 

in a specific direction rather than at equal strength in all directions. 

Directional Microphone – One whose sensitivity to sound varies with 

direction. Such microphones can be aimed so their most sensitive sides 

face the sound source, while their least sensitive sides face sources of 

noise or other undesired sound. 

Directional Source – Light that emanates from a constant direction with 

a constant intensity. This is called the infinite light source. 

Directory – A container in the file system in which you store other directories 

and files. 

Direct-View – A CRT watched directly, as opposed to one projecting its 

image on a screen. 

DIS – Draft International Standard. 

Disable – Process of inhibiting a device function. 

Discrete – Having an individual identity. An individual circuit component. 

Discrete Cosine Transform (DCT) – a) Used in JPEG and the MPEG, 

H.261 and H.263 video compression algorithms, DCT techniques allow 

images to be represented in the frequency rather than time domain. 

Images can be represented in the frequency domain using less information 

than in the time domain. b) A mathematical transform that can be perfectly 

undone and which is useful in image compression. c) Many encoders perform 

a DCT on an eight-by-eight block of image data as the first step in 

the image compression process. The DCT converts the video data from the 

time domain into the frequency domain. The DCT takes each block, which 

is a 64-point discrete signal, and breaks it into 64 basis signals. The output 

of the operation is a set of 64 basis-signal amplitudes, called DCT 

coefficients. These coefficients are unique for each input signal. The DCT 

provides a basis for compression because most of the coefficients for a 

block will be zero (or close to zero) and do not need to be encoded. 

Discrete Time Oscillator – Digital implementation of the voltagecontrolled 

oscillator. 

Disk – An information/digital data storage medium. 

Disk (Menus) – Recall and Store enable effects to be stored, renamed, 

and recalled on 3-1/2" disks in the disk drive provided with the system. 

Disk Drive – The machine used to record and retrieve digital information 

on disk. 

Disk Resource – Any disk (hard, CD-ROM, or floppy) that you can access 

either because it is physically attached to your workstation with a cable, or 

it is available over the network. 

Disk Use – The percentage of space on your disk that contains 

information. 

Dispersion – Distribution of the oxide particles within the binder. A good 

dispersion can be defined as one in which equal numbers of particles 


would be found in equal, vanishingly small volumes sampled from different 

points within the coating. 

Displacement of Porches – Refers to any difference between the level of 

the front porch and the level of the back porch. 

Display – a) The ultimate image presented to a viewer; the process of 

presenting that image. b) CRT, LCD, LED, or other photo luminescent panel 

upon which numbers, characters, graphics, or other data is presented. 

Display Order – The order in which the decoded pictures are displayed. 

Normally this is the same order in which they were presented at the input 

of the encoder. 

Display Signal Processing – An efficient, widely compatible system 

required that distribution be free of detailed requirements specific to display, 

and that necessary additional display processing unique to that display 

class be conducted only at the display. The variety of display systems, 

already numerous, continues to increase. Each system or variant has its 

own set of specifications, performance characteristics, and requirements, 

including electro-optic transfer function, color gamut, scanning sequence, 

etc. Display signal processing might include transformation at the display 

to the appropriate luminance range and chrominance, to display primaries 

and reference white, matrixing to achieve metameric color match, adaptation 

to surround, plus conversion to scanning progressive or scanning 

interlaced, etc. Display processing may not be required for transmission if 

there is unique point-to-point routing clearly identified and appropriate processing 

has been provided in distribution. But it is frequently required for 

emission to a diffuse population of display systems. 

Dissolve – A process whereby one video signal is gradually faded out 

while a second image simultaneously replaces the original one. See Mix. 

Distant Miking – Placing a mike far from a sound source so that a high 

proportion of reflected sound is picked up. 

Distortion – In video, distortion usually refers to changes in the luminance 

or chrominance portions of a signal. It may contort the picture and produce 

improper contrast, faulty luminance levels, twisted images, erroneous colors, 

and snow. In audio, distortion refers to any undesired changes in the 

waveform of a signal caused by the introduction of spurious elements. The 

most common audio distortions are harmonic distortion, intermodulation 

distortion, crossover distortion, transient distortion, and phase distortion. 

Distribution – a) The process of getting a television signal from point to 

point; also the process of getting a television signal from the point at which 

it was last processed to the viewer. See also Contribution. b) The delivery 

of a completed program to distribution-nodes for emission/transmission as 

an electrical waveform, or transportation as a physical package, to the 

intended audiences. Preparation for distribution is the last step of the production 

cycle. Typical distribution-nodes include: release and duplicating 

laboratories, satellite systems, theatrical exchanges, television networks 

and groups, cable systems, tape and film libraries, advertising and program 

agencies, educational systems, government services administration, etc. 

Distribution Amplifier – Device used to multiply (fan-out) a video signal. 

Typically, distribution amplifiers are used in duplication studios where many 

tape copies must be generated from one source or in multiple display 

setups where many monitors must carry the same picture, etc. May also 

include cable equalization and/or delay.

Distribution Quality – The level of quality of a television signal from the 

station to its viewers. Also know as Emission Quality. 

DIT – Discontinuity Information Table. 

DITEC – See Digital Television Communications System. 

Dither – a) Typically a random, low-level signal (oscillation) which maybe 

added to an analog signal prior to sampling. Often consists of white noise 

of one quantizing level peak-to-peak amplitude. b) The process of representing 

a color by mixing dots of closely related colors. 

Dither Component Encoding – A slight expansion of the analog signal 

levels so that the signal comes in contact with more quantizing levels. The 

results are smoother transitions. This is done by adding white noise (which 

is at the amplitude of one quantizing level) to the analog signal prior to 

sampling. 

DLT (Digital Linear Tape) – a) A high capacity data tape format. b) A 

high-density tape storage medium (usually 10-20 gigabytes) used to transport 

and input data to master a DVD. Media is designated as “Type III” or 

“Type IV” for tapes used for DVD. 

DMA – See Direct Memory Access. 

D-MAC – Originally, a MAC (Multiplexed Analog Component) with audio 

and data frequency multiplexed after modulation, currently a term used in 

Europe to describe a family of B-MAC-like signals, one of which is the 

British choice for DBS. See also MAC. 

DMK (Downstream Mixer-Keyer) – See DSK. 

DM-M (Delayed Modulation Mark) – Also called Miller Code. 

DNG (Digital News Gathering) – Electronic News Gathering (ENG) using 

digital equipment and/or transmission. 

DNL – Noise reduction system produced by Philips. 

Document Window – A sub-window inside an application. The size is 

user adjustable but limited by the size of its application window. 

Dolby AC-2 and AC-3 – These are compression algorithms from the 

Dolby Laboratories. The AC-2 coding is an adaptive transform coding that 

includes a filterbank based on time-domain alias cancellation (TDAS). The 

AC-3 is a dedicated multichannel coding, which like AC-2 uses adaptive 

transform coding with a TDAS filterbank. In addition, AC-3 employs a bitallocation 

routine that distributes bits to channels and frequencies depending 

on the signals, and this improves the coding efficiency compared to 

AC-2. The AC-3 algorithm is adopted for the 5.1-channel audio surround 

system in the American HDTV system. 

Dolby – A compression/expansion (companding) noise reduction system 

developed by Ray Dolby, widely used in consumer, professional and broadcast 

audio applications. Signal-to-noise ratio improvement is accomplished 

by processing a signal before recording and reverse-processing the signal 

upon playback. 

Dolby Digital – Formerly AC-3, a perceptual audio coding system based 

upon transform coding techniques and psycho-acoustic principles. 

Frequency-domain processing takes full advantage of noise masking by 

confining quantization noise to narrow spectral regions where it will be 

masked by the audio signal. Designed as an emissions (delivery) system, 

Dolby Digital provides flexible coding of up to 5.1 audio channels at a vari- 



ety of data rates. In addition, Dolby Digital bit streams carry informational 

data about the associated audio. 

Dolby Surround – A passive system that matrix encodes four channels of 

audio into a standard two-channel format (Lt/Rt). When the signal is decoded 

using a Dolby Surround Pro Logic decoder, the left, center, and right 

signals are recovered for playback over three front speakers and the surround 

signal is distributed over the rear speakers. 

Dolby Surround Pro Logic (DSPL) – An active decoding process 

designed to enhance the sound localization of Dolby Surround encoded 

programs through the use of high-separation techniques. Dolby Surround 

Pro Logic decoders continuously monitor the encoded audio program and 

evaluate the inherent sound field dominance, applying enhancement in the 

same direction and in proportion to that dominance. 

Dolly – a) A set of casters attached to the legs of a tripod to allow the tripod 

to roll. b) A forward/backward rolling movement of the camera on top 

of the tripod dolly. 

Domain – The smallest known permanent magnet. 

Doppler Effect – An effect in which the pitch of a tone rises as its source 

approaches a listener, and falls as the source moves away from the 

listener. 

DOS – Disk Operating System. 

Dot Crawl – See Chroma Crawl. 

Dot Matrix – Method of forming characters by using many small dots. 

Dot Pitch – a) The density measurement of screen pixels specified in pixels/mm. 

The more dense the pixel count, the better the screen resolution. 

b) The distance between phosphor dots in a tri-color, direct-view CRT. It 

can be the ultimate determinant of resolution. 

Double Precision Arithmetic – Uses two words to represent each 

number. 

Double-Click – To hold the mouse still, then press and release a mouse 

button twice, very rapidly. When you double-click an icon, it opens into a 

window; when you double-click the Window menu button, the window 

closes. 

Doubling – To overdub the same part that has previously been recorded, 

with the object of making the part appear to have been performed by several 

instruments playing simultaneously. 

Down Converter – This device accepts modulated high-frequency television 

signals and down converts the signal to an intermediate frequency. 

Down Link – a) The frequency satellites use to transmit data to earth stations. 

b) Hardware used to transmit data to earth stations. 

Download – The process of having an effect moved from disk storage into 

the ADO control panel. 

Downmix – A process wherein multiple channels are summed to a lesser 

number of channels. In the audio portion of a DVD, there can be as many 

as eight channels of audio in any single stream and it is required that all 

DVD players produce a stereo version of those channels provided on the 

disc. This capacity is provided as legacy support for older audio systems. 




Downscaling – The process of decimating or interpolating data from an 

incoming video signal to decease the size of the image before placing it 

into memory. 

Downstream – A term describing the precedence of an effect or key. The 

“stream” of video through a switcher allows multiple layers of effects to be 

accomplished, with each successive layer appearing on top of the previous 

one. The most downstream effect is that video which appears as the topmost 

layer. 

Downstream Keyer – The last keyer on the switcher. A key on the DSK 

will appear in front of all other video. Ampex DSKs are actually DMKs, that 

is they also allow mixes and fades with the switcher output. 

Downstream Keyer (DSK) – A term used for a keyer that inserts the key 

“downstream” (last layer of video within switcher) of the effects system 

video output. This enables the key to remain on-air while the backgrounds 

and effects keys are changed behind it. 

DPCM – See Differential Pulse Code Modulation. 

D-Pictures – Pictures for which only DC coefficients are transmitted. 

D-pictures are not part of MPEG-2 but only of MPEG-1. MPEG-2 decoders 

must be able to decode D-pictures. 

Drag – To press and hold down a mouse button, then move the mouse. 

This drags the cursor to move icons, to highlight menu items, or to perform 

other functions. 

DRAM (Dynamic Random Access Memory) – An integrated circuit 

device that stores data bits as charges in thousands of tiny capacitors. 

Since the capacitors are very small, DRAM must be constantly refreshed to 

restore charges in appropriate cells. DRAM is used for short-term memory 

such as frame and screen memory and memory which contains operating 

programs which are loaded from ROM or disk. 

DRC (Dynamic Range Control) – A feature of Dolby Digital that allows 

the end user to retain or modify the dynamic range of a Dolby Digital 

Encoded program upon playback. The amount of control is dictated by 

encoder parameter settings and decoder user options. 

Drift – Gradual shift or change in the output over a period of time due to 

change or aging of circuit components. Change is often caused by thermal 

instability of components. 

Drive – A hardware device that lets you access information on various 

forms of media, such as hard, floppy, and CD-ROM disks, and magnetic 

tapes. 

Drive Address – See SCSI Address. 

Drive Pulse – A term commonly used to describe a set of signals needed 

by source equipment such as a camera. This signal set may be composed 

of any of the following: sync, blanking, subcarrier, horizontal drive, vertical 

drive, and burst flag. Also called pulse drive. 

Driving Signals – Signals that time the scanning at the pickup device. 

Drop Frame – System of modifying the frame counting sequence (dropping 

two frames every minute except on every tenth minute) to allow time 

code to match a real-time clock. 

Drop Frame Time Code – a) SMPTE time code format that skips (drops) 

two frames per minute except on the tenth minute, so that the time code 


stays coincident with real time. b) The television broadcast standard for 

time code. c) The NTSC color coding system uses a 525/60 line/field format, 

it actually runs at 59.94 fields per second, or 29.97 frames per second 

(a difference of 1:1000). Time code identifies 30 frames per second, 

whereas drop frame time code compensates by dropping two frames in 

every minute except the tenth. Note that the 625/50 PAL system is exact 

and does not require drop frame. 

Drop Outs – Small bit of missing picture information usually caused by 

physical imperfections in the surface of the video tape. 

Drop Shadow – a) A type of key border where a key is made to look three 

dimensional and as if it were illuminated by a light coming from the upper 

left by creating a border to the right and bottom. b) A key border mode 

which places a black, white, or gray border to the right and below the title 

key insert, giving a shadow effect. 

Drop-Down List Box – Displays a list of possible options only when the 

list box is selected. 

Dropout – a) A momentary partial or complete loss of picture and/or 

sound caused by such things as dust, dirt on the videotape or heads, 

crumpled videotape, or flaws in the oxide layer of magnetic tape. 

Uncompensated dropout produces white or black streaks in the picture. 

b) Drop in the playback radio frequency level, resulting from an absence of 

oxide on a portion of the videotape, causing no audio or video information 

to be stored there. Dropout usually appears as a quick streak in the video. 

Dropout Count – The number of dropouts detected in a given length of 

magnetic tape. 

Dry Signal – A signal without any added effects, especially without reverb. 

DS (Dansk Standard) – Danish standarding body. 

DS0 (Digital Signal Level Zero) – 64 kbps. 

DS1 – A telephone company format for transmitting information digitally. 

DS1 has a capacity of 24 voice circuits at a transmission speed of 1.544 

megabits per second. 

DS3 (Digital Service 3) – One of a hierarchy of North American data 

transmission rates associated with ISDN and B-ISDN, 44.736 Mbps. The 

terrestrial and satellite format for transmitting information digitally. DS3 has 

a capacity of 672 voice circuits at a transmission speed of 44.736 Mbps 

(commonly referred to as 45 Mbps). DS3 is used for digital television distribution 

using mezzanine level compression – typically MPEG-2 in nature, 

decompressed at the local station to full bandwidth signals (such as HDTV) 

and then re-compressed to the ATSC’s 19.39 Mbps transmission standard. 

DSI – Download Server Initiate. 

DSK (Downstream Keying) – An effect available in some special effects 

generators and video mixers in which one video signal is keyed on top of 

another video signal. The lightest portions of the DSK signal replace the 

source video leaving the dark areas showing the original video image. 

Optionally, the DSK signal can be inverted so the dark portions are keyed 

rather than the lightest portions allowing a solid color to be added to the 

keyed portions. The DSK input is most commonly a video camera or character 

generator. The DSK signal must be genlocked to the other signals.

DSK Monitor – A video output showing program video with the DSK key 

over full time. 

DSM – See Digital Storage Media 

DSM-CC U-N – DSM-CC User-to-Network. 

DSM-CC-U-U – DSM-CC User-to-User. 

DSNG – Digital Satellite News Gathering. 

DSP – Digital Signal Processing. 

DSRC (David Sarnoff Research Center) – Formerly RCA Laboratories 

(now part of SRI International), home of the ACTV research. 

DSS (Direct Satellite System) – An alternative to cable and analog satellite 

reception initially using a fixed 18-inch dish focused on one or more 

geostationary satellites. DSS units are able to receive multiple channels of 

multiplexed video and audio signals as well as programming information, 

email, and related data. DSS typically used MPEG-2 encoding. 

DSSB (Dual Single Sideband) – A modulation technique that might be 

applied to two of the components of ACTV. 

DTE – Data Terminal Equipment. 

DTM – Digital Transmodulation. 

DTMF – Dual Tone Multi-Frequency. 

D-to-A Converter (Digital to Analog Converter) – A device that converts 

digital signals to analog signals. 

DTS (Decoding Time Stamp) – Part of PES header indicating when an 

access unit is to be decoded. 

DTT – Digital Terrestrial Television. 

DTTB – Digital Terrestrial Television Broadcasting. 

DTTV-SA – Digital Terrestrial Television – System Aspects) 

DTV (Digital Television) – a) A term used for all types of digital television 

including High Definition Television and Standard Definition Television. 

b) Another acronym for the new digital television standards. See HDTV. 

DTV Team – Originally Compaq, Microsoft, and Intel, later joined by Lucent 

Technology. The DTV Team promotes the computer industry’s views on digital 

television, namely, that DTV should not have interlace scanning formats 

but progressive scanning formats only. (Intel, however, now supports all the 

ATSC Table 3 formats, including those that are interlace, such as 1080i.) 

DTVB – Digital Television Broadcasting. 

DTVC – Digital Television by Cable. 

Dual Capstan – Refers to a transport system in which a capstan and 

pinchroller are used on both sides of the recording and playback head 

system. 

Dub – A duplicate copy made from one recording medium to another. 

Dubs – Copies of videotape. 

Durability – Usually expressed as a number of passes that can be made 

before a significant degradation of output occurs; divided by the corresponding 

number that can be made using a reference tape. 



Duration – Length of time (in hours, minutes, seconds, and frames) that a 

particular effect or section of audio or video material lasts. 

DV – This digital VCR format is a cooperation between Hitachi, JVC, Sony, 

Matsushita, Mitsubishi, Philips, Sanyo, Sharp, Thomson, and Toshiba. It 

uses 6.35 mm (0.25-inch) wide tape in a range of products to record 

525/60 or 625/50 video for the consumer (DV) and professional markets 

(Panasonic’s DVCPRO, Sony’s DVCAM and Digital-8). All models use digital 

intra-field DCT-based “DV” compression (about 5:1) to record 8-bit component 

digital video based on 13.5 MHz luminance sampling. 

DVB (Digital Video Broadcasting) – Broadcasting TV signals that comply 

with a digital standard. 

DVB-C (Digital Video Broadcasting – Cable) – Broadcasting TV signals 

that comply with a digital standard by cable (ETS 300 429). 

DVB-CA – Support for use of scrambling and conditional access (CA) within 

digital broadcasting systems (ETR 289). 

DVB-CI – Common interface specification for conditional access and other 

digital video broadcasting decoder applications (EN 50221). 

DVB-Cook – A guideline for the use of DVB specifications and standards 

(TR 101 200). 

DVB-CS – Digital video broadcasting baseline system for SMATV distribution 

systems (ETS 300 473). 

DVB-Data – Specification for Data Broadcasting (EN 301 192). 

DVB-DSNG – Digital satellite news gathering (DSNG) specification (EN 301 

210). 

DVB-IRD (Digital Video Broadcasting Integrated Receiver Decoder) – 

A receiving decoder that can automatically configure itself using the 

MPEG-2 Program Specific Information (PSI). 

DVB-IRDI – Interface for DVB-IRDs (EN 50201). 

DVB-M – Measurement guidelines for DVB systems (ETR 290). 

DVB-MC – Digital video broadcasting baseline system for multi-point video 

distribution systems below 10 GHz (EN 300 749). 

DVB-MPEG – Implementation guidelines for the use of MPEG-2 systems, 

video and audio in satellite, cable, and terrestrial broadcasting applications 

(ETR 154). 

DVB-MS – Digital video broadcasting baseline system for multi-point video 

distribution systems at 10 MHz and above (EN 300 748). 

DVB-NIP – Network-independent protocols for DVB interactive services 

(ETS 300 802). 

DVB-PDH – DVB interfaces to plesiochronous digital hierarchy (PDH) networks 

(ETS 300 813). 

DVB-PI – Interfaces for CATV/SMATV headends and similar professional 

equipment (EN 50083-9). 

DVB-RCC – Interaction channel for cable TV distribution system (CATV) 

(ETS 300 800). 

DVB-RCCS – Interaction channel for satellite master antenna TV (SMATV) 

distribution systems. Guidelines for versions based on satellite and coaxial 

sections (TR 101 201). 




DVB-RCDECT – Interaction channel through the digital enhanced cordless 

telecommunications (DECT) (EN 301 193). 

DVB-RCL – Interaction channel for local multi-point distribution system 

(LMDS) distribution systems (EN 301 199) 

DVB-RCT – Interaction channel through public switched telecommunications 

network (PSTN)/integrated services digital networks (ISDN) (ETS 300 

801). 

DVB-S (Digital Video Broadcasting – Satellite) – Broadcasting TV signals 

to a digital standard by satellite (ETS 300 421). 

DVB-SDH – Interfaces to synchronous digital hierarchy (SDH) networks 

(ETS 300 814). 

DVB-SFN – Mega-frame for single frequency network (SFN) synchronization 

(TS 101 191). 

DVB-SI (Digital Video Broadcasting – Service Information) – 

a) Information carried in a DVB multiplex describing the contents of different 

multiplexes. Includes NIT, SDT, EIT, TDT, BAT, RST, and ST. b) The 

DVB-SI adds the information that enables DVB-IRDs to automatically tune 

to particular services and allows services to be grouped into categories 

with relevant schedule information (ETS 300 468). 

DVB-SIM – DVB SimulCrypt. Part 1: headend architecture and synchronization 

(TS 101 197). 

DVB-SMATV – DVB satellite master antenna television (SMATV) distribution 

systems (EN 300 473). 

DVB-SUB – DVB subtitling systems (ETS 300 743). 

DVB-T (Digital Video Broadcasting – Terrestrial) – Terrestrial broadcasting 

of TV signals to a digital standard (ETS 300 744). 

DVB-TXT – Specification for conveying ITU-R system B teletext in DVB bitstreams 

(ETS 300 472). 

DVC – See Digital Video Cassette. 

DVCAM – Sony’s development of native DV which records a 15 micron 

(15x10 6 m, fifteen thousandths of a millimeter) track on a metal evaporated 

(ME) tape. DVCAM uses DV compression of a 4:1:1 signal for 525/60 

(NTSC) sources and 4:2:0 for 625/50 (PAL). Audio is recorded in one of 

two forms – four 12-bit channels sampled at 32 kHz or two 16-bit channels 

sampled at 48 kHz. 

DVCPRO50 – This variant of DV uses a video data rate of 50 Mbps – double 

that of other DV systems – and is aimed at the higher quality end of 

the market. Sampling is 4:2:2 to give enhanced chroma resolution, useful 

in post-production processes (such as chroma-keying). Four 16-bit audio 

tracks are provided. The format is similar to Digital-S (D9). 

DVCPROHD – This variant of DV uses a video data rate of 100 Mbps – 

four times that of other DV systems – and is aimed at the high-definition 

EFP end of the market. Eight audio channels are supported. The format is 

similar to D9 HD. 

DVCPRO P – This variant of DV uses a video data rate of 50 Mbps – double 

that of other DV systems – to produce 480 progressive frames. 

Sampling is 4:2:0. 

DVCR – Digital Video Cassette Recorder. 


DVD – See Digital Versatile Disks or Digital Video Disks. 

DVD-5 – A DVD format in which 4.7 gigabytes of data can be stored on 

one side of a disc in one layer. 


one side of a two-layer disc. 


two sides of a two-layer disc. 

DVD-18 – A DVD format in which 17.0 gigabytes of data are stored on two 

sides of the disc in two layers each. 

DVD-on-CD – A DVD image stored on a one-sided 650 megabyte CD. 

DVD-R – A DVD format in which 3.95 gigabytes of data are stored on a 

one-sided write-once disc. 

DVD-ROM – DVD disks for computers. Expected to eventually replace the 

conventional CD-ROM. The initial version stores 4.7 GB on one disk. 

DVD-ROM drives for computers will play DVD movie disks. 

DVE (Digital Video Effects) – a) These effects are found in special 

effects generators which employ digital signal processing to create two or 

three dimensional wipe effects. DVE generators are getting less expensive 

and the kind of effects they create getting more popular. The Digital Video 

Mixer includes such effects. b) A “black box” which digitally manipulates 

the video to create special effects, for example, the ADO (Ampex Digital 

Optics) system. Common DVE effects include inverting the picture, shrinking 

it, moving it around within the frame of another picture, spinning it, and 

a great many more. 

D-VHS – Digital – Video Home System. 

DVI – See Digital Video Interactive. 

DVTR – Digital Video Tape Recorder. 

Dynamic Gain Change – This distortion is present when picture or sync 

pulse luminance amplitude is affected by APL changes. This is different 

from APL induced Transient Gain Distortions which only occur at the APL 

change transition time. Rather, this distortion refers to gain changes that 

occur after the APL has changed. The amount of distortion is usually 

expressed as a percent of the amplitude at 50% APL, although sometimes 

the overall variation in IRE units is quoted. This is an out-of-service test. 

This distortion causes picture brightness to seem incorrect or inconsistent 

as the scene changes. 

Dynamic Gain Distortion – One of several distortions (long-time waveform 

distortions is another) that may be introduced when, at the sending 

end of a television facility, the average picture level (APL) of a video signal 

is stepped from a low value to a high value, or vice versa, when the operating 

point within the transfer characteristic of the system is affected, 

thereby introducing distortions on the receiving end. 

Dynamic Memory – Memory devices whose stored data must be continually 

refreshed to avoid degradation. Each bit is stored as a charge on a single 

MOS capacitor. Because of charge leakage in the transistors, dynamic 

memory must be refreshed every 2 ms by rewriting its entire contents. 

Normally, this does not slow down the system but does require additional 

memory refresh logic.

Dynamic Metadata Dictionary – The standard database of approved, 

registered Metadata Keys, their definitions, and their allowed formats. 

Dynamic Mike – A mike in which the diaphragm moves a coil suspended 

in a magnetic field to generate an output voltage proportional to the sound 

pressure level. 

Dynamic Range – a) A circuit’s signal range. b) An audio term which 

refers to the range between the softest and loudest levels a source can 

produce without distortion. c) The difference, in decibels, between the 

overload level and the minimum acceptable signal level in a system or 

transducer. d) The ratio of two instantaneous signal magnitudes, one being 

the maximum value consistent with specified criteria or performance, the 

other the maximum value of noise. e) The concept of dynamic range is 

applicable to many measurements beyond characterization of the video signal, 

and the ratios may also be expressed as f-stops, density differences, 

illumination, or luminance ratios, etc. 

Dynamic Range, Display – The range of luminances actually achieved in 

a display. The system’s overall transfer function is the most informative 

specification of dynamic range, inasmuch as nonlinear processing has 

nearly always been applied to the luminance of the reproduced scene. 

Frequently, however, the dynamic range, display is estimated by observing 

the reproduction of a stepped gray-scale having calibrated intervals. 

Conventionally, the dynamic range is reported to include every step whose 

transition can be detected, no matter how miniscule. Human vision is less 

adept at judging luminance of extended areas, but particularly sensitive to 

luminance transitions which may even have been exaggerated by edge 

enhancement. “Resolved steps” may be reported, therefore, even when the 

perceived luminance difference between the areas of adjacent steps is not 

obvious. 



Dynamic Range, Image Capture – The range of luminances actually 

captured in the image is defined and limited by the transfer function which 

is usually nonlinear. Capture and recording systems traditionally limit their 

linear response to a central portion of their dynamic range, and may have 

extended nonlinear shoulder and toe regions. For any scene, it is usually 

possible to place the luminances of interest on a preferred portion of the 

transfer function, with excursions into higher and lower limits rolled off or 

truncated by the respective shoulder and toe of the curve. 

Dynamic Range Compression – Level adjustment applied to an audio 

signal in order to limit the difference, or range of the loudest to the softest 

sounds. 

Dynamic Resolution – The amount of spatial resolution available in moving 

pictures. In most television schemes, dynamic resolution is considerably 

less than static resolution. See also Motion Surprise, Spatial 

Resolution, and Temporal Resolution. 

Dynamic Rounding – The intelligent truncation of digital signals. Some 

image processing requires that two signals are multiplied, for example in 

digital mixing, producing a 16-bit result from two original 8-bit numbers. 

This has to be truncated, or rounded, back to 8-bits. Simply dropping the 

lower bits can result in visible contouring artifacts especially when handling 

pure computer-generated pictures. Dynamic rounding is a mathematical 

technique for truncating the word length of pixels, usually to their normal 

8-bits. This effectively removes the visible artifacts and is non-cumulative 

on any number of passes. Other attempts at a solution have involved 

increasing the number of bits, usually to 10, making the LSBs smaller but 

only masking the problem for a few generations. Dynamic rounding is a 

licensable technique, available from Quantel and is used in a growing number 

of digital products both from Quantel and other manufacturers. 




E 

E – Enhanced/Extended. 

E Mem – Term used for a panel memory system. 

EACEM – European Association of Consumer Electronics Manufacturers 

EAROM – Electrically Alterable. 

Earth Station – Equipment used for transmitting or receiving satellite 

communications. 

EAV (End of Active Video) – A term used with component digital 

systems. 

EB – Errored Block. 

EBR – See Electron Beam Recording. 

EBU (European Broadcasting Union) – An organization of European 

broadcasters that, among other activities, produces technical statements 

and recommendations for the 625/50 line television system. Created in 

1950 and headquartered in Geneva, Switzerland, the EBU is the world’s 

largest professional association of national broadcasters. The EBU assists 

its members in all areas of broadcasting, briefing them on developments in 

the audio-visual sector, providing advice and defending their interests via 

international bodies. The Union has active members in European and 

Mediterranean countries and associate members in countries elsewhere in 

Africa, the Americas, and Asia. 

EBU TECH.3267-E – a) The EBU recommendation for the serial composite 

and component interface of 625/50 digital video signal including embedded 

digital audio. b) The EBU recommendation for the parallel interface of 

625-line digital video signal. A revision of the earlier EBU Tech.3246-E, 

which in turn was derived from CCIR-601 and contributed to CCIR-656 

standards. 

ECC/EDC – Error Correction Code/Error Detection Code. 

Eccentricity – A mathematical constant that, for an ellipse, is the ratio 

between the major and minor axis length. 

Echo (or Reflection) – a) A wave which has been reflected at one or 

more points in the transmission medium, with sufficient magnitude and 

time difference to be perceived in some manner as a wave distinct from 

that of the main or primary transmission. Echoes may be either leading or 

lagging the primary wave and appear in the picture monitor as reflections 

or “ghosts.” b) Action of sending a character input from a keyboard to the 

printer or display. 

Echo Plate – A metal plate used to create reverberation by inducing 

waves in it by bending the metal. 

E-Cinema – An HDTV film-complement format introduced by Sony in 

1998. 1920 x 1080, progressive scan, 24 fps, 4:4:4 resolution. Using a 

1/2-inch tape, the small cassette (camcorder) will hold 50 minutes while 

the large cassette will hold 156 minutes. E-Cinema’s camcorder will use 

three 2/3-inch FIT CCDs and is equivalent to a film sensitivity of ISO 500. 

The format will compress the electronic signal somewhere in the range of 

7:1. The format is based on the Sony HDCAM video format. 


ECL – Emitter Coupled Logic. 

ECM (Entitlement Control Message) – Conditional access information 

specifying control words or other stream-specific scrambling parameters. 

ECMA – European Computer Manufacturers Association. 

ED-Beta (Extended Definition Betamax) – A consumer/Professional 

videocassette format developed by Sony offering 500-line horizontal resolution 

and Y/C connections. 

Edge – a) An edge is the straight line that connects two points. 

b) Synonym for key border. Used by our competitors but not preferred by 

Ampex. c) A boundary in an image. The apparent sharpness of edges can 

be increased without increasing resolution. See also Sharpness. 

Edge Busyness – Distortion concentrated at the edge of objects, characterized 

by temporally varying sharpness or spatially varying noise. 

Edge Effect – See Following Whites or Following Blacks. 

Edge Enhancement – Creating hard, crisp, high-contrast edges beyond 

the correction of the geometric problem compensated by aperture correction, 

frequently creates the subjective impression of increase image detail. 

Transversal delay lines and second-directive types of correction increase 

the gain at higher frequencies while introducing rather symmetrical “undershoot 

followed by overshoot” at transitions. In fact, and contrary to many 

causal observations, image resolution is thereby decreased and fine detail 

becomes obscured. Creating a balance between the advantages and disadvantages 

is a subjective evaluation and demands an artistic decision. 

Edge Enhancing – See Enhancing. 

Edge Numbers – Numbers printed on the edge of 16 and 35 mm motion 

picture film every foot which allows frames to be easily identified in an edit 

list. 

EDH (Error Detection and Handling) – Proposed SMPTE RP-165 for recognizing 

inaccuracies in the serial digital signal. It may be incorporated into 

serial digital equipment and employ a simple LED error indicator. 

Edit – a) The act of performing a function such as a cut, dissolve, wipe on 

a switcher, or a cut from VTR to VTR where the end result is recorded on 

another VTR. The result is an edited recording called a master. b) Any point 

on a video tape where the audio or video information has been added to, 

replaced, or otherwise altered from its original form. 

Edit Control – A connection on a VCR or camcorder which allows direct 

communication with external edit control devices. (e.g., LANC (Control-L) 

and new (Panasonic) 5-pin). Thumbs Up works with both of these control 

formats and with machines lacking direct control. 

Edit Decision List (EDL) – a) A list of a video production’s edit points. An 

EDL is a record of all original videotape scene location time references, 

corresponding to a production’s transition events. EDLs are usually generated 

by computerized editing equipment and saved for later use and modification. 

b) Record of all edit decisions made for a video program (such as 

in-times, out-times, and effects) in the form of printed copy, paper tape, or

floppy disk file, which is used to automatically assemble the program at a 

later point. 

Edit Display – Display used exclusively to present editing data and editor’s 

decision lists. 

Edit Point – The location in a video where a production event occurs. 

(e.g., dissolve or wipe from one scene to another). 

Editing – A process by which one or more compressed bit streams are 

manipulated to produce a new compressed bit stream. Conforming edited 

bit streams are understood to meet the requirements defined in the Digital 

Television Standard. 

Editing Control Unit (ECU) – A microprocessor that controls two or more 

video decks or VCRs and facilitates frame-accurate editing. 

Editor – A control system (usually computerized) which allows you to control 

video tape machines, the video switcher, and other devices remotely 

from a single control panel. Editors enable you to produce finished video 

programs which combine video tape or effects from several different 

sources. 

EDL (Edit Decision List) – A list of edit decisions made during an edit 

session and usually saved to floppy disk. Allows an edit to be redone or 

modified at a later time without having to start all over again. 

EDO DRAM (Extended Data Out Dynamic Random Access Memory) – 

EDO DRAM allows read data to be held past the rising edge of CAS 

(Column Address Strobe) improving the fast page mode cycle time critical 

to graphics performance and bandwidth. EDO DRAM is less expensive than 

VRAM. 

EDTV – See Extended/Enhanced Definition Television. 

E-E Mode (Electronic to Electronic Mode) – The mode obtained when 

the VTR is set to record but the tape is not running. The VTR is processing 

all the signals that it would normally use during recording and playback but 

without actually recording on the tape. 

EEPROM E2, E-squared PROM – An electronically-erasable, programmable 

read-only memory device. Data can be stored in memory and will 

remain there even after power is removed from the device. The memory 

can be erased electronically so that new data can be stored. 

Effect – a) One or more manipulations of the video image to produce a 

desired result. b) Multi-source transition, such as a wipe, dissolve, or key. 

Effective Competition – Market status under which cable TV systems are 

exempt from regulation of basic tier rates by local franchising authorities, 

as defined in 1992 Cable Act. To claim effective competition, a cable system 

must compete with at least one other multi-channel provider that is 

available to at least 50% of an area’s households and is subscribed to by 

more than 15% of the households. 

Effects (Setup) – Setup on the AVC, Century, or Vista includes the status 

of every push-button, key setting, and transition rate. The PANEL-MEM system 

can store these setups in memory registers for future use. 

Effects Keyer (E Keyer) – The downstream keyer within an M/E, i.e., the 

last layer of video. 

Effects System – The portion of the switcher that performs mixes, wipes, 

and cuts between background and/or affects key video signals. The Effects 



System excludes the Downstream Keyer and Fade-to-Black circuitry. Also 

referred to as Mix Effects (M/E) system. 

EIA (Electronics Industries Association) – A trade organization that has 

created recommended standards for television systems (and other electronic 

products), including industrial television systems with up to 1225 

scanning lines. EIA RS-170A is the current standard for NTSC studio equipment. 

The EIA is a charter member of ATSC. 

EIA RS-170A – The timing specification standard for NTSC broadcast 

video equipment. The Digital Video Mixer meets RS-170A. 

EISA (Enhanced Industry Standard Architecture) – In 1988 a consortium 

of nine companies developed 32-bit EISA which was compatible with 

AT architecture. The basic design of EISA is the result of a compilation of 

the best designs of the whole computer industry rather than (in the case of 

the ISA bus) a single company. In addition to adding 16 new data lines to 

the AT bus, bus mastering, automated setup, interrupt sharing, and 

advanced transfer modes were adapted making EISA a powerful and useful 

expansion design. The 32-bit EISA can reach a peak transfer rate of 

33 MHz, over 50% faster than the Micro Channel architecture. The EISA 

consortium is presently developing EISA-2, a 132 MHz standard. 

EIT – Encoded Information Type. 

EIT (Event Information Table) – The EIT contains data concerning events 

(a grouping of elementary broadcast data streams with a defined start and 

end time belonging to a common service) and programs (a concatenation 

of one or more events under the control of a broadcaster, such as event 

name, start time, duration, etc.). Part of DVB-SI. 

Electromagnetic Interference (EMI) – Interference caused by electrical 

fields. 

Electron Beam Recording – A technique for converting television images 

to film using direct stimulation of film emulsion by a very fine long focal 

length electronic beam. 

Electronic Cinematography – Photographing motion pictures with television 

equipment. Electronic cinematography is often used as a term indicating 

that the ultimate product will be seen on a motion picture screen, 

rather than a television screen. See also HDEP and Mathias. 

Electronic Crossover – A crossover network which uses active filters and 

is used before, rather than after, the signal passes through the power amp. 

Electronic Matting – The process of electronically creating a composite 

image by replacing portions of one image with another. One common, if 

rudimentary, form of this process is chroma-keying, where a particular 

color in the foreground scene (usually blue) is replaced by the background 

scene. Electronic matting is commonly used to create composite images 

where actors appear to be in places other than where they are being shot. 

It generally requires more chroma resolution than vision does, causing contribution 

schemes to be different than distribution schemes. While there is 

a great deal of debate about the value of ATV to viewers, there does not 

appear to be any dispute that HDEP can perform matting faster and better 

than almost any other moving image medium. 

Electrostatic Pickup – Pickup of noise generated by electrical sparks 

such as those caused by fluorescent lights and electrical motors. 




Elementary Stream (ES) – a) The raw output of a compressor carrying a 

single video or audio signal. b) A generic term for one of the coded video, 

coded audio, or other coded bit streams. One elementary stream is carried 

in a sequence of PES packets with one and only one stream_id. 

Elementary Stream Clock Reference (ESCR) – A time stamp in the PES 

from which decoders of PES may derive timing. 

ELG (European Launching Group) – Now superseded by DVB. 

EM (Electronic Mail) – Commonly referred to as E-mail. 

Embedded Audio – a) Digital audio is multiplexed onto a serial digital 

data stream. b) Digital audio that is multiplexed and carried within an SDI 

connection – simplifying cabling and routing. The standard (ANSI/SMPTE 

272M-1994) allows up to four groups each of four mono audio channels. 

Embossing – An artistic effect created on AVAs and/or switchers to make 

characters look like they are (embossed) punched from the back of the 

background video. 

EMC – Entitlement Control Message. 

EMC – Electromagnetic Compatibility. 

EMF – Equipment Management Function. 

EMI – Electromagnetic Interference. 

Emission – a) The propagation of a signal via electromagnetic radiation, 

frequently used as a synonym for broadcast. b) In CCIR usage: radio-frequency 

radiation in the case where the source is a radio transmitter or 

radio waves or signals produced by a radio transmitting station. 

c) Emission in electronic production is one mode of distribution for the 

completed program, as an electromagnetic signal propagated to the point 

of display. 

EMM (Entitlement Management Message) – Conditional access information 

specifying authorization level or services of specific decoders. An 

individual decoder or a group of decoders may be addressed. 

Emphasis – A boost in signal level that varies with frequency, usually used 

to improve SNR in FM transmission and recording systems (wherein noise 

increases with frequency) by applying a pre-emphasis before transmission 

and a complementary de-emphasis to the receiver. See also Adaptive 

Emphasis. 

Enable – Input signal that allows the device function to occur. 

ENB – Equivalent Noise Bandwidth. 

Encode – a) The process of combining analog or digital video signals, 

e.g., red, green, and blue, into one composite signal. b) To express a single 

character or a message in terms of a code. To apply the rules of a code. 

c) To derive a composite luminance-chrominance signal from R, G, B signals. 

d) In the context of Indeo video, the process of converting the color 

space of a video clip from RGB to YUV and then compressing it. See 

Compress, RGB, YUV. Compare Decode. 

Encoded Chroma Key – Synonym for Composite Chroma Key. 

Encoded Subcarrier – A reference system created by Grass Valley Group 

to provide exact color timing information. 

Encoder – a) A device used to form a single composite color signal 

(NTSC, PAL, or SECAM) from a set of component signals. An encoder is 


used whenever a composite output is required from a source (or recording) 

which is in component format. b) Sometimes devices that change analog 

signals to digital (ADC). All NTSC cameras include an encoder. Because 

many of these cameras are inexpensive, their encoders omit many of the 

advanced techniques that can improve NTSC. CAV facilities can use a single, 

advanced encoder prior to creating a final NTSC signal. c) An embodiment 

of an encoding process. 

Encoding (Process) – A process that reads a stream of input pictures or 

audio samples and produces a valid coded bit stream as defined in the 

Digital Television Standard. 

Encryption – The process of coding data so that a specific code or key is 

required to restore the original data. In broadcast, this is used to make 

transmission secure from unauthorized reception as is often found on 

satellite or cable systems. 

END – Equivalent Noise Degradation. 

End Point – End of the transition in a dissolve or wipe. 

ENG (Electronic News Gathering) – Term used to describe use of videorecording 

instead of film in news coverage. 

Enhancing – Improving a video image by boosting the high frequency 

content lost during recording. There are several types of enhancement. The 

most common accentuates edges between light and dark images. 

ENRZ – Enhanced Non-Return to Zero. 

Entitlement Management Messages (EMM) – Private Conditional 

Access information which specifies the authorization levels or the services 

of specific decoders. They may be addressed to an individual decoder or 

groups of decoders. 

Entrophy Coding – Variable-length lossless coding of the digital representation 

of a signal to reduce redundancy. 

Entrophy Data – That data in the signal which is new and cannot be 

compressed. 

Entropy – In video, entropy, the average amount of information represented 

by a symbol in a message, is a function of the model used to produce 

that message and can be reduced by increasing the complexity of the 

model so that it better reflects the actual distribution of source symbols in 

the original message. Entropy is a measure of the information contained in 

a message, it’s the lower bound for compression. 

Entry – The point where an edit will start (this will normally be displayed 

on the editor screen in time code). 

Entry Point – The point in a coded bit stream after which the decoder can 

be initialized and begin decoding correctly. The picture that follows the 

entry point will be an I-picture or a P-picture. If the first transmitted picture 

is not an I-picture, the decoder may produce one or more pictures during 

acquisition. Also referred to as an Access Unit (AU). 

E-NTSC – A loosely applied term for receiver-compatible EDTV, used by 

CDL to describe its Prism 1 advanced encoder/decoder family. 

ENTSC – Philips ATV scheme now called HDNTSC. 

Envelope Delay – The term “Envelope Delay” is often used interchangeably 

with Group Delay in television applications. Strictly speaking, envelope

delay is measured by passing an amplitude-modulated signal through the 

system and observing the modulation envelope. Group Delay, on the other 

hand, is measured directly by observing phase shift in the signal itself. 

Since the two methods yield very nearly the same result in practice, it is 

safe to assume the two terms are synonymous. 

Envelope Detection – A demodulation process in which the shape of the 

RF envelope is sensed. This is the process performed by a diode detector. 

Envelope Detector – A form of device in a television set that begins the 

process of converting a broadcast or CATV television signal into a video 

signal that can be displayed. Envelope detectors are sensitive to some of 

the modifications to television signals that have been proposed for 

receiver-compatible ATV systems. 

EPG (Electronic Program Guide) – A program guide delivered by data 

transfer rather than printed paper. The EPG gives the content of the current 

program. 

EPROM (Erasable Programmable Read Only Memory) – A PROM that 

can be reused. Most EPROMs can be erased by exposing them to ultraviolet 

light. 

EPS (Encapsulated PostScript) – A standard file format for highresolution 

PostScript illustrations. 

EPU (European Platforms Union) – EPU is a body that coordinates 

national platforms in Europe for widescreen TV and the migration to HDTV. 

EPU seeks to promote and to coordinate knowledge about widescreen TV, 

embracing broadcasting, medicine, corporate, and cinema use. EPU 

emphasizes digital aspects and the migration to HDTV, but not necessarily 

1250-line HDTV. Through the EPU, the national platforms may exchange 

experience, facts, and views. 

EQ – See Equalization. 

EQTV (Enhanced Quality Television) – See EDTV. 

Equalization (EQ) – a) Process of altering the frequency response of a 

video amplifier to compensate for high-frequency losses in coaxial cable. 

b) The selective amplification or attenuation of certain frequencies. 

Equalizer – The pulses which occur before and after the broad pulses in 

the vertical interval. These pulses help the horizontal oscillator to maintain 

synchronization. See Equalizing Pulses. 

Equalizing Pulses – Pulses of one-half the width of the horizontal sync 

pulses which are transmitted at twice the rate of the horizontal sync pulses 

during the blanking intervals immediately preceding and following the vertical 

sync pulses. The action of these pulses causes the vertical deflection to 

start at the same time in each interval, and also serves to keep the horizontal 

sweep circuits in step during the vertical blanking intervals immediately 

preceding and following the vertical sync pulse. 

Equipment Noise – See Noise. 

Equivalent Input Noise – Noise created by the input stage of an amplifier 

which appears in the output of the amplifier increased in level by the gain 

of the amp. 

Erase Adj. – A control which adjusts the coupling of the bias oscillator to 

the erase head in a manner which purifies the oscillator’s waveform. 



Erase Field Strength – The minimum initial amplitude of a decreasing 

alternating field (normally applied in the longitudinal direction) required to 

reduce the output of a given recorded signal by a specified amount. 

Erase Head – A device used to remove recorded signals from magnetic 

tape. 

Erased Noise – The noise arising when reproducing a bulk-erased tape 

with the erase and record heads completely de-energized. 

Erasure – A process by which a signal recorded on a tape is removed and 

the tape made ready for rerecording. 

Error – In digital recording, either a dropout or a noise pulse that exceeds 

a certain limit is usually termed an error. In video and instrumentation 

recording, an error has no commonly accepted meaning but is defined in 

relation to the particular system requirements. 

Error Blocks – A form of block distortion where one or more blocks in the 

received image bear no resemblance to the current or previous scene and 

often contrast greatly with adjacent blocks. 

Error Concealment – a) A technique used when error correction fails (see 

Error Correction). Erroneous data is replaced by data synthesized from surrounding 

pixels. b) When the error correction program discovers in the 

reproduced signal, an error too extensive to permit reconstruction, the 

redundancy in most image information makes it possible for error concealment 

to make the error nearly inobvious. Video images are frequently nearly 

identical from frame to frame. Adjacent video lines frequently have 

almost the same detail. It becomes possible, therefore, when a “burst 

error” involving the modification or loss of many recorded bits occurs, to 

determine from image segments adjacent in time or in space, a most probable 

substitution. Such substitutions, when infrequent and supported by the 

image redundancy, are often accepted by the viewers as “correct.” (This is 

a degree of freedom in image data recording that obviously is not available 

to scientific and financial data recording. The additional information needed 

by the algorithm for decision and substitution is usually provided by a datastorage 

cache established during reproduction. 

Error Detection and Correction – a) Coding schemes incorporated into 

the information before it is transmitted (or stored) in such a way that errors 

which may arise in transmission can be detected and corrected before 

restoration or retrieval. In PCM systems, error correction effectively 

improves the SNR of the system. b) Ingenious software programs make it 

possible to check that the digital stream of image information has not been 

corrupted by the loss of a few bits here and there. Additional information 

introduced as “overhead” to the image bit stream (thereby increasing the 

bit rate, recording) is chosen to conform to specific rules of construction. 

Departures from this construction can be detected readily, so that many 

potential errors can not only be identified, but corrected so that the information 

can be restored with high probability. Error correction contributes to 

the reliability of recording/reproducing and is a normal part of all data 

recording. 

Error Rate – The ratio of the number of bits incorrectly transmitted to the 

total number of bits of information received. 

ES (Elementary Stream) – Data stream for video, audio, or data. 

Preliminary stage to PES. 




ESAC – Economics and Statistics Advisory Committee. 

ESCR (Elementary Stream Clock Rate) – A time stamp in PES stream 

from which decoders may derive timing. 

Essence – The actual program (audio, video, and/or data) without metadata. 

Essence could also be graphics, telemetry, photographs, or other 

information. 

ESPRIT – European Strategic Program for Research and Development in 

Information Technology. 

Ethernet (IEEE 802.3) – a) A type of high-speed network for interconnecting 

computing devices. Ethernet can be either 10 or 100 Mbps (Fast 

Ethernet). Ethernet is a trademark of Xerox Corporation, Inc. b) A type of 

local area network that enables real-time communication between 

machines connected directly together through cables. A widely implemented 

network from which the IEEE 802.3 standard for contention networks 

was developed, Ethernet uses a bus topology (configuration) and relies on 

the form of access known as CSMA/CD to regulate traffic on the main 

communication line. Network nodes are connected by coaxial cable (in 

either of two varieties) or by twisted-pair wiring. 

ETR – ETSI Technical Report. 

ETS (European Telecommunications Standards) – Issued by the ETSI. 

ETSI (European Telecommunication Standard Institute) – A European 

forum for standardization with participation of major players in the 

telecommunications industry. ETSI replaced the CEPT in 1988 with the 

objective of making the telecommunications standards needed for the 

implementation of the common market in Europe. ETSI has now become a 

leading body on all telecommunications standards, however, and provides a 

strong input to international bodies. This being so, the ETSI focuses on 

standards that involve interactions between public and private networks, 

and specifies the framework of activities that form the telecommunications 

infrastructure. ETSI produces standards through a number of technical 

committees, and uses project teams composed of paid experts to produce 

drafts of standards. The standards produced are called European 

Telecommunications Standards (ETS) or Interim European 

Telecommunications Standards (I-ETS). 

ETV – Educational Television. 

EuroDAB – An organization formed through the EBU with the purpose of 

paving the way for DAB in Europe. The group, which holds more than 100 

broadcasters, manufacturers, regulators, etc., looks into services to be 

offered, identified features, and applications. It researches data services 

and receiver implementation, and monitors national regulations. Finally, the 

group is analyzing satellite DAB projects. 

Eureka – A massive European research effort, sometimes called the 

European version of Star Wars, embracing many separate R&D projects, 

including semiconductors, telecommunications, and computers. The Eureka 

EU-95 project is about ATV systems for 625 scanning line/50 field per second 

countries. 

Europe – A geographic region that led the opposition to the ATSC proposal 

when it was presented to the CCIR as a proposed worldwide standard and 

is developing its own ATV systems. European television currently has 625 

scanning lines and 50 field per second as opposed to NTSC’s 525/59.94. 


Evaluator – Equipment that evaluates physical and magnetic quality of 

tape, usually provided as an adjunct to a winder/cleaner. In contrast to a 

certifier, it does not stop when it detects an error. 

E-Value – The difference in inches between the radii of the outside layer 

of tape in a roll and the outside edge of the reel flange. 

Even Number – The number of scanning lines per frame possible in a 

progressively scanned television system. An interlaced scan system must 

use an odd number of lines so that sequential fields will be displaced by 

one scanning line. 

Event – a) An event is defined as a collection of elementary streams with 

a common time base, an associated start time, and an associated end 

time. b) A grouping of elementary broadcast data streams with a defined 

start and end time belonging to a common service, e.g., first half of a football 

match, News Flash, first part of an entertainment show. 

Event Number – Number assigned by the system (or editor) to each edit 

that is recorded in the EDL. 

EVM – Error Vector Magnitude. 

Event Number – Number assigned by the system (or editor) to each edit 

that is recorded in the EDL. 

EVM – Error Vector Magnitude. 

Exabyte – An 8 mm data tape format. Popular for storing graphics files 

due to its low cost and high capacity (commonly 8 GB, but new models 

hold up to 40 GB). Exabyte is also the number of bytes that comes after 

petabyte. 

Execute (Cycle) – Last cycle of instruction execution. The instruction 

operation is performed during this time. 

Execution Time – Time required for the execution of an instruction. 

Exif (Exchangeable Image Format) – A file format used in digital 

cameras. 

Exit – The point at which an edit will end (normally displayed by time 

code). 

Expander – A device which increases the dynamic range of a signal by 

either reducing the level of soft signals or increasing the level of loud signals 

when the input is above or below a certain threshold level. 

Expansion – An undesired increase in amplitude of a portion of the composite 

video signal relative to that of another portion. Also, a greater than 

proportional change in the output of a circuit for a change in input level. 

For example, expansion of the sync pulse means an increase in the percentage 

of sync during transmission. 

Exponent – Power of ten by which a number is multiplied, used in floating 

point representation. For example, the exponent in the decimal number 

0.9873 x 10 7 is 7. 

Export – To use NFS software to make all or part of your file system available 

to other users and systems on the network. 

Exposure Sheet – In a piece of animation, there are hundreds of frames. 

Typically, they are organized on an exposure sheet. The sheet describes, for 

each piece of artwork used, on which frame the art is first used, what happens 

to it (on a frame by frame basis) while it is used, and on which frame

it disappears. Also noted on the sheet, for each frame, are any changes in 

the animation system (animation table, camera, lights, etc.). Exposure 

sheets on the PictureMaker are created using the SEQ program, and are 

organized somewhat differently than traditional sheets, in order to best use 

the computer. Each level (or layer, or plane) can be one of three types: 

Image (a file of pixel values), object (a 3D database and animation path), 

and explicit command (a PictureMaker command mode command). Each 

level specifies a beginning from and duration (ending frame), and the computer 

keeps track of all levels with respect to their overlaps in both time 

and space. 

Extended/Enhanced Definition Television (EDTV) – a) Extended (or 

Enhanced) Definition Television is a proposed intermediate television system 

for evolution to full HDTV that offers picture quality substantially 

improved over conventional 525-line or 625-line receivers, by employing 

techniques at the transmitter and at the receiver that are transparent to 

(and cause no visible quality degradation to) existing 525-line or 625-line 

receivers. One example of EDTV is the improved separation of luminance 

and color components by pre-combing the signals prior to transmission. 

Also see Improved Definition Television. b) Specifically, a video format with 

sampling frequencies 18 MHz (Y), 4.5 MHz (C), and resolution 960 pixels 

by 576 lines (Y), 480 pixels by 288 lines (C). 

Extended Studio PAL – A 625-line video standard that allows processing 

of component video quality digital signals by composite PAL equipment. 

The signal can be distributed and recorded in a composite digital form 

using D2 or D3 VTRs. 

Extensibility – A property of a system, format, or standard that allows 

changes in performance or format within a common framework, while 

retaining partial or complete compatibility among systems that belong to 

the common framework. 



External Device – In computer systems, any piece of hardware that is 

attached to the workstation with a cable. 

External Key Input – Extra key inputs that may be accessed by keyboard 

that do not appear on the bus rows. Traditionally, these inputs are used 

only for luminance keys, such as simple character generators or titling 

cameras; however, they are not limited to this on Ampex switchers. These 

are sources 9 and 0 on 4100 series switchers, and 31 and 32 on AVC 

switchers. 

External Key Processor – See Processed External Keys. 

Extrusion – The next stop in creating a boundary rep solid is to “extrude” 

the silhouette. Extrusion (or sweeping) is a method of dragging a polygon 

through space in order to define a solid. There are typically two kinds of 

extrusion: translational and rotational. 

Eye Pattern – Waveform monitor pattern produced by random waves 

introduced to verify the ability to test for the presence or absence of pulses 

in a digital system. 

Eye Tracking – The process by means of which eyes follow a person or 

object across a television screen. Many ATV techniques take advantage of 

the fact that human vision cannot simultaneously demand high spatial resolution 

and high temporal resolution to reduce the amount of spatial resolution 

transmitted for moving objects. However, when the eyes track such 

an object, its image is stationary on the retina, and the visual system can 

demand as much resolution as it would for a truly stationary object. See 

also Dynamic Resolution. 




F 

Fade – A video editing term that describes switching from one video 

source to a black level or from black to a video signal. This is commonly 

called a “fade to black”or “fade from black.” 

Fade to Black – The picture luminance is reduced until the screen is 

black. 

Fader – Console control which allows an operator to perform manual dissolves, 

fades, and wipes. 

Fader Bar – A vertical slide controller on audio and video equipment. 

Falling Edge – High-to-low logic or analog transition. 

Fan-In – Electrical load presented by an input. Usually expressed as the 

number of equivalent standard input loads. 

Fan-Out – Electrical load that an output can drive. Usually expressed as 

the number of inputs that can be driven. 

Faroudja – Yves Faroudja and Faroudja Laboratories. First to market an 

advanced NTSC encoder with pre-combing; proponent of the Super-NTSC 

ATV system and of a 1050 scanning line (900 active line), progressive 

scan, 29.97 frame per second, 1.61:1 aspect ratio HDEP system. 

FAS – Frame Alignment Signal. 

Fast Forward – The provision on a tape recorder permitting tape to be run 

rapidly through it in normal play direction, usually for search purposes. 

Fast Forward Playback – The process of displaying a sequence, or parts 

of a sequence, of pictures in display-order faster than real-time. 

Fast Reverse Playback – The process of displaying the picture sequence 

in the reverse of display order faster than real-time. 

Fast-Page Mode – A read or write mode of DRAMs characterized by a 

decrease in cycle time of about 2-3 times and a corresponding increase in 

performance. The data accessed in Fast-Page Mode cycles must be adjacent 

in memory. See EDO. 

FC-AL (Fiber Channel-Arbitrated Loop) – Architecture used to maintain 

high data transfer rates over long distances. With FC-AL storage arrays can 

be separated by as much as 20 kilometers, connected by only one nonamplified 

Fibre Channel fiber optic link. In the dual-loop architecture, data 

transfer rates can reach 200 Mb/s. Another advantage is increased fault 

tolerance. In the unlikely event of a drive failure, port bypass circuits single 

out each failed drive and quickly route around it, with no limitation on the 

number of drives that can be bypassed. 

FCC (Federal Communications Commission) – a) The government 

agency responsible for (among other things) the regulation of the electromagnetic 

spectrum utilization in the United States, and the body that 

licenses radio and television broadcast stations. The FCC is an independent 

government agency, which answers directly to Congress. b) The FCC rules 

and regulations constitute mandatory standards for broadcasters, CATV 

operators, transmission organizations, and others. See also ACATS. 

FCC 73.699 – Federal Communications Commission (FCC) NTSC video signal 

specifications standard. 


FCC Composite Test Signal – 

F-Connector – A video connector characterized by a single metal wire. 

F-connectors may be either push-on or screw-post. 

FDDI (Fiber Distributed Data Interface) – Standards for a 100 Mbps 

local area network, based upon fiber optic or wired media configured as 

dual counter rotating token rings. This configuration provides a high level of 

fault tolerance by creating multiple connection paths between nodes. 

Connections can be established even if a ring is broken. 

FDM – Frequency Division Multiplex. 

Feature Connector – An expansion connector on the VGA that can accept 

or drive video signals to or from the VGA. This is used in applications 

involving video overlay. This is also called VESA Pass-Through Connector. 

FEC (Forward Error Correction) – a) System in which redundancy is 

added to the message so that errors can be corrected dynamically at the 

receiver. b) Error control bits added to useful data in the QAM/QPSK 

modulator. 

Feed – The transmission of a video signal from point to point. 

Feed Reel – Also called “stock,”“supply,”or “storage”reel. The reel on a 

tape recorder from which tape unwinds as the machine records or plays. 

Feedback – a) Information from one or more outputs to be used as inputs 

in a control loop. b) A loop caused by audio or video signal being fed back 

into itself. In video the effect is caused when a camera is directed at its 

receiving monitor. In audio the effect, manifested as an echo or squeal, is 

caused when a microphone is aimed at a speaker. 

Female Connector – A connector that has indentations or holes into 

which you plug a male connector. An example of a female connector is an 

electrical wall outlet that accepts an electrical plug. 

Ferrichrome – A relatively recent word describing the technique of dual 

coating with both a layer of gamma ferric oxide and a layer of chromium 

dioxide. An intermediate level bias position used only for ferrichrome tapes. 

Fetch – Reading an instruction from memory. 

FF – See Full Field.

FFT (Fast Fourier Transform) – A mathematical means of converting 

time-domain information to frequency-domain information. 

Fiber Bundle – A group of parallel optical fibers contained within a common 

jacket. A bundle may contain from just a few to several hundred 

fibers. 

Fiber Channel – See Fibre Channel. 

Fiber Optics – See Optical Fiber. 

Fiber-Optic Cable – “Wires”made of glass fiber used to transmit video, 

audio, voice, or data providing vastly wider bandwidth than standard coaxial 

cable. 

Fibre Channel – A high-speed data link planned to run up to 2 Gbps on a 

fiber optic cable. A number of manufacturers are developing products to 

use the Fiber Channel-Arbitrated Loop (FC-AL) serial storage interface at 

1 Gbps so that storage devices such as hard disks can be connected. 

Supports signaling rates from 132.8 Mbps to 1,062.5 Mbps, over a mixture 

of physical media including optical fiber, video coax, miniature coax, 

and shielded twisted pair wiring. The standard supports data transmission 

and framing protocols for the most popular channel and network standards 

including SCSI, HIPPI, Ethernet, Internet Protocol, and ATM. 

Field – a) In interlaced scan systems, the information for one picture is 

divided up into two fields. Each field contains one-half of the lines required 

to produce the entire picture. Adjacent lines in the picture are in alternate 

fields. b) Half of the horizontal lines (262.5 in NTSC and 312.5 in PAL) 

needed to create a complete picture. c) One complete vertical scan of an 

image. In a progressive scanning system, all of the scanning lines comprising 

a frame also comprise a field. d) An area in a window in which you can 

type text. e) A television picture is produced by scanning the TV screen 

with an electron beam. One complete scan of the screen is called a field. 

Two fields are required to make a complete picture, which is called a 

frame. The duration of a field is approximately 1/60 of a second in NTSC 

and 1/50 or 1/60 of a second in PAL. f) One half of a complete interlaced 

video picture (frame), containing all the odd or even scanning lines of the 

picture. 

Field Alias – An alias caused by interlaced scanning. See also Interlace 

Artifacts. 

Field Blanking – Refers to the part of the signal at the end of each field 

that make the vertical retrace invisible. Also called vertical blanking. 

Field DCT Coding – Discrete cosine transform coding in which every 

block consists of lines from one field. The chrominance blocks in the 4:2:0 

format must never be coded by using field DCT coding, but it is allowed to 

use field-based prediction for this type of block. 

Field, Depth of – a) The range of distance in subject space within which 

a lens (or a system) provides an image that reproduces detail with an 

acceptably small circle of confusion (acceptable focus) usually small 

enough for subjective evaluation as a “point,”defines the depth of field. 

Tables are calculated for lenses as a function of optical aperture and the 

subject distance at which they are focused. Regrettably, these calculations 

are strictly geometric (ignoring the possibility of diffraction effects, of all 

optical aberrations, and of possible differing contributions to focal length 

from different annuli of the optical system). Thus, the tables are at times 



overly optimistic. b) Depth of field for a given imaging system decreases 

with increasing optical aperture of that system, and decreases as the distance 

to the subject decreases. A “maximum acceptable”diameter for the 

“circle of confusion”may depend upon the resolution capabilities of the 

light-sensitive receptor (electronic or photographic) and of the system within 

which it is functioning. Quantitative measurements for actual imaging 

systems may be made on an optical bench. Practical determinations are 

made from subjective examination of the actual images in the system of 

interest. 

Field Dominance – When a CAV laserdisc is placed in the still frame 

mode, it continuously plays back two adjacent fields of information. There 

are no rules in the NTSC system stating that a complete video picture has 

to start on field 1 or field 2. Most of the video in this program is field 1 

dominant. There are two sections of the disc that are field 2 dominant. In 

the case of film translated to video, the start of a complete film picture 

changes from field 1 to field 2 about 6 times a second. There is a code in 

the vertical interval of the disc that tells the player on which field it can 

start displaying each of the disc’s still frames. 

Field Frequency – The rate at which one complete field is scanned, normally 

59.94 times a second in NTSC or 50 times a second in PAL. 

Field Period – The reciprocal of twice the frame rate. 

Field Picture – A picture in which the two fields in a frame are coded 

independently. Field pictures always come in sets of two fields, which are 

called top field and bottom field, respectively. When the first field is coded 

as a P- or a B-picture, the second picture must be coded in the same 

manner; however, if the first field is coded as an I-picture, the second field 

may be coded as either an I-picture or a P-picture (that is predicted from 

the first field). 

Field Rate – Number of fields per second. 

Field Time Linear Distortions – Distortions involving signals in the 

64 µsec to 16 msec range. Field time distortions cause field-rate tilt in 

video signals as shown in the figure below. Error is expressed in IRE or as 

a percentage of a reference amplitude which is generally the amplitude at 

the center of the line bar. Distortion can also be expressed as the K Factor 

of K60Hz . See K60Hz . 

FD = a 

a in % of RA 

a 

0.2 ms 0.2 ms 

Field Bar 

Top of Line Bar 




These distortions will cause top to bottom brightness inaccuracies in large 

objects in the picture. These distortions can be measured with either a 

window signal or a field square wave. See Linear Distortions. 

Field Time Waveform Distortions – See Field Time Linear Distortions. 

FIFO (First-In-First-Out) – a) A memory structure in which data is 

entered at one end and removed from the other. A FIFO is used as a buffer 

to connect two devices that operate asynchronously. b) A storage device 

(parallel shift register) which operates as a Turing machine to buffer asynchronous 

data where the first data stored is the first data read out. FIFOs 

are used to store video and act as “rubber-band”type buffers to keep a 

steady video stream where memory and system clock speeds do not 

match. FIFOs have less delays than standard shift registers as input and 

output are controlled by separate clocks. 

Figure-8 Microphone – A microphone (usually a ribbon type) whose sensitivity 

is greatest to front and rear, and weakest to both sides. 

File – A container in which you store information such as text, programs, 

or images. 

File System – A hierarchy of directories and files. Directories contain 

other directories and files; files cannot contain directories. The root (/) 

directory is at the top of the hierarchy. 

Fill – The video information that replaces a “hole”(video information) cut 

in the video picture by the key signal. 

Fill (Insert) Video – A video signal which replaces a “hole”(video information) 

cut in background video by a key source. 

Fill Bus – A separate bus or buses from which fill videos can be selected 

independently from the key source cutting the hole. 

Fill Light – Fill lights, commonly referred to as “scoops,”provide a softedged 

field of light used to provide additional subject illumination to reduce 

harsh shadows or areas not highlighted by the key light. 

Film Chain – a) Projectors, multiplexers, and cameras connected for the 

purpose of transferring film to video. b) A device that transfers a film 

image to a video image. It is also know as a Telecine chain. 

Film Loop – A piece of file, quite short, which is to be played repeatedly. 

Filter – A device used to remove or pass certain frequencies from a signal. 

Low-pass filters pass the low-frequency content of a signal while highpass 

filters pass the high -frequency content. A bandpass filter passes frequencies 

within a certain “band.” 

Filter Artifacts – Distortions introduced by filters. The most common visual 

artifacts introduced by filters are reduced resolution and ringing. 

Filter, Brick Wall – A low-pass filter with a steep cut-off (such as 

20 dB/octave or greater), such that a negligible amount of higher frequency 

information passes. The filter typically has uniform group delay. 

Filter, Gaussian – A low-pass filter providing a gradual attenuation of the 

higher frequencies. Strictly the attenuation should follow the curve 

V = e^(–af^2). But the term is also applied to attenuation functions that 

only qualitatively resemble the precise power function. 

Filter, Optical – In addition to the familiar optical filters for modifying 

spectral energy distribution, and thereby color rendition, optical filters are 


also produced as low-pass filters for spatial detail in an optical image, 

eliminating high-frequency information that would exceed the Nyquist limit 

of the system and produce excessive aliasing. Many of these filters are cut 

from optically birefringent crystals and function by providing multiple 

images slightly displaced one form another so that fine detail is blurred 

(i.e., low-pass filtered). 

Finite Impulse Response Filter (FIR) – A digital filter that is, in general, 

better than analog filters but also more complex and expensive. Some specialized 

filter functions can only be accomplished using a FIR. 

FIP – Forward Interaction Path. 

FIR – See Finite Impulse Response Filter. 

FireWire (IEEE P1394) – At this writing, the hottest new technology in 

video. FireWire is a special high-speed bus standard capable of over 

100 Mbits/sec sustained data rate. 

Firmware – Program stored in ROM. Normally, firmware designates any 

ROM-implemented program. 

First-Frame Analysis – A transparency technique wherein the first frame 

of the video file is a dummy frame that supplies the color or range of colors 

to be rendered as transparent: the color of the chroma-key background, 

for example. See Transparency, Transparency Frame. 

FITS (Functional Interpolating Transformation System) – A format 

that contains all data used to design and assemble extremely large files in 

a small, efficient mathematical structure. 

Five Step Stair Case – Test signal commonly used to check luminance 

gain linearity. 

Fixed-Point Representation – Number representation in which the decimal 

point is assumed to be in a fixed position. 

Flag – a) A variable which can take one of only two values. b) Information 

bit that indicates some form of demarcation has been reached, such as 

overflow or carry. Also an indicator of special conditions such as interrupts. 

Flags – Menu functions other than the X, Y, or Z parameters which turn 

on/off or enable a selection of one or more system conditions. 

Flanging – Another name for phasing. Originally, the method of phasing 

where phase was varied by resting your thumb on the flanges of the reel to 

slow it down. 

Flash – Momentary interference to the picture of a duration of approximately 

one field or less, and of sufficient magnitude to totally distort the 

picture information. In general, this term is used alone when the impairment 

is of such short duration that the basic impairment cannot be recognized. 

Sometimes called “Hit.” 

Flash Analog to Digital Converter – A high-speed digitizing device 

based on a bank of analog comparators. The analog value to be digitized is 

the input to one side of the comparators bank. The other comparators input 

is tied to a tap of a resistor ladder, with each comparator tied to its own 

tap. The input voltage at each comparator will be somewhere between the 

top and bottom voltages of the resistor ladder. The comparators output a 

high or a low based on the comparison of the input voltage to the resistor 

ladder voltage. This string of 1s and 0s are converted to the binary 

number.

FlashPix – A multi-resolution image format in which the image is stored 

as a series of independent arrays. Developed by Kodak, Hewlett-Packard, 

Live Picture, Inc., and Microsoft and introduced in June 1996. 

Flat Field – As used herein, the entire area viewed by a television camera 

with the viewed area being uniformly white or any single specified color or 

any shade of gray. 

Flat Shading – A polygon rendered so that its interior pixels are all the 

same color has been rendered with “flat”shading. An object represented 

by polygons that is rendered with flat shading will look distinctly faceted. 

No highlights or reflections are visible. 

Flatten – The process of converting a Macintosh file into a self-contained, 

single-forked file so that it is compatible with Windows environment. See 

Self-Contained, Single-Forked. 

Flicker – a) Flicker occurs when the refresh rate of the video is too low 

and the light level on the display begins to decrease before new information 

is written to the screen to maintain the light level. To prevent the 

human eye from seeing flicker, the screen refresh rate needs to be at least 

24 frames per second. b) A rapid visible change in brightness, not part of 

the original scene. See also Flicker Frequency, Fusion Frequency, Judder, 

Large-Area Flicker, and Twitter. 

Flicker Frequency – The minimum rate of change of brightness at which 

flicker is no longer visible. The flicker frequency increases with brightness 

and with the amount of the visual field being stimulated. In a recent study, 

a still image flashed on and off for equal amounts of time was found to 

have a flicker frequency of 60 flashes per second at a brightness of 

40 foot lamberts (fL) and 70 at 500. Television sets generally range around 

100 fL in peak brightness (though some new ones claim over 700). The 

SMPTE recommends 16 fL for movie theater screens (though this is measured 

without film, which reduces the actual scene brightness by at least 

50 percent). One reason for interlaced scanning is to increase television’s 

flashing pictures to the flicker frequency, without increasing bandwidth. 

Flip – Special effect in which the picture is either horizontally or vertically 

reversed. 

Floating – Logic node that has no active outputs. Three-state bus lines, 

such as data bus lines, float when no devices are enabled. 

Floating-Point Representation – Technique used to represent a large 

range of numbers, using a mantissa and an exponent. The precision of the 

representation is limited by the number of bits allocated to the mantissa. 

See Mantissa and Exponent. 

Floppy Disk – Mass-storage device that uses a flexible (floppy) diskette to 

record information. See Disk. 

Flowchart or Flow Diagram – Graphical representation of program logic. 

Flowcharts enable the designer to visualize a procedure. A complete flowchart 

leads directly to the final code. 

FLSD (Fixed Linear Spline Data) – The different modes used to animate 

a value, for example, position, color, or rotation. 

Fluid Head – Refers to a tripod mount that contains lubricating fluid which 

decreases friction and enables smooth camera movement. 



Flutter – Distortion which occurs in sound reproduction as a result of 

undesired speed variations during recording or reproducing. Flutter occurring 

at frequencies below approximately 6 Hz is termed “wow.” 

Flux – Magnetic field generated by a record head, stored on magnetic 

tape, and picked up by the playback head. Also the magnetic field that 

exists between the poles of a magnet. 

Flux Transition – A 180-degree change in the flux pattern of a magnetic 

medium brought about by the reversal of the magnetic poles within the 

medium. 

Flux Transition Density – Number of flux transitions per track length 

unit. 

Fly-Back – See Horizontal Retrace. 

Flying Erase Head – The erase head mounted on the spinning (flying) 

video head drum. Facilitates smooth, seamless edits whenever the camcorder 

recording begins. Without a flying erase head, a video “glitch”may 

occur at scene transitions. 

Flying Head – A video head that engages when the video deck is on 

“pause,”providing a clear still-frame image. 

Fly-Through – A fly-through is a type of animation where a moving 

observer flies through a seemingly stationary world. 

FM – See Frequency Modulation. 

FM Recording – The data signal is used to modulate the frequency of a 

“carrier”having a frequency much higher than any spectral component of 

the data signal. Permits the recording of DC or very low signal frequencies. 

FM-FM – Dual carrier FM-coded discrete stereo transmissions, analogue. 

Can be used for bi-lingual operation under user selection, but no autoselection 

is available. Audio characteristics better than standard mono 

soundtrack. 

FMV – See Full Motion Video. 

Focus – Adjustment made to the focal length of the lens, designed to create 

a sharper, more defined picture. 

Following (or Trailing) Blacks – A term used to describe a picture condition 

in which the edge following a white object is overshaded toward 

black. The object appears to have a trailing black border. Also called “trailing 

reversal.” 

Following (or Trailing) Whites – A term used to describe a picture condition 

in which the edge following a black or dark gray object is overshaded 

toward white. The object appears to have a trailing white border. Also 

called “trailing reversal.” 

Font – A style of type. Many character generators offer the user a menu of 

several fonts. 

Foot Candles – A measure of the amount of light falling on an object (its 

illumination). This is a measure only of the light energy that can be seen by 

the human eye (becoming an obsolete unit; replaced by the Lux). 

1 foot candle = 1 lumen per square foot 

Foot Lamberts – A measurement of the brightness of an object. If 

100 foot candles are illuminating a 60% white chip, its brightness will be 

60 foot lamberts, regardless of viewing distance. Again, remember that 




brightness is measured over the same energy response of a human eye 

(becoming an obsolete unit; replaced by the Nit). 

Footprint – Area on earth within which a satellite’s signal can be received. 

Forbidden – The term forbidden when used in the clauses defining the 

coded bit stream indicates that the value shall never be used. This is usually 

to avoid emulation of start codes. 

Forbidden Value – An excluded value in the coded bit stream. A value 

that is not allowed to appear in the bit stream. 

Forced Display – A DVD feature that forces the display of a sub-picture 

regardless of whether or not the user wanted the sub-picture to be displayed. 

This would be used, for instance, in an English movie in which 

there were non-English words spoken and it was desired that a translation 

be provided even if the subtitle system was turned off. 

Forced Updating – a) The process by which macroblocks are intra coded 

from time-to-time to ensure that mismatch errors between the inverse DCT 

processes in encoders and decoders cannot build up excessively. b) The 

recurrent use of I-coding to avoid build-up of errors between the inverse 

DCT processes in encoders and decoders. 

Foreground (FGND) – May be thought of as the front layer of video in a 

picture. Also used to describe the insert video (on 4100 series) of a key. 

Form – A window that contains buttons that you must click and/or editable 

fields that you must fill in. 

Format – a) The configuration of signals used for interconnecting equipment 

in a specified system. Different formats may use different signal 

composition, reference pulses, etc. A variety of formats are used to record 

video. They vary by tape width (8 mm, 1/2", 3/4", 1"), signal form (composite, 

Y/C, component), data storage type (analog or digital) and signal 

standard (PAL, NTSC, SECAM). b) For data storage media (hard disks, floppies, 

etc.), the process of initializing the media prior to use. Formatting 

effectively deletes any data that was previously on the media. See Format 

Disk. 

Format Conversion – The process of both encoding/decoding and resampling 

of digital rates to change a digital signal from one format to another. 

Format Converter – A device that allows the reformatting of a digital data 

stream originating from one sampling structure (lines per frame, pixels per 

line) into a digital data stream of another sampling structure for the purposes 

of recording or passing the original data stream through distribution 

devices designed to accommodate the latter structure. Since the data still 

represents the original sampling structure, this is not the same as standards 

conversion. 

Format Disk – The process of preparing a disk for data storage by determining 

where data is to be placed and how it is to be arranged on disk. 

Forward Compatibility – A decoder is able to decode a bit stream coming 

from an encoder of a previous generation. A new coding standard is 

forward compatible with an existing coding standard if new decoders 

(designed to operate with the new coding standard) continue to be able to 

decode bit streams of the existing coding standard. 

Forward Motion Vector – Information that is used for motion compensation 

from a reference picture at an earlier time in display order. 


Four-Track or Quarter-Track Recoding – The arrangement by which 

four difference channels of sound may be recorded on quarter-inch-wide 

audio tape. These may be recorded as four separate and distinct tracks 

(monophonic) or two stereo pairs of tracks. Tracks 1 and 3 are recorded in 

the “forward”direction of a given reel, and Tracks 2 and 4 are recorded in 

the “reverse”direction. 

FP – Fixed Part. 

FPGA – Field-Programmable Gate Array. 

FPLL – Frequency- and Phase-Locked Loop. 

Fractals – Mathematically generated descriptions (images) which look like 

the complex patterns found in nature (e.g., the shoreline and topographic 

elevations of a land mass as seen from an aerial photograph). The key 

property of fractal is self-similarity over different domain regions. 

Fragmentation – The scattering of data over a disk caused by successive 

recording and deletion operations. Generally this will eventually result in 

slow data recall, a situation that is not acceptable for video recording or 

replay. The slowing is caused by the increased time needed to randomly 

access data. With such stores, defragmentation routines arrange the data 

(by copying from one part of the disk to another) so that it is accessible in 

the required order for replay. Clearly any change in replay, be it a transmission 

running order or the revision of an edit, could require further defragmentation. 

True random access disk stores, able to play frames in any 

order at video rate, never need defragmentation. 

Frame – a) A frame consists of all the information required for a complete 

picture. For interlaced scan systems, there are two fields in a frame. For 

progressive video, these lines contain samples starting from one time 

instant and continuing through successive lines to the bottom of the frame. 

b) A complete picture composed of two fields. In the NTSC system, 525 

interlaced horizontal lines of picture information in 29.97 frames per second. 

In the PAL system, 625 interlaced horizontal lines of picture information 

in 25 frames per second. c) The metal cabinet which contains the 

switcher’s circuit boards. d) One complete video image, containing two 

fields. There are 30 frames in one second of NTSC video. 

Frame Buffer – a) A block of digital memory capable of buffering a frame 

of video. The amount of memory required for a frame buffer is based on 

the video being stored. For example to store a 640 X 480 image using the 

RGB color space with eight bits per color, the amount of memory required 

would be: 640 x 480 x 3 = 921,600 bytes. b) A frame buffer is a digital 

frame store, containing a large chunk of memory dedicated to pixel memory, 

at least one complete frame’s worth. All the pixels in the buffer have the 

same depth. Each bit of depth is called a bit plane. Frame buffers can use 

the bit planes in a variety of ways. First, a pixel’s bits can store the RGB 

values of colors. This simple method is called full-color mode. In full-color 

mode, it is common to refer to the red plane, or the blue or green plane, 

meaning the bits reserved for specifying the RGB components of the pixel. 

Full-color systems may also have an alpha channel, which encodes the 

transparency of each bit. The alpha channel is like a matte or key of the 

image. Alternately, the bits can store a color number, which selects the 

final color from a color map. Finally, some bit planes may be reserved for 

use as overlay planes.

Frame Capture (Frame Grabber) – Taking one frame of video and storing 

it on a hard drive for use in various video effects. 

Frame DCT Coding – DCT coding in which every block consists of lines 

from both fields which are interlaced. The chrominance blocks in the 4:2:0 

format always have to be coded by using frame DCT coding. 

Frame Frequency – The rate at which a complete frame is scanned, 

nominally 30 frames per second. 

Frame Period – The reciprocal of the frame rate. 

Frame Picture – A picture in which the two fields in a frame are merged 

(interlaced) into one picture which is then coded. 

Frame Rate – a) The rate at which frames of video data are scanned on 

the screen. In an (M) NTSC system, the frame rate is 29.97 frames per 

second. For (B, D, G, H, I) PAL, the frame rate is 25 frames per second. 

b) The number of frames per second at which a video clip is displayed. 

c) The rate at which frames are output from a video decoding device or 

stored in memory. The NTSC frame rate is 30 frames/second while some 

graphics frame rates are as high as 100 frames/second. 

Frame Rate Conversion – The process of converting one frame rate to 

another. Examples include converting the (M) NTSC frame of 29.97 frames 

per second to the PAL frame rate of 25 frames per second. 

Frame Relay – A network interface protocol defined by CCITT 

Recommendation I.122 as a packet mode service. In effect it combines the 

statistical multiplexing and port sharing of X.25 packed switching with the 

high speed and low delay of time division multiplexing and circuit switching. 

Unlike X.25, frame relay implements no layer 3 protocols and only the 

so-called core layer 2 functions. It is a high-speed switching technology 

that achieves ten times the packet throughput of existing X.25 networks by 

eliminating two-thirds of the X.25 protocol complexity. The basic units of 

information transferred are variable-length frames, using only two bytes for 

header information. Delay for frame relay is lower than X.25, but it is variable 

and larger than that experienced in circuit-switched networks. 

Frame Roll – A momentary vertical roll. 

Frame Store – Term used for a digital full-frame temporary storage device 

with memory for only one frame of video. 

Frame Synchronizer – A digital buffer, that by storage, comparison of 

sync information to a reference, and time release of video signals, can 

continuously adjust the signal for any timing errors. A digital electronic 

device which synchronizes two or more video signals. The frame synchronizer 

uses one of its inputs as a reference and genlocks the other video 

signals to the reference’s sync and color burst signals. By delaying the 

other signals so that each line and field starts at the same time, two or 

more video images can be blended, wiped, and otherwise processed 

together. A TBC (Time Base Controller) takes this a step further by synchronizing 

both signals to a stable reference, eliminating time-base errors from 

both sources. The Digital Video Mixer includes a frame synchronizer and 

dual TBCs. 

Free-Run – Process of allowing a digital circuit (typically a microprocessor) 

to run without feedback (open-loop). This is done to stimulate other 

devices in the circuit in a recurring and predictable manner. 



Freeze Frame – Special effect in which the picture is held as a still 

image. It is possible to freeze either one field or a whole frame. Freezing 

one field provides a more stable image if the subject is moving, however, 

the resolution of the video image is half that of a full frame freeze. Digital 

freeze frame is one special effect that could be created with a special 

effects generator or a TBC (Time Base Controller). The Digital Video Mixer 

includes this feature. 

French Proposals – Three HDEP proposals, two closely related, suggested 

by a number of French organizations. For countries with a field rate of 50 

fields per second, there would be 1200 scanning lines, 1150 of them 

active. For countries with a field rate of 59.94 fields per second, there 

would be 1001 scanning lines, 970 of them active. Both systems would 

have identical line rates (60,000 lines per second) and bandwidths (65 MHz 

luminance), and would be progressively scanned. This correspondence 

would allow a great deal of common equipment, as Recommendation 601 

does for digital component video. The third proposal is for a worldwide standard 

based on 1050 scanning lines (970 active), 2:1 interlace, and 100 

field per second. 

Frequency – The number of cycles a signal that occurs per second, measured 

in hertz (repetition rate). In electronics, almost invariably the number 

of times a signal changes from positive to negative (or vice versa) per second. 

Only very simple signals (sine waves) have a single constant frequency; 

the concept of instantaneous frequency therefore applies to any transition, 

the frequency said to be the frequency that a sine wave making the 

same transition would have. Images have spatial frequencies, the number 

of transitions from dark to light (or vice versa) across an image, or per 

degree of visual field. 

Frequency Allocation Table – List of which frequencies can be used for 

transmission of different signals in the U.S. It may require revision for certain 

ATV (Advanced TV) schemes. A similar function is performed internationally 

by the International Frequency Registration Board (IFRB), like the 

CCIR, part of the International Telecommunications Union. 

Frequency Interleaving – The process by which color and brightness signals 

are combined in NTSC. 

Frequency Modulation – a) Modulation of sine wave or “carrier”by varying 

its frequency in accordance with amplitude variations of the modulating 

signal. b) Also referring to the North American audio service broadcast over 

88 MHz to 108 MHz. 

Frequency Multiplex – See Multiplex. 

Frequency Response – a) The range of frequencies which a piece of 

equipment can process. b) A system’s ability to uniformly transfer signal 

components of different frequencies without affecting their amplitudes. This 

parameter is also known as gain/frequency distortion or amplitude versus 

frequency response. The amplitude variation maybe expressed in dB, percent, 

or IRE. The reference amplitude (0 dB, 100%) is typically the white 

bar or some low frequency. Frequency response numbers are only meaningful 

if they contain three pieces of information: the measured amplitude, 

the frequency at which the measurement was made, and the reference frequency. 

There are a number of test signals that can be used to evaluate 

frequency response. They include Multiburst, Multipulse, a swept signal, or 

(Sin X)/X. 




Frequency Response Curve – The curve relating the variation in output 

with frequency of a piece of equipment or magnetic tape when the input is 

kept constant. 

Frequency Response Rolloff – A distortion in a transmission system 

where the higher frequency components are not conveyed at their original 

full amplitude. In video systems, this causes loss of color saturation. 

Frequency Synthesizer – An electronic circuit that generates a number 

of frequencies from a fixed-reference frequency. Some frequency synthesizers 

generate only a relatively small number of frequencies; others generate 

hundreds of different frequencies. 

Fringing – The pickup of extra bass frequency signals by a playback head 

when reproducing a signal recorded by a head with a wider track configuration, 

such as playing a full-track tape with a half-track head. 

From Source – VTR or other device that is generating the video/audio signal 

that is being dissolved or wiped away from. 

Front Porch – The portion of the video signal between the end of active 

picture time and the leading edge of horizontal sync. See Horizontal Timing. 

Front-to-Back Ratio – The ratio between a cardioid microphone’s sensitivity 

to sounds arriving from the front and from the rear, a measure of its 

directionality. 

FSS – Fixed Satellite Services. 

FST – Fast Slant Transform. 

FT – Fixed Termination. 

FTP (File Transfer Protocol) – A client-server protocol which allows 

users to transfer files over a TCP/IP network. FTP is also the name for the 

client program the user executes to transfer files. Though it was once the 

only way to download files on the Internet, it has now been integrated into 

many web browsers. 

FTTC – Fiber to the Curb. 

FTTH – Fiber to the Home. 

FUCE – Full compatible EDTV. A Hitachi ATV scheme filling a Fukinuki hole 

for increased luminance detail, with recent proposed additions to increase 

chroma detail. 


Fukinuki – Takahiko Fukinuki and the Fukinuki Hole named for him. 

Fukinuki is a Hitachi researcher who proposed filling an apparently unused 

portion of the NTSC spatio-temporal spectrum with additional information 

that might be used for ATV. The signal that fills a Fukinuki hole is sometimes 

referred to as a Fukinuki subcarrier. It is extremely similar to the 

color subcarrier and can cause an effect like cross-luminance under certain 

conditions. 

Full Field – All sampled points in the digital component signal as opposed 

to active picture (AP) which are all sampled points in the digital component 

signal with the exception of the points between EAV and SAV. 

Full Field Signals – Signals with video on each line of active video. These 

signals can only be used for out-of-service testing. 

Full Field Testing – See Out-of-Service Testing. 

Full Motion Video (FMV) – Video that plays at 30 frames per second 

(NTSC) or 25 frames per second (PAL). 

Full Track Recording – Recording monophonically on one track whose 

width is essentially the same as the tape’s. 

Full-Color Mode – Full-color mode is distinguished by: each pixel contains 

its own values; a full-color render takes about three times as long as 

color mapped render. Anti-aliasing, transparency, and texture mapping are 

possible only in this mode. Full-color mode makes possible such things as 

transparency, texture mapping, and anti-aliasing. 

Fusion Frequency – The minimum rate of presentation of successive 

images of a motion picture that allows motion to seem smooth, rather than 

jerky. The fusion frequency is almost always lower than the flicker frequency. 

As it applies to the rate at which images are presented, rather than the 

rate at which they were shot, material that appears to be at or above the 

fusion frequency when viewed at normal speed may be below it when 

viewed in slow motion. Techniques to smooth motion presented at a rate 

below the fusion frequency have been developed for such purposes as 

computer-assisted animation; these are sometimes called in-betweening 

techniques. See also Judder. 

Future Reference Picture – A future reference picture is a reference picture 

that occurs at a later time than the current picture in display order.

G 

G.711 – This ITU recommendation defines an 8-bit A-law (European companding) 

and µ-law (American companding) PCM audio format with 8 kHz 

sampling used in standard telephony. G.711 audio is also used in H.320 

videoconferencing. 

G.722 – An ITU-T recommendation which embraces 7 kHz audio coding at 

64 kbit/s. G.722 uses an adaptive differential PCM (ADPCM) algorithm in 

two sub-bands, and is widely used for news and sports commentary links. 

The sound quality is normally considered inferior compared to MPEG audio 

coding, but has the advantage of low coding delay in comparison with 

MPEG. Due to the low delay, and because of the large installed base of 

G.722 equipment, the algorithm will continue to be in service. 

G.726 – This ITU-T recommendation is entitled “40, 32, 24, 16 kbit/s 

adaptive differential pulse code modulation (ADPCM).”It defines the conversion 

between 64 kbit/s A-law or µ-law PCM audio and a channel of the 

rates stated in the title, by using ADPCM transcoding. 

G.728 – This ITU-T recommendation defines coding of speech at 16 kbit/s 

based on code-excited linear prediction (CELP). The delay of about 2 ms in 

G.728 is lower than other typical implementations of this type of coding. 

G.728 audio is used in H.320 videoconferencing. 

GA – See Grand Alliance. 

Gain – a) Any increase or decrease in strength of an electrical signal. Gain 

is measured in terms of decibels or number of times of magnification. 

b) The ratio of output power to the input power for a system or component. 

c) The amount of amplification of a circuit. The term gain is often used 

incorrectly to denote volume and loudness which are psychological factors 

which are the results of “gain.” 

Gain Ratio Error – In a three-wire interconnect CAV system, the gain of 

one signal may be higher or lower than what it should be because of gain 

distortion caused by one channel. This will cause the ratio of signal amplitudes 

to be incorrect. This error manifests itself as color distortions. In 

some cases, errors in gain ratio will generate illegal signals (see the discussion 

on Illegal Signals). The distorted signal may be legal within its current 

format but could become illegal if converted into a different component 

format. 

Gain/Frequency Distortion – Distortion which results when all of the frequency 

components of a signal are not transmitted with the same gain or 

loss. A departure from “flatness”in the gain/frequency characteristic of a 

circuit. Refer also to the Frequency Response discussion. 

Gamma – Since picture monitors have a nonlinear relationship between 

the input voltage and brightness, the signal must be correspondingly predistorted. 

Gamma correction is always done at the source (camera) in television 

systems: the R, G, and B signals are converted to R 1/g, G 1/g, and 

B 1/g. Values of about 2.2 are typically used for gamma. Gamma is a 

transfer characteristic. Display devices have gamma (or at least CRTs do). 

If you measure the actual transfer characteristic of a CRT used for either 



television display or computer display, you will find it obeys a power law 

relationship: 

Light = Volts^gamma 

where gamma is 2.35 plus or minus 0.1. CRTs have values between 2.25 

and 2.45 – 2.35 is a common value. It is a function of the CRT itself, and 

has nothing to do with the pictures displayed on it. CRT projectors are different; 

green tubes are typically 2.2 while red is usually around 2.1 and 

blue can be as low as 1.7. But there are no direct-view CRTs which have 

values lower than 2.1. Pictures which are destined for display on CRTs are 

gamma-corrected which means that a transfer characteristic has been 

applied in order to try to correct for the CRT gamma. Users of TV cameras 

have to accept the characteristic supplied by the manufacturer, except for 

broadcasters who have adjustable camera curves (the video engineers 

adjust the controls until they like the look of the picture on the studio monitor 

in their area). Even so, no TV camera uses a true gamma curve; they 

all use rather flattened curves with a maximum slope near black of 

between 3 and 5. The higher this slope, the better the colorimetry but the 

worse the noise performance. 

Gamma Correction – a) The RGB data is corrected to compensate for the 

gamma of the display. b) Historically, gamma correction was a precompensation 

applied to the video signal at the camera to correct for the nonlinearities 

of the CRT (i.e., power function of the electron gun) and, as such, it 

was the inverse of the electron gun function. It is now widely used, however, 

to describe “the total of all transfer function manipulations”(i.e., including 

the departures from a true power law function), whether inherent or 

intentionally introduced to act upon the video signal for the purpose of 

reducing the bandwidth for signal processing, making the image on the 

final display conform to preconceived artistic objectives, and/or providing 

noise suppression, or even bit rate reduction. c) The insertion of a nonlinear 

output-input characteristic for the purpose of changing the system 

transfer characteristic. As this usage has grown, the IEEE definition correlating 

gamma to an analytical function becomes optimistic. d) An adjustment 

factor used to correct an image’s intensity when it is displayed. 

Display devices can perform gamma correction but raster images can also 

be gamma corrected with software prior to display. 

Gamma Ferric Oxide – The common magnetic constituent of magnetic 

tapes in the form of a dispersion of fine acicular particles within the 

coating. 

Gamma, Electronic – a) The exponent of that power law that is used to 

approximate the curve of output magnitude versus input magnitude over 

the region of interest. b) Video – The power function of the electro gun in a 

CRT. It has become customary in video, as in photography, to extend the 

meaning and to use gamma as a synonym for the complete transfer function 

regardless of curve shape. Note: In the electronics system, increasing 

gamma decreases image contrast. c) Imaging Processing and Display – 

Nonlinear processing is useful in many television systems as a means of 

bandwidth limiting, and is normally applied at the camera. Given the predominance 

of CRT displays, the chosen exponent is related to that of the 




electron gun (typically 2.2 for systems with 525/59.94 scanning, 2.8 for 

systems with 625/50 scanning, and 2.22 for SMPTE 240M). 

Gamma, Photographic – a) The slope of the transfer function: density 

(log of reciprocal transmission ) vs. log exposure. It is thus the power function 

correlating transmission to exposure. b) Gamma in the photographic 

sense was originally applied specifically to the straight-line portion of the 

transfer function. Only if all of the photographic densities corresponding to 

light intensities in the scene lie within that straight-line portion of the 

transfer function is gamma proportional to contrast. It is sometimes loosely 

used to indicate either an average or a point slope of the transfer function. 

Note: In the photographic system, increasing gamma increases image 

contrast. 

Gamma Table – A table of constants which functions as a nonlinear 

amplifier to correct the electron gun drive voltages so that the CRT display 

appears to be linear. Because the gamma function for each color is different 

in a typical CRT, different values for each color are usually contained in 

the gamma table. This processes is called Gamma Correction. 

Gamut – The range of voltages allowed for a video signal, or a component 

of a video signal. Signal voltages outside of the range (that is exceeding 

the gamut) may lead to clipping, crosstalk, or other distortions. 

Gap – The space between the pole pieces of a tape head. 

GAP – Generic Access Profile. 

Gap Depth – The dimension of the gap measured in the direction perpendicular 

to the surface of a head. 

Gap Length – The dimension of the gap of a head measured from one 

pole face to the other. In longitudinal recording, the gap length can be 

defined as the dimension of the gap in the direction of tape travel. 

Gap Loss – The loss in output attributable to the finite gap length of the 

reproduce head. The loss increases as the wavelength decreases. 

Gap Scatter – The phenomenon of the gaps in a multitrack head not 

being in a straight line. 

Gap Smear – This is due to head wear and is the bridging or shorting out 

of the record or reproduce gap as the result of flowing of the pole face 

material in the direction of tape motion. 

Gap Width – The dimension of the gap measured in the direction parallel 

to the head surface and pole faces. The gap width of the record head governs 

the track width. The gap widths of reproduce heads are sometimes 

made appreciably less than those of the record heads to minimize tracking 

errors. 

Gateway – Gateways provide functional bridges between networks by 

receiving protocol transactions on a layer-by-layer basis from one protocol 

(SNA) and transforming them into comparable functions for the other protocol 

(OSI). In short, the gateway provides a connection with protocol translation 

between networks that use different protocols. Interestingly enough, 

gateways, unlike the bridge, do not require that the networks have consistent 

addressing schemes and packet frame sizes. Most proprietary gateways 

(such as IBM SNA gateways) provide protocol converter functions up 

through layer six of the OSI, while OSI gateways perform protocol translations 

up through OSI layer seven. See OSI Model. 


Gauss – The metric unit of magnetic flux density equal to one Maxwell per 

square centimeter. 

GBR Format – The same signals as RGB. The sequence is rearranged to 

indicate the mechanical sequence of the connectors in the SMPTE 


GCR – See Ghost Cancellation Reference Signal. 

GE (General Electric) – A proponent of the ACTV schemes. 

General Purpose Interface (GPI) – A standard interface for control of 

electronic equipment. A connector on the back of the switcher frame or 

editor which allows remote control of the Auto Trans, DSK Mix, Fade to 

Black, or Panel Memory Function or Sequence on the switcher. Usually a 

contact closure (i.e., switch) which provides short to ground. 

General Purpose Serial Interface (GPSI) – A form of translator which 

allows the switcher to talk to other devices, i.e., ADO, and to be given 

instructions serially by devices such as Editors. 

Generation – The number of duplication steps between an original recording 

and a given copy. A second generation duplicate is a copy of the original 

master and a third generation duplicate is a copy of a copy of the original 

master, etc. 

Generation Loss – When an analog master videotape is duplicated, the 

second-generation copy is usually inferior in some way to the master. This 

degradation appears as loss of detail, improper colors, sync loss, etc. 

Limited frequency response of audio/video magnetic tape and imperfections 

in electronic circuitry are the main causes of generation loss. Higher 

performance formats (such as 1") exhibit much less generation loss than 

more basic formats. Digital formats make generation loss negligible 

because each copy is essentially an exact duplicate of the original. Video 

enhancing equipment can minimize generation loss. Some video processors 

pre-enhance the video signal to overcome generation loss. 

Genlock – a) The process of locking both the sync and burst of one signal 

to the burst and sync of another signal making the two signals synchronous. 

This allows the receiver’s decoder to reconstruct the picture including 

luminance, chrominance, and timing synchronization pulses from the 

transmitted signal. b) The ability to internally lock to a non-synchronous 

video. AVC switchers allow genlocked fades on the DSK. 

Genlock Outputs – A timed color black output synchronous with the input 

reference video. The AVC series also provides the DSK genlocked color 

black. On 4100 series switchers, this also includes composite sync, subcarrier, 

vertical and horizontal drive pulses, burst flag pulse, and composite 

blanking. 

Geometric Distortion – Any aberration which causes the reproduced picture 

to be geometrically dissimilar to the perspective plane projection of 

the original scene. 

Geometry – The shape of objects in a picture, as opposed to the picture 

itself (aspect ratio). With good geometry, a picture of a square is square. 

With poor geometry, a square might be rectangular, trapezoidal, pillowshaped, 

or otherwise distorted. Some ATV schemes propose minor adjustments 

in geometry for aspect ratio accommodation. 

Geostationary Orbit – Satellite orbits 22,300 miles above earth’s equator 

where satellites circle earth at the same rate the earth rotates.

Ghost – A shadowy or weak image in the received picture, offset either to 

the left or right of the primary image, the result of transmission conditions 

which create secondary signals that are received earlier or later than the 

main or primary signal. A ghost displaced to the left of the primary image 

is designated as “leading”and one displaced to the right is designated as 

“following”(lagging). When the tonal variations of the ghost are the same 

as the primary image, it is designated as “positive”and when it is the 

reverse, it is designated as “negative.”See Multipath Distortion. 

Ghost Cancellation Reference (GCR) Signal – ITU-R BT.1124 standard 

reference signal found on scan lines 19 and 282 of (M) NTSC systems and 

on line 318 (B, D, G, H, I) of PAL systems. This signal allows for the 

removal of ghosting from TVs by filtering the entire transmitted signal 

based on the condition of the transmitted GCR signal. 

Ghost Point – A supplementary point included on the tangent to the 

acquired point in order to force the line to begin and end on the acquired 

points. 

Ghosting – A weak, secondary, ghost-like duplicate video image in a video 

signal caused by the undesired mixing of the primary signal and a delayed 

version of the same signal. 

GHz (Gigahertz) – Billions of cycles per second. 

Gibbs Effect – The mirage-like haze at the boundaries of picture objects, 

seen in DCT based compression algorithms at (too) high compression 

ratios. The effect is most noticeable around text and high-contrast geometrical 

shapes. 

GIF (Graphic Interchange Format) – A bit-mapped graphics file format 

popular for storing lower resolution image data. 

Gigabyte – One billion bytes. 

Glenn – William and Karen Glenn, researchers for NYIT in Dania, Florida, 

who developed the VISTA ATV scheme. They are often cited for their work 

indicating that human vision cannot simultaneously perceive high spatial 

detail and high temporal detail. 

Glitch – a) A form of low-frequency interference, appearing as a narrow 

horizontal bar moving vertically through the picture. This is also observed 

on an oscilloscope at field or frame rate as an extraneous voltage pip moving 

along the signal at approximately reference black level. b) Slang for 

visual error, i.e., dropout on tape, spikes at switcher pattern boundaries. 

Patterns that jump off screen or any other aberration. c) Slang for a fault 

in data transmission or other error that does not cause a total lock up. 

Glitch Impulse – A term used to define the voltage/time function of a single 

DAC step until the output video level has settled to within ±1 LSB of 

the final value. Glitches are apt to appear in output video as the input to 

the DAC changes from: 

0111 1111 to 1 000 0000 

Global Data Set – A data set with all data essence or metadata elements 

defined in the relevant data essence standard or Dynamic Metadata 

Dictionary. 

Global (Menu) – A separate channel that allows additional rotations to be 

superimposed on an image and, in 3D systems, “motion on motion”in an 

effect. 



Gloss Level – A shiny surface imparted to the magnetic coating due to 

calendering. 

GMSK – Gaussian Filtered Minimum Shift Keying. 

GOP (Group of Pictures) – a) A GOP starts with an I-picture and ends 

with the last picture before the next I-picture. b) A picture sequence which 

can be coded as an entity. For instance, it is possible to cut between GOPs. 

For that reason, the first picture in a GOP has to be intra-coded (I-picture). 

Time codes are carried on GOP levels. 

Gouraud Shading – This type of smooth shading has no true “specular” 

highlights and is faster and cheaper than Phong shading (which does). 

GPI/GPO – General Purpose Input/General Purpose Output. 

Grand Alliance (GA) – The United States grouping, formed in May 1993, 

to produce “the best of the best”initially proposed HDTV systems. The participants 

are: AT&T, General Instrument Corporation, Massachusetts 

Institute of Technology, Philips Consumer Electronics, David Sarnoff 

Research Center, Thomson Consumer Electronics, and Zenith Electronics 

Corporation. The format proposed is known as the ATSC format. 

Graphic Equalizer – An equalizer which indicates its frequency response 

graphically through the position of its controls. When the controls are in a 

straight line at the 0 position, the response is flat. 

Graphics Board – The printed circuit board within a workstation that contains 

the graphics processors. 

Gray Card – A nonselective (color neutral) diffuse reflector intended to be 

lighted by the normal illumination of the original scene, and having a 

reflectance factor of 18% (compared with a perfect reflector at 100% and 

prepared magnesium oxide at 98%). The gray card luminance is used as a 

guide in determining scene exposure so that the image is placed upon the 

most favorable portion of the transfer function curve. 

Gray Scale – a) The luminance portion of the video signal. A scale of 10 

from TV black to TV white indicating the shades of gray a camera can see 

at any one time and to which a camera can be adjusted. A gray scale 

adjustment of 7 is good. b) An optical pattern in discrete steps between 

light and dark. Note: A gray scale with ten steps is usually included in resolution 

test charts. 

Green Tape – An abrasive tape used to clean and lap heads that are 

unevenly worn, stained, scratched, etc. Should be used with caution and 

should not be used on ferrite heads. This also applies to gray tape. 

Ground – A point of zero voltage potential. The point in reference to which 

all voltages are measured. 

Ground Loop – Hum caused by currents circulating through the ground 

side of a piece of equipment due to grounding different components at 

points of different voltage potential. 

Grounded Electrical Outlet – An electrical wall outlet that accepts a plug 

that has a grounding prong. In the USA, all properly wired three-prong outlets 

provide a ground connection. 

Group – A group is any arbitrary collection of polygons; a subset of the 

database, usually the group represents a coherent object. A group could 

contain all the polygons constituting the model of a chair, or it could con- 




tain twenty such chairs and a table. A polygon can only be in one group at 

a time, but it can move to another group. 

Group 1, 2, 3, and 4 – The ITU-T Group 1 to 4 specify compression of 

black and white documents and the operation of facsimile equipment. 

Group 3 (also known as G3 or T.4) is presently the most important standard 

in the world of fax and document storage applications. G3 compression 

features modified Huffman encoding. The ITU-T Group 4 (also known as G4 

or T.6) is an improvement of ITU-T G3, dedicated to digital telephone lines, 

in particular ISDN. 

Group Delay – a) A signal defect caused by different frequencies having 

differing propagation delays. b) This distortion is present when signal components 

of different frequencies experience different delays as they pass 

through a system. Distortions are expressed in units of time. The largest 

difference in delay between a reference low frequency and the other frequencies 

tested is typically quoted as the group delay distortion. Group 

delay problems can cause a lack of vertical line sharpness due to lumi- 


nance pulse ringing, overshoot, or undershoot. The Multipulse or (Sin x)/x 

signals can be used to check for group delay in the same way as these 

signals are used to check for chrominance to luminance delays. 

GSM – Global System for Mobile Communication. 

GSTM – General Switched Telephone Network. 

Guard Interval – Additional safety margin between two transmitting symbols 

in the COFDM standard. The guard interval ensures that reflections 

occurring in the single-frequency network are eliminated until the received 

symbol is processed. 

Guest – A modeling object visualized in the presence of another database 

which will serve as a visualization support but cannot be modified. 

GUI (Graphical User Interface) – A computer interface that allows the 

user to perform tasks by pointing to icons or graphic objects on the screen. 

Windows is a graphics user interface. Most multimedia programs require 

GUIs.

H 

H Drive – See Horizontal Drive. 

H Rate – The time for scanning one complete horizontal line, including 

trace and retrace. NTSC equals 1/15734 seconds (color) or 63.56 µsec. 

H.222 – This ITU-T recommendation is identical to the audio specification 

of MPEG-2. 

H.261 – Recognizing the need for providing ubiquitous video services 

using the Integrated Services Digital Network (ISDN), CCITT (International 

Telegraph and Telephone Consultative Committee) Study Group XV established 

a Specialist Group on Coding for Visual Telephony in 1984 with the 

objective of recommending a video coding standard for transmission at 

m x 384 kbit/s (m = 1, 2,..., 5). Later in the study period after new discoveries 

in video coding techniques, it became clear that a single standard, 

p x 64 kbit/s (p = 1, 2,..., 30), can cover the entire ISDN channel capacity. 

After more than five years of intensive deliberation, CCITT Recommendation 

H.261, Video Codec for Audio Visual Services at p x 64 kbit/s, was completed 

and approved in December 1990. A slightly modified version of this 

Recommendation was also adopted for use in North America. The intended 

applications of this international standard are for videophone and videoconferencing. 

Therefore, the recommended video coding algorithm has to be 

able to operate in real time with minimum delay. For p = 1 or 2, due to 

severely limited available bit rate, only desktop face-to-face visual communication 

(often referred to as videophone) is appropriate. For p>=6, due to 

the additional available bit rate, more complex pictures can be transmitted 

with better quality. This is, therefore, more suitable for videoconferencing. 

The IVS (INRIA Videoconferencing System) is a software implementation of 

H.261 codec which also features PCM and ADPCM audio codecs and 

includes an error control scheme to handle packet losses in the Internet. 

H.261 – The ITU-T H.261 recommendation embraces video codecs for 

audio visual services at p x 64 kbit/s data rate, where p is between 1 and 

30. Thus, the standard is informally called “p x 64.”It is aimed at low bit 

rate media, and is used in the H.320 videoconferencing recommendation. 

H.261 provides a resolution of 352 x 288 pixels (CIF) or 176 x 144 pixels 

(QCIF), independent of bit rate. The H.261 recommendation defines both 

encoding and decoding. However, it defines, more strictly, how to decode 

than to encode the bit stream, and has room for options in the encoder. 

The coding is based on DCT with word-length encoding. H.261 defines 

both independently coded frames (key frames), and frames that frame by 

using block-based motion compensation (non-key frames). H.261 also 

defines error-correction codes, and it allows rate control by varying quantization 

and by dropping frames and jumping blocks. 

H.262 – The H.262 recommendation is identical to the video specification 

of MPEG-2. 

H.263 – An ITU-T recommendation concerning “video coding for low bit 

rate communication.”The H.263 is dedicated to video conferencing via 

H.324 terminals using V.34 modems at 28.8 kbit/s, and to H.323 LANbased 

videoconferencing . The coding algorithm in H.263 is based on 

H.261, but has better performance than the H.261, and it may eventually 

displace H.261. 



H.320 – An ITU-T recommendation for low bit rate visual communication. 

The H.320 is entitled “narrow-band visual telephone systems and terminal 

equipment”and is widely accepted for ISDN videoconferencing. The H.320 

is not a compression algorithm, but is rather a suite of standards for videoconferencing. 

H.320 specifies H.261 as the video compression, and 

defines the use of one of three audio formats: either G.711, G,722, or 

G.728. 

H.324 – ITU recommendation H.324 describes terminals for low bit rate 

multimedia applications, using V.34 modems operating over the general 

telephone system. H.324 terminals may carry real-time voice, data, and 

video or any combination, including video telephony. H.324 makes use of 

the logical channel procedures of recommendation H.245, in which the 

content of each logical channel is described when the channel is opened. 

H.324 terminals may be used in multipoint configurations through MCUs, 

and may interwork with H.320 terminals on ISDN, as with terminals on 

wireless networks. 

HAD – See Half Amplitude Duration. 

Half Amplitude Duration – The 50 percent point on a test waveform. 

Half-Duplex Transmission – Data transmitted in either direction, one 

direction at a time. 

Half Splitting – Troubleshooting technique used for fault isolation. It 

involves the examination of circuit nodes approximately midway through a 

circuit. Once the operational state of these nodes has been determined, the 

source of the fault can be isolated to the circuits either before or after this 

point. This process can then be continued. 

Halo – a) Most commonly, a dark area surrounding an unusually bright 

object, caused by overloading of the camera tube. Reflection of studio 

lights from a piece of jewelry, for example, might cause this effect. With 

certain camera tube operating adjustments, a white area may surround 

dark objects. b) Type of pattern border with soft edges and a mix from a 

vid to border matte gen then to “B”vid. 

Halt – Command to stop the computer. 

Handshake – a) The protocol that controls the flow of information 

between two devices. b) Control signals at an interface in which the sending 

device generates a signal indicating that new information is available, 

and the receiving device then responds with another signals indicating that 

the data has been received. 

Hanging Dots – A form of cross-luminance created by simple comb filters. 

It appears as a row of dots hanging below the edge of a highly saturated 

color. See also Cross-Luminance. 

Hangover – Audio data transmitted after the silence detector indicates 

that no audio data is present. Hangover ensures that the ends of words, 

important for comprehension, are transmitted even though they are often of 

low energy. 

Hard Banding – A variation in thickness or elasticity across the width of 

the tape, it may be a coating defect, or it may be caused by stretch damage 

either during manufacture or in use. It results in a variation of the 




recovered RF due to the effect on head-to-tape contact and may result in 

color saturation banding and velocity errors. 

Hard Border – A hard border usually applies to patterns and is characterized 

by an abrupt change from background video to the border video and 

by an abrupt change from the border video to the foreground video. Also 

sometimes used to describe key borders with a high gain. 

Hardware – a) Term used generically for equipment, i.e., VTRs, switchers, 

etc. b) Individual components of a circuit, both passive and active, have 

long been characterized as hardware in the jargon of the engineer. Today, 

any piece of data processing equipment is informally called hardware. 

Hard-Wired Logic – See Random Logic. 

Harmonic Distortion – If a sine wave of a single frequency is put into a 

system, and harmonic content at multiples of that frequency appears at the 

output, there is harmonic distortion present in the system. Harmonic distortion 

is caused by nonlinearities in the system. 

Harmonics – a) Whole number multiples of a frequency. F x 1 is called 

the fundamental or first harmonic; F x 2 is the second harmonic; F x 3 is 

the third harmonic; etc. b) Integral multiples of a fundamental frequency 

are harmonics of that frequency. A pure sine wave is free of harmonics. 

Adding harmonics to a fundamental frequency will change its wave shape. 

A square wave contains a fundamental frequency plus all the odd harmonics 

of that frequency. 

HARP (High-Gain Avalanche Rushing Amorphous Photoconductor) – 

A very new type of image sensor (target) for a camera tube. HARP target 

tubes are about 10 times more sensitive to light than conventional tube 

types and have been demonstrated to offer hope of overcoming the sensitivity 

drawbacks of HDTV cameras. 

HBF – Half Band Filter. 

HBI – See Horizontal Blanking Interval. 

HBO (Home Box Office) – Time Inc.’s pay-cable and entertainment production 

company, a co-proposer with ATC of C-HDTV and supporter of 

ACTV. 

HD (High Definition) – A frequently used abbreviation for HDEP and 

sometimes HDTV. The term High Definition, applied to television, is almost 

as old as television itself. In its earliest stage, NTSC was considered high 

definition (previous television systems offered from 20 to 405 scanning 

lines per frame). 

HD D5 – A compressed recording system developed by Panasonic which 

uses compression at about 4:1 to record HD material on standard D5 

cassettes. 


HD-0 – A set of formats based on the ATSC Table 3, suggested by the DTV 

Team as the initial stage of the digital television rollout. 

ATSC TABLE 3 

Formats for DTV Transmission 

(i = interlaced, p = progressive) 

Vertical Size Horizontal Size Aspect Ratio Frame Rate 

Value (active) Value (active) Information and Scan 

(HD) 1,080 1,920 16:9 (square pixel) 24p, 30p, 30i 

(HD) 720 1,280 16:9 (square pixel) 24p, 30p, 60p 

(SD) 480 704 4:3 non-square pixel) 24p, 30p, 30i, 60p 

(SD) 480 704 16:9 (non-square pixel) 24p, 30p, 30i, 60p 

(SD) 480 640 4:3 (square pixel) 24p, 30p, 30i, 60p 


Team as the second stage of the digital television rollout, expected to be 

formalized in the year 2000. 


Team as the third stage of the digital television rollout contingent on some 

extreme advances in video compression over the next five years. The added 

format is not part of the ATSC Table 3. 

HDCAM – Sometimes called HD Betacam, is a means of recording compressed 

high-definition video on a tape format (1/2-inch) which uses the 

same cassette shell as Digital Betacam, although with a different tape 

formulation. 

HDDR – High Density Digital Recording. 

HDEP (High Definition Electronic Production) – A term bearing little or 

no implications for transmission and display systems. The SMPTE and the 

ATSC have approved one standard for HDEP, sometimes referred to as 

SMPTE 240M. This standard has 1125 scanning lines per frame, 60 field 

per second, 2:1 interlace, an aspect ratio of 16:9, extended colorimetry, 

and a 30 MHz base bandwidth for each of its three color components. It is 

based on work at NHK, but includes considerable American modifications. 

Clearly, the combined 90 MHz base bandwidth of this DHEP standard cannot 

be practically broadcast (not counting sound or modulation characteristics, 

it takes up as much bandwidth as 15 current broadcast channels). 

That is why there are so many ATV transmission schemes. 

HDLC – High Level Data Link Control. 

HD-MAC (High Definition MAC) – A variety of systems, all European 

except for HDMAC-60. 

HDMAC-60 – The baseband and satellite transmission form of HDS-NA. 

See also MAC. 

HD-NTSC – The Del Rey Group’s ATV scheme, comprised primarily of a 

quincunx scanning scheme referred to as Tri-Scan, which would subsample 

each NTSC pixel three times, in a triangular fashion, for increased 

vertical and horizontal static resolution, at an effective 10 frame-per-second 

rate. Blanking adjustment is used for aspect ratio accommodation. 

HDNTSC – The terrestrial transmission form of HDS-NA, comprised of a 

receiver-compatible, channel-compatible signal and an augmentation channel, 

which may be half-sized and low-power. The augmentation channel

carries increased resolution, improved sound, widescreen panels, and pan 

and scan information to let an ATV set know where to apply the panels. 

HD-PRO – A universal, worldwide HDEP proposal from the Del Rey Group, 

said to accommodate all ATV systems. Details are not available pending 

patent protection. 

HDS-NA (High Definition System for North America) – The Philips 

Laboratories (Briarcliff, NY) ATV scheme, comprised of two separate systems, 

HDMAC-60, a single, satellite-deliverable channel designed to get 

the signal to broadcast stations and CATV head-ends, and HDNTSC, a twochannel 

(receiver-compatible plus augmentation) system to deliver it to 

home TVs. 

HDTV – See High Definition Television. 

HDTV 1125/60 Group – An organization of manufacturers supporting the 

SMPTE HDEP standard. 

HDVS (High Definition Video System) – A Sony trade name for its HDEP 

equipment and ancillary products, such as HD videodisc players. 

Head – In a magnetic recorder, the generally ring-shaped electromagnet 

across which the tape is drawn. Depending on its function, it either erases 

a previous recoding, converts an electrical signal to a corresponding magnetic 

pattern and records it on the tape, or picks up a magnetic pattern 

already on the tape and converts it to an electrical playback signal. 

2-Head: The system used on most cassette recorders, requiring that playback 

occur after the recording has been made. 3-Head: Refers to the 

recording/playback head configuration within the recorder. A 3-head system 

allows simultaneous playback of recorded material. 

Head Alignment – Mechanical adjustment of the spatial relationships 

between the head gaps and the tape. 

Head Block – An assembly holding an erase, record, and playback head in 

a certain physical alignment. 

Head Demagnetizer or Degausser – A device used to neutralize possible 

residual or induced magnetism in heads or tape guides. 

Headend – Facility in cable system from which all signals originate. Local 

and distant television stations, and satellite programming, are picked up 

and amplified for re-transmission through system. 

Head-End – The part of a CATV system from which signals emanate. 

Header – A block of data in the coded bit stream containing the coded 

representation of a number of data elements pertaining to the coded data 

that follow the header in the bit stream. 

Header/Descriptor – See Image File Header/Descriptor. 

Headroom – a) The number of dB increases possible above the operation 

level (0 VU) before unacceptable distortion occurs. b) In composition, the 

space between a subject’s head and the upper boundary of the frame. 

c) The difference between the nominal level (average) and the maximum 

operating level (just prior to “unacceptable”distortion) in any system or 

device. Because it is a pure ratio, there is no unit or reference-level qualifier 

associated with headroom – simply “dB”; headroom expressed in dB 

accurately refers to both voltage and power. 

Heads Out – A way of winding tape so that the beginning of a selection is 

on the outside of the reel. 



Head-to-Tape Contact – The degree to which the surface of the magnetic 

coating approaches the surface of the record or replay heads during normal 

operation of a recorder. Good head-to-tape contact minimizes separation 

loss and is essential in obtaining high resolution. 

Height – The vertical positioning of a head with respect to a piece of tape. 

The size of the picture in a vertical direction. 

Helical Scan – A method of recording video information diagonally on a 

tape, used in home and professional VCRs. High-speed rotating video 

heads scan these diagonal video tracks, giving an effective tape speed 

much higher than the actual tape speed allowing more information to be 

recorded on a given length of magnetic tape. 

Hertz (Hz) – The unit of frequency. Equivalent to cycles per second. 

HEX (Hexadecimal) – Base-16 number system. Since there are 16 hexadecimal 

digits (0 through 15) and only ten numerical digits (0 through 9), 

six additional digits are needed to represent 10 through 15. The first six 

letters of the alphabet are used for this purpose. Hence, the hexadecimal 

digits read: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F. The decimal number 

16 becomes the hexadecimal number 10. The decimal number 26 

becomes the hexadecimal number 1A. 

HFC – Hybrid Fibre Coax. 

HHR (Half Horizontal Resolution) – Part of the MPEG-2/DVB standard 

where half of the normal 720-pixel horizontal resolution is transmitted 

while maintaining normal vertical resolution of 480 pixels. Since it is a 

4:2:0 format, the color information is encoded at 240 pixels vertically and 

176 pixels horizontally. Virtually all the DBS providers use HHR format since 

it dramatically reduces the bandwidth needed for channels, though at the 

expense of picture quality. Special logic in the video decoder chip in the set 

top box re-expands the picture to normal horizontal size by interpolation 

before display. 4:2:2 video at Standard Definition looks as good as the NBC 

analog feeds on GE-1 Ku. High bandwidth 4:2:0 video such as the NBC 

digital feeds on GE-1 Ku come very close to studio quality and the low 

bandwidth video encoded in HHR format looks like DBS. 

Hi Con – A black and white high contrast signal used as a key source. See 

also Matte Reel. 

Hi Impedance Mike – A mike designed to be fed into an amplifier with 

input impedance greater than 20 to 50 ohms. 

Hi-8 – 8 mm videotape format which provides better quality than VHS. An 

improved version of the 8 mm tape format capable of recording better picture 

resolution (definition). A higher-density tape is required which provides 

a wider luminance bandwidth, resulting in sharper picture quality (over 400 

horizontal lines vs. 240 for standard 8 mm) and improved signal-to-noise 

ratio. Camcorders using this format are very small, light, and provide a picture 

quality similar to S-VHS. 

Hidden Line Removal – A wireframed object can be confusing to look at 

because edges that would be hidden are still displayed. Hidden line 

removal is the process of computing where edges are hidden and not 

drawing them. 

Hi-Fi (High Fidelity) – Most commonly used to refer to the high quality 

audio tracks recorded by many VCRs. These tracks provide audio quality 

approaching that of a CD. However, because they are combined with the 




video signal before recording, audio dubs using them are impossible without 

re-recording the video. 

High Definition Films – British organization that began using the term 

High Definition for its electronic cinematography system even before color 

TV was broadcast in the U.S. 

High Definition Television (HDTV) – a) General term for proposed standards 

pertaining to consumer high-resolution TV. b) An ATV term sometimes 

confused with HDEP. HDTV is usually used to describe advanced production 

and delivery mechanisms that will get ATV to the home. As HDEP 

cannot practically be broadcast, all broadcast HDTV schemes must make 

compromises in quality. The line between broadcast HDTV and EDTV, therefore, 

is difficult to define. See Minimum Performance. c) A TV format capable 

of displaying on a wider screen (16x9) as opposed to the conventional 

4x3) and at higher resolution. Rather than a single HDTV standard, the FCC 

has approved several different standards, allowing broadcasters to choose 

which to use. This means new TV sets will have to support all of them. All 

of the systems will be broadcast as component digital. d) By HDTV, we normally 

understand transmission, rendering, and display systems that feature 

about double the number of scanning lines, improved color quality, and less 

artifacts than that of today’s composite systems. The video may be analog, 

like the Japanese MUSE or the European HD-MAC, or digital, like the ATSC 

system in the USA. The European, MPEG-2 based Digital Video 

Broadcasting (DVB) specifications embrace HDTV in addition to 625-line TV. 

In the USA, the Grand Alliance has succeeded in combining various digital 

HDTV systems into the ATSC system – a multiple format system based on 

MPEG-2 video coding – that allows HDTV transmissions to use the same 

frequency bands now used by regular NTSC television. The Japanese, who 

have had regular analog HDTV transmission for some time, are also planning 

to implement digital HDTV. 

High Density Digital Recording (HDDR) – Recording of digital data on a 

magnetic medium, having a flux transition density in excess of 15,000 

transitions per inch per track. 

High Energy Oxide – Any magnetic oxide particle exhibiting a BSHC product 

higher than that of gamma ferric oxide. Chromium dioxide and cobalt 

are the two most common examples at the present time. 

High Energy Tape – A tape made with a high energy oxide. 

High Frequency Subcarrier – An information channel added to a television 

signal where the finest brightness detail is normally transmitted. As 

the human visual system is least sensitive to the finest detail, it is unlikely 

to be bothered by interface from such a subcarrier. This technique was first 

applied to the NTSC color subcarrier; most recently it has been proposed in 

Toshiba’s ATV system. 

High Level – A range of allowed picture parameters defined by the MPEG- 

2 video coding specification which corresponds to high-definition 

television. 

High Line Rate – More than 525 scanning lines per frame. 

High Resolution Sciences (HRS) – Proponent of the CCF ATV scheme. 

HRS plans to offer other ATV schemes, including one using synchronized 

electron beam spatial modulation (turning each scanning line into a series 

of hills and valleys) in both camera and receiver to achieve increased vertical 

resolution. 


High-Frequency Distortion – Undesirable variations that occur above the 

15.75 kHz line rate. 

High-Frequency Interference – Interference effects which occur at high 

frequency. Generally considered as any frequency above the 15.75 kHz line 

frequency. 

High-Level Language – Problem-oriented programming language, as distinguished 

from a machine-oriented programming language. A high-level 

language is closer to the needs of the problem to be handled than to the 

language of the machine on which it is to be implemented. 

Highlight – a) In lighting, to add a light which will cause an area to have 

more light. b) In switchers, to allow one portion of the video to have a 

greater luminance level. c) In screens, monitors, displays, etc., to cause a 

word on the display to be brighter, commonly by inverting and surrounding 

the work with a box of white video. 

Highlighting – In the menu system for DVDs it is necessary to be able to 

indicate a menu selection since there is no “computer mouse”available. 

This highlighting is accomplished through a wide variety of graphic arts 

and post-production techniques coupled with the capabilities provided by 

the DVD itself. 

Highlights – a) Shiny areas that suggest intense reflections of light 

sources. Highlights move when light sources move relative to a surface, but 

are independent of all other lighting types. b) Highlights may be applied to 

a smooth surface by both Gouraud and Phong shading, but only the latter 

computes specular reflections based on the angle between reflected light 

from a light source and the eye’s line of sight. 

High-Lights – The maximum brightness of the picture, which occurs in 

regions of highest illumination. 

High-Order – Most significant bits of a word. Typically, bit 8 through 15 of 

a 16-bit word. 

Highpass Filter – Filter that passes only high frequencies. 

High-Speed Shutter – A feature on video cameras and camcorders that 

allows detail enhancement of fast-moving objects by electronically dividing 

the CCD into imaging sections. 

HIPPI (High Performance Parallel Interface) – A parallel data channel 

used in mainframe computers that supports data transfer rates of 

100 Mbps. 

Hiss – The most common audible noise component in audio recording, 

stemming from a combination of circuit and tape noise. Several noise 

reduction systems are available, such as Dolby, DBX, DNR (Dynamic 

Noise Reduction), DNL (Dynamic Noise Limiter), to help alleviate such 

problems. 

Hit – See Flash. 

Hitachi – Proponent of the FUCE ATV scheme and enhanced versions of 

FUCE. 

Hi-Vision – Japanese term for HDTV. 

HLO-PAL (Half-Line Offset PAL) – An early NHK proposal for an ATV 

transmission scheme. 

HLS – Hue, Luminance, and Saturation.

Hold Time – The time data must be stable following the completion of a 

write signal. 

Holdback Tension – Tension applied by the supply turntable to hold the 

tape firmly against the heads. 

Hole – a) In modeling a 3D world, it is often necessary to create polygons 

and solids which literally have holes in them. PictureMaker can make 2D 

holes in individual surfaces and drill 3D holes through convex portions of 

closed solids. b) A volume in the three-dimensional NTSC spectrum into 

which an auxiliary sub-channel can be placed with minimal impairment. 

Holes are found where horizontal, vertical, and temporal detail are simultaneously 

high. The most famous hole is the Fukinuki hole, but the most 

common hole is the one carrying the NTSC color subcarrier. 

Home Directory – The directory into which IRIX places you each time you 

log in. It is specified in your login account; you own this directory and, typically, 

all its contents. 

Horizontal (Hum) Bars – Relatively broad horizontal bars, alternately 

black and white, which extend over the entire picture. They may be stationary, 

or may move up or down. Sometimes referred to as a “venetian blind” 

effect. Caused by approximate 60-cycle interfering frequency, or one of its 

harmonic frequencies. 

Horizontal Blanking – a) The entire time between the end of the active 

picture time of one line and the beginning of the active picture time of the 

next line. It extends from the start of front porch to the end of the back 

porch. b) The video synchronizing signal before and after each active television 

line that defines the border or black area at the left and right side of 

the display. In a CRT, it hides (blanks out) the electron beam’s retrace path 

as it returns from the right to the left of the display to begin scanning a 

new line. 

Horizontal Blanking Interval (HBI) – That portion of the scanning line 

not carrying a picture. In NTSC, the HBI carries a synchronizing pulse and a 

color reference signal. Some scrambling and other systems add sound 

and/or data signals to the HBI. Some ATV schemes fill it with widescreen 

panel or detail enhancement signals. See also Blanking and Blanking 

Stuffing. 

Horizontal Displacements – Describes a picture condition in which the 

scanning lines start at relatively different points during the horizontal scan. 

See Serrations and Jitter. 

Horizontal Drive – A pulse at the horizontal sweep rate used in TV cameras. 

Its leading edge is coincident with the leading edge of the horizontal 

sync pulse and the trailing edge is coincident with the leading edge of the 

burst flag pulse. 

Horizontal Interval – The time period between lines of active video. Also 

called Horizontal Blanking Interval. 

Horizontal Lock – A subsystem in a video receiver/decoder which detects 

horizontal synchronizing pulses, compares them with the on-board video 

clock in the video system, and uses the resultant data to stabilize the 

incoming video by re-synching to the system clock. In the case of severe 

horizontal instability, a large FIFO memory may be required to buffer the 

rapid line changes before they are compared and re-synchronized. 



Horizontal Resolution – a) Rating of the fine detail (definition) of a TV 

picture, measured in scan lines. The more lines, the higher the resolution 

and the better the picture. A standard VHS format VCR produces 240 lines 

of horizontal resolution, while over 400 lines are possible with S-VHS, 

S-VHS-C, and Hi-8 camcorders. b) Detail across the screen, usually specified 

as the maximum number of alternating white and black vertical lines 

(line of resolution) that can be individually perceived across the width of a 

picture, divided by the aspect ratio. This number is usually expressed as TV 

lines per picture height. The reason for dividing by the aspect ratio and 

expressing the result per picture height is to be able to easily compare 

horizontal and vertical resolution. Horizontal chroma resolution is measured 

between complementary colors (rather than black and white) but can vary 

in some systems (such as NTSC), depending on the colors chosen. 

Horizontal resolution in luminance and/or chrominance can vary in some 

systems between stationary (static resolution) and moving (dynamic resolution) 

pictures). It is usually directly related to bandwidth. 

Horizontal Retrace – The return of the electron beam from the right to 

the left side of the raster after the scanning of one line. 

Horizontal Scan Rate – The rate at which the screen’s scanning beam is 

swept from side to side. For (M) NTSC systems, this rate is 63.556 µs, or 

15.734 kHz. 

Horizontal Sync – a) The –40 IRE pulse occurring at the beginning of 

each line. This pulse signals the picture monitor beam to go back to the 

left side of the screen and trace another horizontal line of picture information. 

b) The portion of the video signal that occurs between the end of one 

line of signal and the beginning of the next. A negative-going pulse from 

the blanking signal used to genlock (synchronize) equipment. It begins at 

the end of the front porch and ends at the beginning of the back porch. 

Horizontal Sync Pulse – See Horizontal Sync. 

Horizontal Timing – 

100 IRE 

714 mV) 

Front 

Porch 

1.5 µs 

±0.1 µs 

4 IRE 

20 IRE 

40 IRE 

(286 mV) 

Breezeway 

0.6 µs 

Blanking 

10.9 µs ±0.2 µs 

Sync to Blanking End 

9.4 µs = ±0.1 µs 

Sync to Burst End 

7.4 µs 

Sync 

4.7 µ +0.1 µs 

Z Z 

Burst 

2.5 µs 

40 IRE 

Ref Burst 

Amptd 

Color 

Back 

Porch 

1.6 µs 

4 IRE 

RS-170A Pulse Width Requirements 

Ref 

White 

Ref Sync 

Amplitude 

Ref Black Level 

7.5 IRE 

Blanking Level 




1.27 µs 

Min. 

+4 IRE 

0 IRE 

-36 IRE 

-40 IRE 

0.254 

µs 

Max. 

-4 IRE 

Host – a) Any system connected to the network. b) A device where module(s) 

can be connected, for example: an IRD, a VCR, a PC. 

Hostname – The name that uniquely identifies each host (system) on the 

network. 

House Sync – a) The black burst signal used to synchronize all the 

devices in the studio or station. b) Sync generated within the studio and 

used as a reference for generating and/or timing other signals (i.e., sync 

gens). 

HPF – High Pass Filter. 

HQTV (High Quality TV) – Another term for HDTV. 

HRS – High Resolution Sciences. 

HSI – See Hue, Saturation and Intensity. 

HSL – See Hue, Saturation, and Lightness. 

HSM (Hierarchical Storage Management) – HSM systems transparently 

migrate files from disk to optical disk and/or magnetic tape that is usually 

robotically accessible. When files are accessed by a user, HSM systems 

transparently move the files back to disk. 

HSV – See Hue, Saturation, and Value. 

HSV Space – The three numbers are hue, saturation, and value. The solid 

is a cone. Also called HSI. 

HSYNC – See Horizontal Synchronization or Sync. 

Hue – a) A color wheel of basic pigments. All the hues of the rainbow 

encircle the cone’s perimeter. b) The wavelength of the color which allows 

color to be distinguished such as red, blue, and green. Often used synonymously 

with the term tint. It is the dominant wavelength which distinguishes 

a color such as red, yellow, etc. Most commonly, video hue is influenced 

by a camera’s white balance or scene lighting. Video color processors, 

such as the Video Equalizer, are the main tools used to adjust and correct 

hue problems. c) One of the three characteristics of television color. Hue is 

the actual color that appears on the screen. See Chroma and Luminance. 

d) Attribute of a visual sensation according to which an area appears to be 

similar to one of the perceived colors, red, yellow, green, and blue, or to a 

combination of two of them. 


10.49 µs Minimum 

11.49 µs Maximum* 

9.22 µs Minimum 

7.94 µs Maximum 

4.45 to 

5.08 µs 

0.254 

µs 

Max. 

0.38 µs 

Min. 

90% to 

110% of 

M Sync 

Amplitude 

FCC Pulse Width Requirements 

* Recommended Values Only 

8 to 11 Cycles of 

Chrominance Subcarrier 

Hue, Saturation, and Intensity (HSI) – Color space system based on the 

values of Hue, Saturation, and Intensity. Intensity, analogous to luma, is the 

vertical axis of the polar system. The hue is the angle and the saturation is 

the distance out from the axis. 

Hue, Saturation, and Lightness (HSL) – Nearly identical to HSI except 

Intensity is called Lightness. Both serve the same function. 

Hue, Saturation, and Value (HSV) – Nearly identical to HSI and HSL 

except Intensity and Lightness are called Value. All three serve the same 

function. 

Huffman Coding – Method of data compression that is independent of the 

data type, i.e., the data could represent an image, audio, or spread sheet. 

This compression scheme is used in JPEG and MPEG-2. Huffman Coding 

works by looking at the data stream that makes up the file to be compressed. 

Those data bytes that occur most often are assigned a small code 

to represent them (certainly smaller than the data bytes being represented). 

Data bytes that occur the next most often have a slightly larger code 

to represent them. This continues until all of the unique pieces of data are 

assigned unique code words. For a given character distribution, by assigning 

short codes to frequently occurring characters and longer codes to 

infrequently occurring characters, Huffman’s minimum redundancy encoding 

minimizes the average number of bytes required to represent the characters 

in a text. Static Huffman encoding uses a fixed set of codes, based 

on a representative sample of data, for processing texts. Although encoding 

is achieved in a single pass, the data on which the compression is based 

may bear little resemblance to the actual text being compressed. Dynamic 

Huffman encoding, on the other hand, reads each text twice; once to determine 

the frequency distribution of the characters in the text and once to 

encode the data. The codes used for compression are computed on the 

basis of the statistics gathered during the first pass with compressed texts 

being prefixed by a copy of the Huffman encoding table for use with the 

decoding process. By using a single-pass technique, where each character 

is encoded on the basis of the preceding characters in a text, Gallager’s 

adaptive Huffman encoding avoids many of the problems associated with 

either the static or dynamic method. 

Hum – Undesirable coupling of 50 Hz (PAL) or 60 Hz (NTSC) power sine 

wave into other electrical signals. 

Human Factors Guidelines – A set of standards and suggestions for 

making the working environment more comfortable and healthy. 

HUT – Households Using Television. 

HVS (Human Visual System) – Eyes and brain. 

HVT (Horizontal, Vertical, and Temporal) – The three axes of the 

spatio-temporal spectrum. 

Hybrid CD-ROM – A single disc containing files for both a Windows PC 

and a Macintosh. See CD-ROM. 

Hybrid Coder – In the archetypal hybrid coder, an estimate of the next 

frame to be processed is formed from the current frame and the difference 

is then encoded by some purely intraframe mechanism. In recent years, the 

most attention has been paid to the motion compensated DCT coder where 

the estimate is formed by a two-dimensional warp of the previous frame 

and the difference is encoded using a block transform (the Discrete Cosine

Transform). This system is the basis for international standards for video 

telephony, is used for some HDTV demonstrations, and is the prototype 

from which MPEG was designed. Its utility has been demonstrated for video 

sequence, and the DCT concentrates the remaining energy into a small 

number of transform coefficients that can be quantized and compactly represented. 

The key feature of this coder is the presence of a complete 

decoder within it. The difference between the current frame as represented 

as the receiver and the incoming frame is processed. In the basic design, 

therefore, the receiver must track the transmitter precisely, the decoder at 

the receiver and the decoder at the transmitter must match. The system is 

sensitive to channel errors and does not permit random access. However, it 

is on the order of three to four times as efficient as one that uses no prediction. 

In practice, this coder is modified to suit the specific application. 

The standard telephony model uses a forced update of the decoded frame 



so that channel errors do not propagate. When a participant enters the 

conversation late or alternates between image sources, residual errors die 

out and a clear image is obtained after a few frames. Similar techniques 

are used in versions of this coder being developed for direct satellite television 

broadcasting. 

Hybrid Editing – Combining nonlinear edited video files with linear (deckto-deck) 

segments of footage. 

Hybrid Scalability – The combination of two or more types of scalability. 

Hybrid Wavelet Transform – A combination of wavelet and transform 

algorithms within the same compression technology. 

Hypercardioid – A directional pickup pattern where maximum discrimination 

occurs at more than 90 and less than 180 degrees off axis. 




I 

I – Improved or Increased; also the in-phase component of the NTSC color 

subcarrier, authorized to have more than twice as much horizontal resolution 

as the Q, or quadrature component. Few TV sets have ever taken 

advantage of this increased chroma resolution, though there is renewed 

interest. 

I, W, Q, B – An NTSC test signal used to check television broadcast equipment. 

It consists of an I signal followed by a white bar, then a Q signal and 

a black level on each line. 

I/O – See Input/Output. 

I/O Mapped I/O – I/O devices that are accessed by using instructions and 

control signals that differ from those of the memory devices in a system. 

Assigns I/O devices to a separate address space. 

I/Q – In Phase/Quadrature Phase. 

IB – In-Band. 

IBA – Britain’s Independent Broadcasting Authority, home of a great deal of 

ATV research. 

IBE – Institution of Broadcast Engineers. 

IBM – Member of the AEA ATV Task Force; also one of the first organizations 

to suggest sub-sampling as a technique for compatibility increasing 

detail. 

IC (Integrated Circuit) – A small device incorporating the equivalent of 

hundreds or thousands of transistors, capacitors, resistors, and other components 

within a small, solid block. 

IC – Interaction Channel. 

ICC (International Color Consortium) – Established in 1993 by eight 

industry vendors for the purpose of creating, promoting, and encouraging 

the standardization and evolution of an open, vendor-neutral, cross-platform 

color management system architecture and components. 

ICCE (International Conference on Consumer Electronics) – 

Sponsored by the Consumer Electronics Society of the IEEE and held annually 

in the Chicago area immediately following CES. ATV has become an 

increasingly important topic at ICCE. 

Icon – A small picture that represents a stowed or closed file, directory, 

application, or IRIX process. 

Iconoscope – A camera tube in which a high-velocity electron beam 

scans a photo-emissive mosaic which has electrical storage capability. 

ICPM (Incidental Carrier Phase Modulation) – A transmission defect 

most noticeable as a cause of sync buzz. 

IDE – Integrated Development Environment. 

IDTV – See Improved Definition Television. 

IEC (International Electrotechnical Commission) – The IEC and its 

affiliated International Organization for Standardization (ISO) are the two 

major global standards-making groups. They are concerned with establishing 

standards that promote interchange of products, agreement upon 


methods of evaluation, and resolution of nonfunctional differences among 

national standards. They are structured as an international federation of the 

more than 50 national standards organizations. The USA is represented by 

the American National Standards Institute (ANSI). 

IEEE – See International Electrical and Electronic Engineers. 

IEEE P1394 (FireWire) – A low-cost digital interface organized by Apple 

Computer as a desktop LAN and developed by the IEEE P1394 Working 

Group. Can transport data at 100, 200, or 400 Mbps. Serial bus management 

provides overall configuration control of the serial bus in the form of 

optimizing arbitration timing, guarantee of adequate electrical power for all 

devices on the bus, assignment of which IEEE P1394 device is the cycle 

master, assignment of isochronous channel ID, and notification of errors. 

There are two types of IEEE P1394 data transfer: asynchronous and 

isochronous. Asynchronous transport is the traditional computer memorymapped, 

load and store interface. Data requests are sent to a specific 

address and an acknowledgment is returned. In addition to an architecture 

that scales with silicon technology, IEEE P1394 features a unique isochronous 

data channel interface. Isochronous data channels provide guaranteed 

data transport at a pre-determined rate. This is especially important for 

time-critical multimedia data where just-in-time delivery eliminates the 

need for costly buffering. 

IEEE Standard 511-1979 Video Signal Transmission Measurement of 

Linear Waveform Distortions – This IEEE standard gives a comprehensive 

technical discussion of linear waveform distortions. 

IETF (Internet Engineering Task Force) – One of the task forces of the 

Internet Activities Board (IAB). The IETF is responsible for solving the shortterm 

engineering needs of the Internet. It has over 40 working groups. 

I-ETS – Interim European Telecommunications Standards. 

IF (Intermediate Frequency) – The first state in converting a broadcast 

television signal into baseband video and audio. 

IFFT – Inverse FFT. 

I-Frame (Intra Frame) – One of the three types of frames that are used 

in MPEG-2 coded signals. The frame in an MPEG sequence, or GOP (Group 

of Pictures), that contains all the data to recreate a complete image. The 

original information is compressed using DCT. 

IIM – Interactive Interface Module. 

IIOP – Internet Inter-ORB Protocol. 

IIT (Illinois Institute of Technology) – Home of most of the research 

into the SLSC ATV scheme. 

Ikegami – Broadcast equipment manufacturer involved in a number of ATV 

schemes, including production of HDEP equipment to the SMPTE standard 

and schemes involving the use of a line doubler either before or after 

transmission. 

Illegal Video – A color or colors that are not acceptable in a given color 

space.

Illuminance – Quotient of the luminous flux dFv incident on an element of 

the surface containing the point by the area dA of the element. The illuminance 

also is commonly used in a qualitative or general sense to designate 

the act of illuminating or the state of being illuminated. Units of luminance 

are lux, foot candle. 

IMA (Interactive Multimedia Association) – IMA has been active in the 

definition of the DVD through its DVD Special Interest Group (IMA DVD SIG). 

The IMA DVD SIG is a committee of DVD manufacturers working for interactive 

DVDs by establishing requirements and influencing specifications. 

IMA ADPCM – The IMA has selected the 4:1 ADPCM audio compression 

scheme from Intel’s DVI as the preferred compressed audio date type for 

interactive media platforms. Intel had offered the algorithm as an open 

standard to the IMA. The algorithm compresses 16-bit audio data at up to 

44.1 kHz sampling into 4-bit ADPCM words. 

Image – A two-dimensional (usually) picture. The picture may be represented 

in digital form or mathematically as an image is a set of planes in 

two dimensions. The two dimensions are the resolution in X and Y 

(columns, lines). The origin (0, 0) of the image is sometimes its lower left 

corner. There are four basic types of images: black and white or color, 

mask or no mask, Z plane or no Z plane, IPR information or no IPR 

information. 

Image Buffer – See Frame Buffer. 

Image Capture – The transducing of the information in a real image into 

the photographic or electronic medium. Normally in motion-reproducing 

systems, synchronous audio information is simultaneously transduced. 

Image Compression – a) Process used to reduce the amount of memory 

required to store an image. See JPEG, MPEG, and Decimation. 

b) Application of an appropriate transfer function to the image signal so as 

to limit dynamic range. c) Application of bandwidth limiting or bit rate 

reduction to an image signal in order to bring it within the limitations of a 

lower capacity channel. 

Image Enhancement – a) Techniques for increasing apparent sharpness 

without increasing actual resolution. This usually takes the form of increasing 

the brightness change at edges. Since image enhancement has 

advanced continuously for nearly 50 years, ordinary NTSC pictures sometimes 

look better than the NTSC pictures derived from an HDEP source, 

particularly when these derived pictures are designed to be augmented by 

other signals in an ATV receiver. It is very difficult to enhance pictures for 

NTSC receivers and then unenhance them for receivers with augmentation. 

b) Once the camera response has been made flat to 400 lines (by aperture 

correction), an additional correction is applied to increase the depth of 

modulation in the range of 250 to 300 lines (in an NTSC system), both vertically 

and horizontally. This additional correction, known as image 

enhancement, produces a correction signal with symmetrical overshoots 

around transitions in the picture. Image enhancement must be used very 

sparingly, if natural appearance is to be maintained. 

Image File – A format for storing digital images. To save disk space, 

images are compressed in a binary file. The image format is contained in a 

file header which is read by all the programs. The header contains: the 

image name, the resolution, the type of image. 



Image File Architecture – The Digital Information Exchange Task Force 

(SMPTE, IEEE, ATSC) on digital image architecture has as its goal the multidisciplinary 

agreement upon and the definition of fully flexible, interoperable, 

scalable, and extensible systems. The objective is agreement on the 

structure of digital image files that will facilitate the exchange of such files 

across the technology interfaces. The scope includes both the rapid, unambiguous 

but concise identification of the file and its utilization, as well as 

the organization of the image data itself. 

Image File Descriptor – The descriptor is a block of data that enhances 

the utility of the main data for the user. It may contain, in standardized format, 

data concerning production, ownership, access, previous processing, 

etc., relevant to the basic interpretation of the data. 

Image File Header – The header is a very compact label that can be 

decoded by a universally accepted algorithm. Specific objectives are: identify 

encoding standard, specify length of the file, indicate whether a readable 

descriptor is included, permit random interception of data stream, and 

offer optional error protection. 

Image File Header/Descriptor – A standard introductory identification 

directing access to a digital image file. The header provides a brief image 

file identification, universally decodable, indicating the format and length of 

the data block. The (optional) descriptor conveys additional information 

improving the usefulness of the data block to the user, such as cryptographic, 

priority, or additional error-protection information as well as 

source, time, authorship, ownership, restrictions on use, processing performed, 

etc. 

Image File Motion-Picture Format – SMPTE Working Group H19.16 has 

proposed SMPTE Standard H19.161 defining the file format for the 

exchange of digital motion-picture information on a variety of media 

between computer-based systems. This flexible file format describes pixelbased 

(raster) images with attributes defined in the binary file descriptor, 

which identifies: generic file information, image information, data format, 

and image orientation information, motion-picture and television industry, 

specific information, user defined information. The draft assumes nonrealtime 

application, with formats for real-time to be considered as the developing 

technology permits. 

Image File Video Index – Proposed descriptor developed by SMPTE 

Working Group P18.41. This proposed SMPTE recommended practice is 

intended to provide a method of coding video index information in which 

various picture and program-related source data can be carried in conjunction 

with the video signal. There are three classes of video index data 

based on type and use of the data. Class 1: Contains information that is 

required to know how to use the signal. Class 2: Contains heritage information 

for better usage of the signal. Class 3: Contains other information 

not required to know how to use the signal. 

Image Generation – The creation of an image in the photographic or 

electronic medium from an image-concept (painted or generated by computer 

graphics, for example). 

Image Innovator – An optional package which adds additional flags and 

menus to ADO 100, including Mosaics, Posterization, Solarization and Mask 

submenu, Target Defocus flag and Background menu, Border flags and 

Sides submenu. 




Image Pac – A multi-resolution image file format developed by Kodak as 

part of the Photo CD System. 

Image Processing, Digital – Digital images are represented by a stream, 

currently of 8-bit or 10-bit values representing the luminance and chrominance 

information, or a stream of 8-bit or 10-bit values representing the 

R', G', and B' information. Image processing sometimes involves multiplication 

of each digital word by: its proportional contribution to the 

processed image, a vector to relocate the pixel, an algorithm to change 

overall image size. To control these processes, additional information may 

be carried in the alpha channel synchronized to the image. As an example 

of the process, if an 8-bit sample is multiplied by an 8-bit factor, the product 

becomes a 16-bit word. At some point, this may have to be rounded or 

truncated back to 8 bits for the next operation. This introduces slight discrepancies 

in the result which may be visible as lagged edges, color bleeding, 

etc. If successive truncations are performed during a sequence of 

image processing steps, the artifacts frequently become increasingly visible. 

Good practice calls for maintaining some or all of the “extra bits” 

throughout as much of the image processing as the facilities permit. 

Experience has shown that digital image processing provides the fewest 

distracting artifacts when the R', G', B' signals are first converted to the 

linear R, G, B. For complex image processing, and for critical results, the 

8-bit encoding may be replaced by 10 bits (or more if that can be accommodated). 

Image Quality Evaluation, Interval-Scaled – For comparisons of perceived 

image quality among significantly different systems, a requirement 

frequently encountered in electronic production, the technique of intervalscaling 

is recommended by most students of psycho-physics. Interval scaling 

gives some indication of the magnitude of preference for one system 

over another. Observers are asked to place a numerical value upon the 

perceived differences (either in total or with regard to a specified characteristic 

such as noise, resolution, color rendition, etc.). 

Image Quality Evaluation, Ordinal-Scaled – For comparisons of perceived 

image quality resulting from a controlled variant within a single system, 

a requirement encountered when fine-tuning a system, the technique 

of ordinal-scaling is frequently employed. The ordinal-scale indicates that 

one image is preferred over another. Observers are asked to evaluate perceived 

image quality on an established scale, usually of five levels, from 

excellent to unacceptable. Correlations among isolated tests are sometimes 

uncertain. 

Image Quality Evaluation, Ratio-Scaled – When images that differ significantly 

in creation, display, and content are being compared and intervalscaling 

becomes necessary, interpretation of the results become more and 

more complex as the number of observers is increased. Ratio-scaling provides 

a means for correlating multiple observations and multiple data 

sources. Observers are asked to assign a numerical value to perceived 

image quality (either in total or with regard to a specified characteristic 

such as noise, resolution, color rendition, etc.). They are also asked to 

identify numerical values for the best possible image, and the completely 

unacceptable image. Each is allowed to choose a numerical scale with 

which the observer feels most comfortable. The relationship between the 

value for the test image and the two extremes provides a useful ratio. 

Analyses involving comparisons among observers, comparisons with other 


systems, correlation of results obtained over periods of time, etc., are 

made by normalizing each observer’s scale (for example, best possible = 

100, completely unacceptable = 0). 

Image Quality, Objective – The evaluation obtained as a result of objective 

measurement of the quantitative image parameters (including tone 

scale, contrast, linearity, colorimetry, resolution, flicker, aliasing, motion 

artifacts, etc.) 

Image Quality, Perceived – The evaluation obtained as a result of subjective 

judgment of a displayed image by a human observer. 

Image Scaling – The full-screen video image must be reduced to fit into a 

graphics window (usually a fraction of the total computer display area), 

while at the same time maintaining a clear and complete image. To do this, 

it is important to remove or avoid visual artifacts and other “noise”such as 

degradation caused by pixel and line dropping, and interlacing problems 

from the scaling process. The challenges increase when dealing with moving 

images and the compression/decompression of large amounts of video 

data. 

Image Stabilization – A camcorder feature which takes out minor picture 

shakiness, either optically or electronically. 

Image Transform – First U.S. organization to modify television scanning 

for electronic cinematography, using 655 scanning lines per frame at 24 

frames per second. Also created ImageVision. 

ImageVision – An early HDEP scheme using 655 scanning lines per frame 

and 24 frames per second, with wide bandwidth video recording and a 

color subcarrier shifted to a higher frequency. Created and used by Image 

Transform for electronic cinematography. 

Imaging Device – The part of the video camera or camcorder that converts 

light into electrical signals. 

Immediate Addressing – In this mode of addressing, the operand contains 

the value to be operated on, and no address reference is required. 

Impact Strength – A measure of the work done in breaking a test sample 

of tape or base film by subjecting it to a sudden stress. 

Impairments – Defects introduced by an ATV scheme. 

Impedance – a) The opposition of a device to current flow. A combination 

of resistance, inductive reactance, and capacitive reactance. When no 

capacitance or inductance is present, impedance is the same as resistance. 

b) A resistance to signal flow. Microphones and audio mixers are 

rated for impedance. 

Impedance Matching – A video signal occupies a wide spectrum of frequencies, 

from nearly DC (0 Hz) to 6 MHz. If the output impedance of 

either the video source, cable, or input impedance of the receiving equipment 

are not properly matched, a series of problems may arise. Loss of 

high-frequency detail and color information as well as image instability, 

oscillations, snow, ghost images, and component heat-up may result. 

Proper connections and cable types provide correct impedances. See Load 

Resistance. 

Improved Definition Television (IDTV) – IDTV is different from HDTV in 

that it uses the standard transmitted (M) NTSC or (B, D, G, H, I) PAL signal. 

IDTV improves the display of these signals by doing further processing of

the signal before displaying it. IDTV offers picture quality substantially 

improved over conventional receivers, for signals originated in standard 

525-line or 625-line format, by processing that involves the use of field 

store and/or frame store (memory) techniques at the receiver. One example 

is the use of field or frame memory to implement de-interlacing at the 

receiver in order to reduce interline twitter compared to that of an interlaced 

display. IDTV techniques are implemented entirely at the receiver and 

involve no change to picture origination equipment and no change to emission 

standards. 

Impulsive Noise – a) The signal-to-impulsive noise ratio is the ratio, in 

decibels, of the nominal amplitude of the luminance signal (100 IRE units) 

to the peak-to-peak amplitude of the noise. b) High level, short duration 

unwanted signals that tend to cause a sparkling effect in the picture and/or 

a percussive effect in the sound. Impulsive noise is often caused by motorized 

appliances and tools. 

IMTC – International Multimedia Teleconferencing Consortium. 

IN – Interactive Network. 

INA – Interactive Network Adapter. 

Incident Light – Light arriving at the surface of an object. 

Incidental Carrier Phase Modulation (ICPM) – A distortion of the picture 

carrier phase caused by changes in either the chrominance or luminance 

video signal levels. This distortion is described in degrees using the 

following definition: 

ICPM = acrtan (quadrature amplitude/video amplitude) 

The picture effects of ICPM will depend on the type of demodulation being 

used to recover the baseband signal from the transmitted signal. ICPM 

shows up in synchronously demodulated signals as differential phase and 

many other types of distortions, but the baseband signal is generally not as 

seriously affected when envelope detection is used. The effects of ICPM 

are therefore rarely seen in the picture in home receivers, which typically 

use envelope detection. However ICPM may manifest itself as an audio 

buzz at the home receiver. In the intercarrier sound system, the picture 

carrier is mixed with the FM sound carrier to form the 4.5 MHz sound IF. 

Audio rate phase modulation in the picture carrier can therefore be transferred 

into the audio system and heard as a buzzing noise. An unmodulated 

5 to 10 stairstep signal or unmodulated ramp can be used to test for this 

distortion. 

In-Circuit Emulator (ICE) – Debugging aid that connects to the system 

under test by plugging into the microprocessor’s socket. This allows the 

ICE to gain full control over the system. Typical features include the ability 

to set breakpoints, single-step a program, examine and modify registers 

and memory, and divide memory and I/O between the system under test 

and the ICE system. 

Increment – Adding the value “one”to the contents of a register or memory 

location. 

Indeo – a) Intel’s series of compressor and decompressor technologies for 

digital video, capable of producing software-only video playback. b) The 

Indeo is a video compression/playback technique from Intel. Just like 

CinePak, playback of Indeo compressed video does not require any special 

hardware. The Indeo algorithm, which used techniques like vector quantiza- 



tion and run-length coding, is used by various other companies. A video file 

compressed with Indeo may be played on systems that support either Video 

for Windows or QuickTime. The new Indeo Video Interactive (IVI) software 

incorporates additional features to support interactive applications, and 

used a hybrid wavelet-based algorithm with bidirectional prediction. IVI may 

be played on systems that support Video for Windows, later also 

QuickTime, without dedicated hardware. Video encoded by IVI may be 

played at up to 640 x 480 pixels resolution and at up to 30 fps, depending 

on hardware configuration. 

Indeo Video Interactive – Intel’s latest compressor and decompressor for 

digital video, incorporating such special features as transparency, scalability, 

and local decode. See Indeo Video, Local Decode, Scalability, 

Transparency. 

Indeo-C – The Indeo-C was a compression algorithm in the Personal 

Conferencing Specification (PCS) from the Personal Conferencing Work 

Group (PCWG), which was an industry group led by Intel. Due to lacking 

support by the industry, the PCWG dropped the PCS, and has now consolidated 

with International Multimedia Teleconferencing Consortium (IMTC) 

which supports ITU-T Red. H.320 videoconferencing. The Indeo-C algorithm 

did not use vector quantizing, as in Indeo, or a hybrid wavelet-based algorithm, 

as in Indeo Video Interactive, but used a transform coding called 

Fast Slant Transform (FST). An FST calculates frequency coefficients of picture 

blocks, like the DCT used in MPEG, but requires less computational 

power. Both intra-frame and inter-frame coding with motion estimation was 

applied in Indeo-C and finally, run-length and Huffman coding. 

Independent Television – Television stations that are not affiliated with 

networks and that do not use the networks as a primary source of their 

programming. 

Index Register – Contains address information used for indexed 

addressing. 

Indexed Addressing – Mode in which the actual address is obtained by 

adding a displacement to a base address. 

Indexing – Creation of a data index to speed up search and retrieval. 

Indirect Addressing – Addressing a memory location that contains the 

address of data rather than the data itself. 

Industrial/Professional – The grade of audio and video equipment that 

falls between consumer (low end) and broadcast quality. Industrial/professional 

equipment is characterized by its durability, serviceability, and moreprofessional 

end-result. 

Inertia Idler – A rotating guide attached to a heavy flywheel to reduce the 

effect of varying supply reel friction on tape speed. 

Information Services – Broad term used to describe full range of audio, 

video, and data transmission services that can be transmitted over the air 

or by cable. 

Initialization – Setting a system to a known state. 

Initialize – a) An auto sequence that causes a machine upon power up to 

arrive at a default condition. b) Record some data on a disk to allow its 

segments to be recognized by a controller. 

In-Point – a) Beginning of an edit. b) The first frame that is recorded. 




Input – The terminals, jack, or receptacle provided for the introduction of 

an electrical signal or electric power into a device or system. 

Input Converter – See Down Converter. 

Input Port – Circuit that connects signals from external devices as inputs 

to the microprocessor system. 

Input/Output (I/O) – a) Typically refers to sending information or data 

signals to and from devices. b) Lines or devices used to transfer information 

outside the system. 

INRS – French acronym for the National Scientific Research Institute of the 

University of Quebec. INRS-Telecommunications shares facilities with Bell 

Northern Research, sort of Canada’s Bell Labs, and has simulated both 

advanced encoders and ATV schemes on its computer simulation system. 

Insert – a) The video that fills a key. Also used to describe the key itself. 

Insert for most keys is “self,”that is, a key that is filled with the same 

video that cuts the hole. Ampex switchers also allow “matte”fill with an 

internally generated color and “bus fill”where any bus source may be 

selected to fill the key. b) An edit mode meaning to record a new video 

over a certain section of an existing video where the entry and exit are 

both defined and no new time code of control track is recorded. 

Insert Editing – The process of television post-production that combines 

audio and video signals on an existing control track. 

Insertion Gain – In a CAV system, this refers to the overall amplitude of 

all three signals that make up the CAV signal and is measured as the 

peak-to-peak voltages of the three video signals (usually including sync on 

luminance levels). 

Insertion Gain Measurement – Measurement of peak-to-peak amplitude 

values. 

Insertion Loss – The decrease in level which occurs when a piece of 

equipment is inserted into a circuit so that the signal must flow through it. 

In-Service (VITS or ITS Mode Testing) – 

Program 

IN 

Test Signal 

Inserter 

(inserts test signals in 

vertical blanking interval) 

Instance – A clone of an object. If you modify the original, all the instance 

objects are likewise modified. 

Instantaneous Value – The amplitude of a waveform at any one instant 

of time. 

Institute of Electrical and Electronics Engineers – The Institute of 

Electrical and Electronics Engineers (IEEE) is the world’s largest technical 

professional society. Founded in 1884 by a handful of practitioners of the 

new electrical engineering discipline, today’s Institute includes 46,000 students 

within a total membership of nearly 320,000 members who conduct 


TV System 

Test Signal 

Monitoring 

Equipment 

Program 

OUT 

(with line select feature) 

and participate in its activities in 150 countries. The men and women of 

the IEEE are the technical and scientific professionals making the revolutionary 

engineering advances which are reshaping our world today. And 

today’s students are the future of the profession. The technical objectives 

of the IEEE focus on advancing the theory and practice of electrical, electronics, 

and computer engineering and computer science. To realize these 

objectives, the IEEE sponsors nearly 800 Student Branches worldwide, as 

well as scholarships and awareness programs, technical conferences, symposia, 

and local meetings; publishes nearly 25% of the world’s technical 

papers in electrical, electronics, and computer engineering; and provides 

educational programs to keep its members’ knowledge and expertise stateof-the-art. 

The main IEEE information system is in Piscataway, New Jersey, 

USA. 

Instruction – Single command within a program. Instructions may be 

arithmetic or logical, may operate on registers, memory, or I/O devices, or 

may specify control operations. A sequence of instructions is a program. 

Instruction Cycle – All of the machine states necessary to fully execute 

an instruction. 

Instruction Decoder – Unit that interprets the program instructions into 

control signals for the rest of the system. 

Instruction Register – Register inside the microprocessor that contains 

the opcode for the instruction being executed. 

Instruction Set – Total group of instructions that can be executed by a 

given microprocessor. Must be supplied to the user to provide the basic 

information necessary to assemble a program. 

Integrated Services Digital Networks – ISDN is a CCITT term for a relatively 

new telecommunications service package. ISDN is basically the telephone 

network turned all-digital end to end, using existing switches and 

wiring (for the most part) upgraded so that the basic call is a 64 kbps endto-end 

channel, with bit manipulation as needed. Packet and maybe frame 

modes are thrown in for good measure, too, in some places. It’s offered by 

local telephone companies, but most readily in Australia, France, Japan, 

and Singapore, with the UK and Germany somewhat behind, and USA availability 

rather spotty. A Basic Rate Interface (BRI) is two 64K bearer (B) 

channels and a single delta (D) channel. The B channels are used for voice 

or data, and the D channel is used for signaling and/or X.25 packet networking. 

This is the variety most likely to be found in residential service. 

Another flavor of ISDN is Primary Rate Interface (PRI). Inside the US, this 

consists of 24 channels, usually divided into 23 B channels and 1 D channel, 

and runs over the same physical interface as T1. Outside of the US 

then PRI has 31 user channels, usually divided into 30 B channels and 1 D 

channel. It is typically used for connections such as one between a PBX 

and a CO or IXC. 

Intensity – Synonymous with luminance. 

Interactive Videodisc – Interactive videodisc is another video-related 

technology, using an analog approach. It has been available since the early 

1980s, and is supplied in the U.S. primarily by Pioneer, Sony, and IBM. 

Intercarrier Sound – A method used to recover audio information in the 

NTSC system. Sound is separated from video by beating the sound carrier 

against the video carrier, producing a 4.5 MHz IF which contains the sound 

information.

Intercast – a) An Intel developed process which allows Web pages to be 

sent in the vertical blanking interval of a (M) NTSC video signal. The 

process is based on NABTS. b) Intercast technology allows television 

broadcasters to create new interactive content-text, graphics, video, or 

data around their existing programming and deliver this programming 

simultaneously with their TV signal to PCs equipped with Intercast technology. 

Intercast content is created with HTML which means that the interactive 

content of broadcast with the TV signal appears to the user as Web 

pages, exactly as if they were using the actual World Wide Web. These 

broadcast Web pages can also contain imbedded hyperlinks to related 

information on the actual Internet. 

Interchange – Transfer of information between two processes. 

Interchannel Timing Error – This error occurs in CAV three-wire or twowire 

interconnect systems when a timing difference develops between signals 

being transmitted through the wires. The error manifests itself as distortions 

around vertical lines, edges, and in color distortions. 

Inter-Coding – Compression that uses redundancy between successive 

pictures; also known as Temporal Coding. 

Interconnect Format – See the Format definition. 

Interconnect Standard – See the Standard definition. 

Interface – Indicates a boundary between adjacent components, circuits, 

or systems that enables the devices to exchange information. Also used to 

describe the circuit that enables the microprocessor to communicate with a 

peripheral device. 

Interference – a) In a signal transmission path, extraneous energy which 

tends to interfere with the reception of the desired signals. b) Defect of 

signal reproduction caused by a combination of two or more signals that 

must be separated, whether all are desired or not. 

Inter-Frame Coding – a) Coding techniques which involve separating the 

signal into segments which have changed significantly from the previous 

frame and segments which have not changed. b) Data reduction based on 

coding the differences between a prediction of the data and the actual 

data. Motion compensated prediction is typically used, based on reference 

frames in the past and the future. 

Interframe Compression – A form of compression in which the codec 

compresses the data within one frame relative to others. These relative 

frames are called delta frames. See Delta Frame, Key Frame. Compare 

Intraframe Compression. 

Interframe Compression Algorithms – MPEG is one of many interframe 

algorithms that use certain key frames in a motion-prediction, interpolation 

system. 

Interlace – a) Technique for increasing picture repetition rate without 

increasing base bandwidth by dividing a frame into sequential fields. When 

first introduced, it also had the characteristic of making the scanning 

structure much less visible. NTSC uses 2:1 interlace (two fields per frame). 

b) A process in which the picture is split into two fields by sending all the 

odd-numbered lines to field one and all the even-numbered lines to field 

two. This was necessary when there was not enough bandwidth to send a 

complete frame fast enough to create a non-flickering image. 



Interlace Artifacts – Picture defects caused by interlace. These include 

twitter, line crawl, loss of resolution, and motion artifacts. In addition to 

causing artifacts, interlaced scanning reduces the self-sharpening effect of 

visible scanning lines and makes vertical image enhancement more difficult 

to perform. 

Interlace Coefficient – A number describing the loss of vertical resolution 

due to interlace, in addition to any other loss. It is sometimes confused 

with the Kell factor. 

Interlace Ratio – Alternate raster lines are scanned producing an odd 

field (odd-numbered lines) and an even field (even-numbered lines). An 

interlace of 1:1 implies vertically adjacent lines comprise the field. 

Interlaced – Display system in which two interleaved fields are used to 

create one frame. The number of field lines is one-half of the number of 

frame lines. NTSC (M) systems have 262.5 lines per field. PAL (B, D, G, H, 

I) scan system have 312.5 lines per field. Each field is drawn on the screen 

consecutively – first one field, then the other. The field scanned first is 

called the odd field, the field scanned second is called the even field. The 

interlaced scanning system is used to prevent screen flicker. If frames were 

scanned on the screen without interlacing fields, the light level created by 

the first frame would decrease noticeably before the next frame could be 

scanned. Interlacing the fields allows the light level of the screen to be 

held more constant and thus prevent flicker. 

Interlaced Carrier – A television subcarrier at a frequency that is an odd 

multiple of one half the line rate (for example, the NTSC color subcarrier). 

Such subcarriers fall onto a line in the spatio-temporal spectrum that is 

simultaneously high in vertical detail and in temporal detail, and is therefore 

not likely to be objectionably visible under normal viewing conditions. 

Interlaced Scanning – A scanning process in which each adjacent line 

belongs to the alternate field. See Interlaced. 

Interlaced Sequence – Sequence of pictures that can be either field picture 

or frame pictures. 

Interlaced Video Mode – A mode in which the video raster is scanned 

over the face of the CRT by the electron gun, tracing alternate scan lines in 

successive refresh cycles. The quality of interlaced video is lower than 

sequentially scanned (non-interlaced) video because only half of the lines 

are refreshed at a time and interlaced video scans at a lower rate than 

non-interlaced video allowing for the manufacture of less expensive video 

monitors. NTSC video (standard TV) uses interlace video. A display system 

where the even scan lines are refreshed in one vertical cycle (field), and 

the odd scan lines are refreshed in another vertical cycle. The advantage is 

that the bandwidth is roughly half that required for a non-interlaced system 

of the same resolution. This results in less costly hardware. It also may 

make it possible to display a resolution that would otherwise be impossible 

on given hardware, The disadvantage of an interlaced system is flicker, 

especially when displaying objects that are only a single scan line high. 

Interlacing – The process of drawing a frame by alternately drawing the 

rows of each field, creating the illusion that the image is being redrawn 

twice as often as it actually is. See Field. 

Interleaver – The RS-protected transport packets are reshuffled byte by 

byte by the 12-channel interleaver. Due to this reshuffle, what were neighboring 

bytes are now separated by at least one protected transport packet: 




i.e., at least 204 bytes apart from each other. The purpose of this is the 

burst error control for defective data blocks. 

Interleaving – A technique used with error correction that breaks up burst 

errors into many smaller errors. 

Interline Flicker – See Twitter. 

Intermodulation Distortion – Signal nonlinearity characterized by the 

appearance of frequencies in the output equal to the sums and differences 

of integral multiples of the component frequencies present in the input signal. 

Harmonics are usually not included as part of the intermodulation 

distortion. 

Internal Drive – A drive that fits inside the workstation and connects to 

an internal port; it is never connected with a cable to a visible external 

port. An internal drive is occasionally referred to as a front-loading drive. 

International Organization for Standardization (ISO) – A Geneva 

based organization for many of the national standardization bodies. 

Together with the International Electrotechnical Commission, IEC, ISO concentrates 

its efforts on harmonizing national standards all over the world. 

The results of these activities are published as ISO standards. Among them 

are, for instance, the metric system of units, international stationery sizes, 

all kinds of bolts and nuts, rules for technical drawings, electrical connectors, 

security regulations, computer protocols, file formats, bicycle components, 

ID cards, programming languages, International Standard Book 

Numbers (ISBN). Over 10,000 ISO standards have been published so far 

and you surely get in contact with a lot of things each day that conform to 

ISO standards you never heard of. By the way, ISO is not an acronym for 

the organization in any language. It’s a wordplay based on the 

English/French initials and the Greek-derived prefix iso- meaning “same.” 

Within ISO, ISO/IEC Joint Technical Committee 1 (JTC1) deals with information 

technology. 

International Thomson – Name used by France’s Thomson group for 

some recently acquired holdings outside of France. International Thomson 

is a strong proponent of progressive-scan ATV and has proposed two such 

schemes for NTSC countries, both of which would offer a 16:9 aspect ratio 

and 60 frames per second. One would have 900 scanning lines (864 

active), matching the number of scanning lines in International Thomson’s 

proposal for non-NTSC countries. The other would have 750 scanning lines 

(728 active), matching the digitization rates in the non-NTSC proposal. 

Interoperability – The capability of providing useful and cost-effective 

interchange of electronic image, audio, and associated data among different 

signal formats, among different transmission media, among different 

applications, among different industries, among different performance 

levels. 

Interpolation – In digital video, the creation of new pixels in the image by 

some method of mathematically manipulating the values of neighboring 

pixels. This is necessary when an image is digitally altered, such as when 

the image is expanded or compressed. 

Interpolation (Line) – In television standards conversion, the technique 

for adjusting the number of lines in a 625-line television system to a 525line 

system (and vice versa) without impairing the picture quality. 


Interpolation (Movement) – A technique used in standards conversion to 

compensate for the degrading effects of different field frequencies on pictures 

which contain movement. Different approximate proportions of successive 

input fields are used in each output field. 

Interpolation (Spatial) – When a digital image is repositioned or resized, 

different pixels are usually required from those in the original image. 

Simply replicating or removing pixels causes unwanted artifacts. With interpolation, 

the new pixels are calculated by making suitably weighted averages 

of adjacent pixels, giving more transparent results. The quality 

depends on the techniques used and the area of original picture, expressed 

as a number of pixels or points. Compare with Interpolation (Temporal). 

Interpolation (Temporal) – Interpolation between the same point in 

space on successive frames. It can be used to provide motion smoothing 

and is extensively used in standard converters to reduce the defects 

caused by the 50/60 Hz field rate difference. This technique can also be 

adapted to create frame averaging for special effects. 

Interrupt – Involves suspension of the normal program that the microprocessor 

is executing in order to handle a sudden request for service 

(interrupt). The processor then jumps from the program it was executing to 

the interrupt service routine. When the interrupt service routine is completed, 

control returns to the interrupted program. 

Interrupt Mask – Register that has one bit to control each interrupt. Used 

to selectively disable specific interrupts. 

Interrupt Service Routine – Program that is executed when an interrupt 

occurs. 

Interrupt Vectoring – Providing a device ID number or an actual branching 

address in response to the interrupt acknowledge signal. Allows each 

interrupt to automatically be serviced by a different routine. 

Interval Timer – Programmable device used to perform timing, counting, 

or delay functions. Usually treated as a peripheral. 

Intra-Coded Pictures (I-Pictures or I-Frames) – Pictures that are 

coded by using information present only in the picture itself and without 

depending on information from other pictures. I-pictures provide a mechanism 

for random access into the compressed video data. I-pictures employ 

transform coding of the pixel blocks and provide only moderate 

compression. 

Intra-Coding – Compression that works entirely within one picture: also 

known as Spatial Coding. 

Intra-Frame Coding – Video coding within a frame of a video signal. 

Intraframe Compression – A form of compression in which the codec 

compresses the data within one frame relative only to itself. Key frames 

are compressed with intraframe compression because they must reconstruct 

an entire image without reference to other frames. See Delta Frame, 

Key Frame. Compare Interframe Compression. 

Intraframe Compression Algorithm – A still image or photo video compression 

standard. JPEG compression ratios vary from 20:1 to 40:1 with a 

lossless ratio of 5:1. JPEG is a symmetrical standard inasmuch as it takes 

the same amount of time to decompress as it does to compress video. 

JPEG works best with smooth transitions and little motion.

Intrinsic Coercive Force – The magnetizing field strength needed to 

reduce flux density from saturation to zero. 

Intrinsic Coercivity – The maximum value of the intrinsic coercive force. 

The intrinsic coercivity is a basic magnetic parameter for the material and 

requires complete saturation of the sample for its measurement as does 

the saturation flux density. 

Intrinsic Flux – In a uniformly magnetized sample of magnetic material, 

the product of the intrinsic flux density and the cross-sectional area. 

Intrinsic Flux Density – In a sample of magnetic material for a given 

value of the magnetizing field strength, the excess of the normal flux density 

over the flux density in vacuum. 

Intrinsic Hysteresis Loop – Graph of magnetic flux (B) plotted against 

the magnetizing force (H) producing it. The value of B when H has dropped 

to zero is the residual magnetism, and the reverse force needed to reduce 

B to zero is known as the coercivity. Units used are: Magnetizing Force (H) 

in oersteds and Flux Density (B) in gauss. Coercivity is measured in 

oersteds. 

INTSC (Improved NTSC) – A term rarely used to describe ATV schemes 

incorporating any combination of techniques. 

Techniques to Improve NTSC Compatibility 

A.Monochrome and Color 

1.Sampling, Aperture, and Interlace Problems 

• Progressive 

• High Line Rate Display 

• Progressive Camera and Prefiltering 

• High Line Rate Camera and Prefiltering 

• Image Enhancement at the Camera 

• Image Enhancement at the Receiver 

2.Transmission Problems 

• Ghost Elimination 

• Noise Reduction 

• Improved Filter Design and Adjustment 

3.Changing Equipment Problems 

• Gamma Correction 

• Adaptive Emphasis 

• Rigid Adherence to Standards 

B.Color Problems 

1.Improved Decoder Filtering 

2.Prefiltering 

3.Full Detail Decoders 

4.Luminance Detail Derived from Pre-Encoded Chroma 

Invar – An expensive, brittle metal used to make the shadow mask in a 

direct-view color picture tube. Incorporating it allows higher picture contrast 

levels from the tube without incurring long-term damage to the shadow 

mask itself. It allows the set manufacturer to offer higher contrast levels. 

Since the phosphors in the tube reach the point of blooming well 

before the need for the Invar mask, anyone properly setting the contrast 

level for no blooming in the picture won’t ever need the features of the 

Invar mask. The high contrast levels permitted by the Invar mask will eventually 

burn the phosphors. 

Inverse Nyquist Filter – A filter that is a complement of the filter used to 

reduce interference in the IF section of a television set. 



Inverted Key – We think of a normal key as, for example, letters superimposed 

over a background. When this key is inverted, the background 

appears inside the key; it appears we are looking through the cut-out key 

and seeing the background. The key insert video appears outside the key. 

IO (Image Orthicon) – The picture-forming tube in a TV camera. 

Ion – A charged atom, usually an atom of residual gas in an electron tube. 

Ion Spot – A spot on the fluorescent surface of a cathode ray tube, which 

is somewhat darker than the surrounding area because of bombardment by 

negative ions which reduce the phosphor sensitivity. 

Ion Trap – An arrangement of magnetic fields and apertures which will 

allow an electron beam to pass through but will obstruct the passage of 

ions. 

IOR – Interoperable Object Reference. 

IP (Internet Protocol) – The network layer protocol for the Internet protocol 

suite. 

IP Address – The number that uniquely identifies each host (system) on 

the network. 

I-Picture (Intra-Coded Picture) – One of three types of digital pictures 

in an MPEG data stream. An I-picture is not predictive and is essentially a 

snapshot picture. This type of picture generally has the most data of any of 

the picture types. A picture coded using information only from itself. For 

that reason, an I-picture can be decoded separately. 

IPCP – Internet Protocol Control Protocol. 

IPS – Inches Per Second. 

IQ – In-Phase/Quadrature Components. 

IQTV (Improved Quality Television) – A rarely used term for IDTV and 

INTSC. 

IRD (Integrated Receiver Decoder) – a) A combined RF receiver and 

MPEG decoder that is used to adapt a TV set to digital transmissions. b) An 

IRD with digital interface has the ability to decode Partial Transport Streams 

(TS) received from a digital interface connected to digital bitstream storage 

device such as a digital VCR, in addition to providing the functionality of a 

Baseline IRD. 

IrDA – Infrared Data Association. 

IRE (Institute of Radio Engineers) – The composite analog television 

signal’s amplitude can be described in volts or IRE units with 140 IRE representing 

a full amplitude composite analog signal. The 0 IRE point is at 

blanking level, with sync tip at –40 IRE and white extending to +100 IRE In 

the studio, the composite analog video signal is typically 1 volt in amplitude. 

Thus in the studio, 1 IRE is equal to 1/140 of a volt or 7.14 mV. IRE 

stands for Institute of Radio Engineers, the organization which defined the 

unit. 

IRE Roll-Off – The IRE standard oscilloscope frequency response characteristic 

for measurement of level. This characteristic is such that at 2 MHz 

the response is approximately 3.5 dB below that in the flat (low frequency) 

portion of the spectrum, and cuts off slowly. 




IRE Scale – An oscilloscope scale in keeping with IRE Standard 50, IRE 

23.S1, and the recommendations of the Joint Committee of TV 

Broadcasters and Manufacturers for Coordination of Video Levels. 

IRE Units – a) A linear scale for measuring the relative amplitudes of the 

various components of a television signal. Reference white is assigned a 

value of 100, blanking a value of 0. b) The values for NTSC composite and 

for SMPTE 240M are shown in the following table. One IRE unit corresponds 

to 7-1/7 mV in CCIR System M/NTSC and to 7.0 mV in all other 

systems. Measurement procedure developed by the Institute of Radio 

Engineers, the predecessor to the IEEE. 

RF Video Baseband 

Modulation (1) Millivolts (2) 

IRE Units % M/NTSC SMPTE 24 

Zero Carrier 120 0 – – 

White Clip (3) 105-110 6.2-9.4 – – 

Reference White (4) 100 12.5 715 (5) 700 

Reference Black 6) 7.5 70.3 54 0 

Blanking 0 75 0 0 

Sync Peaks –40 100 –286 (5) ±350 

(Max Carrier) 

(1) From Benson: Television Engineering Handbook. 

(2) Video waveform specified in ANSI/EIA/TIA 25D-C-1989.It becomes an operational 

requirement to map the scene luminance within the video waveform 

specifications so that subjectively acceptable image recreation can be 

obtained on display. 

(3) Typical (arbitrary) values to limit overload of analog signals, or to define 

maximum digital equivalent. 

(4) Under scene illumination, the light from a nonselective diffuse reflector 

(white card) whose reflectance factor is 90% compared to a “perfect reflector” 

(prepared magnesium oxide = 98%). 

(5) Frequently indicated as +700 and –300, respectively. 

(6) Specified for NTSC in ANSI/EIA/TIA 250-C-1989.Many other systems place 

reference black at blanking level. 

Iredale, Richard – Creator of the HD-NTSC ATV scheme and the HD-PRO 

HDEP scheme. 

IRIG (Inter-Range Instrumentation Group) – Has recently been 

renamed “Range Control Council.” 

IRIS – Any graphics workstation manufactured by Silicon Graphics, Inc. 

Iris – The video camera’s lens opening which regulates the amount of light 

entering a camera. 

IRIX – Silicon Graphics, Inc.’s version of the UNIX operating system. See 

also System Software. 

Iron Oxide/Gamma Ferric Oxide – The most popular oxide particle used 

as a magnetic recording medium produced from an oxide of pure iron. 

IRT (Institut für Rundfunktechnik) – IRT is the research and development 

branch of the public broadcasters in Germany (the ARD and ZDF), 

Austria (the ORF) and in Switzerland (the SRG). Situated in Munich, 

Germany, the IRT participates in both national and international research 

projects, and is highly involved in broadcasting system development. 

Specifically, IRT has participated in the development of digital audio bit rate 


reduction, and is one of the three licensors of MPEG Layer II of which the 

IRT conducts conformance tests. 

IS – International Standard. 

IS&T – Society for Imaging Science and Technology. 

ISA (Industry Standard Architecture) – Originally designed around the 

16-bit 286 microprocessor and called the AT bus, the ISA bus has 24 

address and 16 data lines, sufficient to handle 16 megabyte memory I/O 

addresses. The ISA bus is limited to a slow 8 MHz clock speed and for this 

reason, faster peripherals and memory left the ISA bus behind soon after 

its development. Unlike the earlier 8-bit PC/XT bus, the ISA bus includes 

two connectors. In addition to the single, 62-pin, 8-bit PC/XT bus connector, 

the ISA bus includes a second connector with four additional address 

and eight additional data lines, interrupt, and DMA control lines. Although 

IBM documented every pin on the ISA bus, they never published strict timing 

specifications to signals on the bus. As a result, ISA bus system developers 

designing products for many platforms had to guess at timing. 

Problems developed as a result of holding the ISA bus to 8 MHz for backward 

compatibility. Some anxious manufacturers pushed the system speed 

causing products with marginal operations characteristics, especially when 

extra memory was added to high-speed PCs. Since the IEEE ISA standard 

of 1987, the bus signals have remained unchanged. In 1993, Intel and 

Microsoft announced a joint development, Plug and Play ISA, a method for 

making expansion boards work with the ISA bus, eliminating the need for 

DIP switch settings, jumpers, interrupts, DMA channels, ports, and ROM 

ranges. The Plug and Play card tells the host computer what resources it 

requires. This requires a large software-based isolation protocol which 

keeps an expansion board switched off until it can be addressed, allowing 

one card to be polled at a time because slot-specific-address enable signals 

for expansion cards are not part of the ISA specification. In 1987, the 

ISA bus made way for the IBM PS/2 “clone-killer”computer “Micro 

Channel”bus however, the clone makers initially ignored the PS/2 and 

Micro Channel. 

ISA Transfer – One of the advantages of an ISA transfer is that it allows 

the user to process images as they go through the processor. However, its 

utility is limited by its low bandwidth, Even under ideal conditions, the ISA 

transfer requires three to five BCLK cycles at 8 MHz to transfer a single 

pixel. This represents a severe system throughput penalty; a large percentage 

of the available (and already limited) bandwidth is consumed by the 

transfer. 

ISDB (Integrated Services Digital Broadcasting) – An NHK-suggested 

broadcast equivalent to ISDN. 

ISDN – See Integrated Services Digital Network. 

ISI – Inter Symbol Interference. 

ISO – See International Organization for Standardization. 

ISO Reel – Multiple reels of tape of the same subject recorded simultaneously 

from different cameras on different VTRs. 

Isokey – See External Key. 

Isolated Key – A key where the “hole cutting”or key video is different 

from the “key filling”or insert video. This is most commonly used with 

character generators that provide these two outputs, and allows the char-

acter generator to create a key border that is wider and cleaner than internally 

bordered keys. Such signals may also come from a color camera that 

provides its own keying output or even a monochrome camera looking at 

an art card. An isolated key is always a luminance key, although composite 

chroma keys may be done with an isolated key source, ignoring the isolated 

input. AVC series switchers can defeat isolated inputs to standard type 

keys by turning key borders on. Also referred to as a Processed External 

Key. 

Isoparameters – The curves along a surface resulting from setting u or v 

to a constant value. 

ISP – Internet Service Provider. 

ISVR Pro – See Smart Video Recorder Pro. 

IT – Information Technology. 

Iterative – Procedure or process that repeatedly executes a series of 

operations until some condition is satisfied. Usually implemented by a loop 

in a program. 

ITFS – Instructional Television Fixed Service. 

ITS (Insertion Test Signal) – A test signal which is inserted in one line of 

the vertical interval to facilitate in-service testing. 

ITSTC – Information Technology Steering Committee. 

ITTF – Information Technology Task Force. 

ITU (International Telecommunications Union) – The United Nations 

specialized agency dealing with telecommunications. At present, there are 

164 member countries. One of its bodies is the International Telegraph and 

Telephone Consultative Committee, CCITT. A Plenary Assembly of the 

CCITT, which takes place every few years, draws up a list of “Questions” 

about possible improvements in international electronic communication. In 

Study Groups, experts from different countries develop “Recommendations” 

which are published after they have been adopted. Especially relevant to 

computing are the V series of recommendations on modems (e.g. V.32, 

V.42), the X series on data networks and OSI (e.g., X.25, X.400), the I and 

Q series that define ISDN, the Z series that defines specification and programming 

languages (SDL, CHILL), the T series on text communication 



(teletext, fax, videotext, ODA), and the H series on digital sound and video 

encoding. 

ITU-R (International Telecommunication Union, 

Radiocommunication Sector) – Replaces the CCIR. 

ITU-R.601 – See ITU-R BT.601.2. 

ITU-R.624 – ITU standard that defines PAL, NTSC, and SECAM. 

ITU-R BT.601-2 – a) Standard developed by the International Radio 

Consultative Committee for the digitization of color video signals. ITU-R 

BT.601 deals with the conversion from component RGB to YCbCr, the digital 

filters used for limiting the bandwidth, the sample rate (defined as 

13.5 MHz), and the horizontal resolution (720 active samples). 

b) International standard for component digital television from which was 

derived SMPTE 125M (was RP-125) and EBU 3246E standards. CCIR 

defines the sampling systems, matrix values, and filter characteristics for 

both Y, B-Y, R-Y and RGB component digital television. 

ITU-R BT.653 – Standard that defines teletext systems used around the 

world. 

ITU-R BT.656 – The physical parallel and serial interconnect scheme for 

ITU-R BT.601-2. ITU-R BT.656 defines the parallel connector pinouts as 

well as the blanking, sync, and multiplexing schemes used in both parallel 

and serial interfaces. 

ITU-R BT.709-3 – Part II of the recommendation describes the unique 

HD-CIF standard of 1080 lines by 1920 samples/line interlace and progressively 

scanned with an aspect ratio of 16:9 at both 50 Hz and 60 Hz 

field and frame rates for high definition program production and exchange. 

ITU-T – International Telecommunication Union, Telecommunication 

Standardization Sector. 

ITVA – International Television Association. 

IVUE – A file format associated with FITS technology that enables images 

to be opened and displayed in seconds by showing only as much data on 

the screen as is implied by the screen size and zoom factor. 

IWU – Inter-Working Unit. 




J 

J.41 – A recommendation from the ITU-T covering high-quality coding of 

audio material at 384 kbit/s. In the same family, we find the J.42, the 

J.43, and the J.44 recommendations that define the coding of analog 

“medium quality”sound at 384 kbit/s, “high quality”sound at 320 kbit/s, 

and “medium quality”sound at 320 kbit/s, respectively. 

J.81 – This ITU-T recommendation is identical to the ETSI standard ETS 

300 174 for video broadcast transmission at 34 Mbit/s. 

Jack – Receptacle for a plug connector leading to the input or output circuit 

of a tape recorder or other piece of equipment. A jack matches a specific 

plug. 

Jaggies – a) Slang for the stair-step aliasing that appears on diagonal 

lines. Caused by insufficient filtering, violation of the Nyquist Theory, and/or 

poor interpolation. b) A term for the jagged visual appearance of lines and 

shapes in raster pictures that results from producing graphics on a grid 

format. This effect can be reduced by increasing the sample rate in scan 

conversion. 

Jam Sync – Process of locking a time-code generator to existing recorded 

time code on a tape in order to recreate or extend the time code. This may 

be necessary because, beyond a given point on tape, time code may be 

non-existent or of poor quality. 

Japan Broadcasting Corporation – See NHK. 

JBIG – See Joint Bi-Level Image Experts Group. 

JBOD (Just a Bunch of Disks) – A collection of optical/magnetic disks 

used for storing data. 

JCIC (Joint Committee for Inter-Society Coordination) – A group 

comprised of the EIA, the IEEE, the NAB, the NCTA, and the SMPTE. The 

JCIC created the ATSC in 1982 to handle all of the new advances in TV, 

including HDTV. The ATSC has since grown to 52 member and observer 

organizations. 

JEC – Joint Engineering Committee of EIA and NCTA. 

Jitter – a) An undesirable random signal variation with respect to time. A 

tendency toward lack of synchronization of the picture. It may refer to individual 

lines in the picture or to the entire field of view. b) A rapid, small 

shift in image position characteristic of film projection. Projection jitter can 

reduce the apparent resolution of film. 

Jitter Amplitude – The variation in phase of the bit rate clock expressed 

as a percent of the bit period. 

Jitter Rate – The rate of change of the jitter amplitude expressed as a 

frequency in Hertz. 

JND (Just Noticeable Difference) – A measure of the minimum perceptible 

change in quality. A one JND change is accurately detected 75 percent 

of the time; a three JND change is accurately detected 99 percent of 

the time. There is a large number of JNDs of difference between NTSC as 

it is now received in U.S. homes and HDEP. This difference decreases in 

ATV systems in a hierarchical order. Some feel that a large number of JNDs 

will be necessary for consumers to purchase new TV sets. 


Jog/Shuttle Wheel – A dial on many video decks, VCRs and editing control 

units that controls jog and shuttle functions. 

Jogging – Single-frame forward or backward movement of video tape. 

Joint Bi-Level Image Experts Group (JBIG) – A lossless bi-level (black 

and white) image compression technique. JBIG is intended to replace G3 

fax algorithms. The JBIG technique can be used on either gray-scale or 

color images. Some of the applied techniques have a strong resemblance 

with the JPEG standard. Commercially available implementations of JBIT 

have been scarce, but some find use in remote printing of newspapers. 

Joint Photographic Expert Group (JPEG) – Compression technique for 

still images, such as photographs, a single video frame, etc. JPEG can be 

used to compress motion video. However, it is not as efficient as MPEG 

which has been optimized for motion video compression applications. 

Jot – The text editor that comes as a standard utility on every IRIS. 

Joystick – Affecting control over X, Y, and Z parameters. Typical uses are 

switcher pattern positioner, ADO positioner/controller, ACE switcher preview 

controller. See Positioner. 

JPEG – See Joint Photographic Experts Group. 

JPEG-1 – ISO/IEC DIS 10918-1 begins with a digital image in the format Y, 

CB, CR (such as defined in CCIR 601-2) and provides several levels of 

compression. Predictive coding and transforms are employed, with the 

higher compression ratios selectively recognizing the decrease in human 

visual acuity with increasing spatial frequencies. It is optimized for about 

15:1 compression. As increased data storage and increased processing 

capabilities are becoming available, there is exploration of adapting JPEG-1 

for application to successive frames in real time; i.e., full-motion JPEG. 

JPEG-2 – ISO/IEC CD 11172 describes procedures for compliance testing 

in applications of JPEG-1. 

JPG – Filename extension for graphic image files stored using JPEG 

compression. 

JTC – Joint Technical Committee. 

Judder – a) Jerkiness of motion associated with presentation rates below 

the fusion frequency. b) A temporal artifact associated with moving images 

when the image is sampled at one frame rate and converted to a different 

frame rate for display. As a result, motion vectors in the display may 

appear to represent discontinuously varying velocities. The subjective effect 

of the artifact becomes more obvious when the frame-rate conversions are 

made by simple deletions or repetitions of selected frames (or fields). It 

may become less obvious when interpolated frames (or fields) are generated 

by employing predictive algorithms. 

Jump – Instruction that results in a change of sequence. 

Jump Cut – A mismatched edit that creates a visual disturbance when 

replayed. Usually occurs when cutting between two images which share an 

identical subject but place the subject at different positions in the frame.

K 

K – Symbol for 1000 (103 ). When referring to bits or words, K = 1024 (210 ). 

K Factor Ratings – The K Factor rating system maps linear distortions of 

2T pulses and line bars onto subjectively determined scales of picture 

quality. The various distortions are weighted in terms of impairment to the 

picture. 

W 2 

B 2 

Grat. B 

K 2T 

SD 5% 

2% 

The usual K Factor measurements are Kpulse/bar ,K2T or Kpulse (2T pulse 

response), Kbar and sometimes K60Hz . The overall K Factor rating is the 

largest value obtained from all of these measurements. Special graticules 

can be used to obtain the K Factor number or it can be calculated from the 

appropriate formula. All types of linear distortions affect the K Factor rating. 

Picture effects may include any of the short time, line time, field time, 

and long time picture distortions. Any signal containing the 2T pulse and 

an 18 µsec bar can be used to measure Kpulse/bar ,K2T (Kpulse ), or Kbar . A field 

rate square wave must be used to measure K60Hz . The FCC composite test 

signal contains these signal components. See the discussion on Pulse to 

Bar Ratios. 

K2T or K-2T – K2T is a weighted function of the amplitude and time of the 

distortions occurring before and after the 2T pulse. In practice, a graticule 

is almost always used to quantify this distortion. Different countries and 

standards use slightly different amplitude weighting factors. The figure 

below shows a typical waveform monitor K Factor graticule display. The 

outer dotted lines at the bottom of the graticule indicate 5% K2T limits. See 

the discussion on Pulse to Bar Ratios. 

K60hz – A field-rate square wave is used to measure this parameter. Locate 

the center of the field bar time, normalize the point to 100%, and measure 

the maximum amplitude deviation for each half. Ignore the first and last 

2.5% (about 200 µsec). The largest of the two tilt measurements divided 

by two is the K60hz rating. 

Karaoke – A special DVD format that allows for certain special features. 

The audio portion of this format is distinctive in that it is intended for “sing 

along”formats and may include audio tracks for “guide vocals,”“guide 

melody,”“chorus,”and the main Karaoke left and right channels. The audio 

track for Karaoke in DVD-video is defined to be applicable for multi- 

C 

5% 

W 1 

B 1 



channel setup with five channels maximum. When this vocal part is recorded 

mainly in track 4 and 5 except the main two channels, users can enjoy 

many different playback modes by Karaoke-type DVD players equipped with 

various audio on/off switches. 

Kb (Kilobyte) – A standard unit for measuring the information storage 

capacity of disks and memory (RAM and ROM); 1024 bytes make one 

kilobyte. 

Kbar – A line bar (18 µsecs) is used to measure Kbar . Locate the center of 

the bar time, normalize that point to 100%, and measure the maximum 

amplitude deviation for each half. Ignore the first and last 2.5% 

(0.45 µsec) of the bar. The largest of the two is the Kbar rating. 

Keeper – Term used to indicate the effect, edit was good enough to keep, 

but could possibly be improved on; however, the effect or edit should be 

stored “as is”in case it cannot be improved upon. 

Kell Effect – Vertical resolution of a scanned image subjectively evaluated 

is consistently shown to be less than the geometrically-predicted resolution. 

Observations are usually stated in terms of the ratio of perceived television 

lines to active lines present in the display. From the time that R. Kelt 

published his studies (conducted on a progressive scanned image), there 

have been numerous numerical values and substantiating theories proposed 

for this effect. The range of results suggests that many details of the 

experiments influence the result and make defining a single “Kell Factor” 

impossible. Reported experimental results range at least between 0.5 and 

0.9. In an otherwise comparable display, the “ratio”is lower for interlaced 

scanning than for progressive scanning. 

Kell Factor – A number describing the loss of vertical resolution from that 

expected for the number of active scanning lines. Named for Ray Kell, a 

researcher at RCA Laboratories. Many researchers have come up with different 

Kell factors for progressively scanned television systems. These differences 

are based on such factors as aperture shape, image content, and 

measurement technique. A generally accepted figure for the Kell factor is 

around 0.68, which, multiplied by the 484 active NTSC scanning lines, 

yields a vertical resolution of 330 lines, matched by NTSC’s 330 lines of 

horizontal resolution per picture height (see Square Pixels). It is important 

to note that most studies of the Kell factor measure resolution reduction in 

a progressive scanning system. Interlaces scanning systems suffer from 

both a Kell factor and an interlace coefficient. 

Kelvin – A system or scale used for measuring temperature. Absolute zero 

is 0° Kelvin or –273°C. The “color”of white light is expressed in terms of 

degrees Kelvin, the color of light emitted when an ideal object is heated to 

a particular temperature. 

Kernel – Minimum circuitry required to allow the microprocessor to function. 

Usually consists of the microprocessor, clock circuit, interrupt and 

DMA control lines, and power supply. 

Key – a) A signal that can electronically “cut a hole”in the video picture to 

allow for insertion of other elements such as text or a smaller video picture. 

b) A video that has been overlaid on top of another video. Keys may 




be either determined by the luminance or brightness of the key video, or 

determined by the chroma or hue of the key video. c) A push-button. 

Key Channel – See Alpha Channel. 

Key Fill – Line key effects, the video signal which is said to “fill the hole” 

cut in background video by the key source. 

Key Frame – A frame containing all the data representing an image, 

rather than just the data that has changed since the last frame. The first 

frame of every video file is a key frame; in addition, they occur throughout 

the file to refresh image quality and permit certain operations, such as random 

user access. Compare Delta Frame. 

Key Gain – An adjustment for keys that determines the sharpness of the 

key edges. As key gain is reduced, keys become softer at the edges and 

may be adjusted to be more transparent. 

Key Insert – The video that fills a key. 

Key Invert – a) A luminance key mode which inverts the polarity of the 

key source to allow dark areas of the source video to cut holes in background 

instead of bright areas. b) A chroma key mode which inverts the 

foreground and background positions. 

Key Light – The term used to describe a subject’s main source of illumination. 

When shooting outdoors, the key light is usually the sun. 

Key Mask – A key mode which allows use of independent key mask generators 

to create a pattern to prevent some undesirable portions of the key 

source from cutting a hole in the background. This is also possible using 

externally generated masks on the Vista. 

Key Matrix – The electronic crosspoints which switch and route key signals 

and key insert signals to appropriate key processing electronics. On 

Ampex switchers, these matrices are controlled by keypads and keyer 

insert selector push-button controls and form the Phantom matrix portion 

of the switcher. 

Key Memory – An AVC series feature that allows a key to be fully adjusted 

as soon as it is selected. This is accomplished by a “store”button on the 

key adjust panel that may be pressed when an operator is satisfied with 

the adjustment of a key. From that point on, whenever that key is selected, 

regardless of which keyer it is on, all adjustments and features of that key 

are automatically recalled. 

Key Signal – A hole cutting signal. 

Key Source – A hole cutter. The signal which is said to “cut a hole”in the 

background scene for a key effect. In actuality, this signal controls a video 

mixer which switches between the background scene and the fill video; 

thus, the key source determines the shape of the key effect. 


Key Type – There are three key types on Ampex switchers; luminance 

keys, RGB chroma keys, and composite chroma keys. 

Keyboard – a) Group of push-buttons used for inputting information to a 

system. b) The human interface portion of a computer, typewriter with 

alpha numeric keys, or push-buttons. 

Keyer – The electronics and panel controls that create keys. There are 

many types of keyers, some limited to titles only, and some capable of any 

type of key. All Ampex keyers are full capability. 

Keyframe – a) Keyframes are important frames that are guides in creating 

frames that occur between the keyframes. b) A specific manipulation or 

positioning of the image. An effect is composed of one or more keyframes. 

Keyframe Duration – The length of the keyframe; the time from keyframe 

to the start of the next. 

Keying – The process of replacing part of one television image with video 

from anther image; that is chroma keying and insert keying. 

Keykode – A barcode on the edge of motion picture film which allows the 

film edge numbers to be electronically read and inserted into an edit list. 

Very useful for generating a negative cut list from a video off-line EDL. 

Key-Length-Value (KLV) – The grouping of information concerning a single 

metadata element that combines three pieces of information: its UL 

Data Key, the Length of its instantiation Value in the next field, its instantiated 

Value in the allowed format. 

Keypad – The numbered push-buttons used to enter numerical data, i.e., 

pattern numbers, transition rates, key source numbers, etc. 

KF Flags (Menu) – Miscellaneous keyframe flags, currently used to turn 

Globals off and on. 

kHz (Kilohertz) – One thousand cycles per second. 

Kilobyte – One thousand bytes. Actually 1024 bytes because of the way 

computer math works out. 

Kinescope – Frequently used to mean picture tubes in general. However, 

this name has been copyrighted. 

Kinescope Recording – Motion pictures taken of a program photographed 

directly from images on the face of a kinescope tube. A television 

transcription. 

Knee – By convention, the circuitry introducing white compression into the 

opto-electric transfer function and thereby modifying the curve for a more 

gradual approach to white clip. 

Kpulse/bar or K-PB – Calculation of this parameter requires the measurement 

of the pulse and bar amplitudes. Kpulse/bar is equal to: 

1/4 | (bar-pulse)/pulse | X 100%)

L 

Label – Name assigned to a memory location. When an assembly language 

program is written, a label is assigned to an instruction or memory 

location that must be referred to by another instruction. Then when the 

program is converted to machine code, an actual address is assigned to 

the label. 

LAeq – An Leq measurement using “A”weighting. Refer to Leq and 

Weighting. 

LAN – Local Area Network. 

LANC – See Control-L. 

LAP – Link Access Protocol. 

Lap Dissolve – A slow dissolve in which both pictures are actually overlapped 

for a very brief period of time. Same as Dissolve. 

Large Scale Integration (LSI) – Technology by which thousands of semiconductor 

devices are fabricated on a single chip. 

Large-Area Flicker – Flicker of the overall image or large parts of it. See 

also Flicker Frequency and Twitter. 

Laser Beam Recording – A technique for recording video on film. 

LAT – Link Available Time. 

Latch – a) Hardware device that captures information and holds it (e.g., 

group of flip-flops). b) An electronic circuit that holds a signal on once it 

has been selected. To latch a signal means to hold it on or off. 

Latency – A factor of data access time due to disk rotation. The faster a 

disk spins the quicker it will be at the position where the required data can 

start to be read. As disk diameters have decreased, so rotational speeds 

have tended to increase but there is still much variation. Modern 3-1/2inch 

drives typically have spindle speeds of between 3,600 and 7,200 revolutions 

per minute, so one revolution is completed in 16 or 8 milliseconds 

(ms) respectively. This is represented in the disk specification as average 

latency of 8 or 4 ms. 

Lateral Direction – Across the width of the tape. 

Launch – To start up an application, often by double-clicking an icon. 

Lavaliere – A microphone designed to hang from the performer’s neck. 

Layer – a) A term used to describe which video is on top of which background 

versus foreground and subsequent keys superimposed. b) One of 

the levels in the data hierarchy of the video and system specification. 

Layer-to-Layer Adhesion – The tendency for adjacent layers of tape in a 

roll to adhere to each other. 

Layer-to-Layer Signal Transfer – The magnetization of a layer of tape in 

a roll by the field from a nearby recorded layer, sometimes referred to as 

“print-thru.” 

LBR (Laser Beam Recorder) – It creates the DVD master file. 

LCD (Liquid Crystal Display) – A screen for displaying text/graphics 

based on a technology called liquid crystal, where minute currents change 

the reflectiveness or transparency of selected parts of the screen. The 



advantages of LCD screens are: very small power consumption (can be 

easily battery driven) and low price of mass produced units. Its disadvantages 

presently include narrow viewing angle, somewhat slower response 

time, invisibility in the dark unless the display is back-lit, difficulties displaying 

true colors, and resolution limitations. 

LCP – Link Control Protocol. 

Leader – Special non-magnetic tape that can be spliced to either end of a 

magnetic tape to prevent damage and possible loss of recorded material 

and to indicate visually where the recorded portion of the tape begins and 

ends. 

Leading Blacks – A term used to describe a picture condition in which 

the edge preceding a white object is overshaded toward black. The object 

appears to have a preceding or leading black border. 

Leading Whites – A term used to describe a picture condition in which 

the edge preceding a black object is overshaded toward white. The object 

appears to have a preceding or leading white border. 

Leakage – A term describing the signal picked up by a mike which is 

intended to pick up other signals only. 

Learn – The act of storing switcher control panel data into memory in a 

real-time mode (learning as they happen). 

Learning Curve – An algebraic metaphor for the amount of time a learner 

needs to learn a new task (such as operating an item of television production 

equipment). 

Least Significant Bit (LSB) – The bit that has the least value in a binary 

number or data byte. In written form, this would be the bit on the right. For 

example: 

Binary 1101 = Decimal 13 

In this example, the rightmost binary digit, 1, is the least significant bit, 

here representing 1. If the LSB in this example were corrupt, the decimal 

would not be 13 but 12. 

Lechner Distance – Named for Bernard Lechner, researcher at RCA 

Laboratories. The Lechner distance is nine feet, the typical distance 

Americans sit from television sets, regardless of screen size. The Jackson 

distance, three meters, named for Richard Jackson, a researcher at Philips 

in Britain, is similar. There is reason to believe that the Lechner and 

Jackson distances are why HDTV research was undertaken sooner in 

Japan (where viewing distances are shorter) than elsewhere. See also 

Viewing Distance. 

LED – A light on a piece of hardware that indicates status or error 

conditions. 

Legal Signal – A video signal in which each component remains within 

the limits specified for the video signal format; that is, it does not exceed 

the specified gamut for the current format. 

Lempel-Ziv Welch (LZW) Compression – Algorithm used by the UNIX 

compress command to reduce the size of files, e.g., for archival or transmission. 

The algorithm relies on repetition of byte sequences (strings) in its 




input. It maintains a table mapping input strings to their associated output 

codes. The table initially contains mappings for all possible strings of 

length one. Input is taken one byte at a time to find the longest initial 

string present in the table. The code for that string is output and then the 

string is extended with one more input byte b. A new entry is added to the 

table mapping the extended string to the next unused code (obtained by 

incrementing a counter). The process repeats, starting from byte b. The 

number of bits in an output code, and hence the maximum number of 

entries in the table is usually fixed and once this limit is reached, no more 

entries are added. 

Length – a) The physical length of the tape wound on a reel or on a hub, 

varying from 213 feet in a C45 cassette to 9200 feet in a roll of instrumentation 

tape. b) The number of bytes represented by the items whose 

Length is being described. 

Lens – The curved glass on a video camera or camcorder that collects 

light and focuses it. 

Leq – Leq represents the continuous noise level, equivalent in loudness 

and energy, to the fluctuating sound signal under consideration. Refer to 

LAeq. 

Letterbox – a) A television system that limits the recording or transmission 

of useful picture information to about three-quarters of the available 

vertical picture height of the distribution format (e.g., 525-line) in order to 

offer program material that has a wide picture aspect ratio. b) Term generally 

used for the form of aspect ratio accommodation involving increasing 

vertical blanking. See Blanking Adjustment. 

Level – a) A defined set of constraints on the values which may be taken 

by some parameters within a particular profile. A profile may contain one or 

more levels. b) In MPEG-2, a range of picture parameters. c) Defines the 

bounds of the coding parameters, such as resolution, bit rate, etc. within 

each profile. The variation of performance is inherently wide in a profile. 

Thus, levels have been defined in order to set reasonable constraints. 

LFE (Low Frequency Effects) – The optional LFE channel (also referred 

to as the “boom”channel) carries a separate, limited, frequency bandwidth 

signal that complements the main channels. It delivers bass energy specifically 

created for subwoofer effects or low-frequency information derived 

from the other channels. The LFE channel is the “.1”in 5.1-channel audio. 

Library – As in a book library, it is somewhere one might keep effects, 

i.e., on a disk or collection of disks, hence a library of canned effects. 

LIFO (Last-In-First-Out) – A buffer. Same as Push-Down Stack. See 

Stack. 

Light Valve Technology – A light valve projector uses a bulb as the 

source of light. The valve technology changes the color and intensity of the 

source to form the picture. Film or slide projectors are examples of light 

valve technology. The Digital Micro-Mirror Device (DMD) also known as the 

Digital Light Processor (DLP), the Image Light Amplifier (ILA), and LCD are 

all examples of electronic light valve technology. Obtaining black in a picture 

produced by a light valve projector requires the ability to shut the light 

off in particular areas of the picture. Shutting light off in a small area is 

actually rather difficult. Consequently, the real picture contrast ratio of a 

number of these projectors is rather poor. 


Lightness – The brightness of an area (subjectively) judged relative to the 

brightness of a similarly illuminated area that appears to be white or highly 

transmitting. 

Lightning Measurement Method – This measurement method allows for 

the evaluation of the CAV luminance signal gain and for making chrominance/luminance 

gain comparisons. Tektronix has developed the twodimensional 

display called the “Lightning”display because of the zigzag 

trace pattern as shown below. 

This display is created by plotting luminance versus B-Y in the upper half 

of the display and inverted luminance versus R-Y in the lower half of the 

display. The bright dot in the center of the screen is the luminance blanking 

level. The points above and below this show the plots of the different 

color components based on their signal amplitude. This test requires a 

color bar test signal be used. 

Limiter – A compressor with a ratio greater than or equal to 10:1. 

Limiting – Special circuitry is sometimes included in equipment to limit 

bandwidth or amplitude, i.e., white amplitude in cameras is generally limited. 

Saturation of matte generators in switchers are generally limited to 

stop illegal colors. 

Line Blanking – The blanking signal at the end of each horizontal scanning 

line. Used to make the horizontal retrace invisible. Also called horizontal 

blanking. 

Line Compensation – Use of a video line amplifier to pre-compensate for 

high-frequency video signal transmission losses resulting from long distance 

cable runs (several hundred meters) by boosting those signal frequencies 

most effected. Without such compensation, deterioration is manifested 

as loss of fine details and color distortion. 

Line Count – The total number of horizontal lines in the picture. 

Line Crawl – Tendency of the eyes to follow the sequentially flashing 

scanning lines of interlaced scanning up or down the screen in the same 

way that the eyes follow the sequentially flashing light bulbs on a movie 

theater marquee. Line crawl tends to reduce vertical resolution.

Line Doubling – Any number of schemes to convert interlaced scanning 

to progressive scanning at the display, the simplest of which simply doubles 

each scanning line. More elaborate schemes use line interpolation and 

motion compensation or median filtering. 

Line Frequency – The number of horizontal scans per second, normally 

15,734.26 times per second for NTSC color systems and 15,625 in PAL. 

Line Interpolation – An advanced mechanism used in some line doublers 

that calculates the value of scanning lines to be inserted between existing 

ones. 

Line Mode – A Dolby Digital decoder operational mode. The dialnorm reference 

playback level is –31 dBFS and dynamic range words are used in 

dynamic range compression. Refer to Dynamic Range Compression. 

Line Pair – A measure of resolution often used in film and print media. In 

television, lines are used instead, creating confusion when comparing film 

and video. 

Line Pair, Optical – In optical measurements and specifications, resolution 

is specified in terms of line-pairs per unit distance or unit angle, a line 

pair consisting of one “black”plus one “white”line. Thus one line pair corresponds 

to two television lines. 

Line Pairing – A reduction in vertical resolution caused when a display (or 

camera) does not correctly space fields, resulting in an overlap of odd and 

even numbered scanning lines. See also Random Interlace. 

Line Rate – The rate at which scanning lines appear per second (the number 

of scanning lines per frame times the frame rate); sometimes used 

(non-quantitatively) as an indication of the number of scanning lines per 

frame (e.g., a high line rate camera). 

Line Rate Conversion – Standardized video systems currently exist 

employing the following number of total lines per frame: 525, 625, 1125. 

Furthermore, each of these operates in a 2:1 interlace mode, with 262.5, 

312.5, 562.5 lines per field (with concurrent temporal differences at field 

rates of 50.00, 59.94, or 60.00 fields per second). Additional systems are 

being proposed. While simple transcoding by deletion or repetition can be 

applied, it is more commonly done by applying an algorithm to stored information 

in order to generate predictive line structures in the target system. 

Line Store – A memory buffer which stores a single digital video line. One 

application for line stores is use with video filtering algorithms or video 

compression applications. 

Line Structure Visibility – The ability to see scanning lines. Seeing them 

makes it harder to see the image (like looking out a window through venetian 

blinds or not being able to see the forest for the trees). Some ATV 

schemes propose blurring the boundary between scanning lines for this 

reason. 

Line Time Linear Distortions – Distortions involving signals in the 

1 µsec to 64 µsec range. These distortions cause tilt in line-rate signal 

components such as white bars. The amount of distortion is expressed in 

IRE or as a percent of the line bar amplitude. Line time distortions can also 

be quantified in Kbar units. In large picture details, this distortion produces 

brightness variations between the left and right sides of the screen. 

Horizontal streaking and smearing may also be apparent. Any test signal 

containing an 18 µsec, 100 IRE bar such as the FCC Composite or the 



NTC-7 Composite can be used for this measurement. See the discussion 

on Linear Distortions and Kbar units. 

Line Time Waveform Distortion – See Line Time Linear Distortions. 

Linear Addressing – A modern method of addressing the display memory. 

The display memory (in the IBM PC world) was originally located in a 

128-Kbyte area from A000:0 through BFFF:F, too small for today’s display 

systems with multi-megabyte memories. Linear addressing allows the display 

memory to be addressed in upper memory, where a large contiguous 

area is set aside for it. 

Linear (Assembly) Editing – Editing using media like tape, in which 

material must be accessed in order (e.g., to access scene 5 from the 

beginning of the tape, one must proceed from scene 1 through scene 4). 

See Nonlinear Editing. 

Linear Distortion – Distortions which are independent of signal amplitude. 

These distortions occur as a result of the system’s inability to uniformly 

transfer amplitude and phase characteristics at all frequencies. 

When fast signal components such as transitions and high frequency 

chrominance are affected differently than slower line-rate or field-rate 

information, linear distortions are probably present. These distortions are 

more commonly caused by imperfect transfer characteristics in the signal 

path. However linear distortions can also be externally introduced. Signals 

such as power-line hum can couple into the video signal and manifest 

themselves as distortions. 

Linear Key – a) A term given to a key which contains soft edges and 

information at many different luminance levels. This is the ability of the 

keyer to key many levels linearly and means the keyer has a gain close to 

one. b) A process for the selective overlay of one video image upon another, 

as through chroma key. Control of the ratio of foreground to background 

is determined by the specifications derived from luminance information, 

and provided in the linear key data. Ratios to be applied are carried for 

each picture element in the alpha channel. The process permits realistic 

rendering of semi-transparent objects. 

Linear PCM – One of the allowed types of audio formats for DVD. It may 

have up to eight channels and provide very high sample rates and sample 

depths. Unfortunately, these very high data rates consume so much DVD 

capacity that meaningful quantities of both audio and video become 

problematic. 

Linear Pulse Distribution Amplifier (Linear Pulse DA) – A linear pulse 

distribution amplifier will handle 4 Vp-p signals (pulses) but is limited to 

amplifying and fanning out the signal. Also see Regenerative Pulse DA. 

Linear Select Decoding – Address decoding technique that uses the 

most significant address bits to directly enable devices in the system. 

Linear Time Code (LTC) – Time code recorded on a linear analog track 

on a video tape. 

Linearity – a) The basic measurement of how well analog to digital and 

digital to analog conversion are performed. To test for linearity, a mathematically 

perfect diagonal line is converted and then compared to a copy of 

itself. The difference between the two lines is calculated to show linearity 

of the system and is given as a percentage or range of Least Significant 

Bits. b) The uniformity of scanning speed which primarily affects the accu- 




racy of geometry along a horizontal or vertical line through the picture center. 

c) The measurement of how accurately a piece of electronic equipment 

processes a signal (a measure of its transparency). 

Line-Out Monitor – A monitor connected to a recording device that displays 

the finished product. A line-out monitor may be a video monitor 

(video product), an audio speaker (audio product), or a television (both 

audio and video). 

Liners/Friction Plates – Friction controlling plastic sheets used inside a 

Philips cassette to control winding uniformity and torque level. 

Lines – Scanning lines or lines of resolution. The latter are hypothetical 

lines alternating between white and black (or, in the case of chroma resolution, 

between complementary colors). The combined maximum number of 

black and white lines that might be perceived in a particular direction is 

the number of lines of resolution. Vertical resolution is measured with horizontal 

lines; horizontal resolution is measured with vertical lines; diagonal 

resolution is measured with diagonal lines (no current television system or 

proposal favors one diagonal direction over the other, so the direction of 

the diagonal lines does not really matter). See also PPH. 

Lines, Active Horizontal – In the scanning of a video image, the line 

number associated with the format is the total number of lines assigned to 

one frame. It is in fact a timing specification defining the conjunction with 

the field frequency the time interval allocated to each horizontal line (commonly 

measured in number of samples at the specified sampling rate or in 

microseconds). Some of these lines and intervals carry image information, 

some from the total assigned are dedicated to operational and control 

functions, including returning the scanning beam back to the upper left 

corner to begin the next field. Those allotted time intervals (lines) actually 

carrying image information or image-associated information such as captioning, 

image test signals, etc., are the active lines. In further reduction of 

time allocated to image information, some of each active line is dedicated 

to the horizontal interval to get the scanning beam to return to the leftedge 

starting point for the next line and to reaffirm color subcarrier, etc. In 

the U.S. 525/59.94/2:1/NTSC system, about 7.6% of the total field or 

frame time is assigned to the vertical interval, and about 16% to the horizontal 

interval. Thus, the 525 television lines per frame provide about 480 

active lines. Correspondingly, each active line displays image data about 

84% of its time interval. Image information is thus conveyed for only about 

76.4% of the total time. In digital encoding, it may be possible to reduce 

the number of bits assigned to the vertical and horizontal intervals and 

achieve significant bit rate reduction. 

Lines, Active Vertical – In a scanning standard, the number of raster 

lines per frame that are not required to contain blanking. The active vertical 

lines may include signals containing non-image information. 

Lines, Television – Television images are scanned in a sequence of horizontal 

lines, beginning at the upper left corner, and reaching the bottom 

right corner at the end of the field. Thereupon the scan is returned to the 

upper left corner to begin the next field. As a consequence of the line 

structure, all television images are sampled vertically. Within a line, the signal 

may remain analog or be sampled digitally. A television line is also a 

measure of time, representing the interval allocated to one line. (In the U.S. 

system 525/59.94/2:1, the line duration is 63.5 s). Television lines also 

function as a geometric measure, with resolution (both vertical and hori- 


zontal), for example, specified in terms of “lines per picture height.”Since 

both “black”and “white”lines of a resolution chart are counted, two television 

lines equal one cycle of the electrical waveform. 

List Box – Used to make a selection from a list of options. If the list is too 

long to fit inside the given area, a vertical scroll bar moves the list up and 

down. 

Listener – Device that inputs data from a data bus. 

Little Endian – A process which starts with the low-order byte and ends 

with the high-order byte. Intel processors use the little endian format. 

Live – Actually presented in the studio, with cameras feeding out to the 

lines as the performance is done. 

LLC – Link Layer Control. 

LLME – Lower Layer Management Entity. 

L-Member – Liaison Member. 

LMDS – Local Multi-Point Distribution System. 

LNB – Low-Noise Block Converter. 

LO – Local Origination Channel. 

Local Bus Transfer – The host/local bus transfer consumes a smaller 

percentage of available bandwidth during video/graphics transfers than 

earlier bus standards but the still-noticeable performance penalty may be 

objectionable for some users, especially when compared to systems that 

circumvent it. 

Local Decode – A feature of Indeo video interactive allowing the playback 

application to tell the codec to decode only a rectangular subregion of the 

source video image: the viewport. See Viewport. 

Load Resistance – The impedance or resistance (load) that a cable 

places on a signal being transmitted through it. In the case of a highfrequency 

signal, signal-to-cable matching is essential to prevent signal 

deterioration. The cable should be terminated by a specific load resistance, 

usually 50 or 75 ohms. Improper cable loading results in signal distortion, 

ghost images, color loss, and other adverse phenomena. Most video inputs 

have the proper termination built in. 

Local Tally – A tally of which bus on an M/E is active regardless of 

whether or not it is on air. 

Local Workstation, Drive, Disk, File System, or Printer – The physical 

workstation whose keyboard and mouse you are using, all hardware that is 

connected to that workstation, and all software that resides on that hardware 

or its removable media. 

Locate (Menu) – The 3D function used to move or relocate an image. 

Locate moves the image as if it were in three-dimensional space, even 

though the image is seen on a two-dimensional video screen. 

Location – Shooting locale. 

Locked – A video system is considered to be locked when the receiver is 

producing horizontal syncs that are in time with the transmitter. 

Locking Range – The time range measured in micro- or nanoseconds 

over which a video decoder can “lock”or stabilize a signal. Digital out of

ange signals may require “rubber-band”buffering using a parallel shift 

register (FIFO) to reduce the locking range. 

Lock-Up Time – The time before a machine is activated and the time it is 

ready for use. 

LOF – Loss of Frame. 

Lofting – The ability to stretch a “skin”over shapes that are in fact crosssectional 

ribs. 

Logarithm – A logarithm is the power to which a base (usually 10) must 

be raised in order to arrive at the desired value. 

Logarithmic Scale – A mathematical function which spreads out low values 

and squeezes together higher values. 

Logic Analyzer – Test system capable of displaying 0s and 1s, as well as 

performing complex test functions. Logic analyzers typically have 16 to 32 

input lines and can store sequences of sixteen or more bits on each of the 

input lines. 

Logic Comparator – Test product that compares pin-for-pin operation of 

an IC operating in-circuit with a known good reference IC. 

Logic Probe – Handheld troubleshooting tool that detects logic state and 

activity on digital circuit nodes. 

Logic Pulser – Handheld troubleshooting tool that injects controlled digital 

signals into logic nodes. 

Login – To log in to a workstation is to establish a connection to the workstation 

and to identify yourself as an authorized user. 

Login Account – A database of information about each user that, at the 

minimum, consists of login name, user ID, and a home directory. 

Login Name – A name that uniquely identifies a user to the system. 

Login Screen – The window that you see after powering on the system, 

before you can access files and directories. 

Logout – To log out from a workstation is to finish a connection to the 

workstation. 

Long Shot – Camera view of a subject or scene, usually from a distance, 

showing a broad perspective. 

Long-Time Linear Distortions – Distortions involving signals in the 

greater than 16 msec range. Long-time distortions affect slowly varying 

aspects of the signal such as changes in APL which occur at intervals of a 

few seconds. The affected signal components range in duration from 

16 msecs to tens of seconds. The peak overshoot, in IRE, which occurs as 

a result of an APL change is generally quoted as the amount of distortion. 

Settling time is also sometimes measured. Long-time distortions are slow 

enough that they are often perceived as flicker in the picture. See the discussion 

on Linear Distortions. 

Longitudinal Curvature – Any deviation from straightness of a length of 

tape. 

Longitudinal Direction – Along the length of the tape. 

Longitudinal Time Code (LTC) – Audio-rate time code information that is 

stored on its own audio track. This audio-rate signal allows the editing sys- 



tem to track the position of the tape even at high shuttle speeds where 

VITC data could not be used. 

Look Ahead Preview – See Preview. 

Loop – Piece of tape spliced beginning (head) to end (tail) for continuous 

playback or recording. To fold around. A loop/slack section of film with the 

necessary “play”to allow film which had been previously and continuously 

moving from a reel to be intermittently moved through a grate/projection 

head/optical lens arrangement. Proper loop size is important in threading a 

film projector, i.e., in telecine for film to videotape transfer. 

Loop Through – A video signal entering a piece of equipment is returned 

to the outside world for further use. Loop through circuitry requires careful 

design to prevent signal degradation. 

Looping – a) A term used to describe the chaining of a video signal 

through several video devices (distribution amplifiers, VCRs, monitors, etc.). 

A VCR may be hooked up to a distribution amplifier which is supplied with 

a video input connector and a loop output connector. When a signal is fed 

to the distribution amplifier, it is also fed unprocessed to the loop output 

connector (parallel connection) on the distribution amplifier. In turn, the 

same signal is fed to another device which is attached to the first one and 

so on. Thus a very large number of VCRs or other video devices can be 

looped together for multiple processing. b) An input that includes two connectors. 

One connector accepts the input signal, and the other connector is 

used as an output for connecting the input signal to another piece of 

equipment or to a monitor. 

Lo/Ro (Left Only, Right Only) – A type of two-channel downmix for multichannel 

audio programs. Lo/Ro downmixes are intended for applications 

where surround playback is neither desired nor required. 

Loss – Reduction in signal strength or level. 

Lossless (Compression) – a) Reducing the bandwidth required for transmission 

of a given data rate without loss of any data. b) Image compression 

where the recovered image is identical to the original. See Lossy 

(Compression). 

Lossy (Compression) – a) Image compression where the recovered 

image is different from the original. b) Compression after which some portion 

of the original data cannot be recovered with decompression. Such 

compression is still useful because the human eye is more sensitive to 

some kinds of information than others, and therefore does not necessarily 

notice the difference between the original and the decompressed image. 

c) Reducing the total data rate by discarding data that is not critical. Both 

the video and audio for DTV transmission will use lossy compression. See 

Lossless (Compression). 

Low Band Color – The old, original professional videotape color recording. 

Low Delay – A video sequence does not include B-pictures when the low 

delay flag is set; consequently, the pictures follow in chronological order, 

and low delay is obtained. Normally, when B-pictures are included, the pictures 

used for prediction of a B-picture are sent in advance so they are 

available when the B-picture arrives, but this increases the delay. 

Low End – The lowest frequency of a signal. See High End. 

Low Impedance Mike – A mike designed to be fed into an amplifier or 

transformer with input impedance of 150 to 250 ohms. 




Low-Frequency Amplitude Distortion – A variation in amplitude level 

that occurs as a function of frequencies below 1 MHz. 

Low-Frequency Distortion – Distortion effects which occur at low frequency. 

Generally considered as any frequency below the 15.75 kHz line 

frequency. 

Low-Order – Pertaining to the weight or significance assigned to the digits 

of a number. In the number 123456, the lower order digit is six. The 

three low-order bits of the binary word 11100101 are 101. 

Lowpass Filter – a) Filter that passes frequencies below a specific frequency. 

b) A filter specifically designed to remove frequencies above the 

cutoff frequency, and allow those below to pass unprocessed is called a 

lowpass filter. The effect of a lowpass filter is to reduce the amplitude of 

high frequencies. Common examples include the “treble”controls on many 

lower end radios and stereos, the passive “tone”controls often found on 

electric guitars and basses, hi-cut filters on consoles, and of course, this 

type of filter is found on many synthesizers. 

LPCM (Linear Pulse Code Modulation) – A pulse code modulation system 

in which the signal is converted directly to a PCM word without companding, 

or other processing. Refer to PCM. 

LPTV – Low Power TV. 

LSB – See Least Significant Bit. 

LSI – See Large Scale Integration. 

LS/RS (Left Surround, Right Surround) – The actual channels or speakers 

delivering discrete surround program material. 

LSTTL (Low Power Schottky TTL) – Digital integrated circuits that 

employ Schottky diodes for improved speed/power performance over standard 

TTL. 

LTC – See Linear Time Code or Longitudinal Time Code. 

Lt/Rt (Left Total, Right Total) – Two-channel delivery format for Dolby 

Surround. Four channels of audio, Left, Center, Right and Surround (LCRS) 

are matrix encoded for two-channel delivery (Lt/Rt). Lt/Rt encoded programs 

are decoded using Dolby Surround and Dolby Surround Pro Logic 

decoders. Refer to Dolby Surround and Dolby Surround Pro Logic. 

Luma – See the definition for Luminance. 

Luminance (Component) – A matrix, block or single pel representing a 

monochrome representation of the signal and related to the primary colors 

in the manner defined in the bit stream. The symbol used for luminance is 

Y. 

Luminance (Y) – Video originates with linear-light (tristimulus) RGB primary 

components, conventionally contained in the range 0 (black) to +1 

(white). From the RGB triple, three gamma-corrected primary signals are 

computed; each is essentially the 0.45-power of the corresponding tristimulus 

value, similar to a square-root function. In a practical system such as 

a television camera, however, in order to minimize noise in the dark regions 

of the picture it is necessary to limit the slope (gain) of the curve near 

black. It is now standard to limit gain to 4.5 below a tristimulus value of 

+0.018, and to stretch the remainder of the curve to place the Y-intercept 


at –0.099 in order to maintain function and tangent continuity at the 

breakpoint: 

Rgamma = 1.099 * pow (R,0.45)) – 0.099 

Ggamma = 1.099 * pow (G,0.45)) – 0.099 

Bgamma = 1.099 * pow (B,0.45)) – 0.099 

Luma is then computed as a weighted sum of the gamma-corrected 

primaries: 

Y = 0.299 * Rgamma + 0.587 * Ggamma + 0.114 * Bgamma 

The three coefficients in this equation correspond to the sensitivity of 

human vision to each of the RGB primaries standardized for video. For 

example, the low value of the blue coefficient is a consequence of saturated 

blue colors being perceived as having low brightness. The luma coefficients 

are also a function of the white point (or chromaticity of reference 

white). Computer users commonly have a white point with a color temperature 

in the range of 9300 K, which contains twice as much blue as the 

daylight reference CIE D65 used in television. This is reflected in pictures 

and monitors that look too blue. Although television primaries have 

changed over the years since the adoption of the NTSC standard in 1953, 

the coefficients of the luma equation for 525- and 625-line video have 

remained unchanged. For HDTV, the primaries are different and the luma 

coefficients have been standardized with somewhat different values. The 

signal which represents brightness, or the amount of light in the picture. 

This is the only signal required for black and white pictures; for color systems 

it is obtained as the weighted sum (Y = 0.3R + 0.59G + 0.11B) of 

the R, G, and B signals. 

Luminance Factor β – At a surface element of a nonself-radiating medium, 

in a given direction, under specified conditions of illumination, ratio of 

the luminance of the surface element in the given direction to that of a 

perfect reflecting or transmitting diffuser identically illuminated. No “perfect 

reflectors”exist, but properly prepared magnesium oxide has a luminance 

factor equal to 98% and this is usually employed to define the scale. 

Luminance Key – A key wherein the keying signal is derived from the 

instantaneous luminance of a video signal after chroma has been filtered 

out. That is, for a particular clip level, all parts of a scene that are brighter 

than that level will appear keyed in, leaving background video everywhere 

else. 

Luminance Noise – Noise which manifests itself in a video picture as 

white snow, typically caused by one of the following situations: low signal 

level due to poor lighting conditions, poor video signal processing, low 

quality videotapes, excessively long video cables used without precompensation, 

dirt on the video recorder heads which interferes with reading 

and writing, over-enhancement of the video signal. 

Luminance Nonlinearity – This distortion is also called differential luminance 

and is present if luminance gain is affected by luminance levels.

This amplitude distortion is a result of the system’s inability to uniformly 

process luminance information over the entire amplitude range. 

The amount of luminance nonlinearity distortion is expressed as a percentage. 

Measurements are made by comparing the amplitudes of the individual 

steps in a staircase signal as shown. The result is the difference 

between the largest and smallest steps, expressed as a percentage of the 

largest step. Measurements should be made at both high and low APL and 

the worst error should be quoted. In black and white pictures, luminance 

nonlinearity will cause pictures loss of detail in shadows and highlights 

which are caused by the crushing or clipping of the white or black portions 

of the signal. In color pictures, luminance nonlinearity will cause colors in 

the high luminance portions of the picture to be distorted. 

Luminance Range – The range in measured luminance between the lightest 

and the darkest element of a luminous scene or its display. 

Luminance Range, Display CRT – The luminance range that can be displayed 

on a CRT is the ratio of maximum to minimum luminance on the 

tube face. The maximum practical output is determined by beam current, 

phosphor efficiency, shadow-mask distortion, etc. The minimum is the 

luminance of that portion of the tube face being scanned with beam current 

set to cut-off. The contributions from room illumination, external and 

internal reflections, etc., must be recognized. 

Luminance Range, Display Theater – The luminance range that can be 

displayed on a theater projection screen is the ratio of maximum to minimum 

luminance achievable during projection of film. The maximum achievable 

highlight is determined by light-source output capacity, projection 

optical efficiency, the transmission of minimum film densities, screen gain, 

etc. The minimum is the luminance contribution from house illumination 

and other stray light, plus optical flare raising black levels, and the transmission 

of maximum film densities. Measured values in typical first-run 

theaters show luminance ranges of 500:1 to 300:1 (usually limited by 

house illumination). 

Luminance Range, Recorded – The luminance range, recorded may be 

reduced from the luminance range, scene intentionally and/or by the limitations 

of the recording system. Most systems have a maximum effective signal 

level limiting the high end, and noise limiting the low end. All of the 

scene that is of interest must be placed within these two limits by the 

choice of an appropriate transfer function. Some analog functions permit 

gradual transitions to overload and/or noise. Digital functions have inflexible 

limits imposed by the number of levels permitted by the bit 

assignments. 

Luminance Range, Scene – The luminance range of original scenes 

varies from outdoor scenes in sunlight with a range possibly exceeding 



10000:1, to indoor scenes with controlled lighting, where the range may be 

reduced to 10:1 or even less. Adjustment of or accommodation to the luminance 

range, scene is one of the conditions to be evaluated in determining 

how the scene is to be recorded. It is a test of artistic judgment to place 

the relative luminances for the objects of interest on a suitable portion of 

the opto-electronic or opto-photographic transfer function in order to produce 

the desired subjective quality. 

Luminance Signal – The black and white signal (the brightness signal) in 

color TV. The luminance signal is formed by combining a proportion of 30% 

red, 50% green, and 11% blue from the color signal. This combined output 

becomes the luminance (brightness/monochrome) signal. 

Luminance, Constant (Video) – In an image coding system that derives 

a luminance signal and two bandwidth-limited color-difference signals, 

constant luminance prevails if all of the luminance information is encoded 

into one signal that is supplemented by but totally independent of two color 

signals carrying only chrominance information, e.g., hue and saturation. 

Constant luminance is only achieved when the luminance and chrominance 

vectors are derived from linear signals. The introduction of nonlinear transform 

characteristics (usually for better signal-to-noise and control of 

dynamic range prior to bandwidth reduction) before creating the luminance 

and chrominance vectors destroys constant luminance. Current video systems 

do not reconstitute the luminance and chrominance signals in their 

linear form before further processing and, therefore, depart from constant 

luminance. Note: When R, G, B information is required to be recovered 

from the set of luminance and color-difference signals, the values correlated 

to the original signals are obtained only if the luminance and chrominance 

signals have been derived from the linear functions of R, G, B or 

have been transformed back to linear. Constant luminance not only provides 

a minimum of subjective noise in the display (since the luminance 

channel does not respond to chrominance noise), but also preserves this 

noise minimum through chrominance transformations. 

Luminance, Physics (Generic Usage) – a) Luminance has technical as 

well as colloquial definitions. The generic flux from a light-emitting or lightreflecting 

surface; the subjective response to luminance is brightness. The 

quotient of the luminous flux at an element of the surface surrounding the 

point and propagated in directions defined by an elementary cone containing 

the given direction, by the product of the solid angle of the cone and 

the area of the orthogonal projection of the element of the surface on a 

plane perpendicular to the given direction. b) The luminous flux may be 

leaving, passing through, and arriving at the surface or both. The luminance 

for each element of a surface within the field of view is defined as 

the ratio of luminous flux per solid angle to the unit projected area of the 

surface. Units are candelas per square meter, foot lamberts, nits. 

Luminance, Relative, Scene – A convenient linear scale for measuring, 

in arbitrary units, the relative luminance amplitudes within the scene to be 

recorded in a video or photographic image, as shown below. The relative 

luminance scale is one factor affecting the choice of suitably artistic scene 

reproduction. It may establish the optimum rendition of reference white and 

optimum employment of the nonlinear transfer function in image recording. 

Note: This relative luminance scale (linear in luminance) resembles IRE 

units (linear in voltage) in positioning both black level reference and refer- 




ence white at 0 and 100, respectively, but that it differs in recognizing the 

extended luminance range of many commonly encountered scenes. 

Correlation of Relative Scene Luminance 

Reflectance Relative Scene Relative 

Factor Luminance (1) Camera 

% Scale Stops 

Typical Limit of Interest – 640 +5 

– 320 +4 

– 160 +3 

Reference White (2) 90 100 – 

– 80 +2 

– 40 +1 

Gray Card (3) 18 20 0 

– 10 1 

– 5 –2 

Scene Black 0 0 – 

(1) IEEE Dictionary of Electrical and Electronics Terms defines luminance factor 

as the ratio to a perfect reflector rather than as the ratio to reference white. 

In practical electronic production, relative scene luminance is a more useful 

measure. 


(white card) whose reflectance is 90% compared to a perfect reflector (prepared 

magnesium oxide = 98%). 


(gray card) whose reflectance is 18% compared with that of a perfect 

reflector. 

Luminance, Television – a) When television was monochrome and sensors 

were in approximate conformance to CIE Photopic Spectral Luminous 

Efficiency Function, it became common to think of the video signal as the 

luminance signal. With the introduction of color, a matrix was designed to 

develop a luminance function by weighting the R, G, B signals in accor- 


dance with the CIE Photopic Spectral Luminance Efficiency Function, producing 

a video signal compatible with monochrome receivers. b) A signal 

that has major control of the image luminance. It is a linear combination of 

gamma-corrected primary color signals. c) The specific ratio of color primaries 

that provides a match to the white point in a specified color space. 

d) The definition of luminance, television is identical for NTSC, PAL, and 

SECAM (CCIR Report 624-4), as follows: E'Y = (0.299) E'R + (0.587) E'G 

+ (0.014) E'B. The weighting function is named luminance signal in all of 

the television standards. For convenience and bandwidth conservation, 

however, it is always formed from the gamma correction signals (i.e., R', 

G', B') and not from the initial linear signals, and thus it is not an exact 

representation of luminance, physics. 

Luminescence – The absorption of energy by matter and its following 

emission as light. If the light follows and then completes itself quickly after 

absorption of the energy, the term fluorescence is used. If the process is of 

a longer and more persistent length, the term phosphorescence is applied. 

Luminous Flux – a) The time rate of flow of light. b) The time rate of flow 

of radiant energy evaluated in terms of a standardized visual response. 

Unless otherwise indicated, the luminous flux is defined for photopic vision. 

The unit of flux is the lumen: the luminous flux emitted within unit solid 

angle by a point source having an isotropic luminous intensity of 1 

candela. 

Lux – a) The metric unit for illumination is 1 lumen per square meter. 

1 foot candle = 10.76 Lux. b) A measurement of light. Lux is used in television 

production to determine the minimum amount of light (lux rating) 

needed for camera operation. Hence, a “2 lux”camcorder requires less 

light than a “4 lux”camcorder. 

LV (LaserVision) – Technology used in optical video disk. 

LVDS – Low Voltage Differential Signal.

M 

M – The CCIR designation for 525 scanning-line/30 frame-per-second television. 

U.S. color television is internationally designated NTSC-M. The M 

standard is the world’s second oldest (the oldest was a 405-line/25 frame 

British standard, no longer broadcast). 

M and E Tracks – Stands for music and effects audio tracks. 

M Load – The cassette tape loading mechanism used in VHS videotape 

recorder/playback technology. 

M/E – See Mix Effects. 

M/E Reentries – Those buttons on a bus that allow selection of previous 

M/Es for further processing to be overlaid. 

M/E to M/E Copy – A panel memory enhancement allowing the operator 

to copy all parameters from one M/E to another with three keystrokes. 

M/E to M/E Swap – A panel memory enhancement allowing the operator 

to swap all parameters between two M/Es with three keystrokes. All 

parameters include key clip levels, pattern position, all hues and modifiers 

used as long as the M/Es are similarly equipped. 

M2 – See Miller Squared Code. 

MAA – MPEG ATM Adaptation. 

MAC (Multiplexed Analog Components) – a) A system in which the 

components are time-multiplexed into one channel using time-domain 

techniques; that is the components are kept separate by being sent at different 

times through the same channel. There are many different MAC formats 

and standards. b) A means of time multiplexing component analog 

video down a single transmission channel such as coax, fiber, or a satellite 

channel. Usually involves digital processes to achieve the time compression. 

c) A large family of television signal formats sharing the following two 

characteristics: color remains in a component rather than composite form, 

and luminance and chrominance components are time compressed so that 

active line time remains constant, with chrominance following luminance. 

Most of the MACs also include digital audio/data channels. Since they are 

non-composite, MACs do not suffer from any cross-luminance or crosscolor 

effects. Since they are time compressed, they tend to have a greater 

base bandwidth than composite signals. See also ACLE, A-MAC, B-MAC, 

D-MAC, D-MAC, D2-MAC, HD-MAC, HD-MAC60, MAC-60, MUSE, and 

S-MAC. 

MAC-60 – An early version of the HDMAC-60. 

Machine Code – See Machine Language. 

Machine Cycle – Basic period of time required to manipulate data in a 

system. 

Machine Error – A machine hardware malfunction. 

Machine Language – Binary language (often represented in hexadecimal) 

that is directly understood by the processor. All other programming languages 

must be translated into binary code before they can be entered into 

the processor. 



Machine Operator – A person trained in the operation of a specific 

machine. 

Macro Lens – A lens used for videography when the camera-to-object 

distance is less than two feet. The macro lens is usually installed within the 

zoom lens of the video camera or camcorder. 

Macroblock – a) The four 8 by 8 blocks of luminance data and the two 

(for 4:2:0 chroma format), four (for 4:2:2 chroma format) or eight (for 

4:4:4 chroma format) corresponding 8 by 8 blocks of chrominance data 

coming from a 16 by 16 section of the luminance component of the picture. 

Macroblock is sometimes used to refer to the pel data and sometimes 

to the coded representation of the pel values and other data elements 

defined in the macroblock header. The usage should be clear from the context. 

b) The screen area represented by several luminance and colordifference 

DCT blocks that are all steered by one motion vector. c) The 

entity used for motion estimation, consisting of four blocks of luminance 

components and a number of corresponding chrominance components 

depending on the video format. 

Macrovision – An analog protection scheme developed by Macrovision for 

the prevention of analog copying. It is widely used in VHS and has now 

been applied to DVD. 

Mag Track – This term usually refers to the sound track. It is usually used 

only in reference to the separate sound tape used in double system recording 

and editing. Videotape is a magnetic medium too, but the term mag 

track is only used in reference to sound tape and not to sound on a videotape 

picture. 

Magnetic Density – The amount of magnetic flux within a specific area. 

Magnetic Field – An area under the influence of magnetism. 

Magnetic Film – Sprocketed base with a magnetic coating for audio 

recording and playback. 

Magnetic Force – The amount of magnetic influence/force within a specific 

area/field. 

Magnetic Head – That part of a videotape recorder which converts electric 

variations into magnetic variations and vice versa. 

Magnetic Induction – To magnetize by being put within the magnetic 

influence of a magnetic field. 

Magnetic Instability – The property of a magnetic material that causes 

variations in the residual flux density of a tape to occur with temperature, 

time, and/or mechanical flexing. Magnetic instability is a function of particle 

size, magnetization, and anisotropy. 

Magnetic Recording – The technology and process of recording 

audio/video information using magnetism as the medium for storage of 

information. The term is often used to mean the process/capability of both 

recording and reproduction/playback. 

Magnetic Tape – With a few exceptions, magnetic tape consists of a base 

film coated with magnetic particles held in a binder. The magnetic particles 




are usually of a circular shape and approach single domain size. See 

Gamma Ferric Oxide, Chromium Dioxide, and Cobalt Doped Oxide. 

Magnetic Track – A sound-track recorded on magnetic film or tape. 

Magnetism – The property of certain physical materials to exert a force 

on other physical materials, and to cause voltage to be induced in conducting 

bodies moving relative to the magnetized body. 

Magnetizing Field Strength, H – The instantaneous strength of the magnetic 

field applied to a sample of magnetic material. 

Main Channel – The basic transmission channel of an ATV channel using 

an augmentation channel. 

Main Level – A range of allowed picture parameters defined by the 

MPEG-2 video coding specification with maximum resolution equivalent to 

ITU-R Recommendation 601. 

Main Profile – A subset of the syntax of the MPEG-2 video coding specification 

that is expected to be supported over a large range of applications. 

Male Connector – A connector that has raised edges, pins, or other protruding 

parts that you plug into a female connector. An example of a male 

connector is an electrical plug that you plug into a wall outlet. 

Man Page – An on-line document that describes how to use a particular 

IRIX or UNIX command. 

Mantissa – Fractional value used as part of a floating point number. For 

example, the mantissa in the number 0.9873 x 107 is 0.9873. 

Mapping – a) A technique for taking a 2D image and applying (mapping) 

it as a surface onto a 3D object. b) Conversion of bytes (8 bits) to 2n-bit 

wide symbols. Thus n is the bit width for the I and Q quantization; e.g., at 

64 QAM the symbol width is 2n = 6 bit, n = 3, i.e., I and Q are subdivided 

into 23 = 8 amplitude values each. c) Refers to the definition of memory 

for storing data used by a particular display mode. The range of addresses 

reserved for graphics information in IBM-compatible systems is from 

A000:0 to BFFF:F. 

Mark – Term used to describe the function of indicating to the editor 

where the entry or exit of the edit will be done on the fly. 

Mask – a) A mask image is a black and white image, which defines how 

opaque each pixel is. A mask blocks out certain components of an image 

but lets other parts show through. b) Pattern used to selectively set certain 

bits of a word to 1 or 0. Usually ANDed or ORed with the data. 

Mask Key – A key that is selectively limited in what portions of the key 

source will be allowed to cut the hole. Masks are usually square, however, 

on Ampex switchers mask keys are done by using the pattern system with 

any pattern shape on the switcher. See Preset Pattern. 

Mask Programmed – An IC that is programmed by generating a unique 

photomask used in the fabrication of the IC. 

Masking – Masking is one way of partial compensation for photo-receptor 

dot sensitivity, non-optimum color filters, non-ideal display phosphors, 

unwanted dye absorption. Audio: The phenomenon by which loud sounds 

prevent the ear from hearing softer sounds of similar frequency. The 

process of blocking out portions of a picture area/signal. A psychoacoustic 

phenomenon whereby certain sounds cannot be heard in the presence of 

others. Video: A process to alter color rendition in which the appropriate 


color signals are used to modify each other. Note: The process is usually 

accomplished by suitable cross coupling between primary color-signal 

channels. Photography: Comparable control of color rendition is accomplished 

by the simultaneous optimization of image dyes, masking dyes, and 

spectral sensitivities. 

Mass Storage – Secondary, slower memory for large files. Usually floppy 

disk or magnetic tape. 

Master – The final edited tape recording from a session from which copies 

will be made called sub masters. These may be used for some subsequent 

editing to create other effects. 

Master Reference Synchronizing Generator – A synchronizing pulse 

generator that is the precision reference for an entire teleproduction facility. 

Master/Slave – Software option which allows user to maintain synchronization 

between two or more transports using one machine as control reference 

(master). 

Mastering – The process of making a master pressing disc with a laser 

beam recorder and a metal plating process. This master is then used in the 

replication process to make thousands of copies. The process is conceptually 

similar to processes used to create vinyl LPs. 

Mastering Lathe – A turntable and cutting head used to cut the disk from 

which the plates used to press records are made. 

Matched Dissolve – A dissolve where the main object is matched in each 

camera. 

Matched Resolution – A term sometimes used to describe matching the 

resolution of a television system to the picture size and viewing distance 

(visual acuity); more often a term used to describe the matching or horizontal 

and vertical (and sometimes diagonal) resolutions. There is some 

evidence that the lowest resolution in a system (e.g., vertical resolution) 

can restrict the perception of higher resolutions in other directions. See 

also Square Pixels. 

Match-Frame Edit – Edit in which a scene already recorded on the master 

is continued with no apparent interruption. A match-frame edit is done 

by setting the record and source in-points equal to their respective outpoints 

for the scene that is to be extended. 

Material Editing – Each material has a number of attributes such as 

transparency, ambient, diffusion, refraction, reflection, and so on. 

Mathias, Harry – Cinematographer, designer, teacher, consultant, and 

author who came up with the six priorities of electronic cinematography: 

Harry Mathias’ Priorities for Electronic Cimenatography 

(in order of importance) 

1. Practicality, Flexibility, and Ruggedness 

2. Aspect Ratio 

3. Sensitivity 

4. Gamma or Transfer Characteristic 

5. Resolution 

6. Standards Acceptance (or Standards Conversion) 

Matrix – a) Device that converts the RGB components from the camera 

into color difference signals and the reverse. b) A set of crosspoints in a

particular functional area of a switcher corresponding to a bus (the controls 

for that matrix). See Audio Matrix and Primary Matrix. 

Camera 

R 

G 

B 

Matrix 

Matrix 

Y 

R-Y 

Matrix Switcher – A device which uses an array of electronic switches to 

route a number of audio/video signals to one or more outputs in almost any 

combination. Production quality matrix switchers perform vertical interval 

switching for interference free switching. Matrix switchers may be operated 

with RS-232 or RS-422 controls, enhancing flexibility. 

Matrix Wipe – a) A wipe wherein the screen is divided into square areas, 

each of which can contain the video from either bus. Initially, each square 

contains the first bus video, and as the wipe develops, one or more 

squares switch to the opposite bus video until, at the completion of the 

wipe, all squares contain the second bus video. b) A type of wipe comprised 

of multiple boxes (a matrix of boxes) which turn on various parts of 

the “B”video during the course of a transition from the “A”video, until all 

the boxes have turned on the scene is all “B”video. This operates in either 

direction. 

Matrixing – To perform a color coordinate transformation by computation 

or by electrical, optical, or other means. 

Matsushita – Parent of Panasonic and Quasar, majority owner of JVC, first 

company to demonstrate an HD camera and display in the U.S., has continued 

demonstrations, and developed the QUME and QAM ATV schemes, 

which popularized the idea of quadrature modulation of the picture carrier. 

Matte – An operational image or signal carrying only transparency information 

and intended to overlay and/or control a conventional image or 

image signal. a) Without shine or gloss. Relatively unreflective of light. 

Removal of a portion of a TV picture and replacement of it with another 

picture. b) A solid color, adjustable in hue, luminance, and saturation. 

Matte is used to fill areas of keys and borders. Ampex switchers generate 

many internal matte signal keys. c) A film term used to describe the film 

effect analogous to a key. Sometimes this definition is carried over into 

video and used to describe a video key. d) A black and white high contrast 

image that suppresses or cuts a hole in the background picture to allow 

the picture the matte was made from to seamlessly fit in the hole. 

Matte Channel – See Alpha Channel. 

Matte Edge – An undesirable, unwanted outline around a matted image. 

This is also called Matte Ring, Matte Ride, but more generally called a “bad 

matte.” 

R 

G 

B 

B-Y 

Y 

R-Y 

B-Y 



Matte Fill – A key filled with a solid color instead of “self,”which is the 

video cutting the key. This color is internally generated and adjustable in 

hue, luminance, and saturation. 

Matte Generator – The circuitry which generates the matte. 

Matte In – To add. 

Matte Key – A key effect in which the inserted video is created by a matte 

generator. 

Matte Out – To remove, eliminate. 

Matte Reel – A black and white (hi con) recording on tape used as a key 

source for special effects. 

MATV – Master Antenna TV. 

Maximum Intrinsic Flux – In a uniformly magnetized sample of magnetic 

material, the product of the maximum intrinsic flux density and the crosssectional 

area. 

Maximum Intrinsic Flux Density – The maximum value, positive or negative, 

of the intrinsic flux density in a sample of magnetic material which is 

in a symmetrically, cyclically magnetized condition. 

Maxwell – A unit of magnetic flux. 

MB (Megabyte) – A standard unit for measuring the information storage 

capacity of disks and memory (RAM and ROM); 1000 kilobytes make one 

megabyte. 

MBONE (Multicast Backbone) – A collection of Internet routers that support 

IP multicasting. The MBONE is used as a multicast channel that sends 

various public and private audio and video programs. 

Mbps or Mb/s (Megabits Per Second) – A data transmission rate in millions 

of binary digits per second. 

MBps or MB/s (Megabytes Per Second) – Data rate in millions of bytes 

per second. 

MCI (Media Control Interface) – a) Microsoft’s interface for controlling 

multimedia devices such as a CD-ROM player or a video playback application. 

b) A high-level control interface to multimedia devices and resource 

files that provides software applications with device-independent control of 

audio and video peripherals. MCI provides a standard command for playing 

and recording multimedia devices and resource files. MCI is a platformindependent 

layer between multimedia applications and system lower-level 

software. The MCI command set is extensible inasmuch as it can be incorporated 

in new systems via drivers and can support special features of 

multimedia systems or file formats. MCI includes commands like open, 

play, and close. 

MCPC (Multiple Channels Per Carrier) – An average satellite transponder 

has a bandwidth of 27 MHz. Typically, the highest symbol rate that can 

be used in SR 26 MS/s, and multiple video or audio channels can be transmitted 

simultaneously. MCPC uses a technique called Time Division 

Multiplex to transmit multiple programs, which works by sending data for 

one channel at a certain time and then data for another channel at another 

time. Many encoder manufacturers are currently experimenting with statistical 

multiplexing of MPEG-2 data. Using this technique, channels that need 

high data rate bursts in order to prevent pixelization of the picture, such as 

live sports events will obtain the bandwidth as they need it by reducing the 




data rate for other services that do not. Statistical multiplexing should 

improve perceived picture quality, especially on video that changes rapidly. 

It also has the advantage of requiring no changes in the receiver 

equipment. 

MDCT (Modified DCT) – Used in Layer 3 audio coding. 

MDS – Multipoint Distribution Service. 

Media Conversion – The process of converting data from one type of 

media to another for premastering and mastering. Premastering software 

typically requires input data on hard disk. 

Median Filter – An averaging technique used by PCEC in its IDTV line 

interpolation scheme to take an average of lines in the current and previous 

fields to optimize resolution and avoid motion artifacts without using 

motion compensation. 

Medium – The substance through which a wave is transmitted. 

Medium Scale Integration (MSI) – Technology by which a dozen or more 

gate functions are included on one chip. 

Medium Shot – Camera perspective between long shot and closeup, 

whereby subjects are viewed from medium distance. 

Mega – One million, i.e., megacycle is one million cycles. 

Megabyte (Mbyte) – One million bytes (actually 1,048,576); one thousand 

kilobytes. 

Megahertz (MHz) – One million hertz (unit of frequency). A normal U.S. 

television transmission channel is 6 MHz. The base bandwidth of the video 

signal in that channel is 4.2 MHz. The SMPTE HDEP system calls for 

30 MHz each for red, green, and blue channels. 

Memory – Part of a computer system into which information can be 

inserted and held for future use. Storage and memory are interchangeable 

terms. Digital memories accept and hold binary numbers only. Common 

memory types are core, disk, tape, and semiconductors (which includes 

ROM and RAM). 

Memory Counter (or Rewind) – A system which allows the tape to be 

rewound automatically to any predetermined point on the tape. 

Memory Effect – Loss of power storing capability in NiCad (video camera) 

batteries which occurs when batteries are habitually discharged only partially 

before recharging. To avoid the memory effect, always fully discharge 

NiCad batteries before recharging. 

Memory Map – Shows the address assignments for each device in the 

system. 

Memory-Mapped I/O – I/O devices that are accessed by using the same 

group of instruction and control signals used for the memory devices in a 

system. The memory and I/O devices share the same address space. 

Menu – a) A list of operations or commands that the IRIS can carry out on 

various objects on the screen. b) A group of parameters and flags that 

enable manipulation of the video image. Menus are Target, Rotate, Border, 

Source (with Sides submenu), Digimatte, Timeline, and KF Flags. c) A 

graphic image, either still or moving, with or without audio provided to offer 

the user a variety of choices within the confines of the authoring and prod- 


uct material provided. It is the traditional meaning of a menu like you might 

find in a restaurant. 

MER – Modulation Error Ratio. 

MESECAM – Middle East SECAM or (B, G, D, K) SECAM. 

Meshbeat – See Moiré. 

Metadata – a) The descriptive and supporting data that is connected to 

the program or the program elements. It is intended to both aid the direct 

use of program content and support the retrieval of content as needed during 

the post-production process. b) Generally referred to as “data about 

data”or “data describing other data.”More specifically, information that is 

considered ancillary to or otherwise directly complementary to the essence. 

Any information that a content provider considers useful or of value when 

associated with the essence being provided. 

Metadata Dictionary – The standard database of approved, registered 

data element tags, their definitions and their allowed formats. 

Metal Particle – One of the most recent developments of a magnetizable 

particle for magnetic tape, products from pure iron and having very high 

coercivity in the range of 850 to 1250 oersteds. 

Metamorphosis – Given two databases with the same number of vertices, 

a metamorphosis causes the first to become the second. This is an animation 

tool. 

Mezzanine Compression – Contribution level quality encoded high definition 

television signals. Typically split into two levels: high level at approximately 

140 Mbps and low level at approximately 39 Mbps (for high definition 

with the studio, 270 Mbps is being considered). These levels of compression 

are necessary for signal routing and are easily re-encoded without 

additional compression artifacts (concatenation) to allow for picture manipulation 

after decoding. DS-3 at 44.736 will be used in both terrestrial and 

satellite program distribution. 

MGT – Master Guide Table. 

MHEG – See Multimedia Hypermedia Expert Group. 

MHz – Megahertz. 

MIB – Management Information Base. 

Micro – One millionth. 

Micro-Cassette – A miniature cassette system originated by Olympus, 

allowing 30 minutes of recording per side on a capstan-driven tape, 1/7" 

wide, running at 15/16 ips. 

Microcode – See Microprogram. 

Microcomputer – Complete system, including CPU, memory and I/O interfaces. 

Microdropouts – Low level, short duration dropouts. They correspond to 

RF envelope dropouts of 10 dB or greater with a duration of 0.5 to 

0.8 microseconds. 

Microphone – A transducer which converts sound pressure waves into 

electrical signals. 

Microphone Impedance – In order to obtain the highest quality output 

signal from a microphone, a preamplifier input should provide a load

(impedance) which exactly matches a microphone’s output impedance. 

Microphone output impedances vary from 150 ohms to several megohms. 

Microphone Preamplifier – A microphone is a transducer which converts 

sound waves to electrical impulses. Microphones typically generate very 

low signal levels requiring low noise, high fidelity, pre-amplification to 

boost the output signal to a level compatible with audio amplifier circuitry. 

Good microphone preamplifiers provide precise matching of microphone 

impedance and low-noise electronic components. 

Microphonics – In video transmission, refers to the mechanical vibration 

of the elements of an electron tube resulting in a spurious modulation of 

the normal signal. This usually results in erratically spaced horizontal bars 

in the picture. 

Microprocessor – Central processing unit fabricated on one or two chips. 

The processor consists of the arithmetic and logic unit, control block, and 

registers. 

Microprogram – Program that defines the instruction set. The microprogram 

(also called microcode) tells the CPU what to do to execute each 

machine language instruction. It is even more detailed than machine language 

and is not generally accessible to the user. 

Microsecond – One millionth of a second: 1 x 10 –6 or 0.000001 second. 

A term used to mean very fast/instantaneous. 

Microwave Dish – A parabolic shaped antenna used for high-frequency 

RF signals. 

Microwave Transmission – Communication systems using high-frequency 

RF to carry the signal information. 

Microwaves – Radio frequencies with very short wavelengths (UHF). 

MII – Portable, professional video component camera/recorder format, 

using 1/2" metal particle videotape. 

MII (M2) – Second generation camera/recorder system developed by 

Panasonic. Also used for just the recorder or the interconnect format. MII 

uses a version of the (Y, R-Y, B-Y) component set. 

MII Format – See the MII discussion. 

Mike – Microphone. 

Mike Boom – A rigid extension to which a microphone may be attached. 

Mike Pad – An attenuator placed between the output of a mike and the 

input of a mike preamp to prevent overdriving the preamp. 

Mil – 0.001 of an inch. 

Miller Squared Coding (M2 ) – A DC-free channel coding scheme used in 

D2 VTRs. 

Millimeter – One thousandth of a meter. 

Millimicron – One billionth of a meter. 

Millisecond – One thousandth of a second. 

MIME – Multi-Purpose Internet Mail Extensions. 

Mini-Cassette – A miniature cassette system originated by Philips, allowing 

15 minutes of recording per side on a narrow tape. 

Minimize – To reduce a window to an icon for later use. 



Minimum Performance – The line between EDTV and HDTV. Naturally, 

each ATV proponent defines minimum performance so as to favor its system 

to the detriment of others. 

MIP – Mega-Frame Initialization Packet. 

MIT (Massachusetts Institute of Technology) – Home of the Media Lab 

and its Advanced Television Research Program (ATRP), its Audience 

Research Facility, its Movies of the Future program, and other advanced 

imaging and entertainment technology research. In addition to conducting 

and publishing a great deal of ATV research, MIT has come up with two 

ATV proposals of its own, one called the Bandwidth Efficient Proposal and 

one the Receiver Compatible Proposal. 

Mix – a) A transition between two video signals in which one signal is 

faded down as the other is faded up. Also called a dissolve or cross fade. 

b) This term is most often used as a synonym for additive mix but may 

also refer to a non-additive mix. 

Mix Effects (M/E) – One of the console modules (or its associated signal 

processing boards) which allows an operator to perform wipes, mixes, 

keys, etc. 

Mixer – The audio or video control equipment used for mixing sound 

and/or video. In video, a device for combining several video input signals. 

Mixing – To combine various pictures and/or audio elements together. 

Mixing Console – A device which can combine several signals into one or 

more composite signals, in any desired proportion. 

Mixing, Digital – A step in post-production during which two or more digital 

representations are combined to create an edited composition. In a 

transmission, recording, or reproducing system, combining two or more 

inputs into a common output, which operates to combine linearly the separate 

input signals in a desired proportion in an output signal. Production: 

Generally the editing of digital image data, resulting in composites ranging 

from simple transitions to multilayered collages combining selected information 

from many interim images. The combining of digital images is 

accomplished by suitable arithmetic calculations on related pairs of digital 

words. Data Processing: A process of intermingling of data traffic flowing 

between concentration and expansion stages. 

MJD – Modified Julian Date. 

MJPEG – See Motion JPEG. 

MMCD (Multimedia CD) – A development proposal from Sony and 

Philips, now integrated in the DVD. 

MMDS (Multi-Point Microwave Distribution System) – A terrestrial 

broadcasting technology which uses low-power microwave transmitters, 

and is mainly used for extending the range of cable TV systems and for TV 

distribution in sparsely populated areas or in areas with rough terrain. 

MMDS is not specifically analog or digital. In digital MMDS, the use of 

MPEG is highly attractive to boost the number of channels that may be distributed. 

MMI – Man Machine Interface. 

Mnemonic Code – Codes designed to assist the human memory. The 

microprocessor language consists of binary words, which are a series of 0s 

and 1s, making it difficult for the programmer to remember the instructions 




corresponding to a given operation. To assist the human memory, the binary 

numbered codes are assigned groups of letters (of mnemonic symbols) 

that suggest the definition of the instruction. For example, the 8085 code 

100000 binary means load accumulator and is represented by the 

mnemonic LDA. 

Mobile Unit – Equipment designed to be movable as a unit. A truck/van 

with all the necessary equipment to do photography/production on location. 

Sometimes mobile units have cameras and VTRs within them and sometimes 

they are added for specific jobs. 

Mod – Abbreviation for Modulator on the 4100 series and Modifier on the 

AVC series. 

Model-Based Coder – Communicating a higher-level model of the image 

than pixels is an active area of research. The idea is to have the transmitter 

and receiver agree on the basic model for the image; the transmitter 

then sends parameters to manipulate this model in lieu of picture elements 

themselves. Model-based decoders are similar to computer graphics rendering 

programs. The model-based coder trades generality for extreme efficiency 

in its restricted domain. Better rendering and extending of the 

domain are research themes. 

Modeling – a) The process of creating a 3D world. There are several 

kinds of 3D modeling, including: boundary representation, parametric (or 

analytic), and constructive solid geometry. After the geometry of a model is 

determined, its surface properties can be defined. b) This process involves 

describing the geometry of objects using a 3D design program. 

Modem (Modulator/Demodulator) – An electronic device for converting 

between serial data (typically RS-232) from a computer and an audio signal 

suitable for transmission over telephone lines. The audio signal is usually 

composed of silence (no data) or one of two frequencies representing 

0 and 1. Modems are distinguished primarily by the baud rates they support 

which can range from 75 baud up to 56000 and beyond. Various data 

compression and error algorithms are required to support the highest 

speeds. Other optional features are auto-dial (auto-call) and auto-answer 

which allow the computer to initiate and accept calls without human 

intervention. 

Modifier – Pattern system electronics capable of modulator effects, continuous 

rotation effects, pattern border hue modulation, pattern border 

rainbows, and position modulation. 

Modulate – To impress information on an AC or RF signal by varying the 

signals amplitude, frequency, or phase. 

Modulated – When referring to television test signals, this term implies 

that chrominance, luminance, sync, color burst, and perhaps audio information 

is present. 

Modulated Carrier Recording – Signal information recorded in the form 

of a modulated carrier. 

Modulated Five Step Test Signal – A test signal with five steps of luminance 

change, each step having a constant frequency and phase chromi- 


nance signal. This signal is used to test for Differential Phase distortions. 

There is also a 10 step version of this signal. 

Modulated Pedestal – A test signal which consists of three chrominance 

packets with the same phase, on the same luminance level (50 IRE), with 

different amplitudes (20, 40, and 80 IRE). This signal is used to test for 

chrominance nonlinear phase distortion and chrominance to luminance 

intermodulation distortion. 

Modulated Ramp Test Signal – A test signal with a linear rise in luminance 

and constant chrominance as shown in the figure below. This signal 

is used to test for Differential Phase distortions. 

Modulation – a) The imposing of a signal on some type of transmission or 

storage medium, such as a radio carrier or magnetic tape. b) The process 

(or result) of changing information (audio, video, data, etc.) into 

information-carrying signals suitable for transmission and/or recording. In 

NTSC-M television transmission, video is modulated onto a picture carrier 

using amplitude modulation-virtual sideband, and audio is modulated onto 

a sound carrier using frequency modulation. 

Modulation Noise – a) Noise which results from the agitation of the oxide 

molecules through the recording process. The modulation noise level 

increases as record level increases and disappears when no signal is pres-

ent. b) The noise arising when reproducing a tape which has been recorded 

with a given signal, and which is a function of the instantaneous amplitude 

of the signal. This is related to DC noise and arises from the same 

causes. 

Modulator – a) A section within a VTR that changes the frequency of the 

video signal information coming in from an external source (i.e., an electronic 

camera) to signal information that is compatible with the requirements 

of the VTR heads, while keeping the picture information basically 

unchanged. b) Pattern system electronics capable of distorting the edge of 

a pattern by impressing a sine or other waveform on the vertical or horizontal 

shape of the pattern. c) The device that places information on an RF 

carrier signal. 

Modulator Lock – A feature that synchronizes the modulator or modifier 

effect to the frame rate, thus preventing the effect from drifting or appearing 

incoherent. 

Module – A small device, not working by itself, designed to perform specialized 

tasks in association with a host, for example: a conditional access 

subsystem, an electronic program guide application module, or to provide 

resources required by an application but not provided directly by the host. 

Moiré – a) An image artifact that occurs when a pattern is created on the 

screen where there should not be one. The moiré pattern is generated 

when different frequencies that are part of the video signal, create a new 

unwanted frequency. b) A wavy pattern, usually caused by interference. 

When that interference is cross-color, the pattern is colored, even if the 

picture is not. c) The spurious pattern in the reproduced television picture 

resulting from interference beats between two sets of periodic structures in 

the image. It usually appears as a curving of the lines in the horizontal 

wedges of the test pattern and is most pronounced near the center where 

the lines forming the wedges converge. A Moiré pattern is a natural optical 

effect when converging lines in the picture are nearly parallel to the scanning 

lines. 

MOL (Maximum Output Level) – In audio tape, that record level which 

produces a 3rd harmonic distortion component at 3.0%. 

Mole Technology – A seamless MPEG-2 concatenation technology developed 

by the ATLANTIC project in which an MPEG-2 bitstream enters a 

Mole-equipped decoder, and the decoder not only decodes the video, but 

the information on how that video was first encoded (motion vectors and 

coding mode decisions). This “side information”or “metadata”in an information 

bus is synchronized to the video and sent to the Mole-equipped 

encoder. The encoder looks at the metadata and knows exactly how to 

encode the video. The video is encoded in exactly the same way (so theoretically 

it has only been encoded once) and maintains quality. If an opaque 

bug is inserted in the picture, the encoder only has to decide how the bug 

should be encoded (and then both the bug and the video have been theoretically 

encoded only once). Problems arise with transparent or translucent 

bugs, because the video underneath the bug must be encoded, and therefore 

that video will have to be encoded twice, while the surrounding video 

and the bug itself have only been encoded once theoretically. What Mole 

cannot do is make the encoding any better. Therefore, the highest quality 

of initial encoding is suggested. 



Moment of Inertia – A measure of the rotational force required to accelerate 

or decelerate a reel of tape or other rotating object. 

Monitor – a) A TV set, or a TV set specifically designed for closed circuit 

viewing (i.e., from a VTR) without the electronic capability to receive broadcast 

signals. b) A hardware device that displays the images, windows, and 

text with which you interact to use the system. It is also called a video display 

terminal (VDT). c) Program that controls the operation of a microcomputer 

system and allows user to run programs, examine and modify memory, 

etc. 

Monitor Head – A separate playback head on some tape recorders that 

makes it possible to listen to the material on the tape an instant after it 

has been recorded and while the recording is still in progress. 

Monitor Outputs – A set of outputs from a switcher or video recorder for 

the specific purpose of feeding video monitors (although not limited to that 

purpose). These include preview, individual M/Es, DSK, and bus rows. The 

AVC also provides monitor outputs for RGB signals, aux bus selections, and 

switcher status information. 

Monitor Power Cable – The cable that connects the monitor to the workstation 

to provide power to the monitor. It has a male connector on one end 

and a female connector on the other. 

Monitor Standardization – Although it is customary to make all subjective 

judgments of image quality from the reference monitor display, the infinite 

possibilities for monitor adjustments have hampered reviewers in exercising 

effective program control, and have introduced many disparities and 

great confusion. The SMPTE Working Group on Studio Monitors, S17.28, is 

completing work on three specifications intended to make the monitor display 

follow a known electro-optic transfer function and permit a reliable 

evaluation of the program image quality. 

Monitor Video Cable – The cable that connects the monitor to the workstation 

to transmit video signals. It has large connector on both ends. 

Monitor, Control – A control monitor is one employed primarily for decisions 

on subject matter, composition, and sequences to be selected in realtime. 

It is frequently one of several monitors mounted together in close 

proximity as in a studio – for example, to display multiple sources that are 

to be compared, selected, and combined in editing for immediate, direct 

routing to display. The physical arrangements may make it very difficult to 

control the surroundings for each monitor, as specified by SMPTE Working 

Group on Studio Monitors in Document S17.280 for the reference monitor. 

It is nevertheless essential when sequences on several monitors are being 

compared and intercut that the monitors match in luminance and 

colorimetry. 

Monitor, Reference – A reference monitor is one employed for decisions 

on image quality. Achieving controlled reproducibility for this application is 

the primary objective of the specifications for monitor standardization. 

SMPTE Working Group on Studio Monitors, S17.28, has recognized the 

great disparity now existing among studio monitors and control monitors, 

and has noted the confusing variability among decisions based upon visual 

judgments of program quality as evaluated on different monitors. They are 

working to identify and recommend specifications for the variables affecting 

subjective judgments, coming not only from the monitor capabilities, 




but also from the adjustment of its controls and the bias introduced by 

monitor surround and room illumination. 

Monitor, Standardization – Although it is customary to make all subjective 

judgments of image quality from the reference monitor display, the infinite 

possibilities for monitor adjustments have hampered reviewers in exercising 

effective program control, and have introduced many disparities and 

great confusion. The SMPTE Working Group on Studio Monitors, S17.27, is 

completing work on three specifications intended to make the monitor display 

follow a known transfer function, electro-optic, and permit a reliable 

evaluation of the program image quality. 

Mono, Monophonic – Single-channel sound. 

Monochrome – Literally single color, usually used to indicate black and 

white. There have been monochrome high line rate cameras and displays 

for many years. The EIA has standardized rates of up to 1225 scanning 

lines per frame. NHK developed a monochrome HDTV system with 2125 

scanning lines per frame. Even higher number of scanning lines are used 

in conjunction with lower frame rates in cathode ray tube scanners used in 

printing and in film. These extremely high rates are possible because 

monochrome picture tubes have no triads. 

Monochrome Signal – A “single color”video signal – usually a black and 

white signal but sometimes the luminance portion of a composite or component 

color signal. 

Monochrome Transmission (Black and White) – The transmission of a 

signal wave which represents the brightness values in the picture but not 

the color (chrominance) values in the picture. 

Monophonic – One sound channel/source/signal. Sometimes called 

monaural. 

MooV – The file format used in the QuickTime and QuickTime for Windows 

environments for displaying videos. See QuickTime, QuickTime for 

Windows. 

Morphing – A technique for making an object change into the shape of 

another. 

MOS (Metal Oxide Semiconductor) – Integrated circuits made of field 

effect transistors. All MOS devices originally used metal gate technology, 

but the term is used to describe silicon gate circuits as well. 

Mosaic – Term used for an ADO effect which is to segmentize a video signal 

into rectangles of variable block sizes and aspect ratio. 

Mosquito Noise – This is caused by quantizing errors between adjacent 

pixels, as a result of compression. As the scene content varies, quantizing 

step sizes change, and the quantizing errors produced manifest themselves 

as shimmering black dots, which look like “mosquitoes”and that show at 

random around objects within a scene. 

Most Significant Bit (MSB) – The bit that has the most value in a binary 

number or data byte. In written form, this would be the bit on the left. For 

example: 

Binary 1110 = Decimal 14 

In this example, the leftmost binary digit, 1, is the most significant bit, here 

representing 8. If the MSB in this example were corrupt, the decimal would 

not be 14 but 6. 


Motherboard – See Backplane. 

Motion Adaptive – An ATV scheme that senses motion and changes the 

way it functions to avoid or reduce motion artifacts. 

Motion Artifacts – a) Picture defects that appear only when there is 

motion in the scene. Interlaced scanning has motion artifacts in both the 

vertical and horizontal directions. There is a halving of vertical resolution at 

certain rates of vertical motion (when the detail in one field appears in the 

position of the next field one sixtieth of a second later), and horizontally 

moving vertical edges become segmented (reduced in resolution) by the 

sequential fields. This is most apparent when a frame of a motion 

sequence is frozen and the two fields flash different information. All subsampling 

ATV schemes have some form of motion artifact, from twinkling 

detail to dramatic differences between static and dynamic resolutions. Line 

doubling schemes and advanced encoders and decoders can have motion 

artifacts, depending on how they are implemented. Techniques for avoiding 

motion artifacts include median filtering and motion adaptation or compensation. 

b) In all temporally-sampled systems (i.e., both photographic and 

electronic), realistic motion reproduction is achieved only with sampling 

above the Nyquist limit. The subjective response to motion artifacts is complex, 

influences by the various degrees of smoothing and strobing affecting 

temporal and spatial resolution, integration and tag in the sensing, recording, 

and display elements; sampling geometry and scanning patterns; shutter 

transmission ratio; perceptual tolerances, etc. (Motion appears “normal” 

only when significant frame-to-frame displacement occurs at less than half 

the frame rate; i.e., “significant motion”distributed over at least two 

frames.) Motion artifacts most frequently observed have their origins in the 

following: image components with velocity functions extending beyond the 

Nyquist limit (such as rotating, spoked wheels), motion samples with such 

short exposures there is noticeable frame-to-frame separation of sharply 

defined images (such as synchronized flash illumination), asynchronous 

sampling of intermittent motion (such as frame-rate conversions). A considerable 

number of motion artifacts appear so frequently as to be accepted 

by most viewers. 

Motion Compensation – In MPEG, the use of motion vectors to improve 

the efficiency of the prediction of pel values. The prediction uses motion 

vectors to provide offsets into the past and/or future reference pictures 

containing previously decoded pel values that are used to form the prediction 

error signal. The book Motion analysis for Image Sequence Coding 

by G. Tziritas and C. Labit documents the technical advances made through 

the years in dealing with motion in image sequences. 

Motion Estimation – The process of determining changes in video object 

positions from one video frame to the next. Object position determination is 

used extensively in high-compression applications. For instance if the 

background of a scene does not change but the position of an object in the 

foreground does, it is advantageous to just transmit the new position of the 

object rather then the background or foreground. This technology is used in 

MPEG, H.261, and H.263 compression. 

Motion JPEG – Applications where JPEG compression or decompression 

is speeded up to be able to process 25 or 30 frames per second and is 

applied real-time to video. Even though a video signal is being processed, 

each field is still individually processed.

Motion Path – The movement between keyframes, changed with the Path 

soft key. There are five types of paths. BRK (Break) modifies Smooth 

motion by decelerating speed to zero at each keyframe (a break), then 

starting again. IGN (Ignore) allows selected parameter values to be ignored 

when calculating motion path. SMTH (Smooth) provides a curved path 

between keyframes. The effect speeds up gradually as it leaves the first 

keyframe, and slows down gradually until it reached the last keyframe. LIN 

(Linear) provides a constant rate of change between keyframes, with an 

abrupt change at each keyframe. Linear uses the shortest distance 

between two points to travel from one keyframe to another. HOLD stops all 

motion between keyframes. The result of the motion shows when the next 

keyframe appears. HOLD looks like a video “cut,”from one keyframe to the 

next. 

Motion Path Velocity – A successful motion path has two components: 

geometry and timing. The geometry is created by choosing keyframes. The 

timing of the path is more complex, and can be affected by the geometry. 

Intuitively, the timing of a path is simply the speed of motion of the object 

as it moves along the path. Since PictureMaker starts with keyframes and 

creates in-between positions, PictureMaker determines the velocity by 

deciding how many in-betweens to place between each keyframe (and 

where to place them). Several methods can be used to determine velocity 

along the path. a) Place frame evenly between all keyframes. Closely 

placed keyframes will correspond with slow moving parts of the path. 

b) Specify a relative velocity at selected keyframes, and specify correspondences 

between any keyframe and a frame in the final animation. 

Motion Resolution – See Dynamic Resolution. 

Motion Surprise – A major shift in the quality of a television picture in the 

presence of motion that is so jarring to the viewer that the system might 

actually appear better if it had continuously lower quality, rather than jumping 

from high-quality static image to a lower quality dynamic one. 

Motion Vector – a) A two-dimensional vector used for motion compensation 

that provides an offset from the coordinate position in the current picture 

to the coordinates in a reference picture. b) A pair of numbers which 

represent the vertical and horizontal displacement of a region of a reference 

picture for production. 

Mount – To make a file system that is stored on a local or remote disk 

resource accessible from a specific directory on a workstation. 

Mount Point – The directory on a workstation from which you access 

information that is stored on a local or remote disk resource. 

Mouse – A hardware device that you use to communicate with windows 

and icons. You move the mouse to move the cursor on the screen, and you 

press its buttons to initiate operations. 

Mouse Pad – For an optical mouse, this is the rectangular, metallic surface 

that reads the movements of the mouse. For a mechanical mouse, this 

is a clean, soft rectangular surface that makes the mouse’s track ball roll 

efficiently. 

MOV – The file extension used by MooV format files on Windows. See 

MooV. 

Moving Dots – See Chroma Crawl. 



Moving Picture Experts Group (MPEG) – An international group of 

industry experts set up to standardize compressed moving pictures and 

audio. The first release of the MPEG standard was called MPEG-1. 

Moving Picture Experts Group 1 (MPEG-1) – ISO/IEC CD 11172 is the 

first of the standards designed for handling highly compressed moving 

images in real-time. It accepts periodically chosen frames to be compressed 

as in JPEG-1, predicts the content of intervening frames, and 

encodes only the difference between the actual and the prediction. Audio is 

compressed synchronously. The encoder includes a decoder section in 

order to generate and verify the predictions. At the display, a much simpler 

decoder becomes possible. MPEG-1 is optimized for a data rate of up to 

1.5 Mb/s. MPEG expects to develop a series of compression codes, optimized 

for higher bit rates. 

Moving Picture Experts Group 2 (MPEG-2) – MPEG-2 expands the 

MPEG-1 standard to cover a wider range of applications. 

Moving Picture Experts Group 3 (MPEG-3) – MPEG 3 was originally 

intended for HDTV applications but has since been incorporated into 

MPEG-2. 

Moving Picture Experts Group 4 (MPEG-4) – The goal of MPEG-4 is to 

establish a universal and efficient coding for different forms of audio-visual 

data, called audio-visual objects. Coding tools for audio-visual objects are 

being developed to support various functionalities, such as object-based 

interactivity and scalability. The syntax of the audio-visual objects is being 

developed to allow for description of coded objects and to describe how 

they were coded. This information can then be down loaded into a decoder. 

MPEG-4 is expected to be available by the year 2000. 

Moving-Coil – A microphone whose generating element is a coil which 

moves within a magnetic gap in response to sound pressure on the 

diaphragm attached to it, rather like a small loudspeaker in reverse. The 

most common type of Dynamic Microphone. 

MP – Multi-Link Point-to-Point Protocol. 

MP3 – A commonly used term for the MPEG-1 Layer 3 (ISO/IEC 11172-3) 

or MPEG-2 Layer 3 (ISO/IEC 13818-3) audio compression formats. MPEG-1 

Layer 3 is up to two channels of audio and MPEG-2 Layer 3 is up to 5.1 

channels of audio. MP3 is not the same as MPEG-3. 

MP@HL (Main Profile at High Level) – Widely used shorthand notation 

for a specific quality and resolution of MPEG: Main Profile (4:2:0 quality), 

High Level (HD resolution). 

MP@ML – Main Profile at Main Level. 

MPCD (Minimum Perceptible Color Difference) – A unit of measure, 

developed by the CIE, to define the change in light and color required to be 

just noticeable to the human eye. The human being in this MPCD unit is 

defined as “a trained observer”because there are differences in the way 

each of us perceive light. 

MPEG – A standard for compressing moving pictures. MPEG uses the similarity 

between frames to create a sequence of I, B, and P frames. Only the I 

frame contains all the picture data. The B and P frames only contain information 

relating to changes since the last I frame. MPEG-1 uses a data rate 

of 1.2 Mbps, the speed of CD-ROM. MPEG-2 supports much higher quality 

with a data rate (also called bit rate) of from 1.2 to 15 Mbps. MPEG-2 is 




the format most favored for video on demand, DVD, and is the format for 

transmitting digital television. 

MPEG-1 – See Moving Picture Experts Group 1. 




MPEG 4:2:2 – Also referred to as Studio MPEG, Professional MPEG, and 

442P@ML. Sony’s Betacam SX is based on MPEG 4:2:2. 

MPEG-7 – MPEG-7 is a multimedia content (images, graphics, 3D models, 

audio, speech, video) representation standard for information searching. 

Final specification is expected in the year 2000. 

MPEG Splicing – The ability to cut into an MPEG bitstream for switching 

and editing, regardless of frame types (I, B, P). 

MPEG TS – MPEG Transport Stream. 

MPI – MPEG Physical Interface. 

MPTS – Multi-Port Presentation Time Stamps. 

MPP (Mix to Preset Pattern) – See Preset Pattern. 

MPU (Microprocessing Unit) – See Microprocessor. 

MSB – Most Significant Bit. 

MSDL – MPEG-4 Syntactic Description Language. 

MSI – Medium Scale Integration. 

MSO – Multiple Cable System Operator. 

MTBF – Mean Time Between Failures. 

MTS – Used in conjunction with NTSC/525. Consists of two independent 

carriers each carrying a discrete channel. One channel provides stereo 

sound by providing left/right channel difference signals relative to transmitted 

mono audio track. The second carrier carries the Secondary Audio 

Program (SAP) which is used for a second language or a descriptive commentary 

for the blind. Uses a technique based on the dBx noise reduction 

to improve the frequency response of the audio channel. 

MTTR – Mean Time to Repair. 

MTU – Multi-Port Transceiver Unit. 


Multiburst – The multiburst waveform is shown in the figure below. This 

signal is useful for quick approximations of the system’s frequency 

response and can be used as an in-service VIT signal. 

0.5 1.25 2.0 3.0 3.58 4.1 MHz 

4~ 8~ 10~ 14~ 16~ 18~ (Cycles) 

MultiCrypt – Used to describe the simultaneous operation of several conditional 

access systems. 

Multifrequency Monitor – A monitor that accommodates a variety of horizontal 

and vertical synchronization frequencies. This monitor type accepts 

inputs from many different display adapters, and is typically capable of 

either analog or digital input. 

Multi-Language Support – A DVD has the ability to store eight audio 

streams. This is different than the number of channels each stream might 

have. Thus, each of the streams might contain a multi-channel audio program 

in a separate language. 

Multi-Layer Effects – A generic term for a mix/effects system that allows 

multiple video images to be combined into a composite image. 

Multimedia – A somewhat ambiguous term that describes the ability to 

combine audio, video, and other information with graphics, control, storage, 

and other features of computer-based systems. Applications include presentation, 

editing, interactive learning, games, and conferencing. Current 

multimedia systems also use mass storage computer devices such as 

CD-ROM. 

Multimedia Hypermedia Expert Group (MHEG) – MHEG is another 

working group under the same ISO/IEC subcommittee that feature the 

MPEG. The MHEG is the Working Group 12 (WG 12) of Subcommittee 29 

(SC 29) of the joint ISO and IEC Technical Committee 1 (JTC 1). The 

ISO/IEC standards produced have number 13522. MHEG targets coding of 

multimedia and hypermedia information, and defines an interchange format 

for composite multimedia contents. The defined MHEG format encapsulates 

a multimedia document, so to speak, as communication takes place in a 

specific data structure. Despite the talk about multimedia, there is not very 

much said and written about MHEG, which seems odd given the realm of 

MHEG. The present market significance of MHEG is very low, probably due 

to the high number of proprietary standards for audio visual representation 

in multimedia PC environments. 

Multipath Distortion – A form of interference caused by signal reflections. 

Signals that are reflected more take a longer path to reach the 

receiver than those that are reflected less. The receiver will synchronize to

the strongest signal, with the weaker signals traveling via different paths 

causing ghostly images superimposed on the main image. Since many ATV 

schemes offer increased horizontal resolution, ghosts can have a more 

deleterious effect on them than on ordinary NTSC signals. There have been 

many demonstrations of ghost canceling/eliminating systems and robust 

transmission systems over the years. It is probable that these will have to 

be used for HDTV. 

Multiplane Animation – Multiplane animation refers to a type of cel animation 

where individual cels are superimposed using the painters algorithm, 

and their motion relative to each other is controlled. Here, the word 

“plane”and cel are interchangeable. 

Multiple Blanking Lines – Evidenced by a thickening of the blanking line 

trace or by several distinct blanking lines as viewed on an oscilloscope. 

May be caused by hum. 

Multiple-FIFO Architecture – A display controller architecture characterized 

by having multiple FIFOs or write buffers. There is typically one FIFO or 

write buffer at the CPU interface, and one or more FIFOs in the display 

pipeline. 

Multiplex – a) To take, or be capable of taking, several different signals 

and send them through one source. b) To combine multiple signals, usually 

in such a way that they can be separated again later. There are three major 

multiplexing techniques. Frequency division multiple (FDM) assigns each 

signal a different frequency. This is how radio and television stations in the 

same metropolitan area can all transmit through the same air space and be 

individually tuned in. Time division multiple (TDM) assigns different signals 

different time slots. Different programs can be broadcast over the same 

channel using this technique. More technically, the MADs use TDM for 

luminance and chrominance. Space or path division multiplex allows different 

television stations in different cities to use the same channel at the 

same time or different people to talk on different telephones in the same 

building at the same time. c) A stream of all the digital data carrying one 

or more services within a single physical channel. d) To transmit two or 

more signals at the same time or on the same carrier frequency. e) To 

combine two or more electrical signals into a single, composite signal. 

Multiplexed Analog Component – See MAC. 

Multiplexer (MUX) – Device for combining two or more electrical signals 

into a single, composite signal. 

Multiplexing – Process of transmitting more than one signal via a single 

link. The most common technique used in microprocessor systems is timedivision 

multiplexing, in which one signal line is used for different information 

at different times. 

Multiplier – A control circuit in which a non-video control signal is faded 

down as the other is faded up. 

Multipoint Control Unit (MCU) – A switching device commonly used to 

switch and control a videoconferencing network allowing multiple sites to 

conference simultaneously. 

Multiprotocol Encapsulation – The data broadcast specification profile 

for multiprotocol encapsulation supports data broadcast services that 

require the transmission of datagrams of communication protocols via DVB 

compliant broadcast networks. The transmission of datagrams according to 



the multiprotocol encapsulation specification is done by encapsulating the 

datagrams in DSM-CC sections, which are compliant with the MPEG-2 private 

sector format. 

Multipulse – This signal is a variation of the sine-squared pulses. 

Multipulse allows for the simultaneous evaluation of group-delay errors and 

amplitude errors at the various frequencies. Distortions show up in multipulse 

as distortions of the baseline as was seen in the Chrominance to 

Luminance Gain and Delay measurements or the Group Delay measurement. 

Refer to the figure and to the Sine-Squared pulse discussion. 

1.0 2.0 3.0 3.58 4.2 MHz 

2T 25T 12.5T 12.5T 12.5T 12.5T 

Multi-Scan Monitor – A monitor (also referred to as multi-sync or multifrequency) 

which can synchronize to different video signal sync frequencies, 

allowing its use with various computer video outputs. See Analog 

Monitor. 

Multi-Standard – TV sets, VTRs, etc., that are designed to work using 

more than one technical standard; i.e., a VTR which can record both NTSC 

and PAL signals/recordings is a multi-standard machine. 

Multitrack Tape – A piece of magnetic tape which can be used to store 

two or more discrete signals. 

Munsell Chroma – a) Illuminating Engineering: The index of perceived 

(Y) and chromaticity coordinates (x,y) for CIE Standard Illuminance C and 

the CIE Standard Observer. b) Television: The dimension of the Munsell 

system of color that corresponds most closely to saturation. Note: Chroma 

is frequently used, particularly in English works, as the equivalent of 

saturation. 

Munsell Color System – A system of surface-color specifications based 

on perceptually uniform color scales for the three variables. Munsell hue, 

Munsell value, and Munsell chroma. For an observer of normal color vision, 

adapted to daylight and viewing the specimen when illuminated by daylight 

and surrounded with a middle gray to white background, the Munsell hue, 

value, and chroma of the color correlate well with the hue, lightness, and 

perceived chroma. 

MUSE (Multiple Sub-Nyquist Sampling Encoding) – a. 16:9 aspect 

ratio, high definition, widescreen television being proposed in Japan. b) A 

term originally used for a transmission scheme developed by NHK specifically 

for DBS transmission of HDTV. MUSE has since been extended to a 




family of ATV transmission schemes. MUSE, as it was originally developed, 

is a form of MAC. Recent versions of MUSE (MUSE- and MUSE-9) are said 

to be receiver-compatible and, as such, cannot employ MAC techniques. 

The sub-Nyquist part of the name indicates that MUSE is a sub-sampling 

system and, as such, is subject to motion artifacts. While it is one of the 

oldest ATV transmission schemes still considered viable, MUSE is only four 

years old. 

MUSE-6 – A family of three versions of an ATV transmission scheme said 

to be both receiver-compatible and channel-compatible. Since the original 

MUSE schemes are neither, there is little similarity between them, other 

than the use of sub-sampling. The differences between the three versions 

relate to how the wide aspect ratio is handled and what techniques are 

used for augmentation in an ATV set. Two versions of MUSE-6 use the letterbox 

technique for aspect ratio accommodation and both of these use 

blanking stuffing in the expanded VBI area for vertical resolution enhancement. 

The differences between the two versions relate to the duration of 

the sub-sampling sequence (one frame or two). The third uses the truncation 

technique for aspect ratio accommodation, sending the side panels 

stuffed into the existing VBI and HBI. Additional horizontal detail is transmitted 

via two-frame sub-sampling. 

MUSE-9 – A family of three versions of an ATV transmission scheme said 

to be receiver-compatible and using a 3 MHz augmentation channel. The 

three versions are very similar to the three versions of MUSE-6, except that 

the version using the truncation method sends the wide-screen panels on 

the augmentation channel rather than stuffing them into the HBI and the 

VBI. There are two classes of the three versions of MUSE-9, one with a 

contiguous augmentation channel and one without. The one without is said 

to be somewhat inferior in quality to the one with. 

MUSE-E – MUSE optimized for emission (i.e., broadcasting) rather than 

transmission (i.e., satellite distribution). It is a non-receiver-compatible, 

non-channel-compatible scheme occupying 8.1 MHz of base bandwidth 

and requiring four fields to build up a full-resolution picture. Thus, it 


requires motion compensation (and retains some motion artifacts). It offers 

four channels of high-quality digital audio. It has been tested in the 

Washington, DC area. 

MUSE-II – See MUSE-E. 

MUSE-T – MUSE optimized for transmission (via satellite) rather than 

emission (via terrestrial broadcasting). It occupies twice the bandwidth of 

MUSE-E (16.2 MHz), but is otherwise quite similar. 

Music and Effects Track(s) – Music and effects audio without video. Can 

be on one track, on different tracks on one piece of film or tape, or on different 

tapes, which are combined during an audio “track mix”session. 

Sometimes abbreviated M&E. 

MUSICAM (Masking Pattern Adapted Universal Sub-Band Integrated 

Coding and Multiplexing) – Compression method for audio coding. 

Must Carry – Legal requirement that cable operators carry local broadcast 

signals. Cable systems with 12 or fewer channels must carry at least three 

broadcast signals; systems with 12 or more channels must carry up to 

one-third of their capacity; systems with 300 or fewer subscribers are 

exempt. The 1992 Cable Act requires broadcast station to waive mustcarry 

rights if it chooses to negotiate retransmission compensation (see 

Retransmission consent). 

MUX – See Multiplexer. 

Mux Rate – Defined by MPEG-2 as the combined rate of all video and 

audio elementary stream packets common to one program. This rate also 

includes the VBI and sub-picture private stream data, which MPEG treats 

as a private stream type. Mux rate is always specified as 10.08 mb/s 

because this is the rate at which user data arrives into the track buffer. 

MVDS – Multi-Point Video Distribution System. 

Mylar – A registered trademark of E.I. duPont de Nemours & Co., designating 

their polyester film.

N 

NAB (National Association of Broadcasters) – An association which 

has standardized the equalization used in recording and reproducing. This 

is a station owner and/or operator’s trade association. NAB is also a participant 

in ATV testing and standardization work, and a charter member of 

ATSC. Though not a proponent of any particular ATV system, NAB lobbies 

for the interests of broadcasting as a delivery mechanism and has published 

some of the least biased information on the subject. 

NAB Curves, NAB Equalization – Standard playback equalization curves 

for various tape speeds, developed by the National Association of 

Broadcasters. 

NAB Reel, NAB Hub – Reels and hubs used in professional recording, 

having a large center hole and usually an outer diameter of 10-1/2". 

NABET (National Association of Broadcast Employees and 

Technicians) – NABET is a union of technicians that supplies members 

for many videotape, live, and film productions. 

NABTS – See North American Broadcast Teletext Specification. 

Nagra – A brand of audio tape recorder using 1/4" wide audio tape extensively 

used for studio and location separate audio recording. 

NAM – Non-Additive Mix. 

NANBA – North American National Broadcasters Association. 

Nanosecond – One billionth of a second: 1 x 10 –9 or 0.000000001 

second. 

NAP (North American Philips) – Philips Laboratories developed the 

HDS-NA ATV scheme and was among the first to suggest advanced precombing. 

See also PCEC. 

Narrow MUSE – An NHK-proposed ATV scheme very similar to MUSE (and 

potentially able to use the same decoder) but fitting within a single, 6 MHz 

transmission channel. Unlike MUSE-6 and MUSE-9, narrow MUSE is not 

receiver-compatible. 

Narrowband – Relatively restricted in bandwidth. 

Narrowcasting – Broadcasting to a small audience. 

National Television System Committee (NTSC) – a) The organization 

that formulated the “NTSC”system. Usually taken to mean the NTSC color 

television system itself, or its interconnect standards. NTSC is the television 

standard currently in use in the United States, Canada, and Japan. NTSC 

image format is 4:3 aspect ratio, 525 lines, 60 Hz and 4 MHz video bandwidth 

with a total 6 MHz of video channel width. NTSC uses YIQ. NTSC-1 

was set in 1948. It increased the number of scanning lines from 441 to 

525, and replaced AM sound with FM. b) The name of two standardization 

groups, the first of which established the 525 scanning-line-per-frame/30 

frame-per-second standard and the second of which established the color 

television system currently used in the United States; also the common 

name of the NTSC-established color system. NTSC is used throughout 

North America and Central America, except for the French islands of St. 

Pierre and Miquelon. It is also used in most of the Caribbean and in parts 

of South America, Asia, and the Pacific. It is also broadcast at U.S. military 



installations throughout the world and at some oil facilities in the Middle 

East. Barbados was the only country in the world to transmit NTSC color on 

a non-525-line system; they have since switched to 525 lines. Brazil 

remains the only 525-line country to transmit color TV that is not NTSC; 

their system is called PAL-M. M is the CCIR designation for 525-line/30 

frame television. See also M. 

Native Resolution – The resolution at which the video file was captured. 

NAVA (National Audio-Visual Association) – A trade association for 

audio-visual dealers, manufacturers and producers. 

NBC – Television network that was an original proponent of the ACTV ATV 

schemes. NBC was also the first network to announce its intention to shift 

from NTSC entirely to CAV recording equipment. 

NBC – Non-Backwards Compatible. 

NCTA (National Cable Television Association) – The primary cable TV 

owner and/or operator’s trade association. NCTA is performing similar roles 

to NAB in ATV research and lobbying, with an emphasis on CATV, rather 

than broadcasting, of course, and is a charter member of ATSC. 

NDA – Non-Disclosure Agreement. 

NE – Network Element. 

Near Instantaneous Companded Audio Multiplex (NICAM) – a) A digital 

audio coding system originally developed by the BBC for point-to-point 

links. A later development, NICAM 728 is used in several European countries 

to provide stereo digital audio to home television receivers. b) A digital 

two-channel audio transmission with sub-code selection of bi-lingual 

operation. Stereo digital signals with specifications approaching those of 

compact disc are possible. NICAM uses a 14-bit sample at a 32 kHz sampling 

rate which produces a data stream of 728 kbits/sec. 

Negative Effect – Special effect in which either blacks and whites are 

reversed or colors are inverted. For example, red becomes a blue-green, 

green becomes purple, etc. The Video Equalizer and Digital Video Mixer 

includes a negative effect which can be used to generate electronic color 

slides from color negatives. An electronic color filter can be used for fine 

adjustment of the hues. 

Negative Image – Refers to a picture signal having a polarity which is 

opposite to normal polarity and which results in a picture in which the 

white areas appear as black and vice versa. 

Negative Logic – The logic false state is represented by the more positive 

voltage in the system, and the logic true state is represented by the more 

negative voltage in the system. For TTL, 0 becomes +2.4 volts or greater, 

and 1 becomes +0.4 volts or less. 

Nested – Subroutine that is called by another subroutine or a loop within a 

larger loop is said to be nested. 

NET (National Educational Television) – A public TV Network of stations. 

Network – a) A group of stations connected together for common broadcast 

or common business purposes; multiple circuits. b) A group of computers 

and other devices (such as printers) that can all communicate with 




each other electronically to transfer and share information. c) A collection 

of MPEG-2 Transport Stream (TS) multiplexes transmitted on a single delivery 

system, e.g., all digital channels on a specific cable system. 

Network Administrator – The individual responsible for setting up, maintaining, 

and troubleshooting the network, and for supplying setup information 

to system administrators of each system. 

Neutral – Normal; without power; not in working position; without much 

color or brightness purposes; multiple circuits. 

Neutral Colors – The range of gray levels, from black to white, but without 

color. For neutral areas in the image, the RGB signals will all be equal; 

in color difference formats, the color difference signals will be zero. 

New York Institute of Technology – Private engineering school headquartered 

in Old Westbury, NY, noted for its advanced computer graphics. 

Its Science and Technology Research Center, in Dania, FL, has been 

researching ATV for years. NYIT is a proponent of the VISTA ATV scheme. 

NFS (Network File System) – A distributed file system developed by 

Sun that enables a set of computers to cooperatively access each other’s 

files transparently. 

NG – An often-used term meaning “no good.” 

NHK – See Nippon Hoso Kyokai. 

Nibble – Four bits or half a byte. A group of four contiguous bits. A nibble 

can take any of 16 (24 ) values. 

NiCad (Nickel Cadmium) – Common Rechargeable video camera battery 

type. 

NICAM – See Near Instantaneous Companded Audio Multiplexer. 

Nippon Hoso Kyokai (NHK) – The Japan Broadcasting Corporation, principal 

researchers of HDTV through the 1970s, developers of the 1125 

scanning-line system for HDEP and of all the MUSE systems for 

transmission. 

Nippon Television – See NTV. 

NIST (National Institute of Standards and Technology) – The North 

American regional forum at which OSI implementation agreements are 

decided. It is equivalent to EWOS in Europe and AOW in the Pacific. 

NIT (Network Information Table) – Information in one transport stream 

that describes many transport streams. The NIT conveys information relating 

to the physical organization of the multiplex, transport streams carried 

via a given network, and the characteristics of the network itself. Transport 

streams are identified by the combination of an original network ID and a 

transport stream ID in the NIT. 

Nits – The metric unit for brightness. 1 foot lambert = 3.425 nits. 

NIU – Network Interface Unit. 

NMI (Non-Maskable Interrupt) – A hardware interrupt request to the 

CPU which cannot be masked internally in the processor by a bit, but must 

be serviced immediately. 

NNI (Nederlands Normalisatie-Instituut) – Standards body in the 

Netherlands. 


Node – a) A list of calculations that you can apply to materials as part of 

the rendering tree language. The node can, in turn, serve as input to other 

nodes. b) Any signal line connected to two or more circuit elements. All 

logic inputs and outputs electrically connected together are part of the 

same node. 

Nodules – Clusters of materials, i.e., a large nodule of iron oxide on magnetic 

tape would be a tape defect. 

Noise – Any unwanted electrical disturbances, other than crosstalk or distortion 

components, that occur at the output of the reproduce amplifier. 

System Noise: The total noise produced by the whole recording system, 

including the tape. Equipment Noise: The noise produced by all the components 

of the system, with the exception of the tape. Tape Noise: The 

noise that can be specifically ascribed to the tape. There are several 

sources of tape noise. See DC Noise, Erase Noise, Modulation Noise, 

Saturation Noise, and Zero Modulation Noise. 

Noise Gate – A device used to modify a signal’s noise characteristics. In 

video, noise gates provide optimal automatic suppression of snow (signal 

noise level). In audio, a noise gate provides a settable signal level threshold 

below which all sound is removed. 

Noise Pulse – A spurious signal of short duration that occurs during 

reproduction of a tape and is of magnitude considerably in excess of the 

average peak value of the ordinary system noise. 

Noise Reduction – The amount in dB that the noise added to a signal by 

transmission or storage chain, especially a tape recorder, is reduced from 

the level at which it would be if no noise reduction devices were used. 

Noise Reduction Systems – Refers to electronic circuits designed to 

minimize hiss level in magnetic recording. 

Noise Weighting – An adjustment used in the electrical measurement of 

television signal noise values, to take into account the difference between 

the observable effect of noise in a television picture and the actual electrical 

value of noise. 

Noise/A-Weighted – Unwanted electrical signals produced by electronic 

equipment or by magnetic tape. Mostly confined to the extremes of the 

audible frequency spectrum where it occurs as hum and/or hiss. A-weighted 

noise is noise measured within the audio frequency band using a measuring 

instrument that has a frequency selective characteristic. The frequency 

sensitivity of the measuring instrument is adjusted to correspond to that 

of the average human hearing response. 

Noisy – A description of a picture with abnormal or spurious pixel values. 

The picture’s noise is a random variation in signal interfering with the 

information content. 

Noisy Video – Noisy video (e.g., video from low quality VTRs) is more difficult 

to code than the cleaner version of the same sequence. The reason is 

that the video encoder spends many bits trying to represent the noise as if 

it were part of the image. Because noise lacks the spatial coherence of the 

image, it is not coded efficiently. 

Nomograph – A table that allows for the determination of Chrominance to 

Luminance Gain and Delay errors. Refer to the discussion on Chrominance 

to Luminance Gain and Delay.

Non-Additive Mix (NAM) – The process of combining two video signals 

such that the resultant video signal is instant-by-instant the same as the 

brighter of the two weighted input signals. For example, at 50% fader, the 

brighter of the two videos predominates. The net effect of this type of mix 

is a superimposed appearance, with the picture balance controlled by the 

fader. 

Non-Compatible – Incapable of working together. 

Noncomposite Video – A video which does not contain a synchronizing 

pulse. 

Nondirectional – A pickup pattern which is equally sensitive to sounds 

from all directions. 

Non-Drop Frame – System of time code that retains all frame numbers in 

chronological order, resulting in a slight deviation from real clock time. 

Non-Ferrous – Without iron or iron oxide. 

Noninterlaced – Method of scanning video in which the entire frame is 

scanned at once rather than interleaved. The rate of scan must be fast 

enough that the average light level of the scene does not decrease 

between scans and cause flicker. Another term for a noninterlaced system 

is progressive scan. 

Non-Intra Coding – Coding of a macroblock or picture that uses information 

both from itself and from macroblocks and pictures occurring at other 

times. 

Nonlinear – A term used for editing and the storage of audio, video, and 

data. Information (footage) is available anywhere on the media (computer 

disk or laser disc) almost immediately without having to locate the desired 

information in a time linear format. 

Nonlinear Distortion – Amplitude dependent waveform distortions. This 

includes APL and instantaneous signal level changes. Analog amplifiers are 

linear over a limited portion of their operating range. Signals which fall outside 

of the linear range of operation are distorted. Nonlinear distortions 

include crosstalk and intermodulation effects between the luminance and 

chrominance portions of the signal. 

Nonlinear Editing (NLE) – a) The process of editing using rapid retrieval 

(random access) computer controlled media such as hard disks, CD-ROMs 

and laser discs. Its main advantages are: allows you to reorganize clips or 

make changes to sections without having to redo the entire production and 

very fast random access to any point on the hard disk (typically 20-40 ms). 

b) Nonlinear distinguished editing operation from the “linear”methods 

used with tape. Nonlinear refers to not having to edit material in the 

sequence of the final program and does not involve copying to make edits. 

It allows any part of the edit to be accessed and modified without having to 

re-edit or re-copy the material that is already edited and follows that point. 

Nonlinear editing is also non-destructive, the video is not changed but the 

list of how the video is played back is modified during editing. 

Nonlinear Editor – An editing system based on storage of video and 

audio on computer disk, where the order or lengths of scenes can be 

changed without the necessity of reassembling or copying the program. 

Nonlinear Encoding – Relatively more levels of quantization are assigned 

to small amplitude signals, relatively fewer to the large signal peaks. 



Nonlinearity – The amount by which a measured video signal output differs 

from a standard video signal output. The greater this deviation, the 

greater the video signal distortion and possibility of luminance and chrominance 

problems. Having gain vary as a function of signal amplitude. 

Non-Return-to-Zero (NRZ) – A coding scheme that is polarity sensitive. 

0 = logic low; 1 = logic high. 

0 1 0 0 1 0 1 

Non-Return-to-Zero Inverse (NRZI) – A video data scrambling scheme 

that is polarity insensitive. 0 = no change in logic; 1 = a transition from 

one logic level to the other. 

0 1 0 0 1 0 1 

NRZ 

NRZI 

Non-Synchronous – Separate things not operating together properly, i.e., 

audio and video or the inability to properly operate together with another 

specific piece of equipment or signal. See Synchronous. 

Non-Synchronous Source – A video signal whose timing information differs 

from the reference video by more than 800 ns. 

Non-Uniform B-Splines (NURBS) – A superset of both Bézier and 

Uniform B-Splines. NURBS introduces the feature of non-uniformity. Thus it 

is possible to subdivide a spline, for example, to locally increase the number 

of control points without changing the shape of the spline. This is a 

powerful feature which enables you to insert more control points on a 

spline without altering its shape; cut anywhere on a spline to generate two 

parts; and creates cusps in splines. 

Non-Useful DC Component – Produced by the transmission equipment 

and not related to picture content. The non-useful DC component present 

across the interface point, with or without the load impedance connected, 

shall be zero ±50 µV. 




Normal – a) Relating to the orientation of a surface or a solid, a normal 

specifies the direction in which the outside of the surface or the solid 

faces. b) The normal to a plane is the direction perpendicular to the 

surface. 

Normal Key – On the 4100 series, an RGB chroma key or a luminance 

key, as distinct from a composite (encoded) chroma key. 

Normal/Reverse – The specification of the direction a pattern moves as 

the fader is pulled. A normal pattern starts small at the center and grows 

to the outside while a reverse pattern starts from the edge of the screen 

and shrinks. Normal/Reverse specifies that the pattern will grow as the 

fader is pulled down, and shrink as it is pushed up. This definition loses 

some meaning for wipes that do not have a size per-se such as a vertical 

bar, however, this feature still will select the direction of pattern movement. 

North American Broadcast Teletext Specification – Provisions for 

525-line system C teletext as described in EIA-516 and ITU-R BT.653. 

Notch Filter – A device which attenuates a particular frequency greatly, 

but has little effect on frequencies above or below the notch frequency. 

Notifier – A form that appears when the system requires you to confirm 

an operation that you just requested, or when an error occurs. 

NRZ – See Non-Return-to-Zero. 

NRZI – See Non-Return-to-Zero Inverse. 

NSAP – Network Service Access Point. 

NSF (Norges Standardiseringsforbund) – Standards body of Norway. 

NST – Network Status Table. 

NTC-7 Composite Test Signal – 

NTSC – See National Television System Committee. 


NTSC Artifacts – Defects associated with NTSC: 

What’s Wrong with NTSC 

A.Monochrome and Color Defects 

1.Due to Sampling 

• Temporal Alias 

• Vertical Alias 

• Vertical Resolution Loss (Kell Factor) 

2.Due to aperture 

• Visible Scannig Lines 

• Soft Vertical Edges 

3.Due to Interlace 

• Twitter 

• Line Crawl 

• Vertical Resolution Loss (Interlace Coefficient) 

• Motion Artifacts, Vertical and Horizontal 

4.Due to Transmission 

• Ghosts 

• ICPM 

• Group Delay 

• Impulsive Noise 

• Periodic Noise 

• Random Noise 

• Interference 

• Filter Artifacts 

5.Due to Changing Equipment 

• Non-Linear System Gamma 

B.Color Defects 

1.Visible in Monochrome 

• Cross Luminance 

• Visible Subcarrier 

• Chroma Crawl 

• Gamma Problems 

• Detail Loss Due to Filters 

• Ringing Due to Filters 

2.Visible in Color 

• Cross Color 

• Detail Loss Due to Filters 

• Ringing Due to Filters 

• Detail Loss Due to Triad Size 

C.Characteristics of the System 

(Not Necessarily Defects) 

1.4:3 Aspect Ratio 

2.330 x 330 Resolution 

3.NTSC Colorimetry 

4.15 kHz Sound 

NTSC Color – The color signal TV standard set by the National Television 

Standards Committee of the USA.

NTSC Composite Video Receiver System – 

NTSC Composite Video Transmitter System – 

Light 

from 

the 

Scene 

Red 

Green 

Blue 

RF, IF and 

Detector 

Circuits 

3.579545 MHz 

Subcarrier 

Oscillator 

Camera 

S 

90 Degree 

Phase Shift 

R 

G 

B 

Video 

Amplifier 

3.579545 MHz 

Chroma 

Amplifier 

Matrix 

B-Y 

I 

Demodulator 

Q 

Demodulator 

NTSC Decoder – An electronic circuit that breaks down the composite 

NTSC video signal into its components. 

NTSC Format – A color television format having 525 scan lines (rows) of resolution 

at 30 frames per second (30 Hz). See NTSC. Compare PAL Format. 

NTSC MUSE – Term sometimes used for MUSE-6 and MUSE-9. 

NTSC Standard – Documentation of the characteristics of NTSC. NTSC is 

defined primarily in FCC Part 73 technical specifications. Many of its characteristics 

are defined in EIA-170A. NTSC is also defined by the CCIR. 

NTSC is a living standard; as problems with it are discovered, they are corrected. 

For example, a former EIA standard, RS-170, omitted any phase 

relationship between luminance and chrominance timing, resulting in 

blanking problems. EIA-170A defines that relationship (called SC/H for subcarrier 

to horizontal phase relationship). See also True NTSC. 

NTSC-M – The U.S. standard of color television transmissions. See also 

NTSC and M. 

NTU – Network Termination Unit. 

NTV (Nippon Television Network) – A Japanese broadcaster that is a 

proponent of ATV schemes similar to Faroudja’s SuperNTSC. NTV’s first 

generation EDTV system would use high line-rate and/or progressive scan 

cameras with prefiltering, adaptive emphasis, gamma correction, ghost 

cancellation, a progressive scan display, and advanced decoding at the 

Y 

R-Y 

Y 

Q 

90 Degree 

Phase Shift 

3.579545 MHz 

Subcarrier 

Oscillator 

I 

Matrix 

Adder Transmitter 

S 

B-Y 

Modulator 

B-Y 

Modulator 

R 

G 

B 

C 



receiver. The second generation would add more resolution, a widescreen 

aspect ratio, and better sound. The first generation is scheduled to be 

broadcast beginning in 1988. 

Null Packets – Packets of “stuffing”that carry no data but are necessary 

to maintain a constant bit rate with a variable payload. Null packets always 

have a PID of 8191 (all 1s). 

Number Crunching – Action of performing complex numerical operations. 

NVOD – Near Video On Demand. 

NWK – Network. 

NYIT – See New York Institute of Technology. 

Nyquist – Nyquist Filter, Nyquist Limit, Nyquist Rule, and Harry Nyquist, for 

whom they are named. 

Nyquist Filter – Commonly used in the IF stage of a television receiver to 

separate the desired television channel from potential interference. 

Nyquist Frequency – The lowest sampling frequency that can be used for 

analog-to-digital conversion of a signal without resulting in significant 

aliasing. Normally, this frequency is twice the rate of the highest frequency 

contained in the signal being sampled. 

Nyquist Interval – The maximum separation in time which can be given 

to regularly spaced instantaneous samples of a wave of bandwidth W for 

complete determination of the waveform of the signal. Numerically, it is 

equal to 1/2 W seconds. 

Nyquist Limit – When time-varying information is sampled at a rate R, the 

highest frequency that can be recovered without alias is limited to R/2. 

Aliasing may be generated by under sampling temporally in frame rate, or vertically 

in lines allocated to image height, or horizontally in analog bandwidth or 

in pixel allocation. Intermodulations prior to band limiting may “preserve” 

some distracting effects of aliasing in the final display. Note: Sampling at a 

rate below the Nyquist limit permits mathematical confirmation of the frequencies 

present (as for example in a Fourier analysis of recorded motion). If the 

sampling window is very small (as in synchronized flash exposure), however, it 

may become a subjective judgment whether strobing is perceived in the 

image for motion approaching the limiting velocity (frequency). 

Nyquist Rate Limit – Maximum rate of transmitting pulse signals through 

a channel of given bandwidth. If B is the effective bandwidth in Hertz, then 

2B is the maximum number of code elements per second that can be 

received with certainty. The definition is often inverted, in effect, to read 

“the theoretical minimum rate at which an analog signal can be sampled 

for transmitting digitally.” 

Nyquist Rule – States that in order to be able to reconstruct a sampled 

signal without aliases, the sampling must occur at a rate of more than 

twice the highest desired frequency. The Nyquist Rule is usually observed 

in digital systems. For example, CDs have a sampling frequency of 

44.1 kHz to allow signals up to 20 kHz to be recorded. It is, however, frequently 

violated in the vertical and temporal sampling of television, resulting 

in aliases. See also Alias. 

Nyquist Sampling Theorem – Intervals between successive samples 

must be equal to or less than one-half the period of highest frequency. 




O 

OAM – Operation Administration and Maintenance. 

Object Carousels – The object carousel specification has been added in 

order to support data broadcast services that require the periodic broadcasting 

of DSM-CC User-User (U-U) Objects through DVB compliant broadcast 

networks, specifically as defined by DVB Systems for Interactive 

Services (SIS). Data broadcast according to the DVB object carousel specification 

is transmitted according to the DSM-CC Object Carousel and 

DSM-CC Data Carousel specification which are defined in MPEG-2 

DSM-CC. 

Object Program – End result of the source language program (assembly 

or high-level) after it has been translated into machine language. 

OBO – Output Back Off. 

OC3 (Optical Carrier Level 3) – A 155 Mbps ATM SONET signal stream 

that can carry three DS-3 signals. 

Occlusion – The process whereby an area of the video raster is blocked or 

made non-transparent by controlling selected bits. Occlusion is used when 

more than one picture is displayed or windowed simultaneously. 

OCT – Octal Notation. 

Octal – Base-8 number system. Often used to represent binary numbers, 

since each octal digit corresponds directly to three binary digits. 

Octave – A two to one frequency ratio. 

Odd Number – The number of scanning lines per frame necessary in an 

interlaced scanning system. One line is split between fields to ensure proper 

spacing between scanning lines from different fields. A progressively 

scanned system may use an even number of scanning lines. 

Oersted – A unit of magnetic field strength. 

OFDM – Orthogonal Frequency Domain Multiplex. 

Off-Line Editing – Editing that is done to produce an edit decision list, 

which is used later for assembling that program. A video tape (sometimes 

called a work print) may be produced as a by-product of off-line editing. 

Off-Line Editor – A low resolution, usually computer and disk based edit 

system in which the creative editing decisions can be made at lower cost 

and often with greater flexibility than in an expensive fully equipped on-line 

bay. 

Offline Encoder – The Indeo video codec’s normal mode of operation, in 

which it takes as long as necessary to encode a video file so that it displays 

the best image quality and the lowest and most consistent data rate. 

Compare Quick Compressor. 

OIRT – Organisation Internationale de Radiodiffision-Television. 

OLE (Object Linking and Embedding) – A standard for combining data 

from different applications that updates automatically. 

O-Member – Observing Member. 

Omnidirectional – A microphone type that picks up sound relatively evenly 

from all directions. 


OMWF (Open MPEG Windows Forum) – OMWF is a Japanese industry 

consortium aiming at compatibility in MPEG-based multimedia applications. 

The group, that includes various hardware and software vendors and content 

providers in Japan, has its offspring in the popularity in Japan of CD 

movies and Karaoke. Through cooperation with the Open MPEG Consortium 

in the USA, the OMWF cleared up details in the MCI standard, that impeded 

compatibility. The new specification, called the Video CD specification, 

allows Windows machines to play MPEG-1 video CDs, and allows Windows 

data and applications to be stored on the same CD along with the video 

contents. 

On the Fly – a) Depressing a button causing some change while a switcher 

is transitioning. b) Selecting a tape edit point while VTR is moving. 

On-Air Output – Ready to use for transmission or videotaping, this is the 

PGM output. 

One Wire Interconnect – Interconnect consists of a single wire transporting 

an encoded, composite analog video signal. 

One’s Complement – Number representation system used for signed 

binary integers in which the negative of a number is obtained by complementing 

it. The leftmost bit becomes the sign bit, with 0 for plus, 1 for 

minus. 

On-Line Editing – a) Editing that is done to produce a finished program 

master. b) Final editing session, the stage of post-production in which the 

edited master tape is assembled from the original production footage, usually 

under the direction of an edit decision list (EDL). 

On-Line Editor – An editing system where the actual video master is created. 

An on-line bay usually consists of an editing computer, video switcher, 

audio mixer, one or more channels of DVE, character generator, and 

several video tape machines. 

On-Screen Display – A function on many VCRs and televisions in which 

operational functions (tint, brightness, VCR function, programming, etc.) are 

displayed graphically on the television screen. 

ONU – Optical Node Unit. 

OOB – Out of Band. 

Opcode – See Operation Code. 

OPCR – Original Program Clock Reference. 

Open – To double-click an icon, or to select an icon then choose “Open” 

from a menu in order to display a window that contains the information 

that the icon represents. 

Open Architecture – A concept for television receivers that acknowledges 

an absence of ATV transmission/distribution standards and allows a receiver 

to deal with a multiplicity of standards and delivery mechanisms. 

Open-Ended Edit – a) Assemble mode. b) Edit that has a start time but 

no designated stop time. 

Open-Loop – Circuit or other system operating without feedback.

Open MPEG Consortium – The goal of the Open MPEG Consortium is to 

“create a single API for the playback of MPEG-1 titles under Windows and 

DOS.” The consortium has developed the MPEG Multimedia Control 

Interface (MCI) which defines how MPEG boards operate under Windows. 

Due to some undefined topics, the MCI specification has not been able to 

curb incompatibility, but the consortium has later cooperated with the 

Japanese OMWF group on an enhanced specification. 

Operating Level – A certain level of flux recorded on magnetic tape. 

Operating Program – Computer software program which controls all 

functions of related computers and hardware devices. 

Operation Code (Opcode) – Segment of the machine-language instruction 

that specifies the operation to be performed. The other segments 

specify the data, address, or port. For the 8085, the first byte of each 

instruction is the opcode. 

Optical Fiber – A glass strand designed to carry light in a fashion similar 

to the manner in which wires carry electrical signals. Since light is electromagnetic 

radiation of tremendously high frequency, optical fibers can carry 

much more information than can wires, though multiple paths through the 

fiber place an upper limit on transmission over long distances due to a 

characteristic called pulse dispersion. Many feel that the wide bandwidth of 

an optical fiber eliminates the transmission problems associated with the 

high base bandwidth of HDEP schemes. CATV and telephone companies 

propose connecting optical fibers directly to homes. 

Option Button – Used to select from a list of related items. The selected 

option box has a black dot. (One item in the group must be selected.) 

Option Drive – Any internal drive other than the system disk. Option 

drives include floppy disk drives, secondary hard disk drives, or DAT drives. 

Orientation – a) For animation, many 3D systems fix the viewer’s location 

at a specified distance from the viewing screen. Currently, PictureMaker is 

one of these. In such systems, the database is moved relative to the viewer. 

The set of motions that accomplish any particular view of the world is 

called its “orientation.” Using the three coordinate axes as references, we 

can translate (shuffle on a plane) and rotate objects to create new views. 

During animation, we change the amounts of these motions. A set of numbers 

describes orientation: x-trans, y-trans, z-trans, x-rot, y-rot, z-rot. b) A 

direction of presentation affecting resolution requirements. Horizontal lines 

become vertical lines when their orientation is rotated by 90 degrees; a 

pattern of dots appearing to be in horizontal and vertical rows may not 

appear to be diagonally aligned when its orientation is rotated 45 degrees 

due to characteristics of the human visual system. 

Orientation Animation – We can also use splines to calculate orientations 

for objects in between their orientations at keyframe positions. This 

allows the motions of an object to be smooth rather than robot-like. In traditional 

animation, orientation animation required an artist to redraw the 

object when it rotated out of the plane of the platen (on the animation 

stand) and path animation was limited to repositioning the cells in X and Y 

(although the whole scene could be zoomed). In computer graphics, it is 

easy to rotate and reposition objects anywhere in three dimensions. That’s 

why you see so much of it! 

Orientation Direction – The arrangement of magnetic particles on 

recording tape. In tapes designed for quadraplex recording applications, 



the orientation direction is transverse. For helical and longitudinal recording, 

it is longitudinal. 

Orientation Ratio – In a material composed of oriented particles, the orientation 

ratio is the ratio of the residual flux density in the orientation 

direction to the residual flux density perpendicular to the orientation direction. 

The orientation ratio of conventional tapes is typically about 1.7. 

original_network_id – A unique identifier of a network. 

Origination – The production cycle begins with the introduction of images 

in photographic, electronic imaging, or computational media. Image capture 

in real-time is usually essential for recording live subjects and maintaining 

the impact of realism. Image generation, normally achieved in nonrealtime, 

provides additional subject matter that can be edited into and combined 

with recorded live subjects to achieve programs that are more artistic, 

or more instructional, or both. 

Orthicon (Conventional) – A camera tube in which a low-velocity electron 

beam scans a photoemissive mosaic on which the image is focused 

optically and which has electrical storage capability. 

Orthicon (Image) – A camera tube in which the optical image falls on a 

photo-emissive cathode which emits electrons that are focused on a target 

at high velocity. The target is scanned from the rear by a low-velocity electron 

beam. Return beam modulation is amplified by an electron multiplier 

to form an overall light-sensitive device. 

Orthicon Effect – One or more of several image orthicon impairments that 

have been referred to as “Orthicon Effect” as follows: edge effect, meshbeat 

or Moiré, ghost, halo, burned in image. It is obviously necessary to 

indicate specifically the effects experienced and, therefore, it is recommended 

that use of this term be discontinued. 

Orthogonal Projection – With orthogonal projection, parallel receding 

lines do not converge. The process of projecting from 3D to 2D is particularly 

simple, simply throw away the Z-value of each coordinate. 

Orthogonal Sampling – a) Sampling of a line of repetitive video signal in 

such a way that samples in each line are in the same horizontal position. 

b) Picture sampling arranged in horizontal rows and vertical columns. 

Osborne, Joseph – An ATV proponent issued a patent for a data compression 

transmission scheme for HD signals. The Osborne compression 

system is said to allow channel-compatible but not receiver-compatible 

HDTV. 

OSI (Open Systems Interconnection) – The OSI Reference Model was 

formally initiated by the International Organization for Standardization (ISO) 

in March, 1977, in response to the international need for an open set of 

communications standards. OSI’s objectives are: to provide an architectural 

reference point for developing standardized procedures; to allow internetworking 

between networks of the same type; to serve as a common 

framework for the development of services and protocols consistent with 

the OSI model; to expedite the offering of interoperable, multi-vendor products 

and services. 

OSI Model – The model is similar in structure to that of SNA. It consists of 

seven architectural layers: the physical layer and data link layer, the net- 




work layer; the transport layer; the session layer; the presentation layer; 

the application layer. 

OSI Model 

Physical and Provides the same functions as their SNA counterparts 

Data Link Layers (physical control and data link control layers. 

Network Layer Selects routing services, segments blocks and messages, 

and provides error detection, recovery, and notification. 

Transport Layer Controls point-to-point information interchange, data 

packet size determination and transfer, and the connection/disconnection 

of session entities. 

Session Layer Serves to organize and synchronize the application 

process dialog between presentation entities, manage the 

exchange of data (normal and expedited) during the session, 

and monitor the establishment/release of transport 

connections as requested by session entities. 

Presentation Layer Responsible for the meaningful display of information to 

application entities. More specifically, the presentation 

layer identifies and negotiates the choice of communications 

transfer syntax and the subsequent data conversion 

or transformation as required. 

Application Layer Affords the interfacing of application processes to system 

interconnection facilities to assist with information 

exchange. The application layer is also responsible for the 

management of application processes including initialization, 

maintenance and termination of communications, 

allocation of costs and resources, prevention of deadlocks, 

and transmission security. 

OUI – Organizational Unique Identifier. 

Out-of-Service (Full Field Testing) – 

Program 

IN 

Test Signal 

Inserter 

(capable of full field test signals) 

Outlets – Openings in the hardware to which you attach connectors to 

make an electrical connection. 

Outline – A type of key border effect. An outline key with a character generator 

appears as if the letters have been traced; the background video is 

visible all around the letter as well as inside it. 


TV System 

Test Signal 

Monitoring 

Equipment 

Program 

OUT 

Output – The magnitude of the reproduced signal voltage, usually measured 

at the output of the reproduce amplifier. The output of an audio or 

instrumentation tape is normally specified in terms of the maximum output 

that can be obtained for a given amount of harmonic distortion, and is 

expressed in dB relative to the output that can be obtained from a reference 

tape under the same conditions. 

Output Format – The form in which video is presented by a video chip to 

monitoring or recording systems is called the output format. This can be 

RGB, YUV, YCRCB, etc. 

Output Port – Circuit that allows the microprocessor system to output signals 

to other devices. 

Ovenized Crystal Oscillator – A crystal oscillator that is surrounded by a 

temperature regulated heater (oven) to maintain a stable frequency in spite 

of external temperature variations. 

Overflow – Results when an arithmetic operation generates a quantity 

beyond the capacity of the register. An overflow status bit in the flag register 

is set if an operation causes an overflow. 

Overhead Bits – Bits added to the binary message for the purpose of 

facilitating the transmission and recovery of the message (e.g., frame synchronization 

words, check bits, etc.) 

Overlay – Keyed insertion of one image into another. Overlay is used for 

example, to superimpose computer-generated text on a video image, for 

titling purposes. In video, the overlay procedure requires synchronized 

sources for proper operation. 

Oversampling – Sampling data at a higher rate than normal to obtain 

more accurate results or to make it easier to sample. 

Overscan – Increases scanning amplitudes approximately 20%. Used for 

tube/yoke set-up and sometimes as a precaution against an edge of picture 

“raster burn.” 

Overshoot – An excessive response to a unidirectional signal change. 

Sharp overshoots are sometimes referred to as “spikes.” 

Oxide (Magnetic Oxide) – The magnetizable particle used in the manufacture 

of magnetic tape. 

Oxide Buildup – The accumulation of oxide or, more generally, wear products 

in the form of deposits on the surface of heads and guides. 

Oxide Coating – The magnetic material coated on base film. 

Oxide Loading – A measure of the density with which oxide is packed into 

a coating. It is usually specified in terms of the weight of oxide per unit 

volume of the coating. 

Oxide Shed – The loosening of particles of oxide from the tape coating 

during use.

P 

P – Puncturing. 

Pack – A pack consists of a pack header followed by zero or more packets. 

It is a layer in the system coding syntax. 

Packed 24-Bit – A compression method where a graphics accelerator 

transfers more than one bit on each clock cycle, then reassembles the 

fragmented pixels. For example, some chips can transfer 8, 24-bit pixels in 

three clocks instead of the four normally required, saving bandwidth. 

Packed Pixel – Color information for a pixel packed into one word of 

memory data. For a system with few colors, this packed pixel may require 

only a part of one word of memory; for very elaborate systems, a packed 

pixel might be several words long. See Planar 

Packet – A packet consists of a header followed by a number of contiguous 

bytes from an elementary data stream. It is a layer in the system coding 

syntax. 

Packet Data – Contiguous bytes of data from an elementary data stream 

present in the packet. 

Packet Identifier (PID) – a) A unique integer value used to associate elementary 

streams of a program in a single- or multi-program transport 

stream. b) MPEG-2 transmits transport stream data in packets of 188 

bytes. At the start of each packet is a packet identifier (PID) that tells the 

receiver what to do with the packet. Since the MPEG-2 data stream might 

be in MCPC mode, the receiver has to decide which packets are part of the 

current channel being watched and pass them on to the video decoder for 

further processing. The packets that aren’t part of the current channel are 

simply discarded. There are typically four types of PIDs used by satellite 

receivers. The VPID is for the video stream and the APID is for the audio 

stream. Usually this data is embedded into the video stream, though occasionally 

a PCR (Program Clock Reference) PID is used to synchronize the 

video and audio packets. The fourth PID is used for data such as the program 

guide and information about other frequencies that make up the total 

package. 

Packet Switched Network – Network that transmits data in units called 

packets. The packets can be routed individually over the best available network 

connection and reassembled to form a complete message at the 

destination. 

Packet Switching – The method of dividing data into individual packets 

with identification and address, and sending these packets through a 

switched network. 

Packet Video – The integration of video coding and channel coding to 

communicate video over a packetized communication channel. Usually, 

these techniques are designed to work in the presence of high packet jitter 

and packet loss. 

Packets – A term used in two contexts: in program streams, a packet is a 

unit that contains one or more presentation units; in transport streams, a 

packet is a small, fixed size data quantum. 



Packing Density – The amount of digital information recorded along the 

length of a tape measured in bit per inch (bpi). 

Padding – A method to adjust the average length of an audio frame in 

time to the duration of the corresponding PCM samples, by continuously 

adding a slot to the audio frame. 

Page – Usually a block of 256 addresses. The lower eight bits of an 

address, therefore, specify the location within the page, while the upper 

eight bits specify the page. 

Painter’s Algorithm – In traditional painting, paint is applied in layers, 

and the last paint applied is what is visible. Digitally, the last value placed 

in a pixel determines its color. 

Pairing – A partial or complete failure of interlace in which the scanning 

lines of alternate fields do not fall exactly between one another but tend to 

fall (in pairs) one on top of the other. 

PAL – See Phase Alternate Line. 

PAL Format – A color television format having 625 scan lines (rows) of 

resolution at 25 frames per second (25 Hz). See PAL. Compare NTSC 

Format. 

PALE – See Phase Alternating Line Encoding. 

Palette – The limited set of colors that a computer can simultaneously display. 

A typical palette contains 256 unique colors, chosen from over 16 

million possible colors. An “optimized palette” refers to a palette whose 

colors are chosen to best represent the original colors in a particular 

graphic or series of graphics. 

Palette Flash – A phenomenon caused by simultaneously displaying more 

than one bitmap or video that do not share the same palette. 

PALplus, PAL+ – PALplus (ITU-R BT.1197) is 16:9 aspect ratio version of 

PAL, and is compatible with standard (B, D, G, H, I) PAL. Normal (B, D, G, 

H, I) PAL video signals have 576 active scan lines. If a film is broadcast, 

usually 432 or fewer active scan lines are used. PALplus uses these 

unused “black” scan lines for additional picture information. The PALplus 

decoder mixes it with the visible picture, resulting in a 16:9 picture with 

the full resolution of 576 active scan lines. Widescreen televisions without 

the PALplus decoder, and standard (B, D, G, H, I) PAL TVs, show a standard 

picture with about 432 active scan lines. PALplus is compatible with standard 

studio equipment. The number of pixels of a PALplus picture is the 

same as in (B, D, G, H, I) PAL, only the aspect ratio is different. 

Pan – Term used for a type of camera movement, to swing from left to 

right across a scene or vice versa. 

Pan and Scan – A method of transferring movies with an aspect ratio of 

16:9 to film, tape, or disc to be shown on a conventional TV with a 4:3 

aspect ratio. Only part of the full image is selected for each scene. Pan 

and Scan is the opposite of “letterbox” or “widescreen.” 

Pan Pot – An electrical device which distributes a single signal between 

two or more channels or speakers. 




Pan Vector – Horizontal offset in video frame center position. 

Panel Memory – See STAR system. 

PAP – Password Authentication Protocol. 

Paper Edit – Rough edit decision list made by screening original materials, 

but without actually performing edits. 

Parade – A waveform monitor display mode in which the Y and two 

chrominance components of an analog component video are shown side by 

side on the waveform screen. 

Parallel Cable – A multi-conductor cable carrying simultaneous transmission 

of data bits. Analogous to the rows of a marching band passing a 

review point. 

Parallel Component Digital – The component signal sampling format 

specified by ITU-R BT.601-2 and the interface specified by ITU-R BT.656. 

Parallel Composite Digital – The composite signal sampling format 

specified in SMPTE 244M for NTSC. The EBU is working on the PAL standard. 

The composite signals are sampled at the rate of 4FSC which is 

14.4 MHz for NTSC and 17.7 MHz for PAL. 

Parallel Data – Transmission of data bits in groups along a collection of 

wires (called a bus). Analogous to the rows of a marching band passing a 

review point. A typical parallel bus may accommodate transmission of one 

8-, 16-, or 32-bit byte or word at a time. 

Parallel Device – Any hardware device that requires a parallel cable connection 

to communicate with a workstation. 

Parallel Digital – A digital video interface which uses twisted pair wiring 

and 25-pin D connectors to convey the bits of a digital video signal in parallel. 

There are various component and composite parallel digital video 

formats. 

Parallel HDDR – The recording of multiple PCM data streams which are 

synchronous to a common clock onto multitrack recorder/reproducers. 

Parallel Interface – A PC port which receives or transmits data in byte or 

word form rather than bit form. 

Parallel Port – An outlet on a workstation to which you connect external 

parallel devices. 

Parameter – a) A variable which may take one of a large range of values. 

A variable which can take one of only two values is a flag and not a 

parameter. b) The values shown in X, Y, and Z in each menu, so called 

because they represent the numerical values assigned to each feature of a 

video picture, size, aspect ratio, etc. Changing these values, shown in the 

“X, Y, and Z” columns, produces ADO’s visual effects. c) A setting, level, 

condition, or position, i.e., clip level, pattern position, system condition. 

d) Value passed from one routine to another, either in a register or a memory 

location. 

Parametric Modeling – This method uses algebraic equations (usually 

polynomials) to define shapes and surfaces. The user can build and modify 

complex objects by combining and modifying simple algebraic primitive 

shapes. 

Parental Level – A mechanism that allows control over what viewers may 

see depending on the settings in the DVD player, the parental code on a 


DVD, and the structure of the material on the DVD. This is especially useful 

for youthful viewers whose parents wish to exercise a degree of control 

over what their children can watch. 

Parity – a) An extra bit appended to a character as an accuracy check. 

For example, if parity is even, the sum of all 1s in the character should be 

even. b) Number of 1s in a word, which may be even or odd. When parity 

is used, an extra bit is used to force the number of 1s in the word (including 

the parity bit) to be even (even parity) or odd (odd parity). Parity is one 

of the simplest error detection techniques and will detect a single-bit 

failure. 

Parity Clock – A self-checking code employing binary digits in which the 

total number of 1s (or 0s) in each code expression is always even or 

always odd. A check may be made for even or odd parity as a means of 

detecting errors in the system. 

Partial Transport Stream (TS) – Bitstream derived from an MPEG-2 TS 

by removing those TS Packets that are not relevant to one particular 

selected program, or a number of selected programs. 

Particle Orientation – The process by which acicular particles are rotated 

so that their longest dimensions tend to lie parallel to one another. 

Orientation takes place in magnetic tape by a combination of the sheer 

force applied during the coating process and the application of a magnetic 

field to the coating while it is still fluid. Particle orientation increases the 

residual flux density and hence the output of a tape and improves performance 

in several other ways. 

Particle Shape – The particles of gamma ferric oxide used in conventional 

magnetic tape are acicular, with a dimensional ratio of about 6:1. 

Particle Size – The physical dimensions of magnetic particles used in a 

magnetic tape. 

Particles – Refers to such vague objects as clouds, fire, water, sand, or 

snow that can be rendered using a special program. 

PASC (Precision Adaptive Sub-Band Coding) – The PASC is very close 

to the Layer 1 subset in the MPEG audio specification. The algorithm, 

which is used in the DCC system from Phillips, provides a 384 kbit/s data 

stream. 

Password – A combination of letters and/or numbers that only the user 

knows. If you specify a password for your account or if you are assigned a 

password by the system administrator, you must type it after you type your 

login name before the system lets you access files and directories. 

Past Reference Picture – A past reference picture is a reference picture 

that occurs at an earlier time than the current picture in display order. 

PAT (Program Association Table) – Data appearing in packets having 

PID code of zero that the MPEG decoder uses to determine which programs 

exist in a Transport Stream. PAT points to PMT (Program Map Table), 

which, in turn, points to the video, audio, and data content of each 

program. 

Patch – a) To connect jack A to jack B on a patch bay with a patch cord. 

b) A section of curved, non-planar surface; it can be likened to a rectangular 

rubber sheet which can be pulled in all directions. c) Section of coding 

inserted into a routine to correct a mistake or alter the routine. It is usually 

not inserted into the actual sequence of the routine being corrected, but

placed somewhere else. A jump to the patch and a return to the routine are 

then provided. 

Patch Panel (or Bay, Board, Rack) – A manual method of routing signals 

using a panel of receptacles for sources and destinations and wire jumpers 

to interconnect them. 

Path Length – The amount of time it takes for a signal to travel through a 

piece of equipment or a length of cable. Also called propagation delay. 

Pathname – The list of directories that leads you from the root (/) directory 

to a specific file or directory in the file system. 

Pattern (PTN) – In general switcher terms, a pattern is any geometric 

shape which grows, rotates, or pivots and in so doing removes the foreground 

video while simultaneously revealing the background video. Strictly 

speaking, a pattern is a fully enclosed shape on the screen. This definition 

is our internal view, but not consistent with the industry. Typical patterns 

are rectangles, diamonds, and circles. 

Pattern Border – A variable-width border that occurs at the edges of a 

wipe pattern. The border is filled with matte video from the border matte 

generator. 

Pattern Extender – The hardware (and software in AVC) package which 

expands the standard pattern system to include rotary wipes, and rotating 

patterns (and matrix wipes in AVC). 

Pattern Limit – See Preset Pattern. 

Pattern Modification – The process of altering one or more pattern 

parameters. See Modifier. 

Pattern Modifier – An electronic circuit which modifies basic patterns by 

rotating, moving positionally, adding specular effects to the borders, etc., 

thereby increasing the creative possibilities. 

Pattern System – The electronic circuitry which generates the various 

pattern (wipes). 

Pause Control – A feature of some tape recorders that makes it possible 

to stop the movement of tape temporarily without switching the machine 

from “play” or “record.” 

Payload – Useful data in TS (Transport Stream). Payload refers to the 

bytes which follow the header byte in a packet. For example, the payload of 

a transport stream packet includes the PES_packet_header and its 

PES_packet_data_bytes or pointer_field and PSI sections, or private data. 

A PES_packet_payload, however, consists only of PES_packet_data_bytes. 

The transport stream packet header and adaptation fields are not payload. 

PC – Printed Circuit or Program Counter. 

PC2 – Pattern Compatible Code. 

PCB – Printed Circuit Board. 

PCI (Peripheral Component Interface) – In 1992, Intel introduced the 

Peripheral Component interface bus specification. PCI, a high-speed interconnection 

system that runs at processor speed, became compatible with 

the VL bus by its second release in 1993. PCI includes a 64-bit data bus 

and accommodates 32-bit and 64-bit expansion implementations. PCI is 

designed to be processor-independent and is used in most high-speed 

multimedia systems. PCI is designed so that all processors, co-processors, 



and support chips can be linked together without using glue logic and can 

operate up to 100 MHz, and beyond. PCI specifies connector pinout as well 

as expansion board architecture. 

PCI Bus Mastering – The key technology that has allowed under $1000 

video capture cards to achieve such high quality levels. With PCI bus mastering, 

you get perfect audio sync and sustained throughput levels over 

3 megabits per second. 

PCM (Pulse Code Modulation) – Pulsed modulation in which the analog 

signal is sampled periodically and each sample is quantized and transmitted 

as a digital binary code. 

PCM Disk – A method of recording digital signals on a disk like a standard 

vinyl record. 

PCMCIA (Personal Computer Memory Card International Association) 

– A standard format for credit-card size expansion cards used to add storage 

capacity or peripherals such as modems to a computer. 

PCR (Program Clock Reference) – a) The sample of the encoder clock 

count that is sent in the program header to synchronize the decoder clock. 

b) The “clock on the wall” time when the video is multiplexed. c) Reference 

for the 27 MHz clock regeneration. Transmitted at least every 0.1 sec. 

PCRI (Interpolated Program Clock Reference) – A PCR estimated from 

a previous PCR and used to measure jitter. 

PCS – Personal Conferencing Specification. 

PCWG – Personal Conferencing Work Group. 

PCX (PC Exchange Format) – A file format common to most bitmap file 

format conversions which can be handled by most graphic applications. 

PDH – Plesiochronous Digital Hierarchy. 

PDP – Plasma Display Panel. 

PDU – Protocol Data Unit. 

PE – Phase Error. 

Peak Boost – A boost which is greater at the center frequency than either 

above or below it. 

Peak Indicator – An indicator that responds to short transient signals, 

often used to supplement Recording Level Meters which usually indicate 

average signal levels. 

Peak Magnetizing Field Strength – The positive or negative limiting 

value of the magnetizing field strength. 

Peak Value – The maximum positive or negative instantaneous value of a 

waveform. 

Peaking Equalization – Equalization which is greater at the center frequency 

than at either side of center. 

Peak-Reading Meter – A type of Recording Level Meter that responds to 

short transient signals. 

Peak-to-Peak – The amplitude (voltage) difference between the most positive 

and the most negative excursions (peaks) of an electrical signal. 

Pedding – Raising or lowering the camera while the camera remains level. 

Vertical equivalent of dollying. 




Pedestal – The offset used to separate the active video from the blanking 

level. When a video system uses a pedestal, the black level is above the 

blanking level by a small amount. When a video system doesn’t use a 

pedestal, the black and blanking levels are the same. (M) NTSC uses a 

pedestal set at +7.5 IRE, (B, D, G, H, I) PAL does not. 

Pedestal Level – This term is obsolete; “blanking level” is preferred. 

Pel (Picture Element) – See Pixel. 

Pel Aspect Ratio – The ratio of the nominal vertical height of pel on the 

display to its nominal horizontal width. 

Percent SD – Short time distortion amplitudes are not generally quoted 

directly as a percent of the transition amplitude but rather are expressed in 

terms of an amplitude weighting system which yields “percent-SD.” This 

weighting is necessary because the amount of distortion depends not only 

on the distortion amplitude but also on the time the distortion occurs with 

respect to the transition. The equation for NTSC Systems is SD = at0.67 where “a” is the lobe amplitude and “t” is the time between transitions and 

distortions. In practice, screen graticules eliminate the need for calculations. 

Refer to the figure below. Also see the discussion on Short Time 

Distortions. 

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Percentage Sync – The ratio, expressed as a percentage, of the amplitude 

of the synchronizing signal to the peak-to-peak amplitude of the picture 

signal between blanking and reference white level. 

Perception, Visual – The interpretation of impressions transmitted from 

the retina to the brain in terms of information about a physical world displayed 

before the eye. Note: Visual perception involves any one or more of 

the following: recognition of the presence of something; identifying it; 

locating it in space; noting its relation to other things; identifying its movement, 

color, brightness, or form. 

Periodic Noise – The signal-to-periodic noise ratio is the ratio in decibels, 

of the nominal amplitude of the luminance signal (100 IRE units) to the 

peak-to-peak amplitude of the noise. Different performance objectives are 

sometimes specified for periodic noise (single frequency) between 1 kHz 

and the upper limit of the video frequency band and the power supply hum, 

including low-order harmonics. 


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Peripheral – Any interface (hardware) device connected to a computer 

that adds more functionality , such as a tape drive. Also, a mass storage or 

communications device connected to a computer. See also External 

Devices and Internal Drives. 

Permanent Elongation – The percentage elongation remaining in a tape 

or length of base film after a given load, applied for a given time, has been 

removed and the specimen allowed to hang free, or lightly loaded, for a 

further period. 

Perm’ed – Magnetized to a level which cannot be removed with a handheld 

degausser. 

Perpendicular Direction – Perpendicular to the plane of the tape. 

Perspective – The artistic method in a two-dimensional plane to achieve a 

three-dimensional look. The technique or process of representing on a 

plane or curved surface, the spatial relation of objects as they might 

appear to the eye, one giving a distinct impression of distance. 

Perspective (Menu) – The 3D function that enables changing the skew 

and perspective of an image. Skew X: Uses the X axis to slant the image 

right or left to change the image geometry into a parallelogram. 

Perspective: Uses the Z axis to change the point of view (perspective) of 

an image, to give it a three-dimensional appearance. 

Perspective Projection – When perspective is used, a vanishing point is 

used. With perspective, parallel lines receding into the screen appear to 

converge. To make this happen, the process of converting a 3D coordinate 

(x, y, z) into its 2D perspective on the screen requires dividing the original x 

and y coordinates by an amount proportional to the original z value. Thus, 

the larger z is, points on the parallel lines that are far away will be closer 

together on the screen. 

Perturbation – A method to add noise so as to enhance the details of a 

surface. 

PES (Packetized Elementary Stream) – Video and audio data packets 

and ancillary data of undefined length. 

PES Header – Ancillary data for an elementary stream. 

PES Packet – The data structure used to carry elementary stream data. It 

consists of a packet header followed by PES packet payload. 

PES Packet Header – The leading fields in a PES packet up to but not 

including the PES_packet_data_byte fields where the stream is not a 

padding stream. In the case of a padding stream, the PES packet header is 

defined as the leading fields in a PES packet up to but not including the 

padding_byte fields. 

PES Stream – A PES stream consists of PES packets, all of whose payloads 

consist of data from a single elementary stream, and all of which 

have the same stream_id. 

Petabyte – 1000 terabytes, or 1 million gigabytes. 

P-Frame (Predicted Frame) – One of the three types of frames used in 

the coded MPEG-2 signal. The frame in an MPEG sequence created by predicting 

the difference between the current frame and the previous one. 

P-frames contain much less data than the I frames and so help toward the 

low data rates that can be achieved with the MPEG signal. To see the origi-

nal picture corresponding to a P-frame, a whole MPEG-2 GOP has to be 

decoded. 

PGM – Program. 

Phantom Matrix – That portion of the switcher electronic crosspoints 

which are not controlled by a row of push buttons on the console. See Bus. 

Phantom Points – See Ghost Point. 

Phantom Power – Electricity provided by some broadcast and 

industrial/professional quality audio mixers for use by condenser microphones 

connected to the audio mixer. Some microphones require phantom 

power, and must be connected to audio mixers that provide it. 

Phase – A measure of the time delay between points of the same relative 

amplitude (e.g., zero crossings) on two separate waveforms. 

Phase Adjust – The method of adjusting the color in a (M) NTSC video 

signal. The phase of the chroma information is adjusted relative to the 

color burst and affects the hue of the picture. 

Phase Alternate Line (PAL) – a) European video standard with image 

format 4:3 aspect ratio, 625 lines, 50 Hz and 4 MHz video bandwidth with 

a total 8 MHz of video channel width. PAL uses YUV; The Y component represents 

Luminance, the U component represents B-Y, The V component 

represents R-Y. The V component of burst is inverted in phase from one 

line to the next in order to minimize hue errors that may occur in color 

transmission. b) The color television transmission standard used in Europe 

and other parts of the world. This standard uses a subcarrier which is 

alternated 90 degrees in phase from one line to the next to minimize hue 

errors in color transmission. PAL-I uses a 4.43361875 subcarrier. A single 

frame (picture) in this standard consists of 625 scanning lines. One frame 

is produced every 1/25 of a second. PAL-M uses a 3.57561149 MHz subcarrier 

and 525 scanning lines. One frame is produced every 1/30 of a 

second. c) The television and video standard in use in most of Europe. 

Consists of 625 horizontal lines at a field rate of 50 fields per second. (Two 

fields equals one complete frame.) Only 576 of these lines are used for 

picture. The rest are used for sync or extra information such as VITC and 

Closed Captioning. 

Phase Alternating Line Encoding (PALE) – A method of encoding the 

PCM NTSC signal by reversing the encoding phase on alternate lines to 

align the code words vertically. 

Phase Comparator – Circuit used in a phase-locked loop to tell how 

closely the phase locked loop reference signal and the PLL output are in 

phase with each other. If the two signals are not in phase, the Phase 

Comparator generates an error signal that adjusts the PLL frequency output 

so that it is in phase with the reference signal. 

Phase Distortion – A picture defect caused by unequal delay (phase 

shifting) of different frequency components within the signal as they pass 

through different impedance elements – filters, amplifiers, ionosphere variations, 

etc. The defect in the picture is “fringing”-like diffraction rings at 

edges where the contrast changes abruptly. 

Phase Error – a) A picture defect caused by the incorrect relative timing 

of a signal in relation to another signal. b) A change in the color subcarrier 

signal which moves its timing out of phase, i.e., it occurs at a different 

instant from the original signal. Since color information is encoded in a 



video signal as a relation between the color subcarrier and the color burst 

phase, a deviation in the color subcarrier phase results in a change in the 

image’s hue. 

Phase Shift – The movement of one signal’s phase in relation to another 

signal. 

Phase-Locked Loop – The phase locked loop (PLL) is central to the operation 

of frequency and phase stable circuitry. The function of the PLL is to 

provide a frequency/phase stable signal that is based on an input reference 

signal. 

Phasing – Adjusting the delay of a video signal to a reference video signal 

to ensure they are synchronous. This includes horizontal and subcarrier 

timing. Also called timing. 

PHL – Physical. 

Phon – A unit of equal loudness for all audio frequencies. Phons are related 

to dB, SPL re: 0.0002 microbar by the Fletcher-Munson curves. For 

example, a loudness level of 40 phons would require 40 dB SPL at 1 kHz 

and 52 dB at 10 kHz. 

Phong – A type of rendering (shadows, environmental reflections, basic 

transparency, and textures). 

Phong Shading – A more realistic and time-consuming type of shading, 

Phong shading actually calculates specular reflections. 

Phono – A connector used in audio and video components, characterized 

by its single connection post and metal flanges. See also RCA Connector. 

Photo YCC – A color encoding scheme developed by Kodak for its Image 

PAC file format. 

Photoemissive – Emitting or capable of emitting electrons upon exposure 

to radiation in and near the visible region of the spectrum. 

PIC – A standard file format for animation files. 

Pick-Off Jitter – Jitter is a random aberration in the time period due to 

noise or time base instability. Pick-off means sample point. 

Pick-Up Pattern – The description of the directionality of a microphone. 

The two prominent microphone pick-up patterns are omnidirectional and 

unidirectional. 

Pickup Tube – An electron-beam tube used in a television camera where 

an electron current or a charge-density image is formed from an optical 

image and scanned in a predetermined sequence to provide an electrical 

signal. 

PICT – A standard file format for bit-mapped and object-oriented graphic 

files. 

Picture – a) Source, coded, or reconstructed image data. A source or 

reconstructed picture consists of three rectangular matrices of 8-bit numbers 

representing the luminance and two chrominance signals. For progressive 

video, a picture is identical to a frame, while for interlaced video, 

a picture can refer to a frame, the top field, or the bottom field of the 

frame depending on the context. b) In general, the term “picture” covers a 

coded entity. A picture can either be a frame or a field. It is possible to 

change dynamically between frame coding and field coding from frame to 

frame. Frame coding is preferred when a lot of details, but little motion is 




present, and field coding is best for fast movements. It is also important to 

realize that when the coded material originates from film, the two fields 

cover the exact same time, but when the source material comes from a 

video camera, the two fields relate to different moments. 

Picture Element – The smallest area of a television picture capable of 

being delineated by an electric signal passed through the system or part 

thereof. Note: It has three important properties, namely Pv, the vertical 

height of the picture element; Ph, the horizontal length of the picture element; 

and Pa, the aspect ratio of the picture element. In an analog system 

Pv = 1/N, where N is the number of active scanning lines in the raster, 

Ph = trA/tc, where tr is the average value of the rise and delay times (10% 

to 90%) of the most rapid transition that can pass through the system or 

part thereof, tc is the duration of the part of a scanning line that carries 

picture information, and A is the aspect ratio of the picture. 

Picture Height – In a scanning standard, the number of raster lines that 

contain the vertical extent of a white flatfield between the 50% response 

points, top and bottom. 

Picture Monitor – Refers to a cathode-ray tube and its associated circuits, 

arranged to view a television picture. 

Picture Safety Area – The area of a video signal which will be visible on 

a receiving monitor. Often denoted by marks within the viewfinder of the 

video camera. 

Picture Sharpness – The fine details in a video picture. A picture appears 

sharp when it contains fine details and has good contrast. Picture sharpness 

is easily lost during the recording/playback process. Advanced video 

enhancement equipment is used to improve picture sharpness, especially 

contrast, and can precompensate for potential losses which might alter an 

image during processing. 

Picture Signal – That portion of the composite video signal which lies 

above the blanking level and contains the picture information. 

Picture Tube – A cathode-ray tube used to produce an image by variation 

of the intensity of a scanning beam. 

Picture Width – In a scanning standard, that fraction of a total raster line 

that contains the horizontal extent of a white flatfield between the 50% 

response points, left and right. 

PID (Packet Identifier) – A 13-bit code in the transport packet header. 

PID 0 indicates that the packet contains a PAT PID. PID 1 indicates a packet 

that contains CAT. The PID 8191 (all 1s) indicates null (stuffing) packets. 

All packets belonging to the same elementary stream have the same PID. 

Piezoelectric Microphone – A microphone whose generating element is 

a crystal or ceramic element, which generates a voltage when bent or 

stressed by movement of the diaphragm. 

Pigeons – Noise observed on picture monitors as pulses or bursts of short 

duration, at a slow rate of occurrence; a type of impulse noise. 

Pinchroller – A rubber or neoprene wheel which presses the tape against 

the capstan during recording or play. 

Pink Noise – a) Random noise which has equal energy per octave 

throughout the audio spectrum. b) A type of noise whose amplitude is 

inversely proportional to frequency over a specified range. Pink noise is 


characterized by a flat amplitude response per octave band of frequency 

(or any constant percentage bandwidth), i.e., it has equal energy, or constant 

power, per octave. Pink noise can be created by passing white noise 

through a filter having a 3 dB/octave slope. 

PIP (Picture In Picture) – A digital special effect in which one video 

image is inserted within another allowing several images to share a single 

screen. 

Pipe – A way of stringing two or more programs together so that the output 

of one is fed to the other as input. 

Pipeline – A stage in a processor which executes a partial task. For example, 

a memory pipeline might use pipelined (sequential) stages to calculate 

the address, read the value of the memory cell, and store the value in a 

register. A pipeline allows starting the execution of a cycle before a previous 

cycle has been completed. A processor can start to execute a complex 

instruction in a pipeline before the preceding instruction has been 

completed. 

Pit Art – A type of DVD labeling in which the pits are cut in a design to 

resemble writing or another image. It sometimes has the look of a 

hologram. 

Pitch Control – A circuit which permits the speed of a tape transport’s 

motor to be varied slightly to raise and lower the musical pitch of the 

recording or to slightly lengthen or shorten playing time. 

Pixel (Picture Element) – a) Related to a particular image address in 

digital systems or to the smallest reproducible element in an analog system. 

A single point on the screen. As an example, if a system is said to 

have a display resolution of 1280 by 1024, there are 1280 pixels per horizontal 

line and 1024 horizontal lines from the top of the screen to the bottom. 

b) A pixel is the digital representation of the smallest area of a television 

picture capable of being delineated by the bit stream; i.e., the digital 

value or set of values that defines the characteristics of a picture element. 

A pixel of a full-color image is represented by a minimum of three components, 

reflecting the trichromatic nature of human vision. A pixel of a 

monochrome image may be represented by a single component. Pixels may 

carry additional information such as transparency. The total number of picture 

elements in a complete picture is of interest since this number provides 

a convenient way of comparing systems. c) One of the tiny points of 

light that make up the picture on a computer screen. The smaller and closer 

together the pixels are, the higher the resolution. 

Pixel, Square – a) Picture element with equal vertical and horizontal sample 

spacing, having an aspect ratio of 1:1. Square pixels are used by computers, 

and the software expects the use of square pixels for proper operation. 

Video originally was unconcerned about the aspect ratio of its pixels. 

Increasing dependence upon electronic post-production has emphasized 

the advantage of square pixels. b) System M/NTSC, by comparison, does 

not have square pixels. With 485 active vertical lines per frame, and 768 

samples per active horizontal line (when sampled at four times subcarrier) 

in a 4:3 aspect ratio, the resulting pixels have an aspect ratio 

(width:height) of 0.842. c) During image processing, some transforms that 

manipulate individual pixels as independent picture elements – especially 

those operations involving any image rotation, distortion, or size changes

are performed with simplified programs and less risk of artifacts when the 

pixels are square. 

Pixel, Rectangular – Picture element that has different vertical and horizontal 

sample spacing. Rectangular pixels are usually used by consumer 

video equipment and video conferencing. 

Pixel Clock – This clock divides the incoming horizontal line of video into 

pixels. The pixel clock is very stable relative to the incoming video or the 

picture will not be stored correctly. The higher the frequency of the pixel 

clock, the more pixels that will appear across the screen. 

Pixel Depth – The number of bits of color information per pixel. A system 

using eight bits per pixel can display 256 (28) colors. A system using 16 

bits per pixel can display 65,536 (216) colors. A system using 24 bits per 

pixel can display over 16.7 million colors. Twenty-four-bit color is often 

called true color because the human eye can distinguish among approximately 

six million different colors, or fewer than are available in a 24-bit 

color system. 

Pixel Drop Out – A common source of image artifacts that appear as 

black spots on the screen, either stationary or moving around. Several 

things can cause pixel drop out, such as the ADC not digitizing the video 

correctly or pixel timing being incorrect any where in the system. 

PJ – Phase Jitter. 

Planar – In display terms, the pixel color information is stored in four bits 

across four memory planes. This allows a maximum of 16 colors (24 ). See 

Packed Pixel. 

Planes – A plane is a flat surface, infinitely large. 

Playback – The reproduction of sound previously recorded on a tape. 

Playback Head – A transducer which converts magnetic flux into electrical 

current. 

PLL – See Phase Locked Loop. 

PLUGE (Picture Line-Up Generating Equipment) – The PLUGE signal 

was designed for rapid and accurate adjustment of the black level, reference 

and, hence, the luminance range, display. It provides adjacent vertical 

bars, one at black level, reference and continuous bars slightly above and 

slightly below that reference. Following initial development by the BBC, 

CCIR now recognizes at least eight versions. SMPTE EG 1-1990 includes a 

variant in which the black level, reference is flanked by bars at –4 IRE and 

+4 IRE. When the –4 IRE merges into the black level, reference bar, but 

the +4 IRE bar is distinguishable, black level, reference is correctly set. A 

white patch is included at peak white, to define IRE 100, and the luminance 

range, display CRT. 

Plug-Ins – Software programs that can install into a main nonlinear editing 

software to give you additional features and/or specs. 

PLV (Production Level Video) – A digital video algorithm developed by 

Intel in 1989 which can produce VHS-quality video at 30 frames per second 

at 256 x 240 pixels. Horizontal line doubling is used to produce a VGA 

640 x 480 pixels. 

PM – Pulse Modulation. 

P-Member – Primary Member. 



PMT (Program Map Tables) – The PMT identifies the locations of the 

streams that make up each service and the location of the PCR fields for a 

service. This table is transmitted in sections. Name of programs, copyright, 

reference of the state streams with PIDs, etc., belonging to the relevant 

program. 

Point Source – Light that emanates from a given point with equal intensity 

in all directions with a maximum intensity at its position. It exponentially 

dies out to zero at the distance of its radius. This is called the sphere light 

source. 

Points – Points are locations in 3D space. They are represented in the 

computer as numerical triplets (x, y, z) where x, y, and z measure the 

point’s distance from the origin. A point is also called a vertex (plural is 

vertices). Objects are defined in terms of points. Vertex is a synonym for 

point. A point’s x, y, and Z values are called its coordinates. 

Polar SCH Phase Display – This type of display shows the phase relationship 

of the color oscillator and the 50% point on the leading edge of 

the horizontal sync pulse. The phase of these two can be within 0 to 360 

degrees of each other. In the example below, there is a 12 degree phase 

difference between the two. 

Polarity of Picture Signal – Refers to the polarity of the black portion of 

the picture signal with respect to the white portion of the picture signal. 

For example, in a “black negative” picture, the potential corresponding to 

the black areas of the picture is negative with respect to the potential corresponding 

to the white areas of the picture; in a “black positive” picture, 

the potential corresponding to the black areas of the picture is positive. 

The signal as observed at the broadcasters’ master control rooms and telephone 

company television operating centers is “black negative.” 

Pole Pieces – The metal pieces of a head through which magnetic flux 

passes to or from the gap. 




Polling – One method used to identify the source of an interrupt request. 

The CPU must poll (read) the devices to determine which one caused the 

interrupt. 

Polyester – An abbreviation for polyethylene terephthalate, the material 

most commonly used as a base film for precision magnetic tape. The chief 

advantages of polyester over other base film materials lie in its humidity 

and time stability, its solvent resistance, and its mechanical strength. 

Polygon – A polygon is an enclosed piece of a plane, bounded by vectors. 

Polygon Plane – The plane containing the polygon which defines its 

shape. 

Pop – Operation of reading a word from the stack. Same as Pull. 

Pop Filter – See Blast Filter. 

Port – An outlet to which you attach cable connectors. Point at which the 

I/O devices are connected to the computer. 

Position Words – This term is a purely Cubicomp buzzword. As used within 

their software and documentation, a position word is the set of numbers 

that orient a single keyframe. Each keyframe gets a position word, and a 

position word stores the translations, rotations, and zooms that were used 

to create the view of the world seen in the keyframe. Position words do 

triple duty: They define the current view of the world. A position word is 

made up of nine numbers: x, y, and Z rotation; x, y, and z translation; x and 

y offsets; and scale; They define keyframes (since a keyframe is a particular 

view of the world; Similarly, in-betweens are automatically generated 

views of the world that are in between keyframes. 

Positioner – a) The console device which allows an operator to move a 

pattern around the screen. The AVC has a rate positioner as opposed to an 

absolute positioner. The direction of pattern movement is the same as the 

direction in which the positioner is moved and the rate of pattern movement 

is proportional to the distance the positioner is moved from center. 

When it is released, the pattern stops in its current position and the positioner 

returns to center. The 4100 has an absolute positioner whose angle 

and direction correspond to the location of the pattern on the screen. b) A 

joystick control that allows the origin of a wipe pattern to be moved within 

the active picture area. 

Positive Logic – True level is the more positive voltage level in the system. 

Posterization – a) Special effect in which the picture is reduced to a 

small number of colors or luminance levels removing any fine gradations of 

color and brightness resulting in an oil painting effect. Both the Video 

Equalizer and Digital Video Mixer includes this effect. b) An ADO special 

effect where a frame of video is broken down into flat areas of color. This 

mimics the silk screen printing method used by graphic designers to create 

poster designs, hence the derivations of the name. 

Post-Production – a) All production work done after the raw video 

footage and audio elements have been captured. Editing, titling, special 

effects insertion, image enhancement, audio mixing, and other production 

work is done during post-production. Videonics equipment is ideally suited 

for use in post-production. b) The application of image processing to photographic 

or electronic recorded image information. Usually in addition to 

scene selection and simple scene transitions, rather complex processing 

may be proposed: montage of two or more images; integration of photo- 


graphic and electronic image information; fitting and over-recording; 

changes of size, contrast, hue, or luminance; introduction of computer-generated 

components; simulated motion; creation of multi-layered composites 

with control of transparency. Audio information, maintained in synchronism 

with the images as specified by the script, is processed along with the 

image information. 

Post-Production, Electronic – Performing one or more of the steps in 

the post-production sequence with the image information encoded in the 

electronic mode. The initial and final records, as well as any of the intermediates, 

may employ the photographic and electronic modes in any combination 

or permutation. 

Post-Production, Off-Line – a) Electronic: Complex post-production 

may require such large image bandwidths, such storage requirements, and 

such extensive calculations that it necessitates conduction in non-realtime, 

off-line. b) Photographic: Traditionally all photographic post-production 

has been off-line. 

Post-Production, Studio – When the studio and distribution standard are 

identical, and/or program urgency is great, simplified post-production is 

frequently conducted with all program segment decisions made in real-time 

review. For such applications, the program is usually in distribution or 

emission/transmission format. 

Post-Roll – The number of frames (or seconds and frames) that roll after 

the edit out-point. 

PostScript – A computer language designed to control exactly how and 

where printed elements (lines, type, graphics) will appear on the page. 

Pot (Potentiometer) – Gain control in audio or video. 

Power Cable – The cable that connects the workstation to an electrical 

outlet. 

Power Down – To turn off the power switches on the workstation chassis 

and the monitor. 

Power Supply – The piece of hardware within the chassis that directs 

power from an electrical outlet to the chassis, the monitor, and other internal 

devices. 

Power Up – To turn on the power switches on the workstation chassis and 

the monitor. 

Power!Video – An intra-frame video compression algorithm from Horizons 

Technology, Inc., dedicated to desktop computers, and providing playback 

without additional hardware. The Power!Video Pro version provides additional 

controls and settings. 

Power-On Diagnostics – A series of tests that automatically check hardware 

components of a system each time it is turned on. 

Power-Up Reset – Initialization process whereby storage elements within 

a system are preset to defined conditions when power is first applied. 

PP – See Peak to Peak. 

PPI – PDH Physical Interface. 

P-Picture (Predictive-Coded Picture) – One of the three types of digital 

pictures in an MPEG data stream. A picture that is coded using motioncompensated 

prediction from past reference pictures. The motion compen-

sation is causal, that is, only based on preceding pictures, which can be 

I-pictures or P-pictures. This type of picture generally has more data than 

B-picture types. 

PPP – Point-to-Point Protocol. 

PPT – PDH Path Termination. 

PPV – Pay Per View. 

PQ Information – Information on the disc (or tape) that determines track 

start points, control bits, timing information, etc. 

PRBS – See Pseudo Random Binary Sequence. 

Predicted Pictures (P-Pictures or P-Frames) – Pictures that are coded 

with respect to the nearest previous I- or P-picture. This technique is 

termed forward prediction. P-pictures provide more compression than 

I-pictures and serve as a reference for future P-pictures or B-pictures. 

P-pictures can propagate coding errors when P-pictures (or B-pictures) are 

predicted from prior P-pictures where the prediction is flawed. 

Prediction – a) The use of a predictor to provide an estimate of the pel 

value or data element currently being decoded. b) Prediction of a picture (P 

or B) with indication of a motion vector. 

Prediction Error – The difference between the actual value of a pel or 

data element and its predictor. 

Predictive-Coded Picture – A picture that is coded using motion compensated 

prediction from past reference pictures. 

Predictor – A linear combination of previously decoded pel values or data 

elements. 

Preemphasis (Predistortion) – A change in level of some frequency 

components of the signal with respect to the other frequency components 

at the input to a transmission system. The high-frequency portion of the 

band is usually transmitted at a higher level than the low-frequency portion 

of the band. 

Preenhancement – In many situations, video losses can be anticipated, 

allowing signal precompensation in a way that partially corrects for the 

losses. See Line Compensation. 

Premastering – The process of formatting data into the exact form that 

will appear on a DVD, including file structure and file locations. A premastered 

product is ready to be mastered and replicated. 

Preprocessing – The video signal processing that occurs before MPEG 

encoding. Noise reduction, downsampling, cut-edit identification, and 3:2 

pull-down identification are examples of preprocessing. 

Pre-Production – The universe of tasks that must be completed before 

shooting begins. 

Pre-Read – See Read Before Write. 

Prerecorded Tape – A commercially available recorded tape. 

Pre-Roll – The number of frames (or seconds and frames) between the 

cue point and the edit point which allows ACE to synchronize transports 

prior to an edit. 



Presence – How near the sound source seems to be with respect to the 

listener. Related to the intensity of the frequencies in the 2.5 K to 7.5 kHz 

range. 

Present Pattern – a) An effect selected by the PST PTN push-button 

where a wipe pattern is used. The characteristics of the pattern are set 

using the pattern controls. If the effect is wiped on-air over an existing onair 

background, the wipe pattern will only move as far as the limit set by 

the vertical and horizontal limit controls. This is sometimes called a preset 

wipe or a wipe to a pattern limit. If the effect is mixed on-air, it is called a 

mix to a pattern limit. b) The ability to set both horizontal and vertical limits 

to the size a pattern will grow to when the fader is moved to the B bus. 

Ampex switchers can wipe to a preset size, mix in a pattern already at a 

preset size, and mix or wipe in keys with preset limits. Mixing in a key 

using preset patterns allows portions of the key to be masked off, and this 

is the mask key feature on Ampex switchers. 

Presentation Data – Information, such as video or audio samples, which 

are presented at a specified time. 

Presentation Time Stamp (PTS) – A field that may be present in a PES 

packet header that indicates the time that a presentation unit is presented 

in the system target decoder. 

Presentation Unit (PU) – A decoded audio access unit or a decoded 

picture. 

Preset Background Bus – A row of crosspoint push-buttons used to 

select the video input that will be placed on-air during the next DSM background 

transition. 

Preset Bus – The line of push button switches on the control panel which 

select and indicate the next video that will appear when the DSK fader is 

pulled (AVC series in flip or flip-flop mode only). The idea behind the name 

is that this is a bus that allows one to pre-select (or preset) the next video. 

Preset Wipe – See Preset Pattern. 

Preset/Key Bus – The line of push button switches on the control panel 

which select and indicate the preview output, and represents the next video 

that will appear when the DSK fader is pulled. It can also select and indicate 

key sources to other keyers due to the fact that it is a “split” bus. That 

is, reentries can be selected for the next video as well as bus inputs for a 

key source, both at the same time. This type of bus is exclusive to 4100 

series switchers. 

Pressure Pad – A device that forces tape into intimate contact with the 

head gap, usually by direct pressure at the head assembly. 

Pressure Zone Microphone (PZM) – A microphone consisting of a metal 

plate and a small microphone element. The PZM collects and processes all 

sound waves that strike the metal plate. 

Preview – To rehearse an edit without actually performing edits. 

Preview Bus – A processor function allowing the operator to select any 

incoming video source for viewing prior to actual use. Typically, each signal 

can be previewed on its own monitor. This is an effective method to check 

work before going “on the air.” The Digital Video Mixer includes a separate 

preview output which can be used to preview all four of its video input signals 

on-screen simultaneously. 




Preview Key – The ability to see how a key will appear, and the effect of 

all adjustments on that key, without having to put the key “on-air.” 

Preview Monitor – A video monitor which displays the picture from a 

video source. It is used to evaluate a video source before selecting it. 

Preview Output – The output of the switcher which allows you to observe 

an effect before it is placed on-air. Also called Look Ahead Preview. This 

includes previewing keys. 

Primary Colors – Colors, usually three, that are combined to produce the 

full range of other colors within the limits of a system. All non-primary colors 

are mixtures of two or more of the primary colors. In television, the primary 

colors are specific sets of red, green, and blue. 

Primary Distribution – The links that feed the signals to the transmission 

sites, such as terrestrial transmitters, cable head-ends, and satellite uplinks, 

from the studio or “Play-Out Center,” often via a switching center. 

Primary Inputs – The eight video inputs applied to the Key, Program 

Background, and Preset Background buses. 

Primary Matrix – That portion of the crosspoint electronics associated 

with bus rows accessible from the switcher console. That is, the rows of 

buttons on the left side of a switcher which select the video inputs to the 

M/Es and including the program, preset (or line A/B) and PST/key bus row 

push buttons. 

Primitives – Refer to the most basic three-dimensional shapes, for example 

cubes, cylinders, cones, and spheres. From these you can build more 

complex 3D objects. 

Print Manager – A tool accessed through either the System Toolchest or 

the System Manager that is used to set up printer software and monitor 

jobs that are sent to the printer. 

Print-Thru – The effect of signals being magnetically impressed on adjacent 

portions of tape. This is the effect of magnetic induction and its cause 

can be excessive spooling or heat. Factors affecting spurious printing are 

principally heat, tape thickness, and recording level and, to a lesser extent, 

time. Print-thru increases linearly with the logarithm of the time of contact, 

other factors being constant. 

Priority – Number assigned to an event or device that determines the 

order in which it will receive service if more than one request is made 

simultaneously. 

Proc Amp – See Video Processing Amplifier. 

Processed External Key – Synonym for Isolated Key. 

Processing Amplifier (or Proc Amp) – A set of electronic circuitry used 

to insure that the video output signal of a switcher (or other video equipment) 

maintains proper levels and relationships and that sync and burst 

are clean and useable. The AVC series switcher comes with a limited proc 

amp as a standard feature. This proc amp can pass the video signal as it 

appears at the input, or strip the old sync and add a new sync pulse. It can 

also strip both sync and burst and add new sync and burst prior to the output 

of the switcher. 

Processor – Same as Microprocessor. 

Production – Creation of recorded image information with associated 

audio, including necessary editing to achieve the thematic and artistic con- 


tent desired for distribution. Production includes the three subdivisions: 

origination, post-production, and distribution. During production, there may 

be one or more interconversions of the image information between photographic 

and electronic modes. At the conclusion of the production step, the 

program has its intended final artistic and thematic content. When the 

major portion of the production process has been completed and the program 

is transferred to distribution, it may be required to transform systems 

to whatever formats best meet the program’s distribution requirements. 

Production Switcher – A device that allows transitions between different 

video pictures. Also allows keying and matting (compositing). See Video 

Switcher. 

Production System HDTV – Production system HDTV is the analog of 

studio standard, HDTV, and addresses only a small part of what the SMPTE 

Committee on Hybrid Technology (H19) considers production, and in fact 

only a small part of what they consider electronic production. Thus, in the 

context of SMPTE 240M, Television Signal Parameters 1125/60 High- 

Definition Production System, production has a much more restrictive definition 

than that employed by CCIR, or the SMPTE Committee on Hybrid 

Technology (H19).To illustrate by example from SMPTE 240M, the scope 

explains, this standard defines the basic characteristics of the video signals 

associated with origination equipment operating at the 1125/60 highdefinition 

television production system. It is, therefore, directed to the 

equipment that first encodes the image information into this electronic format, 

for example, the studio camera and its associated electronics. 

Production, Electronic – Performing one or more of the steps in the production 

sequence with the image information encoded in the electronic 

mode. 

Production, Electronic, Digital – The SMPTE Working Group on Digital 

Picture (H19.16) with initial focus upon nonreal-time digital representation 

of images, has been formed to develop standards and recommended practices 

with emphasis upon the production process. The SMPTE Task Force 

on Digital Image Architecture (ST13.20) has been formed to define further 

requirements for the exchange of digital pictures at various resolutions and 

across the interfaces with a variety of video, computer, and data media. 

Profile – a) A defined subset of the syntax of a specification. 

b) Subdivision of video coding into different resolutions. c) Defines the 

amount of functions and compression processes involved. It is, in other 

words, a defined subset of the entire syntax, and limits the number of facilities 

that may be used. For instance, a profile specifies the allowed scalability 

features. 

Program (PGM) – a) Procedure for solving a problem, coded into a form 

suitable for use by a computer. Frequently referred to as software. b) A 

collection of program elements. Program elements may be elementary 

streams. Program elements need not have any defined time base; those 

that do have a common time base and are intended for synchronized presentation. 

c) A concatenation of one or more events under the control of a 

broadcaster, e.g., news show, entertainment show. 

Program Access – Prohibition on exclusive programming contracts 

between cable operators and program services controlled by cable operators, 

designed to give alternative multichannel distributors (such as wire-

less cable and DBS) the opportunity to bid for established cable services 

(such as CNN or Nickelodeon). The rule expires in 2002. 

Program Background Bus – A row of crosspoint push-buttons used to 

select the on-air background output of the switcher. 

Program Bus – a) Similar to the preview bus in concept except that the 

resulting output is the final signal which goes “on the air.” b) The line of 

push button switches on the control panel which select and indicate the 

video source of the switcher output on a flip or flip-flop style switcher. 

Program Clock Reference (PCR) – A time stamp in the transport stream 

from which decoder timing is derived. 

Program Counter (PC) – Register in the CPU that holds the address of 

the next program word to be read. Branching requires loading of the jump 

address into the program counter. Otherwise, the PC is incremented after 

each word is read. 

Program Element – A generic term for one of the elementary streams or 

other data streams that may be included in the program. 

Program Output – The on-air or final output of the switcher as selected on 

the program or line A/B bus and as keyed, mixed, or faded with the DSK. 

Program Specific Information (PSI) – Normative data which is necessary 

for the demultiplexing of transport streams and the successful regeneration 

of programs. 

Program Stream – a) A bit stream containing compressed video, audio, 

and timing information. b) Multiplex of several audio and video PES using 

the same clock. c) Combines one or more packetized elementary streams 

(PES), which have a common time base into a single stream. The program 

stream was designed for use in relatively error-free environments, and is 

suitable for applications which may involve software processing. Program 

stream packets may be of variable length. 

Programming Language – A means of specifying an ordered group of 

instructions that a computer will execute. 

Progressive – Short for progressive scanning. A system of video scanning 

whereby lines of a picture are transmitted consecutively, such as in the 

computer world. 

Progressive Scan – See Noninterlaced Scan. 

Progressive Sequence – Sequence of pictures, that all are frame pictures 

with frame DCT coding. 

Projection – When a database is visualized, it is “projected” from 3D into 

2D (the screen). Two kinds of projection are used, projection and 

orthogonal. 

PROM (Programmable Read-Only Memory) – Integrated circuit memory 

that is manufactured with a pattern of all logical 0s and 1s and has a 

specified pattern written into it by a special hardware programmer. 

PROM Monitor – The interface used to communicate with the system 

after it is powered up, but before it is booted up and running IRIX. 

Prompt – A character or word that the system displays that indicates the 

system is ready to accept commands. 

Propagation Delay – The time it takes for a signal to travel through a circuit, 

piece of equipment, or a length of cable. When the luminance and 



color information of a video signal are separated for processing, then 

reunited at the output of a device, it is critical that the propagation delay 

for each signal component is equal or distortion similar to ghosting will 

result. Propagation delay is most noticeable in color-under VHS players. 

Propagation delay is also a problem when routing computer data and clock 

signals around a chip or circuit board. The faster the clock, the more critical 

the path delays. 

Proshare – A videoconferencing video system by Intel which adapts PCs 

using added circuit boards, to videoconferencing. The Proshare system is 

based on H.320 recommendations for audio and video teleconferencing. 

Protocol – Set of syntax rules defining exchange of data including items 

such as timing, format, sequencing, error checking, etc. 

Provider – A software layer that provides services to other layers. A 

provider may or may not involve dedicated hardware. 

PS – See Program Stream. 

PSA – Public Service Announcement. 

Pseudo-Color – A color relationship scheme in which a color table contains 

available color values; an index into this table is used to refer to a 

color. If a desired color is not found in the table, it may be matched to the 

closest available entry or an existing entry may be overwritten. 

Pseudo-Instruction – Instruction that is used in an assembly language 

program but is an instruction for the assembler. Pseudo-instructions have 

no direct correspondence to machine language. 

Pseudo-Random Binary Sequence (PRBS) – A random sequence of bits 

which repeat after 2 n – 1. 

Pseudo-Random Sequences/Patterns – Certain systems described in 

these standards employ feedback shift registers to modify sequences or 

patterns of bits in a predetermined manner or to restore such modified bit 

patterns to their original sequence. With outputs of suitably selected stages 

added modulo-2 and applied to its feedback loop, an n-stage feedback 

shift register will generate a bit sequence or pattern (2 n – 1) bits long 

before repeating. Because such repeating sequences exhibit many of the 

statistical properties of uniformly distributed random number sequences 

(e.g., their probability density and autocorrelation functions satisfy appropriate 

conditions),they are called pseudo-random. 

PSI (Program Specific Information) – a) Information that keeps track of 

the different programs in an MPEG transport stream and in the elementary 

streams in each program. PSI includes: PAT, PMT, NIT, CAT, ECM, and 

EMM. b) Normative data necessary for the demultiplexing of TSs and the 

regeneration of programs. 

PSI/SI – A general term for combined MPEG PSI and DVB-SI. 

PSIP (Program and System Information Protocol) – A part of the ATSC 

digital television specification that enables a DTV receiver to identify program 

information from the station and use it to create easy-to-recognize 

electronic program guides for the viewer at home. The PSIP generator 

inserts data related to channel selection and electronic program guides 

into the ATSC MPEG transport stream. 

PSK – Phase Shift Keying. 

PST – Preset. 




PSTN – Public Switched Telephone Network. 

PSW – Pan and Scan Window. 

PTS (Presentation Time Stamp) – a) The time at which a presentation 

unit is to be available to the viewer. When the packet should arrive and its 

destination. b) Time stamp for vision and sound integrated into PES, transmitted 

at least every 0.7 sec. 

PTV – See Public Television. 

PU (Presentation Unit) – a) One compressed picture or block of audio. 

b) Decoded AAU or a decoded picture. 

Public Television – Television stations and networks that operate as noncommercial 

ventures. 

Puck – Another name for a capstan idler. 

Pull-Down – Technique that eliminates redundant frames when converting 

film material (24 fps) into NTSC 930 fps). 

Pull-Up Resistor – Used to provide the source current for open-collector 

and three-state logic gates or a termination for unused inputs. Pulls the 

voltage level up when no other device is driving the line. 

Pulse Code Modulation (PCM) – a) Coding where analog input signal is 

represented by a given number of fixed-width digital samples per second. 


Often used for the coding employed in the telephone network. b) A technical 

term for an analog source waveform, for example, audio or video signals, 

expressed as periodic, numerical samples. PCM is an uncompressed 

digital signal. c) This is a form of the digital audio signal used for both CD 

and laserdisc. It is a serial data stream that is coded for transmission or 

recording. PCM is also used for many other types of serial data communications. 

Pulse to Bar Ratios – The amplitude ratio between a 2T pulse and a line 

bar is sometimes used as an indication of short time distortion. The results 

of this measurement can be described in units of K-2T or K-PB. 

Pulse-Bar Inequality – Kpulse/bar = 1/4 | (barpulse)/pulse | X 100% 

Pulser – See Logic Pulser. 

Pulse-to-Bar Ratio – (pulse/bar) X 100% 

Push – Operation of adding a word to the stack. 

Push-Down Stack – See Stack. 

PVW – Preview.

Q 

Q – Quantization. 

Q-1 – Inverse Quantization. 

QAM – See Quadrature Amplitude Modulation. 

QCIF – a) See Quarter Common Interface Format (also called the Quarter 

Common Source Intermediate Format). b) One-quarter-resolution (176 x 

144 pixels) Common Interchange Format. See CIF. 

QE – Quadrature Error. 

QEF (Quasi Error Free) – Less than one uncorrected error per hour at the 

input of the MPEG-2 decoder. 

QEV – Quadrature Error Vector. 

QoS – Quality of Service. 

QPSK (Quaternary Phase Shift Keying) – Type of modulation for digital 

signals (DVB-S). The digital, serial signal components I and Q directly control 

phase shift keying. The constellation diagram with its four discrete 

states is obtained by representing the signal components using the I and Q 

signals as coordinate axes. Due to the high nonlinear distortion in the 

satellite channel, this type of modulation is used for satellite transmission. 

The four discrete states all have the same amplitude that is why nonlinear 

amplitude distortions have no effect. 

QS – Quantization Scaling. 

QSIF – a) See Quarter Square Interface Format. b) One-quarter-resolution 

Source Input Format. See SIF. 

Quad Chroma – Another name for 4FSC because the pixel clock is four 

times the frequency of the chroma burst. For (M) NTSC the pixel clock is 

14.32 MHz (4 x 3.579545 MHz), and 17.73 MHz (4 x 4.43361875 MHz) in 

(B, D, G, H, I) PAL systems. 

Quad Select – The matrix and its control that select the video sources 

feeding each of the four quadrants of a quad split. This is a separate 

option on the 4100 but has been integrated into the quad split on the AVC. 

Quad Split – The visual effect of dividing a picture into four segments, 

each of which may display video from a separate source. Also the name of 

the switcher panel module which controls this effect. 

Quadrature Amplitude Modulation – a) A process that allows two signals 

to modulate a single carrier frequency. the two signals of interest 

Amplitude Modulate carrier signals which are the same frequency but differ 

in phase by 90 degrees (hence the Quadrature notation). The two resultant 

signals can be added together, and both signals recovered at the other 

end, if they are also demodulated 90 degrees apart. b) Type of modulation 

for digital signals (DVB-C). Two signal components I and Q are quantized 

and modulated onto two orthogonal carriers as appropriate for the QAM 

level (4, 16, 32, 64, 128, 256). The constellation diagram is obtained by 

plotting the signal components with I and Q as the coordinate axes. 

Therefore, 2, 3, 4, 5, 6, or 8 bits of a data stream are transmitted with one 

symbol, depending on the QAM level (4, 16, 32, 64, 128, 256). This type of 

modulation is used in cable systems and for coding the COFDM single 

carriers. 



Quadrature Distortion – Distortion resulting from the asymmetry of sidebands 

used in vestigial-sideband television transmission. Quadrature distortion 

appears when detection is used, but can be eliminated by using a 

synchronous demodulator. 

Quadrature Modulation – The modulation of two carrier components, 

which are 90 degrees apart in phase. 

Quality Assessment – The (subjective) process in measuring the quality 

of an image or video sequence as it appears to humans. Humans find certain 

types of errors (image distortions) to be more acceptable than others. 

In video coding, one is often trying to maximize the subjective quality of the 

video produced by the coding algorithm, which is often quite different than 

the mathematical quality (measured, for example, by the peak signal-tonoise 

ratio or PSNR). 

Quantization – a) The process of converting a continuous analog input 

into a set of discrete output levels. b) A process in which the continuous 

range of values of an input signal is divided into non-overlapping subranges, 

and a discrete value of the output is uniquely assigned to each 

subrange. Whenever the signal value falls within a given subrange, the output 

has the corresponding discrete value. 

Quantization Error – The amount that the digital quantity differs from the 

analog quantity. 

Quantization Matrix – A set of sixty-four 8-bit values used by the 

dequantizer. 

Quantization Noise – Inaccurate digital representations of an analog signal 

that occurs during the analog-to-digital signal processing. Typically, the 

digital interpretation of video resolution is limited through the digital sampling 

of the analog video input signal. 

Quantized DCT Coefficients – DCT coefficients before Dequantization. A 

variable length coded representation of quantized DCT coefficients is 

stored as part of the compressed video bit stream. 

Quantizer – A processing step which intentionally reduces the precision of 

DCT coefficients. 

Quantizer Scale – A scale factor coded in the bit stream and used by the 

decoding process to scale the dequantization. 

Quantizing – The process of converting the voltage level of a signal into 

digital data before or after the signal has been sampled. 

Quantizing Error – Inaccuracies in the digital representation of an analog 

signal. These errors occur because of limitations in the resolution of the 

digitizing process. 

Quantizing (Quantization) Noise – The noise (deviation of a signal from 

its original or correct value) which results from the quantization process. In 

serial digital, a granular type of noise only present in the presence of a 

signal. 

Quarter Common Interface Format – This video format is often used in 

low-cost video phones. This format has a luminance resolution of 176 x 




144 active pixels per line, a refresh rate of 29.97 frames per second at 

uncompressed bit rate of 9.115 Mbits/s. 

Quarter Square Interface Format – Defines square pixels used in computer 

applications. 

Quarter-Track – See Four-Track. 

Quick Compressor – A compressor compatible with Indeo video interactive 

that handles data more quickly than the offline compressor. Videos that 

compress in hours can take minutes using the quick compressor. Compare 

Offline Encoder. 

QuickTime – QuickTime is a software platform from Apple that allows 

integration of audio visual data into software applications. It supports various 

algorithms through its built-in image compression manager. The algo- 


rithms supported include CinePak, JPEG, and MPEG. QuickTime files have 

the file extension “.mov.” 

QuickTime for Windows – Apple’s multimedia playback environment for 

Microsoft Windows operating system. You use QuickTime for Windows by 

installing several drivers and libraries on your hard disk. 

Quiet Line – A horizontal line in the vertical interval that is sometimes 

used to evaluate the amount of noise introduced in a certain part of the 

transmission path. A line is reinserted (and is therefore relatively noise 

free) at one end of the transmission path of interest. This ensures that any 

noise measured on that line at the other end was introduced in that part of 

the path. 

Quit – To stop running an application.

R 

R, G, B Color Space – a) An additive color space with colorimetric coordinates 

based on red, green, and blue stimuli or primaries. Color values are 

negative in certain areas outside the gamut defined by the R, G, B primaries. 

The R, G, B values used are intensities. b) The three linear video signals 

carrying respectively the red, the green, and the blue information. By 

convention, the unprimed symbols signify that there is a linear relationship 

between the luminance in each spectral region and the corresponding 

video signal. The spectral composition of the luminance forming each of 

these signals is one of the specifications required of the video system. The 

recently adopted CCIR Rec 709 reflects worldwide agreement on the current 

definition of R, G, B primary colors. CCIR Rec 709 identifies this as an 

interim agreement to be superseded by preferred primary colors encompassing 

a wider color gamut as soon as the technologies and practices 

permit. c) The colorimetric coordinates defined by thee nonlinear video signals 

carrying respectively the red, the green, and the blue information. By 

convention the primed symbols signify that there has been a nonlinear 

transformation of the video signals vs. luminance, relative, scene, with its 

resulting modification of the opto-electric transfer function. 

Rack – The physical setting of a head in the direction toward or away from 

the tape. 

Radio Common Carrier – Common carriers whose major businesses 

include radio paging and mobile telephone services. 

Radix – Total number of distinct characters or numbers used in a numbering 

system. Same as Base. 

RAID (Redundant Array of Independent Disks) – a) Using more than 

one drive to achieve either higher throughput, security, or both. New technology 

has made it possible to create EIDE RAID systems that give excellent 

performance at a very low cost. b) A grouping of standard disk drives 

together with a RAID controller to create storage that acts as one disk to 

provide performance beyond that available from individual drives. Primarily 

designed for operation with computers, RAIDs can offer very high capacities, 

fast data transfer rates, and much increased security of data. The latter 

is achieved through disk redundancy so that disk errors or failures can 

be detected and corrected. A series of RAID configurations is defined by 



levels and, being designed by computer people, they start counting from 

zero. Different levels are suited to different applications. 

Level 0: No redundancy, benefits only of speed and capacity, generated by 

combining a number of disks. Also known as "striping". 

Level 1: Complete mirror system, two sets of disks both reading and writing 

the same data. This has the benefits of Level 0 plus the security of 

full redundancy, but at twice the cost. Some performance advantage 

can be gained in read because only one copy need be read, so two 

reads can occur simultaneously. 

Level 2: An array of nine disks. Each byte is recorded with one bit on each of 

eight disks and a parity bit recorded to the ninth. This level is rarely, if 

ever, used. 

Level 3: An array of n+1 disks recording 512 byte sectors on each of the n 

disks to create n x 512 “super sectors” + 1 x 512 parity sector on the 

additional disk which is used to check the data. The minimum unit of 

transfer is a whole superblock. This is most suitable for systems in 

which large amounts of sequential data are transferred, such as for 

audio and video. For these, it is the most efficient RAID level since it 

is never necessary to read/modify/write the parity block. It is less 

suitable for database types of access in which small amounts of data 

need to be transferred at random. 

Level 4: The same as Level 3 but individual blocks can be transferred. When 

data is written, it is necessary to read the old data and parity blocks 

before writing the new data as well as the updated parity block, 

which reduces performance. 

Level 5: The same as Level 4 but the role of the parity disk is rotated for each 

block. In Level 4, the parity disk receives excessive load for writes 

and no load for reads. In Level 5 the load is balanced across the 

disks. 

RAM (Random Access Memory) – a) The chips in a computer that contain 

its working memory. b) Usually used to mean semiconductor 

read/write memory. Strictly speaking, ROMs are also RAMs. See also 

Random Access. c) This term has come to mean any semiconductor memory 

whose write access time is approximately the same as its read access 

time. This is typically taken to include SRAMs (Static RAMs) and DRAMs 

(Dynamic RAMs). This definition specifically eliminates memories that cannot 

be altered at all and memories that require a special fixture for erasing 

(such as EPROMs). 

Ramped Color – Color intensity extracted from a “smooth” set of predetermined 

values varying from an initial to a final intensity. 

Random Access – a) The process of beginning to read and decode the 

coded bit stream at an arbitrary point. b) Access method in which each 

word can be retrieved in the same amount of time (i.e., the memory locations 

can be accessed in any order). 

Random Interlace – Obsolete form of inexpensive 525 scanning-line system 

with such poor interlace that line pairing was the norm rather than the 

exception. 




Random Logic – Hard-wired (or random) logic design solutions require 

interconnection of numerous integrated circuits representing the logic elements. 

The function of the circuit is determined by the functional blocks 

and their interconnections, rather than by a program. 

Random Noise – Also called thermal noise, a transmission or recording 

impairment that manifests itself as snow in a picture and hiss in sound. A 

number of techniques have been developed to reduce random noise in a 

picture through signal averaging. 

Random Noise (Weighted) – The signal-to-weighted noise ratio is the 

ratio in decibels, of the nominal amplitude of the luminance signal (100 IRE 

units) to the RMS amplitude of the noise measured at the receiving end 

after band limiting and weighting with a specified network. The measurement 

should be made with an instrument having, in terms of power, a time 

constant or integrating time of 0.4 seconds. 

Randomized Rounding – Digitizing technique whereby the contouring 

effects of digital video are minimized by adding a small amount of random 

noise to the signal. Also see Dithering. 

RAS (Row Address Strobe) – A DRAM control signal. 

Raster – a) A series of horizontal scan lines that make up a display. The 

scanned (illuminated) area of the cathode-ray picture tube. b) A set of 

scanning lines; also the type of image sampling using scanning lines (as in 

raster scanning). 

Rate Conversion – a) Technically, the process of converting from one 

sample rate to another. The digital sample rate for the component format is 

13.5 MHz; for the composite format it is either 14.3 MHz for NTSC or 

17.7 MHz for PAL. b) Often used incorrectly to indicate both resampling of 

digital rates and encoding/decoding. 

Rate Distortion Theory – The study of the distortion (error) of a lossy 

coding algorithm as a function of the bit rate. Rate distortion theory sets 

the lower bound on the bit rate as a function of the distortion. 

Raw – A bitstream format in which the video data is uncompressed. See 

Compress, Encode. 

Raw Footage – Videotape recordings that have not been edited. 

Ray Tracing – A method where each pixel is calculated to reflect or 

refract off, or through, any surface encountered to simulate a true optical 

ray. This produces more realistic images but is computationally expensive 

and time-consuming and can involve the use of more memory. 

RBOC (Regional Bell Operating Company) – An acronym sometimes 

applied to the Baby Bell holding companies and sometimes to individual 

Bell telephone companies. See also Baby Bell. 

RC – Return Channel. 

RC Time Code (Rewriteable Consumer) – A time-code system, available 

on 8 mm and Hi-8 formats only, supported by the thumbs up editor. The 

code can be added either before or after video recording without affecting 

the video or audio. 

RCA (Radio Corporation of America) – Now part of GE. RCA was once 

involved in every aspect of television, from camera to receiver, supplying 

production, transmission, consumer electronic, and CATV equipment, and 

operating a television network (NBC) and a satellite transmission carrier. 


RCA developed the first effective HDTV camera tube, proposed several 

HDEP schemes ranging from 750 to 2625 scanning lines, and did extensive 

ATV research at RCA Laboratories (now SRI International’s DSRC). 

RCA’s broadcast equipment group no longer exists, Burle is selling its 

tubes, and its consumer electronics are now part of the Thomson group. 

GE has, thus far, retained the satellite transmission carrier (renaming it GE 

Americom) and the NBC television network, a proponent of the ACTV ATV 

schemes. 

RCA Connector – A type of connector used on all consumer VCRs and 

camcorders to carry the standard composite video and audio signals. See 

also Phono. 

RCC – See Radio Common Carrier. 

RDI – Remote Defect Indication. 

Read Before Write – A feature of some videotape recorders that plays back 

the video or audio signal off of tape before it reaches the record heads, 

sends the signal to an external device for modification, and then applied the 

modified signal to the record heads so that it can be re-recorded onto the 

tape in its original position. 

Real Time – a) Actual elapsed time (as opposed to “tape time”). 

b) Displaying an image or responding to a user’s request almost simultaneously. 

When you display an animation in real time, you perform the 

movements at the speed you made them in the animation. c) Computation 

or processing done in the present to control physical events occurring in 

the present. For example, when a digital effects system operator moves a 

joystick and the video images on the monitor appear to move simultaneously, 

the computations required to make the images move are said to 

have occurred in real time. 

Real Time Clock – Timing signal derived from the house composite sync. 

Real Time Counter – A display showing hours-minutes-seconds of tape 

that has been recorded (elapsed time), or how much tape remains. 

RealAudio – RealAudio is an on-line audio software platform, from the 

company Progressive Networks, dedicated to audio links on the Internet via 

14.4 kbit/s, 28.8 kbit/s or faster connections. RealAudio software features 

a player, a server, and development tools, and is available for Windows, 

Unix, and Apple Macintosh environments. 

Rec Cal – A control which matches the signal level monitored in the input 

position of the output selector switch to that of the signal recorded and 

played back from the tape. 

Rec. 601 – CCIR recommendation (standard) for digital component video, 

equally applicable to 525 and 625 scanning lines, also called 4:2:2. Digital 

component video is about as close in quality as current 525 scanning line 

equipment can come to ATV. See ITU-R BT.601-2. 

Recall – The act of calling stored data out of memory. 

Receiver-Compatible – Term used for an ATV scheme that allows existing 

NTSC television sets to tune into the ATV signal and get pictures and 

sounds; also used to describe an MIT ATV scheme using blanking adjustment 

for aspect ratio accommodation and using various sub-channels to 

carry additional information but requiring a very complex receiver to recover 

that information. It is said to offer 600 lines of vertical and 660 lines of 

horizontal static luminance resolution, with reduced static diagonal resolu-

tion and with dynamic resolution comparable to NTSC. The term Receiver 

Compatibility, as it is usually used, allows some degradation in pictures 

from the highest NTSC quality, in the same way that the receiver-compatible 

NTSC color system introduced cross-luminance to existing black-andwhite 

TV sets. 

Reclocking – The process of clocking the data with a regenerated clock. 

Record Level – The amount of energy delivered to the recording head and 

to the magnetic tape. Indicated by the VU meter and measured in nanowebers 

per meter. 

Record Review – A feature on many video cameras and camcorders that 

allows the videographer to see the last few seconds of video recorded on 

the videotape. 

Record Tabs – Those plastic tabs seen in the back edge of a cassette. 

When removed, sensing fingers prevent the record button from being 

depressed. 

Recorder, Film – Equipment for transducing a video waveform into displayed 

images, and making a record of such images on motion-picture film 

so that they may be stored and subsequently retrieved as film images. 

Recorder, Video – Equipment for making a record of a video waveform so 

that the mapped images may be stored and subsequently retrieved as the 

video waveform. 

Recording Level Meter – An indicator on a tape recorder that provides 

some idea of the signal levels being applied to the tape from moment to 

moment. It is intended as an aid in setting the recording levels. 

Recording Speed (IPS) – Refers to the number of inches per second, or 

centimeters per second, of tape movement. 

Reel – The flanged hub, made of metal, glass, or plastic, on which magnetic 

tape is wound. 

Reel Number – Number assigned by the operator to each reel or cassette 

of video tape used in the editing session. The reel number identifies each 

reel or cassette on the edit list for final assembly or for future revisions. 

Ref Sync Amplitude – Refer to the Horizontal Timing discussion. 

Reference – A space where objects exist as a set of mathematical 

descriptions. In a 3D scene, references are used to organize the objects 

(position, orientation and scaling) by defining a parent-child relationship. 

Reference Black Level – Refer to the Horizontal Timing discussion. 

Reference Picture – Reference pictures are the nearest adjacent I or P 

pictures to the current picture in display order. 

Reference Tape – A tape used as a reference against which the performances 

of other tapes are compared. The use of a reference tape is necessary 

in specifying most performance characteristics because of the difficulty 

of expressing these characteristics in absolute terms. 

Reference Video – a) Video signal which is used to synchronize different 

pieces of video equipment by providing a common timing signal. It is generated 

from a single source and distributed. Typically, reference video consists 

of black color or color bars, and control track pulses. b) A composite 

video signal used to compare all other video signals to for timing purposes. 



Reference White Level – The level corresponding to the specified maximum 

excursion of the luminance signal in the white direction. Refer to the 

Horizontal Timing discussion. 

Reflectance Factor R – Ratio of the radiant or luminous flux reflected in 

the directions delimited by the given cone to the reflected in the same 

directions by a perfect reflecting diffuser identically irradiated or illuminated. 

Reflected Sound – Sound which reaches a mike or listener after one or 

more reflections from surrounding surfaces. 

Reflections or Echoes – In video transmission, this may refer either to a 

signal or to the picture produced. a) Signal: Waves reflected from structures 

or other objects; waves which are the result of impedance or other 

irregularities in the transmission medium. b) Picture: “Echoes” observed in 

the picture produced by the reflected waves. 

Refresh – a) An image drawn on a CRT display remains visible only for a 

few milliseconds (the persistence of the screen phosphor), unless it is 

redrawn continuously. This process is called display refresh or screen 

refresh. Different displays use different refresh rates, but display refresh is 

normally required between 60 and 80 times a second to avoid any visible 

screen flickering. 75 times a second is a common refresh rate. In general, 

a higher refresh rate results in a more stable appearing display. b) Process 

of restoring the charge in a dynamic memory. Refresh logic must rewrite 

the contents of the complete RAM periodically (typically 2 ms), called 

refreshing the memory. See Dynamic Memory. 

Regenerative Pulse Distribution Amplifier (Regenerative Pulse DA) – 

Reconstructs the signal and allows for adjustment of delay. Also see Linear 

Pulse DA. 

Region Coding – Region coding has received attention because of the 

ease with which it can be decoded and the fact that a coder of this type is 

used in Intel’s Digital Video Interactive system (DVI), the only commercially 

available system designed expressly for low-cost, low-bandwidth multimedia 

video. Its operation is relatively simple. Envision a decoder that can 

reproduce certain image primitives well. A typical set of image primitives 

might consist of rectangular areas of constant color, smooth shaded patches, 

and some textures. The image is analyzed into regions that can be 

expressed in terms of these primitives. The analysis is usually performed 

using a tree-structured decomposition where each part of the image is 

successively divided into smaller regions until a patch that meets either the 

bandwidth constraints or the quality desired can be fitted. Only the tree 

description and the parameters for each leaf need then be transmitted. 

Since the decoder is optimized for the reconstruction of these primitives, it 

is relatively simple to build. To account for image data that does not 

encode easily using the available primitives, actual image data can also be 

encoded and transmitted, but this is not as efficient as fitting a patch. This 

coder can also be combined with prediction (as it is in DVI), and the predicted 

difference image can then be region coded. A key element in the 

encoding operation is a region growing step where adjacent image patches 

that are distinct leaves of the tree are combined into a single patch. This 

approach has been considered highly asymmetric in that significantly more 

processing is required for encoding/analysis than for decoding. While hardware 

implementations of the hybrid DCT coder have been built for extremely 

low bandwidth teleconferencing and for HDTV, there is no hardware for a 

region coder. However, such an assessment is deceptive since much of the 




processing used in DVI compression is in the motion predictor, a function 

common to both methods. In fact, all compression schemes are asymmetric, 

the difference is a matter of degree rather than one of essentials. 

Register – a) Single word of memory. Registers within the CPU are more 

readily accessible than external memory locations. Registers external to the 

CPU are simply a group of flip-flops. b) A memory storage location. Each 

can store the data for a complete switcher setup. c) In a VGA controller, 

these are the storage elements that contain data relating to the mode or 

configuration of the device, as opposed to the display memory, which contains 

the image. Traditionally, the registers are divided into six groups: 

General, Sequencer, CRT Controller, Graphics Controllers, Attribute, and 

Extensions. The registers are accessed by a number of addressing 

schemes, usually involving an index or address register and a data register. 

Register-Level Compatibility – If a peripheral is compatible at the register 

level with another peripheral, it means that every bit in every register of 

the two devices has precisely the same meaning. This implies that application 

programs can circumvent the BIOS and directly program registers in a 

peripheral device without functionality problems. 

Registration – The accuracy of having all three images (red, green, and 

blue) with exactly the same geometry. 

Relative Addressing – Specifying an address as a distance from the current 

address (e.g., three bytes ahead or four bytes backwards). 

Relative Burst Gain Error – The change in gain (amplitude) of the color 

burst signal relative to the gain (amplitude) of the chrominance subcarrier, 

in the active line time, caused by processing the video signal. 

Relative Burst Phase Error – The change in phase of the color burst signal 

relative to the phase of the chrominance subcarrier, in the active line 

time, caused by processing the video signal. 

Relative Chroma Level – See Chrominance-to-Luminance Gain. 

Relay – An electromagnetically operated switch. 

Reluctance – Resistance to the flow of magnetic flux. 

Remanance – The amount of magnetism left in a magnetic material after 

the removal of the magnetizing force. 

Remote – Any program originating outside the studio. 

Remote Socket – A socket on a VCR or video camera which when connected, 

permits remote control of the unit. Remotes may be wired or wireless 

(infrared) and allow such control as play, pause, record, fast forward, 

and rewind. See Edit Control. 

Remote Workstation, Drive, Disk, File System, or Printer – A hardware 

device or the information or media it contains that can be accessed 

across the network; they are not physically connected to the workstation. 

Render to Disk – Since it can take considerable time to render a single 

3D image, and most of that time is CPU compute time, many facilities 

using PC-based rendering systems have used large Winchester disks to 

which they send their final rendered images. This frees up the frame buffer 

for other work in the meantime. Later, when the animation is fully computed, 

the disk images can be quickly recalled and placed in the frame buffer, 

before being sent to videotape. 


Rendering – a) The process of drawing the database, making it visible, is 

called rendering. There are many ways to render the same database; as a 

“wireframe,” as a wireframe with “hidden” lines removed, or as a solid with 

various types of “shading.” b) The process by which the video editing software 

and hardware convert the raw video, effects, transitions, and filters 

into a new continuous video file. c) The process of non-real time drawing 

of a picture relying on computer processing speed for graphics and 

compositing. 

Repeater – Repeaters are transparent devices used to interconnect segments 

of an extended network with identical protocols and speeds at the 

physical layer (OSI layer 1). An example of a repeater connection would be 

the linkage of two carrier sense multiple access/collision detection 

(CSMA/CD) segments within a network. 

Replication – One method of hardware zooming is accomplished by multiplying 

the number of pixels and is known as pixel replication or simply, 

replication. Because replication increases the size of pixels and the effect 

is a blocky picture when zoomed, interpolation is a preferred technology 

where intermediate pixels are approximated causing less block video. 

Reproduce Level – A control which determines the output level of signals 

played back from the tape by the reproduce head. 

Resampling – Video image information may be presented in a specific 

system with, for example, its own frame rate, line count per frame, and line 

resolution (if the system is analog, resolution = video bandwidth; if the system 

is digital, resolution = pixels per line) and need to be recast into a target 

system differing in one or more of the specifications. Or in post-production, 

it may be desirable to change image size, to crop or zoom, or to 

distort geometrically, etc. The original signal is sampled and the samples 

processed by a suitable algorithm to generate a new set of samples compatible 

with the specifications of the target system. 

Reserved – The term “reserved” when used in the clause defining the 

coded bit stream, indicates that the value may be used in the future for ISO 

defined extensions. Unless otherwise specified within the present document 

all “reserved” bits shall be set to “1.” 

reserved_future_use – The term “reserved_future_use,” when used in 

the clause defining the coded bit stream, indicates that the value may be 

used in the future for ETSI defined extensions. Unless otherwise specified, 

all “reserved_future_use” bits shall be set to “1.” 

Reset – To activate a restart sequence to a CPU, ILC, or other device 

which has locked up or is for some other reason not responding correctly. 

Reset Button – A physical button on the workstation that you press to 

reinitialize the processor and some other hardware without removing power 

to the workstation. You should never press this button while IRIX is running, 

unless all attempts to shut down the system using software fail. See also 

Shut Down. 

Residual Flux – In a uniformly magnetized sample of magnetic material, 

the product of the residual flux density and the cross-sectional area. 

Residual flux is indicative of the output that can be expected from a tape at 

long wavelengths. 

Residual Flux Density, Br Gauss – The magnetic flux density at which 

the magnetizing field strength is zero when a sample of magnetic material

is in a symmetrically cyclically magnetized condition. Normally, the residual 

flux density of a tape is measured in the orientation direction, using an 

alternating magnetizing field of amplitude 1000 Oe. Residual flux density is 

indicative of the output that can be expected from a tape at short wavelengths. 

Residual Subcarrier – The amount of color subcarrier information in the 

color data after decoding a composite color video signal. Values appears as 

–n dB where the larger n, the better. 

Residual-to-Maximum Flux Ratio – In tapes consisting of oriented, acicular 

particles, this ratio is an indication of the degree of particle orientation. 

Theoretically, the ratio varies from 0.5 for randomly oriented particles 

to 1.0 for completely oriented particles. In practice, oriented tapes typically 

have ratios between 0.70 and 0.76. 

Resistance – Opposition to the flow of electrons. 

Resolution – The sharpness or “crispness” of the picture. Resolution can 

be measured numerically by establishing the number of scanning lines 

used to create each frame of video. a) The number of bits (four, eight, ten, 

etc.) determines the resolution of the digital signal; 4-bits = a resolution of 

1 in 16, 8-bits = a resolution of 1 in 256 (minimum for broadcast TV), 

10-bits = a resolution of 1 in 1024. b) The basic measurement of how 

much information is on the screen. It is usually described as the number of 

pixels in the horizontal axis by the number of horizontal lines. The higher 

the numbers, the better the system’s resolution. Some typical resolutions 

are: NTSC VHS – 240 x 485; NTSC broadcast – 330 x 485; NTSC laserdisc 

– 425 x 485; ITU-R BT.601 (525/60) – 720 x 485; Computer screen – 

1280 x 1024. c) The capability of making distinguishable individual parts 

of an image. A measure of how clear the picture looks. d) Perceivable 

detail. See also Chroma Resolution, Diagonal Resolution, Dynamic 

Resolution, Horizontal Resolution, Spatial Resolution, Static Resolution, and 

Temporal Resolution. e) The amount of detail in an image. Higher resolution 

equals more detail. Generally expressed in “lines.” It is the number of vertical 

line pairs that the system can distinguish, and has no relationship to 

the number of horizontal scan lines. 

Resolution Independent – A term to describe equipment that can work in 

more than one resolution. Dedicated TV equipment is designed to operate 

at a single resolution although some modern equipment, especially that 

using the ITU-R 601 standard, can switch between the specific formats 

and aspect ratios of 525/60 and 625/50. By their nature, computers can 

handle files of any size, so when applied to imaging, they are termed resolution 

independent. As the images get bigger, so the amount of processing, 

storage, and data transfer demanded increases in proportion to the resulting 

file size. So, for a given platform, the speed of operation slows. Other 

considerations when changing image resolution may be reformatting disks, 

checking if the RAM is sufficient to handle the required size of file, allowing 

extra time for RAM/disk caching, and how to show the picture on an 

appropriate display. 

Resolution, Color – The number of simultaneous colors is determined by 

the number of bits associated with each pixel in the display memory. The 

more colors, the more bits. If n bits per pixel are used, 2n color combinations 

can be generated. EGA uses from 1-4 bits per pixel, permitting up to 

16 (24 ) colors to be displayed on the screen simultaneously. The BGA has 



an added mode that supports 8 bits per pixel, or 256 (28 ) simultaneous 

colors. 

Resolution, Horizontal – The amount of resolvable detail in the horizontal 

direction in a picture. It is usually expressed as the number of distinct vertical 

lines, alternately black and white, which can be seen in three-quarters 

of the width of the picture. This information usually is derived by observation 

of the vertical wedge of a test pattern. A picture which is sharp and 

clear and shows small details has a good, or high resolution. If the picture 

is soft and blurred and small details are indistinct it has poor, or low resolution. 

Horizontal resolution depends upon the high-frequency amplitude 

and phase response of the pickup equipment, the transmission medium 

and the picture monitor, as well as the size of the scanning spots. 

Resolution, Image – In the practical sense, resolution is usually judged 

by imaging test targets bearing sets of spaced black-and-white lines in a 

square-wave pattern, and determining the minimum spacing for which the 

lines are distinguishable in the resultant image. With instrumentation readout, 

resolution target charts are less ambiguous and more useful if they 

bear sets of spaced “black” and “white” lines sinewave modulated in density, 

rather than square-wave modulated. Whereas square-wave targets 

introduce a Fourier series of higher frequencies, sinewave targets limit the 

analysis to a single frequency for each line set. Quantitative measurement 

of the modulations provides convenient determination of the transfer 

function. 

Resolution, Spatial – The number of pixels in an area or on the screen. 

Resolution is typically specified as pixels per scan line and scan lines per 

frame. Higher resolution images require more processing and greater storage 

requirements per image. In addition, monitor costs increase with resolution, 

particularly above about one million pixels. Different applications 

require different resolutions. 

Resolution, Vertical – The amount of resolvable detail in the vertical 

direction in a picture. It is usually expressed as the number of distinct horizontal 

lines, alternately black and white, which can be seen in a test pattern. 

Vertical resolution is primarily fixed by the number of horizontal scanning 

lines per frame. Beyond this, vertical resolution depends on the size 

and shape of the scanning spots of the pickup equipment and picture monitor 

and does not depend upon the high-frequency response or bandwidth 

of the transmission medium or picture monitor. 

Resolution, Visual – a) Qualitatively: Capacity for seeing distinctly fine 

details that have a very small angular separation. b) Quantitatively: Any 

of a number of measures of spatial discrimination such as the reciprocal of 

the value of the angular separation in minutes of arc of two neighboring 

objects (points or lines or other specified stimuli) which the observer can 

just perceive to be separate. c) In system design, the reference value for 

normal human visual limiting resolution is 30 cycles/degree, i.e., 60 TV 

lines per angular degree subtended at the viewing position. For systems of 




current interest, the maximum viewing distances for discrete vertical resolution 

of the number of lines presented are shown in the following table. 

Limiting Resolution of Vertical Detail (1) 

TV Per Subtended Maximum 

Line Frame Vertical Viewing 

Total Active Angle Distance (1) (2) 

525 485 8.08" 7.1h (3) = 5.3w (4) 

625 575 9.58" 6.0h = 4.5w (4) 

1125 1035 17.25" 3.3h = 1.9W (5) 

(1) No adjustment has been applied for possible interlace or Kell effects. 

(2) Assumes a shadow mask, if present, is not limiting. 

(3) h is vertical height of display. 

(4) w is horizontal width of display for 4:3 aspect ratio. 

(5) W is horizontal width of display for 16:9 aspect ratio. 

Resolving Power – Classically, two point objects are considered resolved 

when the centers of their diffraction disks in the image are separated by at 

least one disk diameter. This leads to a theoretical minimum angular separation 

for objects at a distance: a = (1.22)(lambda)/D. Resolving power of a 

lens increases with increasing optical aperture. Systems vary enormously 

in the closeness with which their actual resolving power approaches this 

diffraction-controlled ultimate limit. 

Resonant Frequency – The frequency at which a parallel LC circuit has 

highest opposition to current and at which a series LC circuit has the lowest 

opposition to current. 

Resource – A unit of functionality provided by the host for use by a module. 

A resource defines a set of objects exchanged between module and 

host by which the module uses the resource. 

Restore – To return a register or other computer word to its initial or preselected 

value. 

Restore (Files) – To copy files that once resided on your hard disk from 

another disk or a tape back onto your hard disk. 

Restorer – As used by the telephone company, a network designed to 

remove the effects of predistortion or preemphasis, thereby resulting in an 

overall normal characteristic. 

Restricted Slice Structure – In order to conform to “restricted slice 

structure,” all slices added together must cover the picture. This applies to 

Main Profile, for instance. 

Retentivity – The maximum value of the residual flux density corresponding 

to saturation flux density. 

Retiming – Adjustment of a local synchronizing generator which has been 

locked to a distant source. This permits the local facility to use the distant 

source in real-time production through a video switcher. 

RETMA – Radio Electronic Television Manufacturers Association. 

Retrace (Return Trace) – The movement of the electron beam from the 

right-hand edge of the display to the left-hand edge or from bottom to top. 

Retrace occurs during the blanking time. See Horizontal Retrace and 

Vertical Retrace. 


Retransmission Consent – Local TV broadcasters’ right to negotiate a 

carriage fee with local cable operators, as provided in 1992 Cable Act. 

Return – In particular, an instruction at the end of a subroutine that causes 

control to resume at the proper point in the main routine. 

Return Loss – A measure of the similarity of the impedance of a transmission 

line and impedance at its termination. It is a ratio, expressed in 

dB, of the power of the outgoing signal to the power of the signal reflected 

back from an impedance discontinuity. 

Reverberation – The persistence of a sound after the source stops emitting 

it, caused by many discrete echoes arriving at the ear so closely 

spaced in time that the ear cannot separate them. 

RF (Radio Frequency) – A term used to describe the radio signal band of 

the electromagnetic spectrum (about 3 MHz to 300 GHz). RF connectors, 

such as those used for the cable TV or antenna inputs on a monitor, carry 

modulated RF television signals. 

RF Distribution – The process of supplying an RF signal to several 

devices simultaneously. 

RF Mode – A Dolby Digital decoder operational mode intended primarily 

for cable set-top boxes that are connected to the RF (antenna) input of a 

television set. The dialnorm reference playback level is –20 dBFS and 

compr words are used in dynamic range compression. Refer to Dynamic 

Range Compression. 

RF Modulation – The process of combining a video signal and/or audio 

signal with an RF source so the result can be transmitted to a radio receiver, 

television, or VCR. 

RF Modulator – An electronic device that modifies and RF signal using an 

audio and/or video signal. 

RF Pattern – A term sometimes applied to describe a fine herringbone 

pattern in a picture. May also cause a slight horizontal displacement of 

scanning lines resulting in a rough or ragged vertical edge of the picture. 

Caused by high-frequency interference. 

RF Signal – Modulated composite (video and audio) signal produced by 

television stations and VCRs, and to be processed by televisions. 

RF Splitter – A device that provides multiple RF signals. An RF splitter is 

used to send the signal from one VCR to two or more televisions. 

RFC – Request For Comment. 

RGB (Red, Green, and Blue) – a) The basic parallel component analog 

signal set (red, green, blue) in which a signal is used for each primary 

color. These three color signals are generated by the camera and are used 

in the color television’s additive color reproduction system to produce a 

picture. Also used to refer to the related equipment, interconnect format or 

standards. The same signals may also be called “GBR” as a reminder of 

the mechanical sequence of connections in the SMPTE interconnect standard. 

b) A color model used chiefly for computer displays in which colors 

are specified according to their red, green, and blue components. Compare 

YUV. 

RGB Chroma Key – A chroma key wherein the keying signal is derived 

from the separate red, green and blue camera video signals, as opposed to

composite chroma key. It is an option to all switchers that allows chroma 

keys to be performed. See Chroma Key. 

RGB Format – There are four RGB formats. The main difference between 

them are in the voltage levels as shown below. These voltage levels can 

make the formats incompatible with each other. 

SMPTE/ NTSC NTSC 

EBU N10 (no setup) (setup) MII 

Max 700 mV 714 mV 714 mV 700 mV 

Min 0 mV 0 mV 54 mV 53 mV 

Range 700 mV 714 mV 660 mV 647 mV 

Sync –300 mV –286 mV –286 mV –300 mV 

P-P 1 V 1 V 1 V 1 V 

Following are the basic RGB waveforms found in the four RGB standards. 

The signals are full amplitude unlike their color difference counterparts. 

Refer to the color difference discussion for an example of the color difference 

waveforms. 

GREEN BLUE RED 

(PEAK VIDEO) 

(BLANKING 

AND BLACK) 

(SYNC TIP) 

RGB System – See the RGB discussion. 

RHC (Regional Holding Company) – See Baby Bell. 

Ribbon Mike – A mike which uses a thin metal foil ribbon which moves in 

a fixed magnetic field in response to sound waves and thus generates an 

output for the mike. 

RIFF (resource Interchange File Format) – Not an actual file format 

(like the name implies), RIFF is a tagged multimedia file structure. It is a 

specification upon which many file formats are defined. RIFF files have the 

advantage of extensibility; file formats based on RIFF can be used by future 

software inasmuch as format changes can be ignored by existing 

applications. 

Ringing – a) A common filter artifact, manifesting itself in television pictures 

as ghost-like images of sharp edges. b) An oscillatory transient 

occurring in the output of a system as a result of a sudden change in 

input. Results in close-spaced multiple reflections, particularly noticeable 

when observing test patterns, equivalent square waves, or any fixed objects 

whose reproduction requires frequency components approximating the cutoff 

of the system. 

RIP (Raster Image Processor) – A piece of hardware or software that 

converts object-oriented graphics and fonts into the bitmaps required for 

output on a printer. 

Rise Time – The time it takes a signal to make a transition from one state 

to another, usually measured between the 10% and 90% completion points 



on the transition. Faster rise times require more bandwidth in a transmission 

channel. 

Rising Edge – Low-to-high logic transition. 

RLC – See Run Length Coding. 

RLE – See Run Length Encoding. 

RMS (Root Mean Square) – The value assigned to an alternating current 

or voltage that results in the same power dissipation in a given resistance 

as DC current or voltage of the same numerical value. Calculated as 0.707 

of peak amplitude of a sine wave at a given frequency. 

RMS Value – The effective value of a wave. The value of continuous 

(direct current) signal that would produce the same power as the wave in 

question. 

RNRZ – Randomized Non-Return-to-Zero Code. 

Robust – Term for a transmission or recording scheme that can tolerate 

significant impairments, without catastrophic failure (severe degradation). 

Roll – A lack of vertical synchronization which causes the picture as 

observed on the picture monitor to move upward or downward. 

Roll Off – The effect that occurs when a piece of equipment can no longer 

process the frequency which is being fed into it (a reduction in amplitude 

with an increase of frequency). 

Roll-Off – A gradual attenuation of gain frequency response at either or 

both ends of the transmission pass band. 

ROM (Read-Only Memory) – Permanently programmed memory. Maskprogrammed 

ROMs are programmed by the chip manufacturer. PROMs 

(Programmable ROMs) can be programmed by the user. EPROMs (Erasable 

PROMs) can be erased with ultraviolet light and then reprogrammed. 

Root – a) The base directory from which all other directories stem, directly 

or indirectly. It is designated by the slash (/) character in many systems or 

a backslash (\) in PCs. b) The directory at the top of the file system 

hierarchy. 

Root Account – The standard UNIX or IRIX login account reserved for use 

by the system administrator. This account’s home directory is the root (/) 

directory of the file system; the user of the root account has full access to 

the entire file system (that is, can change and delete any file or directory). 

The user of this account is sometimes referred to as the superuser. 

Rotary Wipe – A pattern system effect that creates a design for revealing 

video using segments that have angular movement. This definition is our 

internal view, but not consistent within the industry. 

Rotate (Menu) – The function used to turn or rotate an image. Rotate 

turns the image around the intersection of the X, Y, and Z axes, the center 

point for rotation. Rotate does not move or reposition the center point of 

the image. 

Rotating Pattern – A pattern system effect that reveals video through a 

shape or shapes that spin about an axis on the screen. This definition is 

our internal view, but not consistent within the industry. 

Rotational Extrusion – In rotational extrusion, the silhouette is rotated 

about an axis, like using a lathe to create a fancy table leg. The cross-sec- 




tion of an object created this way is circular. Such objects are often called 

“solids of revolution.” 

Rotoscope – When animators want to capture the realism of a live 

object’s motion, a technique called rotoscoping is used. In traditional film 

animation, film footage of the motion is rear-projected, one frame at a 

time, onto a frosted screen that is mounted on the animators worktable. 

The artist traces the frames onto cels. This process is called rotoscoping. 

The video equivalent is called keying or matting. Digital rotoscoping has 

recently become possible. Here, the frame buffer is used to hold the 

incoming action, and software picks out the image of interest from the 

background, assuming the subject was shot against a solid color. 

Rough Cut – Preliminary edit of raw footage to establish tentative 

sequence, length of approximate sequence, and content of the eventual 

video program. 

Rounding – Deleting the least-significant digits of a quantity and applying 

some rule of compensation and correction to the part retained. 

Router – Routers connect networks at OSI layer 3. Routers interpret packet 

contents according to specified protocol sets, serving to connect networks 

with the same protocols (DECnet to DECnet, TCP/IP (Transmission 

Control Protocol/Internet Protocol) to TCP/IP). Routers are protocol-dependent; 

therefore, one router is needed for each protocol used by the network. 

Routers are also responsible for the determination of the best path for data 

packets by routing them around failed segments of the network. 

Routing Switcher – An electronic device that routes a user-supplied signal 

(audio, video, etc.) from any input to any user-selected output(s). 

RP-125 – See SMPTE 125M. 

RPC – Remote Procedure Call. 

RRT – Region Rating Table. 

RS Protection Code – A 16-byte long error control code added to every 

187 (scrambled) +1 syncbyte-long transport packet with the following 

result. The packet has a length of 204 bytes and the decoder can correct 

up to T = 8 errored bytes. This code ensures a residual error bit rate of 

approximately 1x10 –11 at an input error rate of 2x10 –4 . 

RS-170A – Now called EIA-170A, this is the EIA NTSC Video Signal specification 


RS-232 – a) A standard, single-ended (unbalanced) interconnection 

scheme for serial data communications. b) Computer communication standard 

used in video for the control of certain video equipment. Computer 

controlled VCRs, edit controllers, switchers, and other studio equipment 

can commonly be found in professional video studios. Successfully linking 

two devices, at the very least, requires that they use the same communication 

protocol. 

RS-422 – A medium range (typically up to 300 m/1000 ft or more) balanced 

serial data transmission standard. Data is sent using an ECL signal 

on two twisted pairs for bidirectional operation. Full specification includes 

9-way D-type connectors and optional additional signal lines. RS-422 is 

widely used for control links around production and post areas for a range 

of equipment. 


RS-343 – Specification for higher-resolution video such as used in 

computers. 

RST (Running Status Table) – Accurate and fast adaptation to a new 

program run if time changes occur in the schedule. 

RSVP (Resource Reservation Protocol) – Defines signaling methods for 

IP networks to allocate bandwidth. 

RTE – Residual Target Error. 

RTF (Rich Text File) – A standard method of encoding text and graphics 

using only 7-bit ASCII characters, The format includes font sizes, type 

faces, and styles as well as paragraph alignment, justification, and tab 

control. 

RTP (Real Time Protocol) – Defines packet formats for real-time data. 

RTSP (Real Time Streaming Protocol) – Defines client/server interaction 

for streaming media. 

Run-Length Coding – a) A type of data compression where a string of 

identical values is replaced by codes to indicate the value and the number 

of times it occurs. Thus, a string of 70 spaces can be replaced by two 

bytes. One to indicate the string consists of spaces and a byte to indicate 

there are 70 of them. Run-Length Coding is not as efficient as DCT for 

compression of pictures or video, since long sequences of the same values 

rarely exist in images. Run-Length Coding is part of JPEG, MPEG, H.261, 

and H.263 compression schemes. b) A coding scheme that counts the 

number of similar bits instead of sending them individually. c) Coding of 

data with different numbers of bits. Frequently reoccurring data has the 

smallest number of bits, data seldom reoccurring have the highest number 

of bits. 

Run-Length Encoding – A compression scheme. A run of pixels or bytes 

of the same color or value are coded as a single value recording the color 

or byte value and the number of duplications in the run. 

R-Y – The human visual system has much less acuity for spatial variation 

of color than for brightness. Rather than conveying RGB, it is advantageous 

to convey luma in one channel, and color information that has had luma 

removed in the two other channels. In an analog system, the two color 

channels can have less bandwidth, typically one-third that of luma. In a 

digital system each of the two color channels can have considerably less 

data rate (or data capacity) than luma. Green dominates the luma channel; 

about 59% of the luma signal comprises green information. Therefore, it is 

sensible, and advantageous for signal-to-noise reasons, to base the two 

color channels on blue and red. The simplest way to remove luma from 

each of these is to subtract it from the difference between a primary color 

and luma. Hence, the basic video color-difference pair is B-Y, R-Y (pronounced 

“B minus Y, R minus Y”). The B-Y signal reaches its extreme values 

at blue (R = 0, G = 0, B = 1; Y = 0.114; B-Y = +0.886) and at yellow 

(R = 1, G = 1, B = 0; Y = 0.886; B-Y = –0.886). Similarly, the extreme of 

R-Y, ±0.701, occur at red and cyan. These are inconvenient values for both 

digital and analog systems. The color spaces YPbPr, YCbCr, PhotoYCC, and 

YUV are simply scaled versions of Y, B-Y, R-Y that place the extreme of the 

color difference channels at more convenient values. The R-Y signal drives 

the vertical axis of the vectorscope.

S 

S/F – Sound over film, meaning the film is silent and sound will come. 

S/N – Signal-to-Noise Ratio. 

SA – Scientific-Atlanta. 

SAA – Standards Australia. 

SABC – South Africa Broadcasting Corporation. 

Safe Action Area – This amounts to about 90% of the total picture area. 

It is symmetrically located inside of the picture border. Home sets are overscanned. 

The entire picture isn’t seen, the edges being lost beyond the 

border of the screen. Safe action area is designated as the area of the picture 

that is “safe” to put action that the viewer needs to see. 

Safe Area – This allows the material positioning of video images to be 

checked. Both safe title and safe action boundaries are included. This signal 

can be keyed by any switcher or special effects generator that incorporates 

the luminance keying function. 

Safe Title Area – Generally, the center 80% of the entire overscan video 

image area or that area which will display legible titles regardless of how a 

TV monitor is adjusted. 

Sampled Data – Sampled data is that in which the information content 

can be, or is, ascertained only at discrete intervals of time. Note: Sampled 

data can be analog or digital. 

Samples Per Picture Width – In a digital video system, the number of 

pixels corresponding to the reference picture width. Some pixels at the borders 

of the picture region may be corrupted by the picture blanking transitions 

and by the effects of post-production image processing. Currently, 

SMPTE 260M defines a clean aperture within the production aperture, confining 

visible artifacts around the image to a thin border. 

Sampling – a) Process where analog signals are measured, often millions 

of times per second for video, in order to convert the analog signal to digital. 

The official sampling standard definition for television is ITU-R 601. For 

TV pictures 8 or 10 bits are normally used; for sound, 16 or 20 bits are 

common, and 24 bits are being introduced. The ITU-R 601 standard 

defines the sampling of video components based on 13.5 MHz, and 

AES/EBU defines sampling of 44.1 and 48 kHz for audio. b) The process of 

dealing with something continuous in discrete sections. Sampling is probably 

best known as the first step in the process of digitization, wherein an 

analog (continuous) signal is divided into discrete moments in time. Yet, 

even analog television signals have already been sampled twice; once temporally 

(time being sampled in discrete frames) and once vertically (the vertical 

direction being divided into discrete scanning lines). If these initial 

sampling processes are not appropriately filtered (and they rarely are in 

television), they can lead to aliases. See also Alias, Digitization, and 

Nyquist. 

Sampling Frequency – The number of discrete sample measurements 

made in a given period of time. Often expressed in megahertz for video. 

These samples are then converted into digital numeric values to create the 

digital signal. 



Sampling, Orthogonal – In digital video, the sampling is orthogonal if the 

luminance and color-difference samples are generated from pixels 

arranged in common, continuous vertical and horizontal lines on a rectilinear 

grid that remains constant field/frame to field/frame. 

Sampling, Quincunx – a) In a digital video system, the sampling is quincunx 

if the luminance and color-difference samples are generated from 

pixels arranged on one of two congruent rectilinear grids, the one being 

displaced horizontally from the other by half the horizontal pixel spacing. 

The alternate grid is usually chosen for alternate lines, but may instead be 

chosen for alternate field/frames. b) In a digital video system, a sampling 

structure with an array of samples wherein alternate rows of pixel samples 

are displaced horizontally in the grid by half of the pitch of the pixel samples 

along the remaining rows. 

SANZ – Standards Association of New Zealand. 

SAP – See Secondary Audio Program. 

SAR – Segmentation and Re-Assembly Sublayer. 

Sarnoff, David – As general manager, president, and chair of the board of 

RCA, he strongly shaped the future of television; also the David Sarnoff 

Research Center named for him, currently part of SRI International, formerly 

RCA Laboratories, home of ACTV research and development. 

SAS – Subscriber Authorization System. 

SAT – Saturation. 

Saturated Color – A color as far from white, black, or gray as it can be 

(e.g., vermilion rather than pink). 

Saturation – a) The property of color which relates to the amount of white 

light in the color. Highly saturated colors are vivid, while less saturated colors 

appear pastel. For example, red is highly saturated while pink is the 

same hue but much less saturated. b) In signal terms, saturation is determined 

by the ratio between luminance level and chrominance amplitude. It 

should be noted that a vectorscope does not display saturation; the length 

of the vectors represents chrominance amplitude. In order to verify that the 

saturation of the colors in a color bar signal is correct, you must check 

luminance amplitudes with a waveform monitor in addition to observing the 

vectors. c) The amount of gray, as opposed to hue, in a color. See Hue. 

Saturation Flux Density, BS – The maximum intrinsic flux density possible 

in a sample of magnetic material. The intrinsic flux density asymptotically 

approaches the saturation flux density as the magnetizing field 

strength is increased. A magnetizing field strength in excess of 5000 Oe is 

necessary to obtain an accurate measure of the saturation flux density of a 

typical tape. 

Saturation Moment – The maximum magnetic moment possible in a 

sample of magnetic material. 

Saturation Noise – The noise arising when reproducing a uniformly saturated 

tape. This is often some 15 dB higher than the bulk erased noise and 

is associated with imperfect particle dispersion. 

SAV – See Start of Active Video. 




SBE – Society of Broadcast Engineers. 

SC – Subcommittee. 

SCA – See Subsidiary Communications Authorizations. 

Scalability – a) Scalability is the ability of a decoder to decode an 

ordered set of bit streams to produce a reconstructed sequence. Moreover, 

useful video is output when subsets are decoded. The minimum subset that 

can thus be decoded is the first bit stream in the set which is called the 

base layer. Each of the other bit streams in the set is called an enhancement 

layer. When addressing a specific enhancement layer, lower layers 

refer to the bit stream which precedes the enhancement layer. b) A characteristic 

of MPEG-2 that provides for multiple quality levels by providing 

layers of video data. Multiple layers of data allow a complex decoder to 

produce a better picture by using more layers of data, while a more simple 

decoder can still produce a picture using only the first layer of data. c) The 

degree video and image formats can be combined in systematic proportions 

for distribution over communications channels for varying capacities. 

d) Scalability implies that it is possible to decode just a fraction of the 

information in a bit stream. In MPEG, we find SNR scalability, spatial scalability, 

and temporal scalability, and even in combination (hybrid scalability). 

In connection with scalability we find the terms “lower layer,” which represents 

the basic information, and the “enhancement layer,” which represents 

the additional information. In case of hybrid scalability, up to three layers 

are found. All types of scalability may be used for transmission systems 

with split data channels with different error rate. The lower layer is transmitted 

on a channel with high protection rate, whereas the enhancement 

layer is transmitted on a channel with higher bit error rate. e) A feature of 

the Indeo video codec with which quality can be optimized during playback 

depending on the system resources being used to play the video. 

Scalable Coding – The ability to encode a visual sequence so as to 

enable the decoding of the digital data stream at various spatial and/or 

temporal resolutions. Scalable compression techniques typically filter the 

image into separate bands of spatial and/or temporal data. Appropriate 

data reduction techniques are then applied to each band to match the 

response characteristics of human vision. 

Scalar Quantization – The mapping of a (large) number of signal levels into 

a smaller number of levels. The quantization may be uniform or nonlinear. 

Scaling – The act of changing the effective resolution of the image. 

Images can be scaled down so that more images can be displayed or 

scaled up such that the image takes up more screen space. 

Scaling Moving Images – Moving images present a unique set of scaling 

challenges. In NTSC TV, fields alternate every 16.6 ms. Any object that 

moves significantly between field-refresh times will appear distorted. If an 

image is scaled in the Y direction by assembling two fields into a single 

frame, the distortion is even more exaggerated. When the full frame is 

scaled down using decimation (line-dropping), a group of lines from one 

field can end up adjacent to a group of lines from another field, causing a 

jagged, stepped appearance in the scaled image. This distortion is often 

more noticeable than the distortion in the original TV image. Therefore, a 

general rule for scaling down is to use either the even or odd field from 

each frame. If the final image is to be less than one-half the size of the 

original, scale the single field down to the required size. If the final image 


is to be greater than one-half the size of the original, use one field, then 

increase image to the required number of lines with line replication. 

Scan Converter – External device that converts a computer’s VGA output 

to video, it can be displayed on a TV or VCR. 

Scan Line – An individual horizontal sweep across the face of the display 

by the electron beam. It takes 525 of these scan lines to make up a single 

frame of an NTSC picture and 625 for PAL. 

Scan Velocity Modulation (SVM) – SVM is one of the many tricks manufacturers 

use to get more light out of a picture tube, at the cost of real picture 

detail. It changes the speed or velocity of the beam as it is scanned 

from the left to the right side of the picture. In the process, it distorts real 

picture detail, causing dark areas of the picture on light backgrounds to be 

reproduced much larger than normal and light areas on dark backgrounds 

to be reproduced much smaller than normal. When the beam spends more 

time “writing” light areas, the phosphors receive more energy and produce 

more light output. The fact that this will contribute to phosphor blooming, 

as well as detail distortion seems to be lost on a number of manufacturers 

calling it a “feature.” The presence or absence of SVM can be easily 

detected by displaying the needle pulse test pattern. In the test pattern, the 

width of the white line on the black background, and black line on the 

white background are the same. In a set with SVM, the width of the black 

line will be much larger than the white line. If SVM is found on a set, look 

for an ability to turn it off. Several sets provide this option in the mode of 

the set designed to accurately reproduce the signal source. In some other 

sets, it is easily defeated by a qualified service technician. 

Scanner, Motion-Picture Film – a) A device for scanning photographic 

motion-picture images and transcoding them into an electronic signal in 

one of the standardized or accepted video formats. b) Film scanner is a 

general term, and may be applied to slow-rate as well as real-time 

transcoding, and may provide the input to a recorder, a signal processor, a 

transmission channel, or any other desired peripheral system. 

Scanning – The process of breaking down an image into a series of elements 

or groups of elements representing light values and transmitting this 

information in time sequence. 

Scanning Circuitry – Camera or display subsystems designed for moving 

an electron beam around to form a raster. 

Scanning Lines – a) A single, continuous narrow strip of the picture area 

containing highlights, shadows and half-tones, determined by the process 

of scanning. b) Horizontal or near-horizontal lines sampling a television

image in the vertical direction. In tube-type cameras and displays equipped 

with CRTs, the scanning lines are caused by electron beam traces. 

Scanning Lines Per Frame 

525 – NTSC 

625 – Most non-NTSC broadcast systems 

655 – Used for electronic cinematography with 24 frames per second 

675 – EIA industrial standard 


750 – RCA and International Thomson progressive scanning proposal 

819 – CCIR System E (used in France) 


900 – International Thomson progressive scanning proposal 


1001 – French progressive scanning proposal for NTSC countries 



1049 – Double NTSC with interlaced scanning 

1050 – Double NTSC with progressive scanning, French interlace proposal 

1125 – ATSC/SMPTE HDEP standard 

1200 – French progressive scanning proposal for non-NTSC countries 


1249 – Double non-NTSC with interlaced scanning 

1250 – Double non-NTSC with progressive scanning 

1501 – Early BBC proposal 

2125 – Early NHK monochrome system 

2625 – RCA electronic cinematography proposal 

Scanning Spot – Refers to the cross-section of an electron beam at the 

point of incidence in a camera tube or picture tube. 

Scanning Standard – The parameters associated with raster scanning of 

a computer display, camera, or video recorder. Denoted by the total line 

count, field rate, and interlace ratio. 

Scanning Structure – A term sometimes used to describe a number of 

scanning lines per frame, interlace ratio, and frame rate; also sometimes 

used to describe what appears when scanning lines are visible. 

Scanning, Interlaced – A scanning process in which the distance from 

center to center of successively scanned lines is two or more times the 

nominal line width, and in which the adjacent lines belong to different 

fields. For a given number of active vertical lines per frame, and a given 

frame-rate, interlaced scanning provides system-limited definition for still 

images. Moving images, however, provide reduced perceived spatial definition. 

Although the interlaced scanning field-rate at a multiple of the framerate 

could improve temporal resolution, this is seldom perceived. When 

scanning interlaced 2:1 in either capture or display mode, the lines constituting 

one frame of the image are scanned and/or presented in two successive 

fields one-half the lines in one field and the other half interleaved 

as the following field. In a system based upon a nominal 60 Hz, for exam- 



ple, the generation and presentation of the two fields in succession require 

a total of 1/30 sec per frame, with a continual temporal progression from 

start to finish of the scanning. Note: Interlaced scanning may be introduced 

in the original scanning for image capture, or may be developed from progressive 

scanning of the original. 

Scanning, Progressive – a) A rectilinear scanning process in which the 

distance from center to center of successively scanned lines is equal to the 

nominal line width. b) A display mode for electronic imaging in which all of 

the scanned lines are presented successively, and each field has the same 

number of lines as a frame. Also known as sequential scanning. For a 

given number of active vertical lines per frame, and a given frame rate, 

progressive scanning requires the same bandwidth as interlaced scanning. 

When compared at a given field rate, progressive scanning requires twice 

the bandwidth of 2:1 interlaced scanning. Note: Most image processing in 

electronic post-production requires that a progressive scanned image first 

be captured or created. The image information may have originated in progressive 

scanning, or it may have been interpolated from an origination in 

interlaced scanning. 

Scanning, Sequential – See Scanning, Progressive. 

SCART – See Syndicat des Constructeurs d’Appareils Radio Recepteurs et 

Televiseurs. 

Scene – A collection of entities that can change over time. 

Scene Complexity – The intrinsic difficulty of the image sequence to 

code. For example, the “talking head” video sequences which occurs often 

in video conferencing applications are much easier to code than an actionfilled 

movie for entertainment applications. 

SCH Phase (Subcarrier to Horizontal Phase) – This is a measurement 

of the color oscillator frequency and phase as set by the color burst in 

relation to the 50% point on the leading edge of the horizontal sync pulse. 

50% Point of Leading Edge of the H Sync Pulse 

Color Burst 

Color Oscillator 

Frequency and Phase 

Based on the Color Burst 

Schmidt Trigger – Circuit with hysteresis used for input signals that are 

noisy or have slow transition times. 

Scientific-Atlanta – CATV, satellite transmission, and production equipment 

firm that has been selling B-MAC equipment for years and is a proponent 

of the HDB-MAC ATV scheme. 

Scope – Short for oscilloscope (waveform monitor) or vectorscope, devices 

used to measure the television signal. 

SCPC (Single Channel Per Carrier) – Type of transmission where only a 

part of the available transponder is used for the signal, allowing the satellite 

operator to sell the remaining space on the transponder to other 

uplinkers. SCPC is typically used for feeds rather than for direct programming. 

The advantage of SCPC over MCPC is that the signals uplinked to the 




same transponder can be transmitted up to the satellite from different 

locations. 

SCR (System Clock Reference) – a) Reference in PS (Program Stream) 

for synchronizing the system demultiplex clock in the receiver, transmitted 

at least every 0.7 sec. Integrated into PES (Packetized Elementary Stream). 

b) A time stamp in the program stream from which decoded timing is 

derived. 

Scrambling – a) Usually used as a synonym for encryption, controlled disordering 

of a signal to prevent unauthorized reception. b) Sometimes used 

to describe controlled disorganization of a signal to improve its robustness. 

This form is more often called shuffling. c) To transpose or invert digital 

data according to a prearranged scheme in order to break up the lowfrequency 

patterns associated with serial digital signals. d) The digital signal 

is shuffled to produce a better spectral distribution. e) The alteration of 

the characteristics of a video, audio, or coded data stream in order to prevent 

unauthorized reception of the information in a clear form. This alteration 

is a specified process under the control of a conditional access 

system. 

Scratchpad – Memory containing intermediate data needed for final 

results. 

Screen – The portion of the monitor that displays information. The face of 

a monitor, TV, or terminal. 

Screw Assembly – Refers to the method of joining the two plastic parts 

of a cassette with screws, as opposed to sonically welding. 

Scroll – Graphics that roll from the bottom to the top of the screen, for 

example, end credits. 

SCSI (Small Computer System Interface) – a) Special type of disk drive 

designed for moving very large amounts of information as quickly as possible. 

b) A very widely used high data rate general purpose parallel interface. 

A maximum of eight devices can be connected to one bus, for example a 

controller, and up to seven disks or devices of different sorts – Winchester 

disks, optical disks, tape drives, etc., and may be shared between several 

computers. SCSI specifies a cabling standard (50-way), a protocol for 

sending and receiving commands and their format. It is intended as a 

device-independent interface so the host computer needs no details about 

the peripherals it controls. But with two versions (single-ended and balanced), 

two types of connectors and numerous variations in the level of 

implementation of the interface, SCSI devices cannot “plug & play” on a 

computer with which they have not been tested. Also, with total bus cabling 

for the popular single-ended configuration limited to 18 feet (6 meters), all 

devices must be close to each other. 

SCSI, Differential – An electrical signal configuration where information is 

sent simultaneously through pairs of wires in a cable. Information is interpreted 

by the difference in voltage between the wires. Differential interfaces 

permit cable lengths up to 75 feet (25 meters). 

SCSI, Single-Ended – An electrical signal configuration where information 

is sent through one wire in a cable. Information is interpreted by the 

change in the voltage of the signal relative to two system ground. Singleended 

interfaces permit cable lengths up to 18 feet (6 meters). 


SCSI Address – A number from one to seven that uniquely identifies a 

SCSI device to a system. No two SCSI devices that are physically connected 

to the same workstation can have the same SCSI address. 

SCSI Address Dial – A small plastic dial connected to every SCSI device 

supplied by Silicon Graphics, Inc. You click on its small buttons to select a 

SCSI address for a new SCSI device. Each device on a SCSI bus normally 

should have a unique address. 

SCSI Bus Line – The combined length of all internal and external SCSI 

cables in a system. 

SCSI Cable – A cable that connects a SCSI device to a SCSI port on a 

workstation. 

SCSI Device – A hardware device that uses the SCSI protocol to communicate 

with the system. Hard disk, floppy disk, CD-ROM, and tape drives 

may be SCSI devices. 

SCSI Terminator – A metal cap that you plug into any open SCSI port on 

a SCSI bus line. No SCSI devices on a SCSI bus line will work unless all 

SCSI ports are occupied by either a cable or terminator. 

SD (Super Density) – A proposal for an optical disc format from Toshiba, 

Time Warner and an alliance of several other manufacturers. The SD format 

is now integrated in the DVD format. 

SDDI – Serial Digital Data Interface. 

SDDS – Sony Dynamic Digital Sound. 

SDH – Synchronous Digital Hierarchy. 

SDI – Serial Digital Interface. 

SDL – Specification and Description Language. 

SDP – Severely Disturbed Period. 

SDT (Service Description Table) – A table listing the providers of each 

service in a transport stream. The SDT contains data describing the services 

in the system, i.e., includes names of services, the service provider, etc. 

SDTI (Serial Digital Transport Interface) – SMPTE 305M. Allows fasterthan-real-time 

transfers between various servers and between acquisition 

tapes, disk-based editing systems, and servers, with both 270 Mb and 

360 Mb, are supported. With typical real-time compressed video transfer 

rates in the 18 Mbps to 25 Mbps range, SDTI’s 200+ Mbps payload can 

accommodate transfers up to four times normal speed. The SMPTE 305M 

standard describes the assembly and disassembly of a stream of 10-bit 

words that conform to SDI rules. Payload data words can be up to 9 bits. 

The 10th bit is a complement of the 9th to prevent illegal SDI values from 

occurring. The basic payload is inserted between SAV and EAV although an 

appendix permits additional data in the SDI ancillary data space as well. A 

header immediately after EAV provides a series of flags and data IDs to 

indicate what is coming as well as line counts and CRCs to check data 

continuity. 

SDTV (Standard Definition Television) – a) The new HDTV standards 

call for a range of different resolutions. Those that are higher than today’s 

NTSC are considered HDTV. The ones that are comparable to NTSC are 

considered SDTV. Because SDTV is component and digital, it will still be 

higher quality than NTSC. b) This term is used to signify a digital television 

system in which the quality is approximately equivalent to that of NTSC.

Also called standard digital television. See also Conventional Definition 

Television and ITU-R Recommendation 1125. 

Seam Elimination – Techniques to make picture panel seams invisible. 

Seams – Vertical lines in the picture where separately transmitted 

widescreen panels are joined to the center of the image. CBS proved that 

seams could be made invisible in its two-channel ATV transmission 

scheme. 

SECAM – See Sequential Color and Memory. 

Secondary Audio Program – An audio track(s) separate from the normal 

program audio. This second tack is commonly used to transmit a second 

language but may be used for other purposes. 

Secondary Distribution – The links that radiate from the cable TV headend, 

or the path from a satellite up-link and beyond, or a link directly feeding 

TVs in the homes. 

Section – A table is subdivided into several sections. If there is a change, 

only the section affected is transmitted. 

SEDAT (Spectrum Efficient Digital Audio Technology) – A proprietary 

audio compression algorithm from Scientific-Atlanta, used for satellite 

links. 

SEG (Special Effects Generator) – Device designed to generate special 

effects. The simplest devices process a single video signal, change its 

color, generate sepia tones, invert the picture to a negative, posterize the 

image, and fade or break up the image into various patterns. More sophisticated 

equipment uses several video sources, computer-generated graphics 

and sophisticated animation with digital effects. 

Segment Marker – A marker indicating the segment ends on curves. 

Select – To position the cursor over an icon then click the (left) mouse 

button. (To select an option button.) Once an icon is selected, it is the 

object of whatever operation you select from a menu. 

Self Fill Key – A key which is filled with the same video that was used to 

cut the hole for the key. 

Self Key – A key effect in which a video signal serves as both the key 

source and fill. 

Self-Contained – In PC video, a MooV file that contains all of its video 

and audio data, instead of including references to data in other files. See 

MooV. 

Self-Demagnetization – The process by which a magnetized sample of 

magnetic material tends to demagnetize itself by virtue of the opposing 

fields created within it by its own magnetization. Self-demagnetization 

inhibits the successful recording of short wavelengths or sharp transitions 

in a recorded signal. 

Self-Erasure – The erasure of high frequencies which occurs during 

recording due to the formation of a secondary gap after the trailing edge of 

the record head. Self-erasure is increased by excess bias and by excess 

high-frequency signal levels (especially at low tape speeds). 

Self-Test – Test performed by a product on itself. 

SelSync – A configuration which enables the engineer to play back the 

signal from the record head for use in overdubbing. 



SelSync Bias Trap – A control used to remove bias signal from adjacent 

recording heads which can leak into the record head being used to play 

back a signal. 

SelSync Gain – A control used to equalize the gain of SelSync playback 

from the record head with the gain of playback from the reproduce head. 

Sensitivity – a) The magnitude of the output when reproducing a tape 

recorded with a signal of given magnitude and frequency. The sensitivity of 

an audio or instrumentation tape is normally expressed in dB relative to the 

sensitivity of a reference tape measured under the same recording conditions. 

b) The amount of signal a camera can emit from a particular sensor 

illumination at a particular SNR, sometimes expressed as a certain scene 

illumination (in lux or foot-candles) at an assumed reflection and signal 

strength, at a particular lens transmission aperture, at a particular SNR. 

The sensitivity of a camera can be truly increased by improving its image 

sensor, increasing its transmission aperture, or slowing its frame rate; it 

can be seemingly increased by allowing the SNR to be reduced. All other 

things being equal, at this time the sensitivity of an HDEP camera is less 

than the sensitivity of an NTSC camera. The sensitivity of first-generation 

HDTV 1125 scanning-line cameras is two to three stops less sensitive than 

that of a 525-line camera (needing four to eight times as much light). 

HARP tubes and new CCD advances may offer a solution to this problem. 

SEP – Symbol Error Probability. 

Separation – The degree to which two channels of a stereo signal are 

kept apart. 

Separation Loss – The loss in output that occurs when the surface of the 

coating fails to make perfect contact with the surfaces of either the record 

or reproduce head. 

Sepia Tone – A process used in photography to generate a brownish tone 

in pictures giving them an “antique” appearance. The same idea has been 

electronically adapted for video production where a black and white image 

can be colored in sepia. 

Sequence – A coded video sequence that commences with a sequence 

header and is followed by one or more groups of pictures and is ended by 

a sequence end code. 

Sequential Color and Memory (Sequential Couleur avec Memoire) – 

a) French developed color encoding standard similar to PAL. The major differences 

between the two are that in SECAM the chroma is frequency 

modulated and the R'-Y' and B'-Y' signals are transmitted line sequentially. 

The image format is 4:3 aspect ratio, 625 lines, 50 Hz and 6 MHz video 

bandwidth with a total 8 MHz of video channel width. b) A composite color 

standard based upon line-alternate B-Y and R-Y color-difference signals, 

frequency modulated upon a color subcarrier. All applications are in 

625/50/2:1 systems. 

Sequential Logic – Circuit arrangement in which the output state is 

determined by the previous state and the current inputs. Compare with 

Combinational Logic. 

Sequential Scanning – Progressive scanning, so named because scanning 

lines are transmitted in numerical sequence, rather than in odd- or 

even-numbered fields, as in interlaced scanning. 

SER – Symbol Error Rate. 




Serial Device – Any hardware device that requires a serial connection to 

communicate with the workstation. 

Serial Digital – Digital information that is transmitted in serial form Often 

used informally to refer to serial digital television signals. 

Serial Digital Data Interface (SDDI) – A way of compressing digital 

video for use on SDI-based equipment proposed by Sony. Now incorporated 

into Serial Digital Transport Interface. 

Serial Digital Interface (SDI) – The standard based on a 270 Mbps 

transfer rate. This is a 10-bit, scrambled, polarity independent interface, 

with common scrambling for both component ITU-R 601 and composite 

digital video and four channels of (embedded) digital audio. Most new 

broadcast digital equipment includes SDI which greatly simplifies its installation 

and signal distribution. It uses the standard 75-ohm BNC connector 

and coax cable as is commonly used for analog video, and can transmit the 

signal over 600 feet (200 meters) depending on cable type. 

Serial Digital Video – Uses scrambled channel coding and NRZI signal 

format as described in SMPTE 259M and EBU Tech. 3267. The various 

serial digital data rates are: 143 Mb/s for serial composite NTSC; 

177 Mb/s for serial composite PAL; 270 Mb/s for serial component 

525/59.94 and 625/50; 360 Mb/s for serial component 16:9 aspect ratio. 

Serial HDDR – The recording of a digital data stream onto a single recording 

track. With multitrack recorders, multiple streams can be recorded as 

long as each stream is recorded on a separate track. There is no requirements 

that multiple streams have a common synchronous clock nor is it 

required that the multiple streams be the same recording code. 

Serial Interface – An option to switcher which allows all switcher functions 

to be controlled remotely by a computer editor. Data is transmitted 

serially between the editor and the switcher at selectable baud (transmission) 

rates. 

Serial Port – a) A computer l/O (input/output) port through which the 

computer communicates with the external world. The standard serial port 

uses RS-232 or RS-422 protocols. b) An outlet on a workstation to which 

you connect external serial devices. 

Serial Storage Architecture (SSA) – A high-speed data interface developed 

by IBM and used to connect numbers of storage devices (disks) with 

systems. Three technology generations are planned: 20 Mbps and 40 Mbps 

are now available, and 100 Mbps is expected to follow. 

Serial Video Processing – A video mixing architecture where a series of 

video multipliers, each combining two video signals, is cascaded or 

arranged in a serial fashion. The output of one multiplier feeds the input of 

the next, and so on, permitting effects to be built up, one on top of the 

other. 

Serializer – A device that converts parallel digital information to serial 

digital. 

Serration Pulses – Pulses that occur during the vertical sync interval, at 

twice the normal horizontal scan rate. These pulses ensure correct 2:1 

interlacing and eliminate the buildup of DC offset. 

Serrations – A term used to describe a picture condition in which vertical 

or nearly vertical lines have a sawtooth appearance. The result of scanning 

lines starting at relatively different points during the horizontal scan. 


Server, File – A storage system that provides data files to all connected 

users of a local network. Typically, the file server is a computer with large 

disk storage which is able to record or send files as requested by the other 

connected (client) computers, the file server often appearing as another 

disk on their systems. The data files are typically at least a few kilobytes in 

size and are expected to be delivered within moments of request. 

Server, Video – A storage system that provides audio and video storage 

for a network of clients. While there are some analog systems based on 

optical disks, most used in professional and broadcast applications are 

based on digital disk storage. Aside from those used for video on demand 

(VOD), video servers are applied in three areas of television operation: 

transmission, post production and news. Compared to general purpose file 

servers, video servers must handle far more data, files are larger and must 

be continuously delivered. There is no general specification for video 

servers and so the performance between models varies greatly according 

to storage capacity, number of channels, compression ratio, and degree of 

access to stored material, the latter having a profound influence. Store 

sizes are very large, typically up to 500 gigabytes or more. Operation 

depends entirely on connected devices, edit suites, automation systems, 

secondary servers, etc., so the effectiveness of the necessary remote control 

and video networking is vital to success. 

Service – A set of elementary streams offered to the user as a program. 

They are related by a common synchronization. They are made of different 

data, i.e., video, audio, subtitles, other data. 

Service Information (SI) – Digital data describing the delivery system, 

content and scheduling/timing of broadcast data streams, etc. It includes 

MPEG-2 PSI together with independently defined extensions. 

service_id – A unique identifier of a service within a TS (Transport 

Stream). 

Servo – In cameras, a motorized zoom lens. Originally a brand name, 

servo is now a generic name for any motor-controlled zoom lens. A servo is 

usually operated by pressing buttons labeled “T” (telephoto) and “W” (wideangle) 

on the video camera’s hand grip. 

Servo System – An electrical device controlling the speed of a moving or 

rotating device such as a capstan/pinchroller rotating speed. 

SES – Seriously Errored Second. 

Set – A studio or part thereof which has a particular function (i.e., news) 

and hence includes all props, desks, etc. 

Set/Trim In, Set/Trim Out – Function of entering edit in- and out-points 

in the time-code format. Preceding the numeric entry with a + or – adds to 

or subtracts from already existing edit points. 

Settling Time – Settling time is the time it takes the output analog signal 

of a DAC to attain the value of the input data signal. This time (usually 

measured in nanoseconds) is measured from the 50% point of full-scale 

transition to within ±1 LSB of the final value. 

Setup – a) In NTSC systems, video black is typically 7.5 IRE above the 

blanking level. This 7.5 IRE level is referred to as the black setup level, or 

simply setup. b) The ratio between reference black level and reference 

white level, both measured from blanking level. It is usually measured in 

percent. Black level reference expressed as a percentage of the blanking-

to-reference-white excursion. Conventionally 7.50% in system M, conforming 

to ANSI/EIA/TIA 250-C. Conventionally zero in all other systems where 

blanking level and black level reference are identical. 

Setup Mode – The functional level in which you can program the system’s 

baud rate, parity, and bus address to match the communications standards 

of an external editor. 

Set-Up Time – Time that data must be stable prior to a write signal. 

SFDMA – Synchronous Frequency Division Multiple Access. 

SFN (Single Frequency Network) – A TV transmitter network in which all 

the transmitters use the same frequency. The coverage areas overlap. 

Reflections are minimized by guard intervals. The transmitters are separated 

by up to 60 km. The special feature of these networks is efficient frequency 

utilization. 

SFP (Societe Francaise de Production et de Creation Audiovisuelles) – 

Drafter of the French proposals. 

Shading – In order to look solid, a polygon must be “shaded” with color. 

This happens when the polygon is rendered. There are several ways to 

shade a polygon. These have varying degrees of realism and cost. A polygon’s 

shading depends on its surface properties, the properties and location 

of the lights with which it is lit. The shading methods (types) available 

on PictureMaker are constant, flat, Gouraud, and Phong. The latter two are 

“smooth” shading types. 

Shadow – A type of key border effect. A shadow key with a character generator 

appears as if the letters have been raised off the surface slightly 

and a light is shining from the upper left; a shadow appears to the right 

and bottom of the characters. 

Shadow Chroma Key – The ability to key a subject as a regular chroma 

key, while using the border channel of the keyer to mix in the low luminance 

portions of the key signal. This allows a true shadow effect where 

any shadow in the key video appears as if it is in the background. All 

Ampex switchers have this feature, with variable shadow levels and densities 

(bdr adj and bdr lum respectively). 

Shadow Mask – A perforated metal plate which is mounted close to the 

inside of a color CRT display surface. This plate causes the red, green and 

blue electron beams to hit the proper R, G, or B phosphor dots. 

Shannon’s Theorem – A criterion for estimating the theoretical limit to 

the rate of transmission and correct reception of information with a given 

bandwidth and signal-to-noise ratio. 

Sharpness – a) Apparent image resolution. High sharpness may be the 

result of high resolution, or it might be an optical illusion caused by image 

enhancement or by visible edges in a display, such as the vertical stripes 

of an aperture grille CRT (e.g., Trinitron). Visible scanning lines can actually 

increase perceived sharpness. This may be one reason why, in some subjective 

ATV tests, some viewers have expressed a preference for NTSC pictures 

over ATV. b) Sharpness is the casual, subjective evaluation of detail 

clarity in an image. It is often assumed that sharpness and resolution are 

directly related, in that images possessed of greater sharpness are 

assumed to have greater resolution. An increase in subjective sharpness is 

usually reported when objects are more clearly delineated from each other 

and from background having hard, sharply-defined edges. A major contri- 



bution to subjective sharpness is this high contrast at edge transitions, as 

is emphasized by both edge enhancement and aperture correction, for 

example. In many practical systems, increasing the contrast at edge transitions 

is often accompanied by a reduction in fine detail, and under these 

conditions, sharpness and resolution may describe opposite characteristics. 

Shedding – A tape’s giving off of oxide or other particles from its coating 

or backing, usually causing contamination of the tape transport and, by 

redeposit, on the tape itself. 

Shell – a) The command interpreter between the user and the computer 

system. b) A window into which you type IRIX, UNIX, or DOS commands. 

SHF (Super High Frequency) – The band of frequencies ranging from 

3 GHz to 30 GHz, currently including all communications satellite signals 

and most microwave transmissions. SHF has been suggested as a band to 

be used for terrestrial ATV transmission channels. 

Shielded Cable – A cable with a conductive covering which reduces the 

possibility of interference with radio, television, and other devices. 

Shift – To move the characters of a unit of information right or left. For a 

binary number, this is equivalent to multiplying or dividing by two for each 

shift. 

Shoot and Protect – A concept of aspect ratio accommodation central to 

the selection of the 16:9 aspect ratio for the SMPTE HDEP standard. In a 

shoot and protect system, in production the action is confined to certain 

bounds (the shoot range) but a larger area (the protect range) is kept free 

of microphone booms, lights, and other distracting elements. Shoot and 

protect has been used for years in film, where the shoot aspect ratio is the 

1.85:1 used in NTSC. The 16:9 aspect ratio was selected mathematically 

as the one requiring the least area to protect both 1.33:1 television and 

2.35:1 widescreen film. In such a system, both the shoot and the protect 

aspect ratios would be 16:9. A rectangle of shoot width and protect height 

would be 1.33:1 (12:9); a rectangle of shoot height and protect width 

would be 2.35:1 (about 21:9). The concept of 3-perf film conflicts strongly 

with 1..85:1 shoot and protect. 

Short Time Linear Distortions – These distortions cause amplitude 

changes, ringing, overshoot, and undershoot in fast rise times and 2T pulses. 

The affected signal components range in duration from 125 nsec to 

1 µsec. A 1T pulse must be used to test for these distortions. See the discussion 

on Linear Distortions. Errors are expressed in “percent-SD.” The 

presence of distortions in short time domain can also be determined by 

measuring K2T or Kpulse/bar . See the discussion on K Factor. Picture effects 

include fuzzy vertical edges. Ringing will sometimes generate chrominance 

artifacts near vertical edges. 

Shortwave – Transmissions on frequencies of 6 to 25 MHz. 

Shot – Picture information recorded by a camera. 

Shotgun Microphone – Long, highly directional microphone designed to 

pick up sounds directly in front of the microphone, rejecting sound from 

other directions. Named for its appearance. 

Shoulder – On the characteristic curve for a photographic material (the 

plot of density vs. log exposure) that portion representing nonlinear 

response at the higher densities. For the electronic relationship of a positive 

video image to the shoulder of photographic negatives. 




Showscan – A film process using 70 mm (65 mm in the camera) film at 

60 frames per second. It seems an ideal film production format (expense 

considerations aside) for transfer to ATV and has been demonstrated as 

such. 

Shut Down – To safely close all files, log out, and bring the workstation to 

a state where you can safely power it down. 

Shuttle – A variable-rate search, forward or reverse, of a videotape using 

a video deck or VCR capable of such an operation. 

SI (Service Information) – SI provides information on services and 

events carried by different multiplexes, and even other networks. SI is 

structured as six tables (PAT, NIT, CAT, SDT, EIT, and BAT). The applications 

are only concerned with NIT, BAT, SDT, and EIT. 

Side Information – Information in the bit stream necessary for controlling 

the decoder. 

Side Panels – Additional sections of picture that, when added to a television 

image, change a 1.33:1 aspect ratio into a wider one. Many ATV 

schemes transmit these panels separately from the main picture. 

Sideband – A signal that is a consequence of some forms of modulation. 

When modulation forms two sidebands, one can sometimes be filtered out 

to increase efficiency without sacrificing information. 

Sides (Submenu) – Under Source, the function that enables each side of 

the video image to be cropped. 

SIF (Standard Interchange Format) – A half-resolution input signal used 

by MPEG-1. See Standard Input Format. This is also known as “Source 

Input Format” and “Standard Interchange Format.” 

SIGGRAPH – The Association of Computing Machinery (ACM) Special 

Interest Group on Computer Graphics. Internet: www.siggraph.org 

Signal Amplitude – The nominal video signal amplitude shall be 1.0 volt 

peak-to-peak (140 IRE units). 

Signal Polarity – The polarity of the signal shall be positive, i.e., so that 

black-to-white transitions are positive going. 

Signal, Chrominance – Video: The color-difference signal(s) and the 

equation(s) for their derivation. Color Television: The sidebands of the 

modulated chrominance subcarrier that are added to the luminance signal 

to convey color information. 

Signal, Luminance – Video: The signal that describes the distribution of 

luminance levels within the image and the equation for deriving that information 

from the camera output. Television, Composite Color: A signal 

that has major control of the luminance. Note: The signal is a linear combination 

of gamma-corrected primary color signals. 

Signaling Rate – The bandwidth of a digital transmission system 

expressed in terms of the maximum number of bits that can be transported 

over a given period of time. The signaling rate is typically much higher than 

the average data transfer rate for the system due to software overhead for 

network control, packet overhead, etc. 

Signal-to-Noise Ratio (SNR) – a) The ratio of signal to noise expressed 

in dB. In general, the higher the signal to noise ratio the better. If there is a 

low signal-to-noise ratio, the picture can appear grainy, snowy, and 

sparkles of color may be noticeable. Equipment will not be able to synchro- 


nize to extremely noisy signals. b) It may not be possible to directly compare 

SNRs for ATV and for NTSC as the eye’s sensitivity to noise varies 

with the detail of the noise. c) The measurement of the dynamic range of a 

piece of equipment, measuring from the noise floor (internally generated 

noise) to the normal operating level or the level prior to limiting. 

Signature – Four-digit value generated by a signature analyzer, which is 

used to characterize data activity present on a logic node during a specific 

period of time. 

Signature Analysis – Technique used to facilitate the troubleshooting of 

digital circuits. Nodes of the circuit, stimulated during a test mode, produce 

“signatures” as the result of the data compression process performed by 

the signature analyzer. When a node signature is compared to a known 

good documented signature, faulty nodes can be identified. 

Signature Analyzer – Instrument used to convert the long, complex serial 

data streams present on microprocessor system nodes into four-digit 

signatures. 

Silhouette – In a boundary rep system, the typical method for creating a 

solid begins by drawing a silhouette outline of it; a plan view (in architectural 

terminology). 

SIMM (Single In-Line Memory Module) – A small printed circuit board 

with several chips that contain additional megabytes of random-access 

memory (RAM). 

SIMM Removal Tool – An L-shaped metal tool used to loosen SIMMs that 

are installed in the SIMM socket. 

SIMM Socket – A long, thin, female connector located on the CPU board 

into which you insert a SIMM. 

Simple Profile – MPEG image streams using only I and P frames is less 

efficient than coding with B frames. This profile, however, requires less 

buffer memory for decoding. 

Simple Surface – Consists of a regular patch mesh and is created with a 

single surface creation operation such as extrude, revolve, sweep, and 

smooth lofts. 

Simulation – A technique for trying an ATV scheme inside a computer 

without actually building specialized equipment. Some question the validity 

of ATV simulations. 

Simulator – Special program that simulates the logical operation of the 

microprocessor. It is designed to execute machine language programs on a 

machine other than the one for which the program is written. This allows 

programs for one microprocessor to be debugged on a system that uses 

another processor. 

Simulcast (Simultaneous Broadcast) – Prior to the advent of multichannel 

television sound broadcasting, the only way to transmit a stereo 

television show to homes was by simultaneous broadcasting on TV and 

radio stations. Proponents of non-receiver compatible ATV schemes suggest 

the same technique to achieve compatibility with existing NTSC TV 

sets: The non-compatible ATV signal will be transmitted on one channel 

and a second channel will carry a standards-converted NTSC signal. It is 

sometimes suggested that such simulcast techniques of ATV transmission 

are more efficient than augmentation techniques since, when the penetration 

of ATV sets into households reaches some limit, the NTSC simulcast

channel can be eliminated, conserving bandwidth. In Britain, an almost 

identical situation occurred when 625 scanning-line television replaced 

405. For many years, all programming was simulcast in both line rates with 

405 eventually eliminated. 

SimulCrypt – a) DVB SimulCrypt specifically addresses the requirements 

for interoperability between two or more CA systems at a headend. b) A 

process that facilitates using several conditional access (CA) systems in 

parallel, in conjunction with the DVB common scrambling algorithm, to control 

access to pay-TV services. 

Simultaneous Colors – The number of colors in a display system that 

can be displayed on the screen at one time. This number is limited by the 

circuitry of the display adapter, and is often much smaller than the number 

of colors the display device can actually support. The number of simultaneous 

colors a display adapter supports is normally determined by the number 

of color planes, or bits per pixel, that it uses. For example, a device 

with 4 bits per pixel supports 16 simultaneous colors. 

(Sin X)/X Pulse – This signal has equal energy present at all harmonics of 

the horizontal scan frequency up to a cutoff point of 4.75 MHz. This allows 

it to produce a flat spectral display when viewed on a spectrum analyzer. 

(Sin X)/X is primarily designed for use with a spectrum analyzer or an automatic 

measurement set such as the VM700A/T. Very little information is 

discernible in a time-domain display. The waveform is shown in the figure 

below. his signal is used for Frequency Response measurements. Refer to 

the Frequency Response discussion. 

Sine-Squared Pulses – Fast rise time square waves cannot be used for 

testing bandwidth-limited systems because attenuation and phase shift of 

out-of-band components will cause ringing in the output pulse. These outof-band 

distortions can obscure the in-band distortions that are of interest. 

Sine-squared pulses are bandwidth limited and are useful for testing bandwidth-limited 

television systems. Description of the Pulse: Sine-squared 

pulses look like one cycle of a sine wave as shown. Mathematically, a sinesquared 

wave is obtained by squaring a half-cycle of a sine wave. 

Physically, the pulse is generated by passing an impulse through a sinesquared 

shaping filter. T Intervals: Sine-squared pulses are specified in 

terms of half amplitude duration (HAD) which is the pulse width measured 

at the 50% pulse amplitude points. Pulses with HADs which are multiples 

of the time interval T are used to test bandwidth limited systems. T, 2T, and 

12.5T pulses are common examples. T is the Nyquist interval, or 1/2 fc 

where fc is the cutoff frequency of the system to be measured. For NTSC, 

fc is taken to be 4 MHz, thus T is 125 nsec. T Steps: The rise times of 

transitions to a constant luminance level (such as the white bar) are also 



specified in terms of T. A T step has a 10% to 90% rise time of nominally 

125 nsec, while a 2T step has a rise time of 250 nsec. Refer to the figure 

below. Energy Distribution: Sine-squared pulses possess negligible energy 

at frequencies above f = 1/HAD. The amplitude of the envelope of the 

frequency spectrum at 1/(2 HAD) is one-half of the amplitude at zero 

frequency. 

HAD 

125 msec 

T 2T 

HAD 

250 msec 

Rise and Fall 

125 msec for 

T Rise Step 

Single Channel – Channel-compatible, an ATV scheme fitting into 6 MHz 

of bandwidth. 

Single-Domain Particle – All ferromagnetic materials are composed of 

permanently magnetized regions in which the magnetic moments of the 

atoms are ordered. These domains have a size determined by energy consideration. 

When a particle is small enough, it cannot support more than 

one domain and is called a single-domain particle. 

Single-Forked – A MooV file whose resources have been moved into the 

data fork, creating a file that can be played on a PC. See MooV. 

Single-Page Mapping – Refers to always using Offset Register 0 (GR9) 

as the window into display memory. The mode is selected when GRB(0) is 

programmed to “0.” 

Single-Step – Process of executing a program one instruction or machine 

cycle at a time. 

Sink Current – Current input capability of a device. 

SIS (Systems for Interactive Services) – ETS 300 802. 

SIT – Selection Information Table. 

Sizing – The operation of shrinking or stretching video data between a 

system’s input and display. Normally, a combination of scaling and 

zooming. 

Skew – a) Passage of tape over a head in a direction other than perpendicular 

to the height of the gap. b) Term used for an ADO action whereby 

rectangles become trapezoids. 

Skipped Macroblock – A macroblock for which no data is encoded. 

Slapback – Discrete repeats created by either digital or tape delay. 

Slate – a) To label with a take number by recording a voice on the tape. 

b) Term used for a frame of video text usually recorded after bars prior to 

countdown sequence at the top of a commercial or program containing 

information on date recorded, ad agency, direction, etc. 

Slice – A series of macroblocks, all placed within the same row horizontally. 

Slices are not allowed to overlap. The division of slices may vary from 

picture to picture. If “restricted slice structure” is applied, the slices must 

cover the whole picture. If “restricted slice structure” is not applied, the 




decoder will have to decide what to do with that part of the picture which 

is not covered by a slice. Motion vectors are not allowed to point at the 

part of the picture, which is not covered by a slice. Note that Main Profile 

uses “restricted slice structure,” that is, all the slices put together must 

cover the picture. 

Slow-In/Slow-Out – In real life, when an object at rest begins to move, it 

starts slowly. Similarly, when an object changes its speed, or direction, it 

rarely does so instantaneously, but rather makes the change gradually 

(that’s one reason we use splines to describe motion paths in computer 

animation). In order to create satisfying animation, it is important to be 

sensitive to the rate at which objects change their direction and speed; 

these factors are the most expressive component of path animation, like 

tempo and dynamics in music. In particular, the term slow-in/slow-out 

refers to an object at rest which gradually accelerates, reaches a final 

velocity, then slows and stops. 

SLSC (Split-Luminance, Split-Chrominance) – A family of ATV 

schemes proposed by Bell Labs and IIT. SLSC is a receiver-compatible, 

non-channel compatible ATV scheme using a high line rate camera and 

prefiltering with receiver line doubling to increase vertical resolution and 

additional bandwidth to increase horizontal resolution and help reduce 

NTSC artifacts. Aspect ratio is increased by blanking stuffing in the HBI. 

SLSC schemes have been proposed with at least two types of chroma 

encoding and three types of widescreen panel transmission. 

S-MAC (Studio MAC) – a) A MAC standard proposed for studio intraconnection 

by the SMPTE working group on CAV standards. The S-MAC system 

uses time compression and time-domain multiplexing techniques to 

convey (Y, CR ,CB ) video signals – a version of (Y, R-Y, B-Y). b) A MAC 

designed for single transmission of CAV signals in a television facility or 

between facilities. See also MAC. 

Small Scale Integration (SSI) – Technology of less complexity than 

medium scale integration. Usually means less than ten gate functions in 

the IC. 

Smart Video Recorder Pro – Intel’s PC video capture card that can capture 

and even compress video in real-time, using Indeo technology. 

SMATV – Satellite Master Antenna Television. 

SMATV-DTM – SMATV system based on digital trans-modulation. 

SMATV-IF – SMATV system based on distribution at IF (Intermediate 

Frequency). 

SMATV-S – SMATV system based on distribution at extended super band. 

Smear – A term used to describe a picture condition in which objects 

appear to be extended horizontally beyond their normal boundaries in a 

blurred or “smeared” manner. 

SMI – Storage Media Interoperability. 

Smooth Shading – Even though an object may be represented by polygons, 

with smooth shading the facets can be made to appear to blend into 

each other, making the object look smooth. Smooth shading also makes 

possible the simulation of “highlights.” 

SMPTE (Society of Motion Picture and Television Engineers) – 

American standardizing body. SMPTE 240M is the first SMPTE HDEP stan- 


dard, calling for 1125 scanning lines, 2:1 interlace, a 16:9 aspect ratio, 

and 60 fields per second, among other characteristics. It is identical to the 

HDEP standard approved by ATSC. It need not be SMPTE’s only HDEP standard, 

however. The Society has current standards for more than ten different 

videotape recording formats, with more pending. There are indications 

that members of SMPTE’s WG-HDEP are interested in a progressivelyscanned 

HDEP system, an evolution of the 1125-line interlace standard. 

SMPTE 120M – NTSC color specification. 

SMPTE 125M – SMPTE standard for Bit-Parallel Digital Interface – 

Component Video Signal 4:2:2. SMPTE 125M (formerly RP-125) defines 

the parameters required to generate and distribute component video signals 

on a parallel interface. 

SMPTE 170M – Proposed SMPTE standard for Television – Composite 

Analog Video Signal, NTSC for Studio Application. This standard describes 

the composite color video signal for studio applications, system M/NTSC, 

525 lines, 59.94 fields, 2:1 interface, with an aspect ratio of 4:3. This 

standard specifies the interface for analog interconnection and serves as 

the basis for the digital coding necessary for digital interconnection of system 

M/NTSC equipment. Note: Parts of the system M/NTSC signal defined 

in this document differ from the final report of the Second National 

Television System Committee (NTSC 1953) due to changes in the technology 

and studio operating practices. 

SMPTE 240M – SMPTE standard for Television – Signal Parameters – 

1125/60 High-Definition Production System. This standard defines the 

basic characteristics of the video signals associated with origination equipment 

operating in the 1125/60 high-definition television production system. 

As this standard deals with basic system characteristics, all parameters 

are untoleranced. 

SMPTE 244M – Proposed SMPTE standard for Television System M/NTSC 

Composite Video Signals Bit-Parallel Digital Interface. This standard 

describes a bit-parallel composite video digital interface for systems operating 

according to the 525-line, 59.94 Hz NESC standard 35 described by 

SMPTE 170M, sampled at four times color subcarrier frequency. Sampling 

parameters for the digital representation of encoded video signals, the 

relationship between sampling phase and color subcarrier, and the digital 

levels of the video signal are defined. 

SMPTE 259M – Proposed SMPTE standard for Television 10-Bit 4:2:2 

Component and 4fsc NTSC Composite Digital Signals – Serial Digital 

Interface. This standard describes a serial digital interface for system M 

(525/60) digital television equipment operating with either 4:2:2 component 

signals or 4fsc NTSC composite digital signals. 

SMPTE 260M – Standard for high definition digital 1125/60. 

SMPTE 267 – Defines the serial digital signal format for 16:9 aspect ratio 

television. The signal rate is 360 Mb/s. 

SMPTE 267M – Standard for component digital video with a 16:9 aspect 

ratio that uses both 13.5 MHz and 18 MHz sampling. 

SMPTE 272M – The SMPTE recommended practice for formatting 

AES/EBU audio and auxiliary data into digital video ancillary data space. 

SMPTE 274M – 1920 x 1080 Scanning And Interface. 

SMPTE 291M – Ancillary Data Packet And Space Formatting.

SMPTE 292M – The SMPTE recommended practice for bit-serial digital 

interface for high definition television systems. 

SMPTE 293M – 720 x 483 Active Line At 59.94 Hz Scan, Digital 

Representation. 

SMPTE 294M – 720 x 483 Active Line At 59.94 Hz scan, Bit Serial 

Interfaces. 

SMPTE 295M – 1920 x 1080 50 Hz Scanning and Interfaces. 

SMPTE 296M – 1280 x 720 Scanning, Analog and Digital Representation 

And Analog Interface. 

SMPTE 297M – Serial Digital Fiber Transmission For SMPTE 295M 

Signals. 

SMPTE 298M – Universal Labels For Unique Identification Of Digital Data. 

SMPTE 299M – The SMPTE recommended practice for 24-bit digital audio 

format for HDTV bit-serial interface. Allows eight embedded AES/EBU audio 

channel pairs. 

SMPTE 305M – The SMPTE standard for Serial Digital Transport Interface. 

SMPTE 308M – Television – MPEG-2 4:2:2 Profile At High Level. 

SMPTE 310M – Television – Synchronous Serial Interface For MPEG-2 

Transport Streams. 

SMPTE 312M – Television – Splice Points For MPEG-2 Transport Streams. 

SMPTE 314M – Television – Data Structure For DV Based Audio, Data And 

Compressed Video – 25 Mb/s and 50 Mb/s. 

SMPTE 318M – Reference Signals For The Synchronization Of 59.95 Hz 

Related Video And Audio Systems In Analog And Digital Areas (Replaces 

RP 154). 

SMPTE Format – In component television, these terms refer to the SMPTE 

standards for parallel component analog video interconnection. The SMPTE 

has standardized both an RGB system and a (Y, PR ,PB ) color difference 

system – a version of (Y, R-Y, B-Y). 

SMPTE RP 154 – Standard that defines reference synchronizing signals 

for analog or digital 525-line systems including recommendations for black 

burst. 

SMPTE RP 155 – Standard for digital audio reference levels for digital 

VTRs. This is being revised into a studio standard. 

SMPTE RP 165 – Standard for error detection and handling in serial digital 

component and composite systems. 

SMPTE RP 168 – Standard for vertical interval switching points for 

525/625 systems. 

SMPTE Standard – See the SMPTE format discussion. 

SMPTE Time Code – Binary time code denoting hours, minutes, seconds, 

and frames. See also Time Code. 

SMPTE-VITC – SMPTE’s vertical interval time code (VITC) format standard. 

The term VITC, used alone, usually refers to SMPTE-VITC. 

SMS – Subscriber Management System. 

SN – Sequence Number. 



SNA – Systems Network Architecture entered the market in 1974 as a 

hierarchical, single-host network structure. Since then, SNA has developed 

steadily in two directions. The first direction involved tying together mainframes 

and unintelligent terminals in a master-to-slave relationship. The 

second direction transformed the SNA architecture to support a cooperative-processing 

environment, whereby remote terminals link up with mainframes 

as well as each other in a peer-to-peer relationship (termed Low 

Entry Networking (LEN) by IBM). LEN depends on the implementation of two 

protocols: Logical Unit 6.2, also known as APPC, and Physical Unit 2.1 

which affords point-to-point connectivity between peer nodes without 

requiring host computer control. The SNA model is concerned with both 

logical and physical units. Logical units (LUs) serve as points of access by 

which users can use the network. LUs can be viewed as terminals that provide 

users access to application programs and other services on the network. 

Physical units (PUs) like LUs are not defined within SNA architecture, 

but instead, are representations of the devices and communication links of 

the network. 

SNAP – Sub Network Attachment Point. 

SNG – Satellite News Gathering. 

SNMP – Simple Network Management Protocol. 

Snow – Heavy random noise. 

SNR – See Signal-to-Noise Ratio. 

SNR Scalability – A type of scalability where the enhancement layer(s) 

contain only coded refinement data for the DCT coefficients of the base 

layer. SNR scalability is aimed at transmission in noisy environments, and 

offers a form of graceful degradation. Under poor reception conditions, only 

the lower layer (which is covered by the highest error protection) is decoded. 

The picture quality is then not the best, of course, but at least a picture 

is available. The alternative is a total loss of picture (the “brick wall” effect) 

below a certain SNR. The lower layer and the enhancement layer operate 

with the same resolution, but the enhancement layer may contain the higher 

frequencies of the picture. 

SOF (Sound On Film) – The sound track is on the film itself. 

Soft Border – a) The quality of diffusion between adjacent visual areas in 

a picture around a pattern. b) A wipe pattern border which is missing 

between the “A” bus video and “B” bus video on the edges to give a soft 

effect. This has no matte color added. 

Soft Edge – An edge between two video signals in which the signals are 

mixed together for a soft transition effect, used on both patterns and keys. 

Soft Key – a) A selector on the display that changes state or initiates an 

action when you touch it on screen. You use soft keys to select test signals 

or a sub-window of functions or to enter a file name. b) A soft key’s function 

changes to match the block above it, in the bottom line of the screen. 

c) The softening of a key edge by reducing the gain of the keyer. 

Software – Operating instructions loaded into computer memory from disk 

that controls how system hardware will execute its operation. See 

Programs. 

Software Option – Any software product that you buy other than the standard 

system software that comes on your system disk. 




Solarization – Special effect in which the lightest and darkest values of a 

picture are made dark while the middle tones become light. An ADO effect. 

Also a photo-optic process. 

Solder Bridge – Glob of excess solder that shorts two conductors. A common 

problem on production PC boards. 

Solid – Polygons meshed together to create closed volumes. It is a compact 

set of contiguous points in three-dimensional space. 

Solo – To listen to one mike or track of a tape without listening to the others 

through the use of a solo button. 

Sone – A unit of loudness. 2 sones are twice as loud as 1 sone. 

Sonic Welded Assembly – Refers to the joining of the two plastic parts 

of a cassette by the use of a sonic weld, actually melting the plastic at the 

point of joining. 

Sony – First company to sell an HDEP recorder, making HDEP practical. 

Also the strongest HDEP proponent, spending a great deal to promote it 

and going so far as to display the products of some of its competitors, as 

long as they complied with the 1125 scanning-line system. 

Sound Booth – Term for a small acoustically dead room from which an 

announcer will record voice overs. 

Sound Pressure Levels (SPL) – a) A measure of the sound pressure created 

by a sound, usually in the units of dB referred to 0.0002 microbar of 

pressure. b) A measure of acoustic wave force. The force that sound can 

exert against an object; our ear drums are an example. It is measured in 

dB and is “0” referenced to 1 dyne per square centimeter. 

Sound-on-Sound – A method by which material previously recorded on 

one track of a tape may be rerecorded on another track while simultaneously 

adding new material to it. 

Source – Video producing equipment such as cameras, tape recorders, or 

character generators. 

Source (Menu) – The function that changes the aspect ratio and size of 

the image. The word Source refers to the image generated by the input 

video, which occupies “Source Space” on the screen. a) Source Aspect 

uses the X and Y axis. b) Source Size uses the Z axis. The image does not 

move. 

Source Code – Program written in other than machine language. May be 

assembly language or a high-level language. 

Source Coding – Coding that uses a model of the source from which 

parameters are extracted and transmitted to the decoder. When used particularly 

for voice, the coders are called vocoders. 

Source Current – Current output capability of a device. 

Source Stream – A single, nonmultiplexed stream of samples before compression 

coding. 

Source Synchronizing Generator – A synchronizing pulse generator 

used to drive a specific piece of source equipment. It is referenced to a 

master reference synchronizing generator. 

Source Timing Modules – A synchronizing generator on a module that is 

used to adjust the timing of a specific piece of source equipment. It is kept 

in time by a reference sync pulse generator. 


Source/Tape Switch – A control found on control amplifiers with tape 

monitor jacks, and on recorders with monitor heads, allows comparison of 

the signal being fed to the tape (source) with the signal just recorded. 

Southwestern Bell – A Baby Bell, and the first organization to transmit 

HDHEP 9, as opposed to some bandwidth-reduced form of ATV), a long distance, 

via optical fiber. 

Sparkle – An ADO DigiTrail effect. 

Spatial – Relating to the area of an image. 

Spatial Resolution – What is usually referred to as resolution, linearly 

measurable detail in an image in the vertical, horizontal, or diagonal 

directions. 

Spatial Scalability – A type of scalability where an enhancement layer 

also uses predictions from pel data derived from a lower layer without 

using motion vectors. The layers can have different frame sizes, frame 

rates or chroma formats. Spatial scalability offers a layering of the picture 

resolution, suitable for HDTV transmissions, for instance. By decoding of 

the lower layer, a “normal” picture is obtained, and by decoding of the 

enhancement layer, the HDTV picture may be constructed. 

Spatio-Temporal Filtering – Filtering in both space and time. 

Spatio-Temporal Spectrum – A three-dimensional representation of the 

energy distribution of a television signal. The three dimensions are horizontal, 

vertical, and time. 

S/PDIF (Sony/Philips Digital Interface Format) – A consumer version 

of the AES/EBU digital audio interconnection standard. The format uses a 

75-ohm coaxial cable with RCA connectors and has a nominal peak-topeak 

value of 0.5 V. The frame ordering differs slightly than that of 

AES/EBU, specifically in the channel status information. Refer to AES/EBU 

interface. 

Special Effects – Artistic effects added to a video production in order to 

enhance the production by creating drama, enhancing the mood or furthering 

the story. Special effects may vary from the limited addition of patterns 

or the mixing of several video images together, to sophisticated digital 

effects such as picture compression, page flipping, and three-dimensional 

effects. Special effects are usually created using SEGs such as those 

included in the Video Equalizer, Video TitleMaker 2000, and Digital Video 

Mixer. 

Special Effects Generator – A video component that processes video 

signals and has the ability to manipulate the signal with a variety of wipes 

and distortions. 

Special Magnetic Moment – The value of the saturation moment per unit 

weight of a magnetic material expressed in emu/gm. The specific magnetic 

moment is the most convenient quantity in which to express the saturation 

magnetization of fine particle materials. 

Spectra Key – An enhancement to a standard RGB chroma key, employing 

a patented chroma nulling circuitry, thereby removing any color from the 

background video. This enables keys to be performed through glass or 

smoke or with shadows. This would otherwise not be possible without the 

blue or green fringing effect typical of standard RGB keyers.

Spectral Analysis – a) Determination of the monochromatic components 

of the luminance considered. b) Objective detailed specification of a white 

reference, of a color, or of the transmission function, with respect to wavelength 

and intensity. 

Spectral Sensitivity – Quotient of the detector output dY(lambda) by the 

monochromatic detector output dXc(lambda) = Xclambda(lambda)dlambda 

in the wavelength interval dlambda as a function of the wavelength 

lambda. 

Spectrophotometric Match – Spectrophotometry determines the spectral 

transmittance and the spectral reflectance of objects … to compare at 

each wavelength the radiant flux leaving the object with that incident upon 

it. A spectrophotometric match thus occurs only when the two objects 

being compared are identical in their color structure. Such a match will be 

maintained regardless of viewing conditions. Spectrophotometric matches 

are seldom encountered and rarely necessary; in practice, the usual objective 

is to achieve a metameric match. Metameric matches, however, appear 

identical only under one set of specified viewing conditions. 

Spectrum Allocation – Designation of certain bandwidths at certain frequencies 

for certain purposes. For example, channel 2 has been allocated 

6 MHz of bandwidth from 54 MHz to 60 MHz for television broadcasting. All 

ATV transmission schemes require some form or another of spectrum allocation. 

See also Frequency Allocation Table. 

SPI – Synchronous Parallel Interface. 

Spike – See Overshoot. 

SPL (Sound Pressure Level) – The SPL of a sound is equal to twenty 

times the logarithm (base 10) of the ratio of the root-mean-square sound 

pressure to the reference sound pressure. As a point of reference, 0 dB- 

SPL equals the threshold of hearing, while 140 dB-SPL produces irreparable 

hearing damage. 

Splice – A physical join between pieces of tape. 

Splicing – Concatenation of, or switching between, two different streams 

of compressed data. 

Splicing Tape – A special pressure-sensitive, non-magnetic tape used for 

joining two lengths of magnetic tape. 

Spline – a) A type of mathematical model used to represent curves. They 

are usually displayed as polylines with a large number of very small sides. 

The importance of splines is that they give very smooth curves for a relatively 

small number of points. b) In wooden ships, the curved skeleton of a 

hull is built by attaching bendable strips of wood to small, fixed, and 

angled blocks of wood. The strips are splines. In computer graphic splines, 

the blocks of wood are called control points. In computer graphics, curved 

lines are always visualized by drawing many short vectors. However, since 

each vector requires a fair amount of storage, curves are often stored in 

terms of their control points; whenever the curve is needed, the spline is 

recreated. Another advantage of storing splines as curves is the ease with 

which a spline curve is manipulated by moving its control points. Instead of 

moving the curve’s vectors one at a time, a large section of the curve is 

moved by dragging its control point. Splines convert discontinuity into 

smoothness. These properties make splines very useful in animation. When 

we create a keyframe for path animation, the object’s position becomes a 



control point for a spline that defines the entire path for all the in-between 

frames as well. This allows us to get smooth motion between all the 

keyframes, and avoid instantaneous (single frame) changes of direction. 

Such changes would be highly unrealistic and could never yield satisfying 

animation. Another tremendous advantage of splines is that they are resolution 

independent. Magnifying and then redrawing a shape that is represented 

by a spline does not reveal the short vectors that represent the 

curve on the screen, because these vectors are recalculated to take into 

account the new magnification. Spline represented objects can also be 

easily rotated or skewed in 3D, again with no loss in clarity. So called “vector-based” 

systems make use of these features by representing fonts and 

shapes with splines, rather than the traditional bitmap. Bitmap systems, on 

the other hand, cannot represent or manipulate shapes nearly as handily. 

Split Edit – Type of edit transition where either the video or audio of the 

source is delayed from being recorded for a given time. 

Split Screen – An electronic process which allows the viewing of two 

video images, side by side or above and below, on-screen simultaneously. 

Split Sync Scrambling – Video scrambling technique, used with horizontal 

blanking inversion, active video inversion, or both. In split sync, the horizontal 

sync pulse is “split,” with the second half of the pulse at +100 IRE 

instead of the standard –40 IRE. Depending on the scrambling mode, 

either the entire horizontal blanking interval is inverted about the +30 IRE 

axis, the active video (after color burst and until the beginning of front 

porch blanking) is inverted about the +30 IRE axis, both are inverted, or 

neither is inverted. By splitting the horizontal sync pulse, a reference of 

both –40 IRE and +100 IRE is available to the descrambler. Since a portion 

of the horizontal sync is still at –40 IRE, some sync separators may still 

lock on the shortened horizontal sync pulses. However, the timing circuits 

that look for color burst a fixed interval after the beginning of horizontal 

sync may be confused. In addition, if the active video is inverted, some 

video information may fall below 0 IRE, possibly confusing sync detector 

circuits. The burst is always present at the correct frequency and timing, 

however, the phase is shifted 180 degrees when the horizontal blanking 

interval is inverted. 

Spoking – A form of buckling in which the tape pack is deformed into a 

shape which approximates a polygon. 

Spot – Term used for a commercial. 

Spot Light – A unidirectional source geometrically defined by its position 

and target. 

Spotlight – a) The effect of a spotlight falling on a video scene, and the 

switcher feature that allows this to be accomplished. On the AVC, the spotlight 

control adjusts attenuation of the A bus video. A typical spotlight 

effect is obtained by selecting the same source on both buses, a soft bordered 

circle wipe, and using size and position control. Many other effects 

are also possible with this feature. b) A highlight effect produced by a fullstrength 

video signal shaped by a wipe pattern and an attenuated (darkened) 

signal from the same video source. This is activated by selecting 

spotlight on the M/E effects group of buttons, and adjusting spotlight control 

on the pattern adjust group of controls to darken the desired area. 

Sprites – In MPEG-4, static background scenes. Sprites can have dimensions 

much larger than what will be seen in any single frame. A coordinate 




system is provided to position objects in relation to each other and the 

sprites. MPEG-4’s scene description capabilities are built on concepts used 

previously by the Internet community’s Virtual Reality Modeling Language 

(VRML). 

Square Pixels – Pixels generated in a television system having the same 

horizontal and vertical resolution. There is some evidence that a large mismatch 

between horizontal and vertical resolution prevents the higher resolution 

from being fully perceived by the human visual system. NTSC was 

created with square pixels with a resolution of approximately 330 by 330 

lines. 

Squareness – A measure of magnetic behavior expressed as a ratio. 1.00 

would be considered perfect and the normal range for magnetic material is 

0.7 to 0.9. 

Squeal – Audible tape vibrations, primarily in the longitudinal mode, 

caused by frictional excitation at heads and guides. 

Squeeze – A change in aspect ratio. Anamorphic lenses sometimes 

squeeze a widescreen scene by a factor of two horizontally, so it will fit on 

a 1.33:1 aspect ratio frame. In projection, another anamorphic lens 

“expands” the squeeze (squeezes vertically) to restore the original aspect 

ratio. When a widescreen film is presented on television without being 

expanded, it is said to be squeezed. An unexpanded film print is said to be 

a squeeze print (the opposite is “flat”). 

SRI (Stanford Research Institute) – SRI International owns DSRC, developer 

of the ACTV schemes. 

SRM – Session and Resource Manager. 

SSA – See Serial Storage Architecture. 

SSI – See Small Scale Integration. 

SSCG – Spread-Spectrum Clock Generator. 

ST – Stuffing Table. 

Stack – Block of successive memory locations that is accessible from one 

end on a last-in-first-out basis (LIFO). For most processors, the stack may 

be an block of successive locations in the read/write memory. 

Stack Pointer – Contains the address of the top of the stack. In general, 

the stack pointer is decremented immediately following the storage in the 

stack of each byte of information. Conversely, the stack pointer is incremented 

immediately before retrieving each byte of information from the 

stack. 

Stand-Alone Workstation – A workstation that is not connected to a 

network. 

Standard – a) The specific signal configuration, reference pulses, voltage 

levels, etc., that describe the input/output requirements for a particular 

tape of equipment. Some standards have been established by professional 

groups or government bodies (such as SMPTE or EBU). Others are determined 

by equipment vendors and/or users. b) A set of rules or characteristics 

defining a particular television system. Some standards (such as those 

contained in FCC rules and regulations) are mandatory. Most (including 

those of the EIA, IEEE, and SMPTE) are voluntary. The establishment of a 

standard often freezes development at a certain level but allows users and 

manufacturers to deal with a much larger array of products than might be 


available without a standard. There is currently one U.S. HDEP standard, 

the ATSC/SMPTE 1125 scanning-line system. CCIR system E is an HDTV 

transmission standard, used in France, calling for 819 scanning lines in a 

14 MHz bandwidth. 

Standard Bodies – Any country having a national group of people consisting 

of experts from industry and universities who develop standards for 

all kinds of engineering problems. 

Standard Definition Television – See SDTV. 

Standard Input Format – Video format developed to allow the storage 

and transmission of digital video. The 625/50 SIF format has a resolution 

of 352 x 288 active pixels and a refresh rate of 25 frames per second. The 

525/59.94 SIF format has a resolution of 352 x 240 active pixels and a 

refresh rate of 29.97 frames per second. MPEG-1 allows resolutions up to 

4095 x 4095 active pixels, however, there is a “constrained subset” of 

parameters defined as SIF. The computer industry, which uses square pixels, 

has defined SIF to be 320 x 240 active pixels, with a refresh rate of 

whatever the computer is capable of supporting. 

Standards Converter – A device for converting signals from one standard 

to another. Converting between different color schemes with the same 

scanning structure is called transcoding. Converting between different 

scanning structures requires line and field interpolation, which usually 

introduces artifacts. Standards conversion between 525 scanning line and 

625 scanning line signals is performed regularly. Conversion from DHEP to 

either NTSC or a receiver-compatible ATV system will require standards 

conversion. It may seem that it is more difficult to convert from 1125 scanning 

lines to 525 than from 1050 to 525, but in a pre-filtering converter, 

the difference, if any, may not be large. For dealing with the field-rate difference 

(HDEP 60 and NTSC 59.94), some DHEP to NTSC conversions are 

performed by slowing the HDEP recorders to 59.94-field playback. Others 

are performed through standards converters that periodically omit fields. 

Standing Wave Ratio – The ratio of transmitted power to reflected power 

in transmission lines, antenna systems, connectors, etc. 

STAR System (Setup Swap, Transfer and Recall Panel Memory 

System) – Describes the possible operations of this feature, using the 

concept of a setup as an instantaneous snapshot of a complete switcher 

panel, including all button selections, adjustments, positions, and fader values. 

Setups may be broken down into each of the six major modules on the 

switcher, with the ability to store or recall them independently into any of 

eight setup registers. This system also provides the capability of transferring 

the setup of one M/E to another, or swapping their setups. 

Start Codes (System and Video) – 32-bit codes embedded in that coded 

bit stream that are unique. They are used for several purposes including 

identifying some of the structures in the coding syntax. Start codes consist 

of a 24-bit prefix (0x000001) and an 8-bit stream_id. 

Start of Active Video (SAV) – Digital data that indicates the start of 

active video time in serial digital component video systems. 

Static Electricity – Whenever your body comes in physical contact with 

metal parts (including printed circuit boards) of computer equipment there 

is the potential for you to feel an electrical shock (electro-static discharge 

or ESD) which could damage the equipment. To prevent this you must

always wear a wrist strap when working with internal parts of a 

workstation. 

Static Memory – Memory devices that do not need clocks or refreshing. 

Static Resolution – Detail in a stationary image. Any amount of bandwidth 

is sufficient for the transmission of HDTV images with high static 

resolution, even a telephone line; the smaller the bandwidth, the longer it 

takes to transmit all of the resolution. Therefore, many ATV schemes with 

reduced bandwidths offer the static resolution of HDEP with limited dynamic 

resolution, resulting in motion artifacts such as motion surprise. 

Statistical Multiplexing – Increases the overall efficiency of a multichannel 

digital television transmission multiplex by varying the bit-rate of 

each of its channels to take only that share of the total multiplex bit-rate it 

needs at any one time. The share apportioned to each channel is predicted 

statistically with reference to its current and recent-past demands. 

Status – Present condition of the device. Usually indicated by flag flip-flips 

or special registers. See Flag. 

Status Monitor – A B/W video output available as an option on AVC series 

switchers that provides display of all switcher adjustments, pattern menus, 

and diagnostic tools. 

STB – Set Top Box. 

STC (System Time Clock) – The common clock used to encode video 

and audio in the same program. A 27 MHz clock regenerated from PCR for 

a jitter-free readout of MPEG data. 

STD – System Target Decoder. 

STD Input Buffer – A first-in, first-out buffer at the input of a system target 

decoder for storage of compressed data from elementary streams 

before decoding. 

STE – System Target Error. 

STED – System Target Error Deviation. 

STEM – System Target Error Mean. 

Stderr – Standard error file. Error messages sent by programs are displayed 

on the screen, which is by default, the Stdout. 

Stdin – Standard input file. 

Stdout – Standard output file. 

Stereo – Sound received from two separate sources. Simulates human 

hearing. 

Stereo Mixing – Simultaneous processing of both left and right audio 

channels. 

Stereophonic, Stereo – Using two or more channels to create a spatial 

effect. 

Stiction – A term loosely used to describe the phenomenon of tape adhering 

to transport components such as heads or guides. 

Still Picture – A coded still picture consists of a video sequence containing 

exactly one coded picture which is intra coded. This picture has an 

associated PTS, and the presentation time of succeeding pictures, if any, is 

later than that of the still picture by at least two picture periods. 

Still Store – Device for storage of specific frames of video. 



STL – Studio Transmitter Link. 

Storage – See Memory. 

Storage Capacity – Using the ITU-R 601 4:2:2 digital coding standard, 

each picture occupies a large amount of storage space, especially when 

related to computer storage devices such as DRAM and disks. So much so 

that the numbers can become confusing unless a few benchmark statistics 

are remembered. Fortunately, the units of mega, giga, tera, and penta 

make it easy to express the very large numbers involved. The capacities 

can all be worked out directly from the 601 standard. Bear in mind that 

sync words and blanking can be regenerated and added at the output, only 

the active picture area need be stored. 

Store – The action of retaining in memory panel parameters (in the case of 

switchers), edit decision lists (in the case of editors), frames of video (in 

the case of machines like AVA, ESS and CGs). 

Storyboard – A storyboard is an animator’s sketch, or rough of all the 

keyframes involved in a particular piece of animation. Used as a visual 

script or shooting plan. 

Stow – To reduce a window to an icon for later use. In Windows® it is 

called “minimize.” 

Streaking – A term used to describe a picture condition in which objects 

appear to be extended horizontally beyond their normal boundaries. This 

will be more apparent at vertical edges of objects when there is a large 

transition from black to white or white to black. The change in luminance is 

carried beyond the transition, and may be either negative or positive. For 

example, if the tonal degradation is an opposite shade to the original figure, 

(white following black), the streaking is called negative; however, if the 

shade is the same as the original figure, (white following white), the streaking 

is called positive. Streaking is usually expressed as short, medium, or 

long streaking. Long streaking may extend to the right edge of the picture, 

and in extreme cases of low-frequency distortion, can extend over a whole 

line interval. 

Stream – A collection of digital data of one type; such as a video stream, 

an audio stream, or a subtitle stream. Each stream, for example an audio 

stream, may also have channels within it. 

Stress Testing – Introducing mechanical, electrical, or thermal stress on 

electrical devices so as to modify their operation and allow intermittent 

problems and/or failures to be observed. 

STU – Set Top Unit. 

Studio Address System – An intercom system that allows communication 

between control-room personnel and personnel working on the studio floor. 

Studio Standard, HDTV – a) Approaches to the specification of a studio 

standard, HDTV have been in the context of present operations in 

525/59.94 and 625/50: i.e., operations in the studio conform to the specifications 

for transmission and broadcast. The studio standard with its implication 

of no systems transform, therefore, might be described also as one 

of the distribution standards – expected to be one of the inputs to display, 

and to be evaluated by subjective judgment of the display. b) As employed 

by CCIR Rep 801-4 and its annexes, the term studio standard loosely 

embraces everything from image capture through distribution. To illustrate 

the interpretation by examples from the document. (a) Sec 1, Introduction: 




A single standard could be beneficial to program producers as well as 

broadcasting organizations and viewers. (b) Sec 2, Technical Matters: This 

entire section is concerned with defining the system by reference to the 

subjective, visual appraisal of the final display. (c) Annex II, entitled 

Parameter Values for Signal Generation in HDTV Studios and For 

International Exchange of HDTV Programs. (d) Sec 1e explains that the 

advantages of a single HDTV worldwide standard includes lower HDTV 

equipment costs for broadcasters and viewers, easier exchange of programs 

and technical information, and encouragement to the ideal of international 

solutions to common technical problems. These concepts of a studio 

standard accordingly address only a small part of what the SMPTE 

Committee on Hybrid Technology considers production. 

Stuffing (bits); Stuffing (bytes) – Code-words that may be inserted into 

the compressed bit stream that are discarded in the decoding process. 

Their purpose is to increase the bit rate of the stream. 

STV – Subscription Television. 

Sub-Band Coding – A pure sub-band coder performs a set of filtering 

operations on an image to divide it into spectral components. Usually, the 

result of the analysis phase is a set of sub-images, each of which represents 

some region in spatial or spatio-temporal frequency space. For 

example, in a still image, there might be a small sub-image that represents 

the low-frequency components of the input picture that is directly viewable 

as either a minified or blurred copy of the original. To this are added successively 

higher spectral bands that contain the edge information necessary 

to reproduce the original sharpness of the original at successively 

larger scales. As with DCT coder, to which it is related, much of the image 

energy is concentrated in the lowest frequency band. For equal visual quality, 

each band need not be represented with the same signal-to-noise ratio; 

this is the basis for sub-band coder compression. In many coders, some 

bands are eliminated entirely, and others are often compressed with a vector 

or lattice quantizer. Succeedingly higher frequency bands are more 

coarsely quantized, analogous to the truncation of the high-frequency coefficients 

of the DCT. A sub-band decomposition can be the intraframe coder 

in a predictive loop, thus minimizing the basic distinctions between DCTbased 

hybrid coders and their alternatives. 

Subcarrier – a) The modulation sidebands of the color subcarrier contain 

the R-Y and B-Y information. For NTSC, the subcarrier frequency is 

3.579545 MHz. For PAL the subcarrier is approximately 4.43 MHz. b) An 

auxiliary information carrier added to the main baseband signal prior to 

modulation. The most common example in television is the NTSC color subcarrier. 

Many ATV schemes propose adding additional subcarriers to NTSC. 

c) A sine wave which is imposed on the luminance portion of a video signal 

and modulated to carry color information. Subcarrier is also used to form 

burst. The frequency of the subcarrier is 3.58 MHz in NTSC and PAL-M and 

4.43 MHz in PAL. d) The high-frequency signal used for quadrature amplitude 

modulation of the color difference signals. 

Sub-Channel – A transmission path within the main transmission path. 

Subcarriers are examples of sub-channels, but there are others. 

Quadrature modulation of the picture carrier provides a sub-channel; so 

does blanking stuffing. 

Submaster – High quality copy of a master tape used to make additional 

copies. See also Dub. 


Sub-Nyquist Sampling – A scheme for sampling at a frequency lower 

than that prescribed by the Nyquist sampling theorem. 

Sub-Picture Information – Captions, subtitles, or other text that can be 

displayed or hidden. 

Sub-Pixel – A spatial resolution smaller than that of a pixel. Although digital 

images are composed of pixels, it can be very useful to resolve image 

detail to smaller than pixel size, i.e., sub-pixel. For example, the data for 

generating a smooth curve on television needs to be created to a finer 

accuracy than the pixel grid itself, otherwise the curve will look jagged. 

Again, when tacking an object in a scene or executing a DVE move, the 

size and position of the manipulated picture must be calculated, and the 

picture resolved, to a far finer accuracy than the pixels, otherwise the move 

will appear jerky. 

Subroutine – Self-contained portion of a program that performs a welldefined 

task. May be used at any place in the same program. 

Subsampled – Signal that has been sampled at a lower rate than some 

other signal in the system. A good example of this is the Y'CbCr color 

space used in component serial video (ITU-R BT.601). For every two luma 

(Y') samples, only one Cb and Cr sample is taken causing the Cb and Cr 

signals to be subsampled. 

Sub-Sampling – Sampling within samples. For example, dividing an NTSC 

pixel into three or four sub-pixels is an example of sub-sampling. Some 

ATV schemes use such pixel subdivision to transmit a high-definition image 

over a sequence of multiple fields or frames, with only one sub-pixel being 

transmitted per field or frame. The resulting potential artifacts include 

motion surprise and twinkle. 

Subsidiary Communications Authorizations – Authorizations granted 

to FM broadcasters for using subcarriers on their channels for other communications 

services. 

Substrate – A DVD half-disc. Two substrates, each 0.6 mm thick, are 

bonded together to form a 1.2 mm thick DVD disc. 

Subtractive Color System – Color specification system in which primary 

colors are subtracted from a reference color to achieve a desired color. 

Examples include the cyan/magenta/yellow (CMY) and luminance/red – 

luminance/blue – luminance (Y, R-Y, B-Y) systems. 

Super – See Title. 

Super Black – Keying signal that is embedded within the composite video 

signal as a level between black and sync. It is used to improve luma selfkeying 

because the video signal contains black, making a good luma selfkey 

hard to implement. Where the downstream keyer detects the super 

black level, it inserts the second composite video signal. See Blacker-than- 

Black. 

Super NTSC – An ATV scheme proposed by Faroudja. It combines progressive 

scanning, pre-filtering, pre-combing, image enhancement, and gamma 

correction at the transmission end with complementary processing and line 

doubling at the receiver. It is both channel-compatible and receiver-compatible 

and is one of the few ATV schemes that keep an aspect ratio of 

12:9. 

Super VHS – S-VHS is an enhancement to regular VHS video tape decks. 

S-VHS provides better resolution and less noise than VHS. S-VHS video

tape decks support separate luma (Y') and chroma (C) video inputs and 

outputs, although this is not required. It does, however, improve the quality 

by not having to continuously merge and then separate the luma and chroma 

signals. 

Superimpose (Super) – To place in front of video, e.g., placing text over 

a video signal. 

Superimposition (or Super) – a) Two images simultaneously picked up 

by two different cameras and electronically mixed on the face of a kinescope 

tube in such a manner that both images are visible. b) A film term 

describing the mixing of two or more video sources such that they appear 

to be overlaid. 

Superstation – Local television station whose signal is retransmitted via 

satellite to cable systems beyond reach of over-the-air signal. 

Superuser – An alternate name for the user of the root login account. See 

also System Administrator. 

Sup-Picture – A simple picture intended to be superimposed over the 

video. Display size varies but is bound to CCIR 601 picture dimensions 

(720 x 480 for NTSC-rate displays or 720 x 576 for PAL-rate displays). 

Supply Turntable – The turntable which feeds tape to the heads of a tape 

deck. 

Surface – A set of one or more patches which have been connected 

together. 

Surface Asperities – Small, projecting imperfections on the surface of 

the coating that limit and cause variations in head-to-tape contact. A term 

useful in discussions of friction and modulation noise. 

Surface Properties – To allow more realism to 3D models, the surfaces of 

an object can have distinctive attributes or properties: ambient light, diffuse 

light, transparency, texture (these four in PictureMaker). Other systems 

have other properties such as true metallic versus plastic (or other material) 

surface types. 

Surface Treatment – Any process by which the surface smoothness of 

the tape coating is improved after it has been applied to the base film. 

Surge Protector – An electronic device which protects electronic equipment 

from power fluctuations. 

Surround Sound – This usually implies an audio system with more than 

two channels of information. The additional channels provide “ambiance” or 

sound information that is happening somewhere other than from the left or 

right speaker. 

S-VHS (Super VHS) – a) An improved version of the VHS tape format 

capable of recording better picture resolution (definition). A higher-density 

tape is required which provides a wider luminance bandwidth, resulting in 

sharper picture quality (>400 horizontal lines vs. 240 for standard VHS) 

and improved signal-to-noise ratio. Because the equipment is usually 

smaller and lighter than 3/4" equipment, it is ideally suited for ENG/EFP 

applications. b) Super VHS, a consumer videotape format offering horizontal 

resolution somewhat greater than that offered by NTSC broadcasting 

but allowing component recording and playback without cross-luminance or 

cross-color artifacts through a four-pin S-Video connection. 

SVHS, S-VHS – See Super VHS. 



S-VHS-C (Super VHS-C) – An improved version of the VHS-C tape format 

capable of recording better picture resolution (definition). 

S-Video (Separated Video) – The standard for the way a signal is carried 

on the cable itself. The industry has settled on a 4-pin mini plug connector. 

S-Video does not have any relation to the resolution or refresh rate of the 

signal. Do not confuse S-Video with S-VHS. S-VHS is a tape/signal standard. 

S-Video is a hardware standard that defines the physical cable jacks. 

S-Video allows you to bypass the comb filter in a device. Generally, less 

processing of the signal results in a better picture. The comb filter separates 

the chroma (color) and luma (brightness) components of a video signal 

into separate parts. This is also called Y/C, where Y represents brightness 

and C color. When color and brightness are not separated, when they 

are combined in the signal, it is called a composite signal. S-Video cables 

have separate wires for the color and brightness. That is, they carry a Y/C 

signal. The best picture comes when the color and brightness is separate 

from the source. VCRs record this way, and DSS broadcasts this way too. 

Laserdiscs store a composite picture rather than Y/C separated. Even when 

the signals have been combined at some point on their way to the monitor, 

different comb filters perform to different degrees of quality, so one can 

pick how to connect one’s components to try to use the best comb filter. 

Some older sets with S-Video input jacks may actually combine the Y/C in 

a crude way, making the S-Video input no better than a typical composite 

signal. Newer sets do not do this. 

Sweep Signal – Line rate and field rate sweep signals can be used to 

measure the frequency response of a system. In a sweep signal, the frequency 

of the waveform is continuously increased over the length of the 

line or field. A sweep signal allows you to examine the frequency response 

continuously over the interval of interest rather then at only discrete frequency 

intervals as tested by the multiburst or multiphase signals. The 

Sweep signal however cannot be used for VITS, thus is limited to out-ofservice 

testing. See the Frequency Response discussion. 

Sweetening – a) The final combining and enhancing of a video program’s 

audio tracks. b) Electronically improving the quality of an audio or video 

signal, such as by adding sound effects, laugh tracks, and captions. 

Switcher – General term for a device used to select different signals 

(audio, video, or RF) from various sources. See Video Switcher. 

Switching – a) The process of connecting and routing digital data on a 

network. b) The editing and splicing together of program segments. 

Symmetrically, Cyclically, Magnetized Condition – A magnetic material 

is in this condition when, using the influence of a magnetizing field 

cycled between equal but opposite values, its successive hysteresis loops 

coincide. 

Symmetry – An adjustment that allows distortion of the aspect ratio of a 

pattern. 

Sync – a) Abbreviation for synchronization. Usually refers to the synchronization 

pulses necessary to coordinate the operation of several interconnected 

video components. When the components are properly synchronized, 

they are said to be “in sync.” b) Signals which control the sweep of 

the electron beam across the face of the display. The horizontal sync, or 

HSYNC for short, tells the display where to put the picture in the left-toright 

dimension, while the vertical sync (VSYNC) tells the display where to 




put the picture from top-to-bottom. c) The portion of an encoded video signal 

which occurs during blanking and is used to synchronize the operation 

of cameras, monitors, and other equipment. Horizontal sync occurs within 

the blanking period in each horizontal scanning line, and vertical sync 

occurs within the vertical blanking period. 

Sync Buzz – A noise containing harmonics of 59.94 Hz, heard on television 

set speakers under certain signal and transmission conditions. One 

such condition is the transmission of electronically generated characters of 

high level and resolution greater than can be carried in NTSC. The ringing 

resulting when those signals hit an NTSC filter causes the television carrier 

to momentarily disappear. Since the characters are within a television field, 

the rate of appearance and disappearance is a multiple of the field rate, 

59.94 Hz. 

Sync Compression – The reduction in amplitude of the sync signal, with 

respect to the picture signal, occurring between two points of a circuit. 

Sync Generator – Circuit that provides sync signals. A sync generator 

may or may not have genlock capability. 

Sync Level – The level of the tips of the synchronizing pulses. 

Sync Noise Gate – Circuit used to define an area within the video waveform 

where the sync stripper is to look for the sync pulse. 

Sync Pulse – Timing pulses added to a video signal to keep the entire 

video process synchronized in time. 

Sync Restoration – A process which replaces distorted and missing sync 

information by checking incoming sync, analyzing the frequencies involved, 

and generating new fully restored sync. 

Sync Stripper – Circuit which removes the sync information from the 

composite signal. 

Sync to Blanking End – Refer to the Horizontal Timing discussion. 

Sync to Burst End – Refer to the Horizontal Timing discussion. 

Sync to Subcarrier Time Base Error – A random variation in the phase 

relationship between sync and subcarrier. 

Sync Word – A synchronizing bit pattern which is different from the normal 

bit stream pattern for purposes of synchronization or clocking. 

Synchronizing words usually consist of unique bit patterns which are easily 

recognized as a clock or sync signal. Sync words are used for framing in 

serial receivers. 

Synchronization – The maintenance of one operation in step with another. 

The precise coincidence of two or more sync pulses. 

Synchronization Word – a) A synchronizing bit pattern differentiated 

from the normal data bit patterns, used to identify reference points in the 

television signal; also to facilitate word framing in a serial receiver. b) A 

fixed pattern of bits inserted in a binary message for the purpose of synchronizing 

the message interpreting unit. 

Synchronized – To happen at the same time. 

Synchronizer – Device that ensures audio and video signals from varying 

sources are coordinated by timing them against a reference signal and 

advancing or delaying them as needed. 


Synchronizing Pulse Generator – Equipment that generates synchronizing 

pulses needed by source equipment. Also called sync generator or 

SPG. 

Synchronous – A transmission procedure by which the bit and character 

stream are slaved to accurately synchronized clocks, both at the receiving 

and sending end. 

Synchronous Data Streaming – a) Streaming of data with timing 

requirements in the sense that the data and clock can be regenerated at 

the receiver into a synchronous data stream (i.e., E1, T1). b) Streaming of 

data with timing requirements in the sense that the data within the stream 

can be played back in synchronization with other kinds of data streams 

(e.g., audio, video). See Asynchronous Data Streaming, Synchronous Data 

Streaming. 

Synchronous Detection – A demodulation process in which the original 

signal is recovered by multiplying the modulated signal with the output of a 

synchronous oscillator locked to the carrier. 

Synchronous Motor – A motor with speed controlled by the frequency of 

the applied voltage. 

Syncro-Edit – Wired control protocol which activates/deactivates a VCR’s 

record pause function. Many non-compatible versions of this protocol exist. 

Syndicat des Constructeurs d’Appareils Radio Recepteurs et 

Televiseurs (SCART) – A 21-pin connector for European audio/video consumer 

products. It supports mono/stereo audio, composite video, S-video, 

and RGB video to be transmitted between equipment. 

Syndrome – Initial result of an error checking calculation. Generally, if the 

syndrome is zero, there is assumed to be no error. 

Sysinfo – The program used to retrieve the system identifier of your 

Silicon Graphic workstation. 

System – An organized assembly of equipment, personnel, procedures, 

and other facilities designed to perform a specific function or set of 

functions. 

System Administration – The tasks associated with setting up, maintaining, 

and troubleshooting a networked or stand-alone workstation or a network 

of workstations. 

System Administrator – The individual responsible for setting up, maintaining, 

and troubleshooting a network of workstations. The system administrator 

uses the root login account to perform most administrative tasks. 

System Clock Reference – See SCR. 

System Crash – When the operating system fails and the system will not 

accept keyboard or mouse input. 

System Disk – The physical disk that contains the standard operating 

system software, the software that makes a workstation run. 

System Gamma – The overall light-in/light-out characteristic of a television 

system, from camera through receiver. In an ideal system, the gamma 

should be one. In practice, it appears to be about 1.4. 

System Header – The system header is a data structure that carries 

information summarizing the system characteristics of the Digital Television 

Standard multiplexed bit stream.

System Manager – A set of tools that the administrator uses to set up 

and manage the IRIS. You access the System Manager through the System 

Toolchest. 

System Software – The standard operating system software and tools 

that come on the system disk and on the tape or DC-ROM that you use in 

the event of a system crash. 



System Target Decoder – See STD. 

System Toolchest – The toolchest in the upper left-hand corner of the 

screen labeled System. You start system tools such as the Workspace and 

System Manager using its menu. 




T 

T – Tele- or Time. 

T Intervals – See the definition of Sine-Squared Pulses. 

T Steps – See the definition of Sine-Squared Pulses. 

T.120 – A set of specifications for multipoint communications and data 

sharing for PC platforms. T.120 is based on the H.320 broad-based PB 

platform standard for Personal Teleconferencing. 

T1 – In telecommunications, the pared cable used to transport DS-1 

service. 

T1Q1.5 – The T1Q1.5 Video Teleconferencing/Video Telephony (VTC/VT) 

ANSI Subworking Group (SWG) was formed to draft a performance standard 

for digital video. Important questions were asked, relating to video digital 

performance characteristics of video teleconferencing/video telephony: 

a) Is it possible to measure motion artifacts with VTC/VT digital transport? 

b) If it can be done by objective measurements, can they be matched to 

subjective tests? c) Is it possible to correlate the objective measurements 

of analog and digital performance specification? The VTC/VT Subworking 

Group’s goal is to answer these questions. It has become a first step to the 

process of constructing the performance standard. 

Table – a) Collection of data in a form suitable for ready reference, frequently 

stored in sequential memory locations. b) A table is comprised of a 

number of sub_tables with the same value of table_id. 

Table Look-Up – Obtaining a value from a table of values stored in the 

computer. 

Taboos – Empty channel spaces in the frequency allocation table to which 

broadcast channels cannot be assigned due to potential interference. The 

most obvious one is the co-channel taboo: two different television or radio 

stations cannot operate on the same frequency in the same geographical 

area. Other taboos cover geographical spacing for adjacent channels and 

for “images” (spurious frequencies akin to aliases) that are caused by 

reception in existing television sets. The taboos effectively knock out much 

of the UHF television band, so some ATV proponents wonder whether they 

might be too strict. 

Tachometer – A device which counts the number of revolutions per second 

of a motor or other rotating device. 

Tag – The tag forms the most important part of a cache directory entry. 

Using the tag, the cache controller determines whether a cache hit or miss 

occurs. The tag holds the address of the assigned cache line. 

Tails Out – A way of winding tape such that the end of the selection is at 

the outside of the reel. 

Take – A cut that takes place on-air. Also, the flip or flip-flop of sources on 

a preset/program style switcher. 

Takeup Reel – The reel on the tape recorder that accumulates the tape as 

it is recorded or played. 

Takeup Turntable – The turntable which takes up the tape after it passes 

by the heads. 


Talent – A term used to refer to on-camera subjects in a video production. 

Talker – Device that outputs data to a data bus. A ROM is a talker. 

Tally – a) An indication of all sources that are contributing to a switcher’s 

final output at any given time. b) A light which lights up to indicate that the 

associated push-button has been selected or to indicate that the associated 

input to the switcher is on-air. c) A relay closure to activate a remotely 

situated lamp, i.e., on top of a camera, to warn the production crew which 

camera is on-air. Most monitors have tally lights and common practice is to 

connect them to the switcher tally output so that the director can see 

which source is on-air. 

Tally Lamp – A signal lamp or LED installed on a video camera which 

informs performers and crew members that the camera is currently live. 

Tally Relay – Contacts provided on the switcher to allow users to activate 

tally lamps on cameras, monitors, and otherwise indicate what sources are 

on-air. 

Tangential Signal-to-Noise Measurement Method – This is one 

method of measuring a signal’s signal-to-noise ratio. It requires a waveform 

monitor such as the 1780R. Refer to the 1780R operator’s manual for 

a complete description of the signal-to-noise measurement technique. 

Tape – A tape with a magnetizable layer on which data can be stored. 

Usually a workstation’s tape is packaged in a cartridge. 

Tape Delay – Using magnetic tape as a storage medium for a brief period 

of time to delay the playback of a signal. Delay time equals the distance 

between the record and playback heads divided by the tape speed. 

Tape Drive – A mechanism for controlling the movement of magnetic 

tape, commonly used to move magnetic tape past a read head or write 

head, or to allow automatic rewinding. 

Tape Guides – Grooved pins or rollers mounted between and at both sides 

of the tape head assembly to position the magnetic tape correctly on the 

head as it is being recorded or played. 

Tape Lifters – A system of movable guides that automatically prevents the 

tape from contacting the recorder’s heads during fast forward or rewind 

modes of operation, thus preventing head wear. 

Tape Loop – A length of magnetic tape with the ends joined together to 

form an endless loop. It makes possible the repetitive playback of a recording 

without rewinding the tape. 

Tape Pack – The form taken by the tape wound on to a reel. A good pack 

is one that has a uniform wind, has an acceptable E-value and is free from 

spoking, cinching, and layer-to-layer adhesion. 

Tape Player – A unit that is not capable of recording and is used only for 

playing recorded tapes. 

Tape Skew – The deviation of a tape from following a linear path when 

transported across the heads, causing a time displacement between signals 

recorded on different tracks and amplitude differences between the 

outputs from individual tracks owing to variations in azimuth alignment. The

adjectives static and dynamic are used to distinguish between the steady 

and fluctuating components of tape skew. 

Tape Speed – The speed at which tape is transported from feed (supply) 

to takeup reels during normal recording or reproduction. 

Tape Speed Override (TSO) – Allows the editor to manually control the 

capstan speed of the selected transport + and –10% using the joystick. 

TSO is especially important when tape machines need to be exactly synchronized 

before finalizing an edit. If audio monitors for all transports are 

left up, the edit point on the transport can be selected by listening for the 

audio echo and adjusting the transport speed until the machines are in 

exact synchronization. 

Tape Transport – The mechanism that extracts magnetic tape from a 

storage device, moves it across magnetic heads at a controlled speed, and 

then feeds it into another storage device. Typical storage devices are tape 

loops, bins, reels, and magazines (cassettes, cartridges). The tape transport 

is one part of a magnetic tape recorder/reproducer system that normally 

consists of: magnetic heads, magnetic tape, tape transport, record electronics, 

and reproduce electronics. 

Tape-to-Head Speed – The relative speed of tape and head during normal 

recording or replay. The tape-to-head speed coincides with the tape 

speed in conventional longitudinal recording but is considerably greater 

than the tape speed in systems where the heads are scanned across or 

along the tape. 

Target – A picture monitor displaying ADO video output can be thought of 

as a window which reveals a finite area of target space. 

Target (Menu) – The 2D function that moves or sizes the image on the 2D 

plane, which is “Target Space.” In 3D systems, Target is used to move an 

image without perspective and to “fine tune” an effect. 

Tariff – Common carrier’s statement describing services it offers and rates 

it charges. 

T-Axis – Time axis of the spatio-temporal spectrum. 

TBC – See Time Base Corrector. 

TCM – Trellis Coded Modulation. 

TCP (Transport Control Protocol) – The major transport protocol in the 

Internet suite of protocols providing reliable, connection-oriented, fullduplex 

streams. Uses IP for delivery. 

TCP/IP – The standard networking software that is included in the system 

software. 

TDAC (Time Domain Aliasing Cancellation) – A coding technique used 

in AC-3 audio compression. 

TDF – See Telediffusion de France and Time Division Frequency. 

TDL (Telecine Decision List) – A list of the edits made in a telecine session 

which can be loaded into an off-line editor. 

TDM – See Time Division Multiplex. 

TDMA – Time Division Multiple Access. 

TDT (Time and Data Table) – UTC time and date. Used in DVB-SI. 



Tear Strength – The force, usually in gm, required to initiate and/or propagate 

a tear in a specially shaped specimen of tape or base film. 

Tearing – A lateral displacement of the video lines due to sync instability. 

Visually, it appears as though parts of the images have been torn away. 

Telecine – A term used to describe a device used to convert film to video. 

In advanced telecine machines, the movie film is digitally sampled and 

converted to video, frame by frame in real-time. Frame rate is the biggest 

problem encountered in film-to-video conversion. Movie film has a frame 

rate of 18, 24, or 30 fps (frames per second) contrasting with the 30 and 

25 fps video frame rates of NTSC and PAL respectively. See Flicker. 

Telediffusion de France (TDF) – A proponent of the French proposals. 

Teleprompter – A device for displaying large, readable text on a partially 

transparent screen for video production. The teleprompter uses a monitor 

mounted under the camera lens, facing up, and a mirrored glass which 

reflects the monitor’s image toward the talent. Since the camera shoots 

through the mirrored glass and the mirrored glass is transparent to the 

camera, the talent can look directly into the camera lens as they read the 

script from the glass. 

Teletext – A method of transmitting data with a video signal. ITU-R BT.653 

lists the major teletext systems used around the world. World System 

Teletext (WST) is system B; North American Broadcast Teletext Specification 

(NABTS) is 525-line system C. 

TeleText – An information service of 200-700 “pages” covering a wide 

range of topics including TV Schedules, News, Financial Market prices, 

Comment, Reviews, Concert and Theater information. Subtitles are typically 

transmitted on page 888 in the UK, on pages 199/299/399 in Belgium and 

Holland, on page 150 in Germany, and on page 777 in Italy. There are a 

number of variant character sets used, but the encoding is identical and all 

English alphabet characters plus numbers and most punctuation can be 

handled by any decoder. Includes support for eight colors, and limited 

block graphics, and selective revealing of underlying TV picture. 

Transmitted on a variable number of lines (specified in header which contains 

basic information such as time, date, and channel), starting on line 

12 and continuing for 7-8 lines typically. Found on broadcasts and some 

Laserdiscs; recording of TeleText signals is marginal on S-VHS, almost 

impossible on VHS, hence, the PAL/625 version of CC. 

Television – A combination tuner, RF demodulator, picture tube, and audio 

speaker that converts RF signal into picture and sound. 

Television, Broadcast – Generally refers to terrestrial radiation of television 

signals in one or more of the frequency bands defined by CCIR (and in 

the U.S. reaffirmed by the FCC). The U.S. has 59 television channels, each 

6 MHz wide, for video plus correlated audio. 

Television, Digital (for Studios) – An extensive family of compatible digital 

coding standards for studio use with current television systems is 

defined by CCIR Red 601-2, equally applicable to component encoded 

525/60 Hz and 625/50 Hz systems. The member of the family to be used 

for the standard digital interface between main digital studio equipment 

and for international program exchange (i.e., for the interface with video 

recording equipment and for the interface with the transmission system) 

should be that in which the luminance and color-difference sampling frequencies 

are related in the ratio 4:2:2. Specifications include: Coded 




Signals; luminance (Y) plus two color-difference signals (CR and CB). 

Sampling Frequency; luminance 13.5 MHz, color-difference 6.75 MHz 

(for each of the two signals); Samples (8-bit) per Digital Active Line; 

luminance 720, color-difference 360 (for each of CR and CB). Other more 

detailed specifications are included in CCIR Rec 601-2. Compressed and 

expanded derivations (4:1:1 and 4:4:4 specifically) are postulated variants 

with minimum or maximum color information. 

Television, Digital Component – A signal format in which either the tristimulus 

value red (R), green (G), and blue (B) signals representing the picture 

contents or a matrixed version consisting of the luminance (Y) and two 

color-difference signals (R Y, L3 Y) – are individually digitized and combined 

into a single data stream. SMPTE 125M describes a digital component 

television signal interface for 525-line/59.94 field/sec television systems. 

Specifications for digital magnetic video tape recording of component 

digital video of 525-line or 625-line structure sampled at 13.5 MHz are 

grouped into the D1 VTR standards. For 525-line, samples at 13.5 MHz, 

the specifications are SMPTE 224M, 225M, 226M, 227M, RP 155, and 

EG 10. An index to the specifications for D1, both 525-line and 625-line 

versions, is SMPTE EG 22. 

Television, Digital Composite – A signal format in which the signal 

matrix representing the picture contents consisting of the luminance and 

the two color-difference signals modulated on a color subcarrier are digitized 

in the matrixed form as a single data stream. SMPTE 244M describes 

a digital composite television signal interface for 525-line/59.94 field/sec 

television systems. Specifications for digital magnetic video tape recording 

of composite digital video of 525-line or 625-line structure are grouped 

into the D2 VTR standards. For 525-line, sampled at 14.32 MHz, the specifications 

are SMPTE 245M, 246M, 247M, 248M, EG 20, and RP 155. An 

index to the specifications for D2 is SMPTE EG 22. 

Television, Digital HDTV – An extensive family of compatible digital coding 

standards for studio use with high-definition television is under study 

and test by the SMPTE Committee on Television Signal Technology (S17). 

Digital representation of the 1125/60 system is documented in SMPTE 

260M. 

Television, Enhanced (ETV or EDTV) – The term “enhanced television” 

designates a number of different improvements applicable to 525/60 Hz 

and 625/50 Hz television systems. They include all television systems not 

specified in CCIR Report 624-4, Characteristics of Television Systems and 

Report 801-4, The Present State of High-Definition Television, either with 

unchanged or new radiation standards and without specification of aspect 

ratio. 

Television, High-Definition (HDTV) – A high-definition television system 

is a system designed to allow viewing at about three times the picture 

height, such that the system is virtually, or nearly, transparent to the quality 

of portrayal that would have been perceived in the original scene or performance 

by a discerning viewer with normal visual acuity. Such factors 

include improved motion portrayal and improved perception of depth. A 

high-definition system generally implies in comparison with conventional 

television systems: spatial resolution in the vertical and horizontal directions 

of about twice that available in CCIR Red 601-2; any worthwhile 

improvements in temporal resolution beyond that achievable with CCIR Red 


601-2; improved color rendition; a wider aspect ratio; multichannel highfidelity 

sound. 

Temporal – Relating to time. 

Temporal Aliasing – a) A visual defect that occurs when the image being 

sampled moves too fast for the sampling rate. A common example is 

wagon wheels that appear to rotate backwards. b) An alias caused by violation 

of the Nyquist limit on sampling in time with frames. 

Temporal Resolution – The finest moments of time that can be perceived 

in a particular system. It is not the same as dynamic resolution, which is 

spatial resolution when an image is changing. As an example, suppose a 

spoked wheel is turning. If the spokes are a blur when the wheel is not 

turning, the system has poor static resolution; if they are clear, it has good 

static resolution (for the spokes). If they are a blur when the wheel is turning, 

the system has poor dynamic resolution and poor temporal resolution. 

If they are clear when the wheel is turning, the system has good dynamic 

resolution. If, though clear, they appear to be stationary, or turning in the 

wrong direction, or turning at the wrong speed, or flashing rapidly in different 

positions so it is impossible to tell which way or at what speed they are 

turning (a temporal blur), the system has poor temporal resolution. A great 

deal of evidence indicates that the human visual system cannot simultaneously 

perceive high spatial resolution and high temporal resolution. 

Temporal Scalability – A type of scalability where an enhancement layer 

also uses predictions from pel data derived from a lower layer using motion 

vectors. The layers have identical frame rates size, and chroma formats, 

but can have different frame rates. 

Terabyte – 1 trillion bytes. A 2-hour HDTV movie at the maximum resolution 

of 1920 x 1084 would take about 1 terabyte to store in an uncompressed 

format. 

Terminal – A computer interface comprised of a monitor, keyboard, and 

usually some memory. 

Termination – In order to accurately send a signal through a transmission 

line, there must be an impedance at the end which matches the impedance 

of the source and the line itself. Amplitude errors and reflections will 

otherwise result. Video is a 75-ohm system, so a 75-ohm terminator must 

be put at the end of the signal path. 

Termination Switch – A switch that connects and disconnects a load 

resistance to a video input, used to terminate the line. In order for a video 

signal to be correctly transmitted without loss, proper end of line impedance 

is essential. Amplitude errors and reflections will otherwise result. A 

50- or 75-ohm resistor is usually employed to accomplish this. When the 

termination switch is off, the unterminated video signal is looped to the 

next device where the signal can be transmitted in parallel. The final device 

in the chain must be terminated using the termination switch.

Terrestrial Transmission Standards – 

Scan Frequency Sound 

Code Frames Lines Band Offset In Use 

Terrestrial Transmission Standards 

A 25 405 VHF –3.5 MHz No 

B 25 625 VHF +5.5 MHz Yes 

C 25 625 VHF +5.5 MHz Yes 

D 25 625 VHF +6.5 MHz Yes 

E 25 819 VHF +11 MHz No 

F 25 819 VHF +5.5 MHz No 

G 25 625 UHF +5.5 MHz Yes 

H 25 625 UHF +5.5 MHz Yes 

I 25 625 UHF +6.0 MHz Yes 

K 25 625 UHF +6.5 MHz Yes 

KI 25 625 UHF +6.5 MHz Yes 

L 25 625 UHF +6.5 MHz Yes 

M 30 525 VHF/UHF +4.5 MHz Yes 

N 25 625 VHF/UHF +4.5 MHz Yes 

Satellite Transmission Standards 

Ku-Band Any Any ~11 GHz +6.50 MHz Yes 

C-Band Any Any ~4 GHz +6.50 MHz Yes 

Tessellated Sync – European designation for serrated sync. 

Test Pattern – A chart with special patterns, placed in front of a television 

camera to generate a known reference signal that can be used to adjust 

the camera and all the equipment downstream from the camera. 

Test Signal Generators – These instruments provide a variety of known 

test and synchronization signals for the characterization of television 

systems. 

TEV – Target Error Vector. 

Text Box – Used to enter text. 

Text Mode – A graphics adapter mode where only the characters of a certain 

character set can be displayed on the monitor. The pixels cannot be 

addressed individually and are generated by a hardware character 

generator. 

Texture Map – A texture map is a 2D image that can be created with a 

paint program such as AVA3 or TIPS, or scanned into a frame buffer from a 

video source, and then mapped onto the surface of a 3D object. ADO 

effects are a simple, real-time, on-line version of this general process. 

Texture Mapping – Texture mapping is made possible by full color mode. 

Texture mapping refers to the process of covering the surface of a polygon 

with values what come from a “texture” that come from some picture 

stored elsewhere in the system, say a scanned in image. 

TGA – The TARGA file format (TGA) and TARGA board were developed for 

graphics prior to the advent of large-screen, super VGA displays. 

THD – Total Harmonic Distortion. 



Thomson – Major French electronics firm that recently purchased GE/RCA 

Consumer Electronics and previously purchased German consumer electronics 

interests, the latter sometimes referred to as International Thomson. 

Through its GE/RCA holdings, Thomson is a proponent of the ACTV ATV 

schemes; through International Thomson, it has proposed progressive 

schemes. Thomson also sells television production equipment and for a 

time owned the production equipment branch of CBS Laboratories, then 

called Thomson-CSF Laboratories. 

Three-Wire Interconnect – Interconnect consisting of three wires. One 

wire transports luminance while the other two wires each transport a colordifference 

signal. This system is commonly used for connecting equipment 

in a “component facility” because it is more compatible with non-VTR video 

sources, time-base correctors, displays, and monitoring equipment. 

Three-State – Logic device whose output can be placed into a highimpedance 

(off) state, in addition to the usual high and low states. This 

feature allows more than one device output to be connected to the same 

logic node. Three-state operation is a fundamental requirement for devices 

used on microprocessor data buses. Same as Tri-State (registered trademark). 

Threshold of Feeling – The sound pressure level at which people feel 

discomfort 50% of the time. Approximately 118 dB SPL at 1 kHz. 

Threshold of Hearing – The sound pressure level at which people hear 

only 50% of the time. Approximately 0 dB SPL at 1 kHz. 

Threshold of Pain – The sound pressure level at which people feel actual 

pain 50% of the time. Approximately 140 dB SPL at 1 kHz. 

Throughput – Speed with which problems or segments of problems are 

performed. Throughput will vary from application to another. 

Thumbscrew – The ridged knob attached to a screw in a cable connector 

that you turn to secure the connector to an outlet. 

Thunk – Thunk refers to the byte-shuffling that occurs when 32-bit code 

must communicate with 16-bit code. 

TIF – A file format (tagged image format file) preferred over the bitmap 

(BMP) file format for Windows applications. TIF files may be compressed or 

uncompressed and contain a header similar to BMP files. A special version 

of TIF is used for compressed data FAX transmission. 

TIFF (Tag Image File Format) – The standard file format for highresolution 

bit-mapped graphics, especially from scanners. 

TIFF-EP (Tag Image File Format for Electronic Photography) – A version 

of TIFF file format used by Kodak digital cameras to store non-image 

data with many different types of image data. 

Tilt – Term used for camera movement in an up and down mode. 

Timbre – The harmonic content of a tone and the relative intensities of the 

different harmonics. 

Time and Control Code – a) SMPTE 12M – A digital code recorded by 

video and audio magnetic tape recorders, identifying each frame with a 

unique and complete address. Unassigned bits permit limited production 

identification. The time and control code was developed for 525-line/60field 

systems. An international version compatible with SMPTE 12M is 

described in IEC Publication 461. Variants have evolved for 24- and 25- 




frame systems. b) Cinematography – A digital code format applicable to 

motion-picture film at 24, 25, or 30 frames/sec. Two types are described: 

Type C, a continuous code very similar to SMPTE 12M and IEC Publication 

461 to be read from continuously moving film, and Type B, a non-continuous 

block-type code for intermittently moving film, but still decodable with 

the same type of electronic equipment used to read Type C. 

Time Base Corrector (TBC) – a) Device used to correct for time base 

errors and stabilize the timing of the video output from a tape machine. 

Machines like VHS players where a single pass of the video head represents 

many video lines are particularly susceptible to tape stretch, jitter, 

and speed variations which cause some recorded video lines to be shorter 

or longer than others. The TBC acts as a “rubber-band” storage device to 

line up each horizontal line at its proper location allowing for synchronous 

playback. b) A device used to rectify any problems with a video signal’s 

sync pulses by generating a new clean time base and synchronizing any 

other incoming video to this reference. The Digital Video Mixer includes two 

infinite window, full field TBCs. 

Time Code – a) A digital code number recorded onto a videotape for editing 

purposes. When decoded, the time code identifies every frame of a 

videotape using digits reading hours:minutes:seconds and frames. Each 

individual video frame is assigned a unique address, a must for accurate 

editing. The three time code systems used for video are VITC, LTC, and RC 

(consumer). b) Electronically generated digital clock information which is 

recorded onto tapes on a special track such that an editor can accurately 

locate individual frames (fields) of video information for editing purposes. 

The SMPTE standard for encoding time in hours, minutes, seconds, and 

frames and video. 

Time Code Generator – Signal generator designed to generate and transmit 

SMPTE time code. 

Time Compressed Video-On-Demand – The ideas of electronic video 

rental could be realized through the techniques of time compression: video 

data compression is used for “less than real time” delivery of video/audio 

as opposed to real-time, compressed video in “normal” distribution 

applications. 

Time Compression – A technique used in many ATV schemes (including 

all of the MACs) for squeezing a signal of a certain duration into a time 

period of lesser duration. This effectively multiplies the bandwidth of the 

original signal by the compression factor. If the higher bandwidth is not 

available, horizontal resolution is lost. Time compression is most frequently 

used for color components (which can often afford the resolution loss due 

to restricted visual acuity) and for widescreen panels (with the resolution 

loss made up via some sub-channel). 

Time Division Frequency (TDF) – The management of multiple signals 

by transmitting or receiving each on its own assigned frequency. 

Time Division Multiplex (TDM) – The management of multiple signals on 

one channel by alternately sending portions of each signal and assigning 

each portion to particular blocks of time. 

Time Domain – Information that is a direct function of time. An oscilloscope 

displays information in the time domain. 


Time Line – The graphical interface used by most nonlinear editing software. 

You simply drag and drop your clips onto the time line then your 

transitions, effects, filters, and titles. 

Time Multiplex – In the case of CCIR-601, a technique for transmitting 

three signals at the same time on a group of parallel wires (parallel cable). 

See also Multiplex. 

Time Stamp – A term that indicates the time of a specific action such as 

the arrival of a byte or the presentation of a presentation unit. 

Timeline (Menu) – The time function that performs (runs) the keyframes 

of an effect in sequence and enables the timing of the effect to be 

modified. 

Timing Reference Mark – The 50% point on the leading edge of the horizontal 

sync pulse. In an RGB system, the green signal’s horizontal sync 

pulse is used. In color-difference formats, the Y signal’s horizontal sync 

pulse is used. 

Timing Reference Signal Identification (TRS-ID) – A four-word reference 

used to maintain timing in serial composite digital systems. 

Timing Reference Signals (TRS) – A four-word reference signal used in 

serial composite digital systems to synchronize the conversion of serial 

data back to parallel. 

768 - 782 

Word 

Address 

End of Analog Active Line 

End of Digital Active Line 

50% 

784 

785 

787 790 - 794 

TRS-ID 

3FF 

000 

000 

000 

ID 

795 - 849 

ANC Data 

(Optional) 

Title – A caption or super is a graphic, usually text, from a character generator 

i.e., chyron, 3M, or from a title camera (black/white high resolution 

camera). 

Title Bar – Located at the top of the application window, it contains the 

name of the application and sometimes the name of the open file. 

Title Key – A key effect which imposes a caption over a background 

scene. The source of the title key signal may be a character generator or a 

graphics camera. 

Titling – The addition of text, symbols, and graphic elements to a video 

image. Titles may be added to a video scene during shooting or in postproduction. 

Sophisticated titling devices allow the user to prepare text and 

graphics in various sizes, fonts, and colors to be triggered later, one-byone, 

at appropriate places within a production. Many video cameras include 

basic titlers or permit externally-generated titles to be mixed with the video 

850 

851 

852 

ID Shows: Line Numbers 1 - 31 Only 

Color Fields 1 - 4 (8 for PAL)

image during shooting. The Video TitleMaker 2000 is a powerful tool for 

titling. 

TMC (Time Multiplex Component) – An old CBS ATV proposal for delivery 

via two NTSC-capable DBS channels. One channel would carry a MAC 

signal of NTSC characteristics; the other would carry additional vertical 

resolution and widescreen panels. This was the first system to prove that 

widescreen seams could be rendered invisible. 

To Source – Video source that is supplying the video and/or audio that is 

being cut, dissolved, or wipe to. 

Toe – On the characteristic curve for a photographic material (the plot of 

density vs. log exposure), that portion representing nonlinear response at 

the lower densities. For electronic image, relationship to photographic negatives 

or positives. 

Toggle – Switch back and forth from one state or value to another (i.e., 

on, off, on, off, etc.) by alternately opening and closing an electric circuit. 

Tolerance – The allowable deviation from the stated nominal width or 

length. 

Tool – A graphic entity on the screen which is not an object. 

Top Field – One of two fields that comprise a frame of interlaced video. 

Each line of a top field is spatially located immediately above the corresponding 

line of the bottom field. 

Toshiba – One of the first television set manufacturers to demonstrate an 

IDTV set. Also a proponent of a widescreen ATV system using highfrequency 

subcarriers to carry the side panels in a receiver-compatible, 

channel-compatible signal. 

TOT (Time Offset Table) – UTC time and date with indication of local time 

offset. 

Total Thickness – Normally, the sum of the thicknesses of the base film 

and the magnetic coating. The total thickness governs the length of tape 

that can be wound on a given reel. 

Touchscreen – Term used for a special type of machine controller which 

has a matrix of photovoltaic transmitters and receivers across the face of a 

monitor such that placing a finger on the desired point of the screen intersects 

this light matrix and automatically activates the corresponding 

switch. 

TOV – Threshold of Visibility. 

TPS – Transmission Parameter Signaling. 

Tracer – See Current Tracer. 

Track – An area of tape surface that coincides with the location of the 

recorded magnetization produced by one record gap. 

Track Spacing – The distance between the center lines of adjacent 

tracks. 

Track Width – The width of the track corresponding to a given record gap. 

Tracking – The angle and speed at which the tape passes the video 

heads. Due to small differences in head-to-tape alignment between VCRs, 

it is sometimes necessary to adjust the tracking control on a VCR when 

playing a tape recorded on another deck. 



Tracking Shot – A shot containing camera movement. 

Trailing Edge – The place on the record head where the recording actually 

takes place. 

Training Signal – A Philips-proposed signal to be used in a two-channel 

ATV transmission scheme that would alert the receiver to flaws that may 

have been introduced in the transmission of the second channel so that it 

can compensate for them. 

Trajectory – A curve using a set of control points to interpolate inbetween 

points. 

TRANS – Transition. 

Transcoder – Device that converts one component format to another, e.g., 

to convert (Y, R-Y, B-Y) signals to (RGB) signals. 

Transducer – A device which converts energy from one medium to another. 

Transfer Function – A complex function of frequency response (and correlated 

levels) relating the output to the input of the device as a function of 

frequency. A mathematical, graphical, tabular statement of the influence 

which a module has on a signal or action compared at input and at output 

terminals. 

Transfer Function, Electro-Optic – a) Display – The relationship 

between the video signal supplied to a display device and the luminance of 

the resulting image produced by that display device. b) Recorder, Film – 

The relationship between the video signal supplied to the recorder and the 

resultant illuminance exposing the film. 

Transfer Function, Monitor Electro-Optic – The relationship between 

video input to the monitor and the luminance of the CRT. Monitors are 

required to conform to a narrower range of performance specifications than 

is expected of commercial receivers. Confirming these tighter tolerances 

requires attention to measurement details since, for example, the luminance 

may vary if different areas of the tube face are selected. Light output 

is routinely measured in the center of large, uniform “patches” or windows. 

Since there is significant “bleeding” of light within a CRT face, the 

monitor transfer function also decreases with decreasing size of the windows 

(it is thus reduced for fine detail) and with increasing video level of 

the raster surrounding the windows. 

Transfer Function, Opto-Electronic – The relationship between scene 

luminances and the corresponding video signal. There may be several 

opto-electronic transfer functions for a single system, depending upon 

where in the progression of possible nonlinear processing, bandlimiting, 

etc., the video signal is being identified. When referred to the camera output 

before bandlimiting and processing, however, it is essentially a linear 

function. 

Transfer Manager – A tool that you access through the System Toolchest 

used to copy files to and from local and remote tapes or disks. 

Transform Coding – a) A method of encoding a picture by dividing each 

picture into sub-pictures, performing a linear transformation on each subpicture 

and then quantizing and coding the resulting coefficients. b) The 

conversion of a signal from one domain to another, e.g., the conversion of 

two-dimensional picture samples into the frequency domain by means of 

DCT, which is used in MPEG. 




Transform, Systems – Electronic production requires that images originating 

in a multiplicity of systems and formats be made compatible in 

post-production for image processing. The necessary transforms may 

include temporal, spatial, resolution, colorimetry, etc. 

Transformation – Refers to geometric motion or change to an object’s 

orientation (i.e., translate, rotate, scale). 

Transient Gain Distortions – Transient gain distortion, also referred to as 

transient nonlinearity, is present when abrupt changes in APL temporarily 

affect signal amplitudes. The error is defined as the maximum transient 

departure in amplitude of a sync pulse from the amplitude it had before the 

change to the amplitude after the change. Measurement of transient gain 

distortions is done as an out-of-service test and should be checked for 

transitions of low-to-high APL and high-to-low APL. If the transient gain 

distortion only affects the sync pulse and then not so severely as to cause 

the sync to be unusable, then the viewable picture would not be affected. 

However if the sync pulse is affected, the rest of the picture is also normally 

affected; when transient gain distortions affect the picture, it appears as 

abnormal transient brightness effects. A test signal generator capable of 

producing a “bouncing” flat-field signal is used to test for transient gain 

distortions. A typical signal is shown below. The time between bounces 

(APL level changes) must be longer than the transient effects so that all 

the transient effects can be viewed before the next APL change occurs. 

IRE 

100 

80 

60 

40 

20 

0 

-40 

X Seconds 

Transient Nonlinearity – See the discussion on transient gain distortion. 

Transients – Signals which endure for a brief time. These may include 

overshoots, damped sinusoidal waves, etc., and, therefore, additional qualifying 

information is necessary. 

Transition – a) A change from one picture to another. Any mix, wipe, cut, 

non-additive mix, or introduction of a key. b) The moving of a fader arm or 

initiating an “auto transition” to accomplish any of the above effects. 

Transition Mode – Exclusively on the AVC series, an operator may choose 

automatic transitions that are not linear, that is that do not have the same 

rate as they progress. One may choose logarithmic, starting rapidly and 

finishing slowly; exponential, starting slowly and finishing rapidly; or sinusoidal, 

starting and finishing slowly but fast in the middle. 


X Seconds 

X Seconds 

10% APL 90% APL 10% APL 

Transition Rate – The duration of an automatic transition from one bus to 

the other is defined as the transition rate. The transition rate may be 

applied to a mix, wipe or E key, and is operator-selectable from 0 to 9.9 

seconds. 

Translate – To move an object without rotation in a straight line, either left 

or right, up or down, in or out, or any combination thereof, in three-dimensional 

space. 

Translating – The process for converting one color difference signal format 

to another. See the discussion on Matrix. 

Translational Extrusion – In translational extrusion, the silhouette follows 

a linear path. 

Translator – Broadcast station that rebroadcasts signals of other stations 

without originating its own programming. 

Transmission – a) The electrical transfer of a signal, message, or other 

form of intelligence from one location to another. b) The transfer of a video 

waveform from point to point by conductive cable or fiber. 

Transmission Aperture – A number used to compare the amounts of 

light passed through optical systems, such as camera lenses. Transmission 

aperture takes into consideration both the f-stop (geometric aperture) and 

the amount of light absorbed or reflected in the optical system. 

Transmission Standard – A standard to be used for transmitting signals 

to the home, not necessarily for producing them. The scanning structure of 

NTSC is identical for both production and transmission, but this need not 

be the case in ATV schemes. For example, an HDEP standard of 1125 

scanning lines might be used with a transmission standard of 1050 lines. 

Standards converters translate one standard into another. 

Transparency – a) Defines the amount of incident light that passes 

through a surface. Both ambient and diffuse light falling on a transparent 

polygon are transmitted through the polygon, but highlights are not. In 

paint systems, a similar property called “opacity” determines how opaque 

the paint loaded on the artist’s brush really is. b) Full-color mode makes it 

possible for a polygon to be translucent by assigning a transparency 

between 0% and 100% (0 = opaque, 100 = fully transparent). To implement 

transparency, we assume that a semi-transparent polygon covers 

only a fraction of each pixel which it covers. The final pixel’s value is a 

blend of the background and the polygon. Again, color maps have too few 

colors to do this. c) A feature in Indeo Video interactive codec in which 

software emulates chroma keying, allowing foreground video objects to be 

composited dynamically over a different background, a bitmap or possibly 

even another video. See Chroma Key. 

Transparency Frame – In the transparency technique first-frame analysis, 

the first frame of the video file. It contains no video data, but merely 

supplies the color or range of colors to be rendered as transparent. See 

First-Frame Analysis, Transparency. 

Transponder – Satellite transmitter/receiver that picks up signals transmitted 

from earth, translates them into new frequencies and amplifies them 

before retransmitting them back to ground. 

Transport – Term used for any machine using motors usually meaning a 

VTR, DTR, or video disk.

Transport Stream – A multiplex of several program streams that are carried 

in packets. Demultiplexing is achieved by different packet IDs (PIDs). 

See PSI, PAT, PMT, and PCR. 

Transport Stream Packet Header – The leading fields in a transport 

stream packet up to and including the continuity_counter field. 

transport_stream_id – A unique identifier of a TS within an original 

network. 

Transportation – The delivery in physical form of a program prepared for 

distribution. The completed program may be in the form of a tape recording, 

a film print, an optical disc, etc. 

Transverse – Across the width of the tape. 

Trellis Coding – Trellis coding is a source coding technique that has 

resulted in numerous publications and some very effective source codes. 

Unfortunately, the computational burden of these codes is tremendous and 

grows exponentially with the encoding rate. A trellis is a transition diagram, 

that takes time into account, for a finite state machine. Populating a trellis 

means specifying output symbols for each branch, specifying an initial 

state yields a set of allowable output sequences. A trellis coder is defined 

as follows: given a trellis populated with symbols from an output alphabet 

and an input sequence x of length n, a trellis coder outputs the sequence 

of bits corresponding to the output sequence x that maximizes the SNR of 

the encoding. 

Trellis Diagram – The time sequence of the bits (DVB-S) is predefined by 

convolutional coding and, like the state diagram of a finite automaton, is 

represented as a trellis diagram. 

Triad – Three colored phosphor dots on the faceplate of a tri-color CRT. 

Some tri-color CRTs use vertical stripes of different color phosphors or vertically 

oriented oblong dots. These dots or stripes are the ultimate determinants 

of maximum horizontal resolution. When the dots are round, they are 

also the maximum determinants of vertical resolution. The finer the dot 

pitch, the higher the resolution, since it is not possible to reduce the size of 

a black-and-white pixel below the size of one triad. Triad spacing also cannot 

be optimized for all numbers of scanning lines. Thus, a tube optimized 

for 1125 scanning lines will not yield optimum performance with a signal 

of 1050 scanning lines, or vice versa. Neither black-and-white CRTs nor 

the three single-color CRTs used in most projection TV sets suffer from 

these limitations as their faceplates are uniformly covered with a layer of 

phosphor; resolution is ultimately determined by the size of the electron 

beam and the projection optics. Picture tubes with striped apertures can 

deal effectively with multiple scanning rates, but still restrict horizontal resolution 

to the width of three stripes. 

Trigger – Slang term for the button on the video camera or camcorder 

that, when depressed, sends a signal to the videotape recorder to begin or 

stop recording. 

Trim – a) To add or subtract from and EDK time or switcher sequence 

duration. b) To perform some minor adjustment or X, Y, or Z axis on ADO or 

switcher effects. 

Trim Curves – Curves that define holes on or parts cut away from a surface; 

they are linked to the surface. 



Tripod – A three-legged video camera or camcorder mounting device that 

provides steady, tireless service. 

Tripod Dolly – A combination tripod and dolly. 

Tri-Scan – Term for the technique of sub-sampling each NTSC pixel into 

three sub-pixels used in the HD-NTSC ATV scheme. 

Tristimulus Values – a) Amounts of the three reference color stimuli in a 

given trichromatic system required to match the color of the stimulus considered. 

Note: In the CIE standard colorimetric systems, the tristimulus values 

are represented by the symbols X, Y, Z and X~, Yn, Zn. b) The amounts 

of the three reference or matching stimuli required to give a match with 

the light considered in a given trichromatic system. 

Troubleshoot – To seek the cause of a malfunction or erroneous program 

behavior in order to remove the malfunction. 

Troubleshooting Tree – Flow diagram consisting of tests and measurements 

used to diagnose and locate faults in a product. 

TRS – See Timing Reference Signals. 

TRS-ID – See Timing Reference Signal Identification. 

TRT (Total Running Time) – Usually expressed in hr:min:sec:frames or 

min:sec:frames. 

Truck – Term used for a type of camera movement where the camera 

actually moves left to right (or vice versa) across a scene. 

True Color – An image in which each pixel is individually represented 

using three color components, such as RGB or Y'CbCr. The color components 

of each pixel may be independently modified. 

True NTSC – A concept of an idealized NTSC that is identical throughout 

the NTSC world. Unfortunately, the NTSC standards are loose enough to 

allow various sub-channel schemes, though these schemes may be mutually 

incompatible. It is possible that some years from now an NTSC television 

set designed for one form of enhanced NTSC may be receiver-incompatible 

with transmission of another form of enhanced NTSC. 

Truncation – a) Deletion of lower significant bits on a digital system. 

Usually results in digital noise. b) Shortening the word length of a sample 

or coefficient by removing low-order bits. c) To terminate a computational 

process in accordance with some rule. For example, when digital mixing or 

other operations create extra bits per sample (such as 16 bits from multiplication 

of two 8-bit samples), it is usually necessary at some point to 

truncate (or round) the result back to the original bit length, and to apply 

some rule to the correction of the part retained. Various rules have been 

introduced for how this may be done with digital video images for the least 

noticeable result. 

TS – Transport Stream. 

TS Header – The first four bytes of each TS packet contain the data (PID) 

required for the demultiplexer in addition to the sync byte (0x47). These 

bytes are not encoded. 

TSB – Telecommunication Standardization Bureau. 

TSDT – Transport Stream Description Table. 

T-STD (Transport Stream System Target Decoder) – A decoder having 

a certain amount of buffer memory assumed to be present by an encoder. 




TTL (Transistor Transistor Logic) – Family of digital integrated circuits 

that have bipolar transistor inputs and outputs. 

TTY – Teletype. 

Tuner – An element of a television set that allows the user to select specific 

signals and frequencies (channels) to be shown on the picture tube 

and played through the speaker. 

TV Lines – Measure of resolution. A TV line is either black or white, so two 

TV lines (one black and one white) form one cycle of spatial resolution. TV 

lines are often confused with scanning lines. For vertical resolution, scanning 

lines multiplied by the Kell factor (and, when appropriate, by the interlace 

coefficient) yield TV lines. 

TWAIN – A scan-control program that pops up within an application to 

allow for the adjustment of brightness, contrast, etc. 

Twinkle – A sparkling effect that can be caused by sub-sampling, since 

the finest detail is transmitted at a rate below the flicker frequency (and 

sometimes even below the fusion frequency). 

Twitter – A flickering of fine horizontal edges caused by interlaced scanning. 

A fine line appearing in only one field is presented below the flicker 

frequency; therefore, it flickers. Twitter is eliminated in line doubling 

schemes that change from interlaced to progressive scanning, as most of 

the IDTV schemes do. Interestingly, twitter was much less of a problem in 


the early days of NTSC, than it is today, because early cameras and displays 

didn’t have sufficient detail to confine an edge to one scanning line. 

Two-Wire Interconnect – Interconnect consisting of two wires. One wire 

transports the luminance signal while the other transports the multiplexed 

chrominance signals. This system allows efficient dubbing between 

recorders because recorders normally record the luminance on one tape 

channel and the two color difference signal on a single channel. To record 

the two-color difference signals on a single channel, the two-color difference 

signals are compressed and then multiplexed together. Transferring the 

two video signals between tape recorders in the two-wire format prevents 

the two tape recorders from having to do additional signal processing. 

Two’s Complement Numbers – Numbering system commonly used to 

represent both positive and negative numbers. The positive numbers in 

two’s complement representation are identical to the positive numbers in 

standard binary. However, the Two’s complement representation of a negative 

number is the complement of the absolute binary value plus 1. Note 

that the eighth or most significant bit indicates the sign: 0 = plus, 1 = 

minus. 

Two-Track Recording – On 1/4" wide tape, the arrangement by which 

only two channels of sound may be recorded, either as a stereo pair in one 

direction or as separate monophonic tracks (usually in opposite directions).

U 

U – The B-Y signal after a weighting factor of 0.493 has been applied. The 

weighting is necessary to reduce peak modulation in the composite signal. 

UART (Universal Asynchronous Receiver Transmitter) – a) A serial to 

parallel and parallel to serial converter. b) A serial interface which serializes 

parallel data and inserts start, stop, and parity bits. It may also change 

a serial data stream into parallel bits or bytes and separate start, stop, and 

parity bits. 

US – Upstream Channel. 

UDF Bridge – A “bridge” ties several specifications together, In DVD, 

bridges are drawn to UDF, MPEG-2, and Dolby C-3. 

UDP (User Datagram Protocol) – A transport protocol in the Internet 

suite of protocols. UDP, like TCP, uses IP for delivery; however, unlike TCP, 

UDP provides for exchange of datagrams without acknowledgements or 

guaranteed delivery. 

UDTV (Ultra Definition TV) – UDTV with a 2,000-line (or more) display is 

being contemplated in Japan. The ideas underline the importance of scalability 

in future broadcast technology, and suggest that rigid standards will 

only have a limited life span. The MPEG-2 syntax would support the level of 

resolution found in UDTV, but actual tests of conformance at this resolution 

are not planned so far. In addition, a question of interoperability with other 

digital TV services will also have to be investigated. 

UHF – See Ultra High Frequency. 

UI – Unit Interval. 

Ultimate Tensile Strength – The force per unit cross-sectional area 

required to break a tape or length of base film, usually given in pounds per 

square inch (psi). Ultimate tensile strength is also quoted in terms of 

pounds per tape sample of given width and base thickness. 

Ultra High Frequency (UHF) – The frequency band (300 MHz to 

3,000 MHz). In television, UHF refers to a subset of that band, the range 

from 470 MHz to 890 MHz, once allocated to TV channels 14 through 83. 

Demands of other transmission services (such as police radios) have eaten 

into both the lower and the upper reaches of the UHF TV allocations. 

Taboos eliminate still more channels. Nevertheless, the UHF TV band is 

seen by many ATV proponents as the most likely place to situate receiverincompatible 

and augmentation ATV channels. 

Ultra SCSI (Ultra Wide SCSI) – Currently, the newest and best kind of 

drives for DV. New technology makes these drives better than AV optimized. 

Unbalanced Line – A line using two conductors to carry a signal, where 

one of the conductors is connected to ground. 

Underscan – Most televisions use overscanning, resulting in some of the 

video being lost beyond the edges of the screen. Underscanning modifies 

the video timing so that the entire video signal appears in a rectangle centered 

on the television screen with a black border. The resolutions for 

square-pixel underscan and overscan images are: 

NTSC overscan: 640 x 480 PAL overscan: 768 x 576 

NTSC underscan: 512 x 384 PAL underscan: 640 x 480 



UNI (Ente Nazionale Italiano di Unificazione) – Italian standardization 

body. 

Unidirectional – a) A pickup pattern which is more sensitive to sounds 

arriving from one direction than from any other. b) Wire or group of wires 

in which data flows in only one direction. Each device connected to a unidirectional 

bus is either a transmitter, or a receiver, but not both. 

Unidirectional Mike – A microphone which picks up signals primarily 

from one direction and discriminates against or rejects sounds arriving 

from other directions. 

Unidirectional Prediction – A form of compression in which the codec 

uses information only from frames that have already been decompressed. 

Compare Bidirectional Prediction. 

Uniform B-Spline – A curve that rarely passes through its control point. 

Usually very smooth and may be controlled locally without generating 

breakpoints (cusps). 

Uniformity – The extent to which the output remains free from variations 

in amplitude. Uniformity is usually specified in terms of the positive and 

negative deviations from the average output within a roll, and in terms of 

the deviations in the average outputs between one roll and another. 

Uniformity is normally quoted in percent or dB. 

Uni-Key – A dedicated ISO keyer on the Vista switcher for use of a digital 

effects unit or character generator. 

Universal Label (UL) – A mechanism defined in SMPTE 298M used to 

identify the type and encoding of data within a general purpose data 

stream or file. 

Universal Label Code – A code in the Universal Label created by concatenating 

the first two sub-identifiers for ISO and ORG. For the SMPTE UL, 

this field must be “2B” in hexadecimal (hex) notation (0x2B). 

Universal Label Data Key – The 16-byte Universal Label that identifies 

the data being represented. Equivalent to “descriptor” in the terminology of 

MPEG-7 requirements. 

Universal Label Header – The first three octets of a Universal Label containing 

information unique to the label. 

Unmodulated – When used to describe television test signals, this term 

refers to pulses and pedestals which do not have high-frequency chrominance 

information added to them. 

Unmount – To make a file system that is accessible from a specific directory 

on a workstation temporarily inaccessible. 

UNO-CDR – Universal Networked Object-Common Data Representative. 

UNO-RPC – Universal Networked Object-Remote Procedure Call. 

Up-Down Buttons – The replacement for potentiometers on AVC switchers. 

These allow three speeds of adjustment and may be assigned to any 

module. They offer a more compact package, and eliminate the problem of 

recalling an event that has different settings than the physical pots may 

have. 




Upgrade – Hardware that you add to the basic hardware that increases 

performance, such as additional memory (SIMMs) or faster graphics 

boards. 

Uplink – The carrier used by Earth stations to transmit information to a 

satellite. 

Upscaling – The process of creating extra data from an incoming video 

stream to increase the image size by interpolating or replicating data 

before placing it into memory. 

Upstream – A term describing the precedence of an effect or key. The 

“stream” of video through a switcher allows multiple layers of effects to be 

accomplished, with each successive layer appearing on top of the previous 

one. A module or effect whose video priority is lower, or underneath subsequent 

modules or effects is said to be upstream. 


USB – Universal Serial Bus. 

User Bits – Bits in a time code sequence that are user definable; i.e., to 

give the sequence a name or to add the date, etc. 

User Data – All data above the channel layer. That includes video, audio, 

systems packet overhead, sub-pictures, navigation data, DSI packets, and 

file management data. The DVD reference data rate is specified as 

11.08 Mb/s. 

User ID – A number that uniquely identifies a user to the system. 

UTC (Universal Time, Coordinated) – Greenwich meantime. 

Utilities – Auxiliary functions or operations.

V 

V – The R-Y signal after a weighting factor of 0.877 has been applied. The 

weighting is necessary to reduce peak modulation in the composite signal. 

VADIS – Video-Audio Digital Interactive System. 

Valid Signal – A video signal that will remain legal when translated to any 

other format. A valid signal is always legal, but a legal signal is not necessarily 

valid. Signals that are not valid will be processed without problems in 

their current format, but problems may be encountered if the signal is 

translated to a new format. 

Value – a) The amount of black mixed into pigment. b) The instance of 

information described by the UL Data Key. 

Vaporware – Software or hardware that is talked about, but may never 

actually appear. 

Variable Bit Rate (VBR) – Operation where the bit rate changes with time 

during the decoding of a compressed bit stream. Although variable bit rate 

is acceptable for plain linear playback, one important consideration not to 

use variable bit rate is that reasonably quick random access becomes 

nearly impossible. There is no table of contents or index in MPEG. The only 

tool the play back system has for approximating the correct byte position is 

the requested play back time stamp and the bit rate of the MPEG stream. 

MPEG streams do not encode their play back time. To approximate an 

intermediate position in a variable bit rate stream, the play back system 

must grope around near the end of the stream to calculate the playback 

time, and assume the stream is approximately constant bit rate. The groping 

around for the correct position can take several seconds. This is not 

appropriate for an interactive presentation or game. This groping around is, 

at least, annoying when trying to view a portion of a movie but it is not 

even possible for video streams because there are no time stamps (the 

SMPTE. time codes in video streams need not be continuous or unique). 

Audio streams are always fixed bit rate. 

Variable Length Coding – A reversible procedure for coding that assigns 

shorter code-words to frequent events and longer code-words to less frequent 

events. 

VAU (Video Access Unit) – One compressed picture in a program 

stream. 

VBI – See Vertical Blanking Interval. 

VBR – See Variable Bit Rate. 

VBV – See Video Buffering Verifier. 

VCI – Virtual Channel Identifier. 

VCR – Video Cassette Recorder. 

Vector – a) A vector is a directed edge. That is, given points A and B, the 

line that connects A and B becomes a vector if we specify its direction 

(i.e., which point is the start point). The vector that goes from A to B is not 

the same vector as the one that goes from B to A. Vectors exist in 3D; they 

connect points in 3D space. b) An entity that possesses the attributes of a 

norm and a direction. It can be defined in 3D space by two points, one representing 

the origin and the other, the extremity. c) A motion compensation 



parameter that tells a decoder how to shift part of a previous picture to 

more closely approximate the current picture. 

Vector Interrupt – See Interrupt Vectoring. 

Vector Quantization – a) A compression technique in which groups of 

picture samples (the vectors) are represented by predetermined codes. 

Encoding is done by matching the vectors with code words in a code book, 

and the addresses of the code book are then sent to the decoder. The picture 

quality depends widely on suitable code books and the match algorithms. 

b) A technique where a vector (usually a square of samples of one 

color component of an image) are represented by a single number. This 

number is an index into a code book by which the vector is reconstructed. 

The major issues are finding (calculating) a robust code book and how to 

choose the “best” code book entry for a given input vector. 

Vectorscope – A specialized oscilloscope which demodulates the video 

signal and presents a display of R-Y versus B-Y. The angle and magnitude 

of the displayed vectors are respectively related to hue (R-Y) and saturation 

(B-Y). The vectorscope allows for the accurate evaluation of the chrominance 

portion of the signal. Some vectorscopes can select either 75% or 

100% color bars. Make sure the correct mode is selected or the chroma 

gain can be misadjusted. 

Vertical Alias – An alias caused by unfiltered sampling in the vertical 

direction by scanning lines. Vertical aliasing is frequently noticed when 

reading vertical resolution on a resolution chart. The wedge-like lines 

become finer and finer until they reach the limit of the vertical resolution of 

the system, but then they may appear to widen or to change position. This 

is caused by lines on the chart sometimes falling between scanning lines 

and sometimes on them. In a properly filtered television system, detail finer 

than the vertical resolution of the system would be a smooth blur. 

Vertical Blanking – a) Refers to the blanking signals which occur at the 

end of each field. b) The time during which the electron beams of an output 

device are turned off and positioned to the upper left edge of the display. 

c) A video synchronizing signal that defines the border or black area 

at the top and bottom of the display and, in a CRT, hides (blanks out) the 

electron beam’s retrace path from the bottom to the top of the display. 

Vertical Blanking Interval (VBI) – a) That part of the video signal where 

the voltage level is at 0 IRE and the electron beam sweeps back from the 

bottom to the top of the screen. b) A period during which the electron 

beam in a display is blanked out while it travels from the bottom of the 

screen to the top. It is the black bar that becomes visible when the vertical 

hold on a television set is not correctly adjusted. The VBI is usually measured 

in scanning lines. When the VBI is subtracted from the total number of 

scanning lines, the result is the number of active scanning lines. In NTSC, 

the VBI has a duration of 20.5 or 21 lines (depending on the field), of 

which nine lines are devoted to the vertical synchronizing signal that lets 

television sets know when a field has been completed. The remaining lines 

have long been used to carry auxiliary information, such as test and reference 

signals, time code, and encoded text, such as captions for the hearing 

impaired. Some ATV schemes propose expanding the VBI to accommo- 




date widescreen images by the letterbox technique; some propose using it 

as a sub-channel for additional picture information. See also Blanking. 

Vertical Drive – A pulse at field rate used in TV cameras. Its leading edge 

is coincident with the leading edge of the vertical blanking pulse and its 

duration may be 10.5 lines. 

Vertical Interval – a) The synchronizing information which appears 

between fields. The vertical interval signals the picture monitor to go back 

to the top of the screen to begin another vertical scan. b) The portion of 

the video signal that occurs between the end of one field and the beginning 

of the next. During this time, the electron beams in the cameras and 

monitors are turned off so they can return from the bottom of the screen to 

the top to begin another scan. 

Vertical Interval Reference (VIR) – A signal used as a reference for 

amplitude and phase characteristics of a color television program (FCC 

assigned to line 19). 

Vertical Interval Switching – Randomly switching from one video signal 

to another will often result in a jump in the picture upon playback. The 

problem is compounded when the tape is copied. To avoid this problem, 

switching is best performed on synchronized signals during the vertical 

blanking retrace period, known also as the vertical interval. This allows 

complete replacement of one whole frame by a second whole frame resulting 

in a very smooth on-screen switch. 

Vertical Interval Test Signal (VITS) – a) Test signal that is inserted on 

one line in the vertical interval. These signals are used to perform inservice 

tests. b) Signals transmitted on lines 17 and 18 in both fields for 

evaluation of system performance. Usually color bars, multi-burst, modulated 

stairstep, and composite are transmitted. 

Vertical Interval Time Code (VITC) – a) Time-code information stored 

on specific scan lines during the vertical blanking interval. A popular 

method for recording time code onto videotape. A time-code address for 

each video frame is inserted in the vertical interval (the vertical blanking 

retrace period) of the video signal, where it is invisible on-screen yet easily 

retrieved, even when a helical scanning VCR is in pause mode. The most 

common form of VITC is SMPTE-VITC. The Thumbs Up editor supports 

SMPTE-VITC (as well as RC time code). b) Time code stored in the vertical 

interval of the video signal. Has the advantage of being readable by a VTR 

in still or jog. Multiple lines of VITC can be added to the signal allowing the 

encoding of more information than can be stored in normal LTC. 

Vertical Resolution – The amount of detail that can be perceived in the 

vertical direction; the maximum number of alternating white and black horizontal 

lines that can be counted from the top of the picture to the bottom. 

It is not the same as the number of scanning lines. It is the number of 

scanning lines minus the VBI times the Kell factor (and, where appropriate, 

times the interlace coefficient). 

Vertical Retrace – The return of the electron beam from the bottom to 

the top of the raster after completion of each field. 

Vertical Serrations – A vertical synchronizing pulse contains a number of 

small notches called vertical serrations. 

Vertical Size – Vertical size (from the top to the bottom of the screen) can 

be reduced making objects appear short and squat or increased making 


objects appear tall and thin. Vertical size which is not unity is distortion. 

The control comes from analog video where a control was made available 

to compensate for unstable sweep circuitry. Vertical size in digital video is 

controlled by line replication or line interpolation. 

Vertical Sync Pulse – The synchronizing pulse at the end of each field 

which signals the start of vertical retrace. 

Vertical-Temporal Pre-Filtering – Filtering at the camera or transmission 

end to eliminate vertical and temporal aliases. When a high line rate, 

progressively scanned camera is pre-filtered to NTSC rates, the resulting 

image is not only alias-free but can also be used by an advanced receiver 

to provide vertical and temporal resolution beyond that normally found in 

NTSC. The Kell factor of such a system can be close to one. 

Vertical-Temporal Sampling – Sampling that occurs in every television 

signal due to individual frames (which sample in time) and individual scanning 

lines (which sample in the vertical direction). This sampling can cause 

aliases unless properly pre-filtered. 

Very High Frequency (VHF) – The range from 30 MHz to 300 MHz, within 

which are found U.S. television channels 2 through 13. VHF television 

channels seem about as filled as current technology allows, which is why 

much ATV debate centers on channel allocations in UHF and/or SHF. Some 

ATV proponents, however, feel that a robust, low-level digital augmentation 

channel might be squeezed into adjacent VHF channels without interference, 

perhaps even two augmentation channels per adjacent channel. If 

that can be done, every U.S. television broadcaster would be able to have 

an ATV augmentation channel. 

Very Large Scale Integration (VLSI) – Technology by which hundreds of 

thousands of semiconductor devices are fabricated on a single chip. 

Vestigial Sideband – The vestige of a sideband left after filtering. 

Vestigial Sideband Transmission – A system of transmission wherein 

the sideband on one side of the carrier is transmitted only in part. 

VESA Local Bus (VL) – In late 1992, VESA (Video Electronics Standard 

Association) completed the specification for a local bus expansion for PCs. 

One of the most important things about VL Bus design is that it specified 

connector pinout. The VL Bus, considered a high-speed bus with a maximum 

speed of 66 MHz, was designed with the Intel 486 in mind. The 32bit 

bus, which includes unbuffered control, data, and address signals is 

compatible with 16-bit operations. One drawback of the VL Bus implementation 

is that the more expansion connectors used, the slower the operation 

of the bus. For example, using two connectors, the highest recommended 

speed is 40 MHz. When multiple bus slots are desired, multiple VL Bus 

subsystems can be built into a single PC. 

VHF – See Very High Frequency. 

VHS (Video Home System) – Consumer videocassette record/playback 

tape format using half-inch wide magnetic tape. The most common home 

VCR format in the U.S. 

VHS Hi-Fi – An improved stereo audio recording/playback system found on 

some camcorders and VCRs. Because the audio tracks are mixed and 

recorded with the video signal, audio only dubbing of these tracks is not 

possible.

VHS-C (VHS-Compact) – A miniature version of the VHS tape format 

using smaller cassettes that may also be played on standard VHS machines 

by using an adapter cartridge. 

Video – a) A term pertaining to the bandwidth and spectrum position of 

the signal which results from television scanning and which is used to 

reproduce a picture. b) A complex and sophisticated electronic signal 

which, when properly processed by a television receiver can be used to 

provide full-color pictures. c) An electrical signal used to carry visual information. 

Composite video includes sync and blanking signals. Non-composite 

video does not include sync. 

Video Band – The frequency band used to transmit a composite video 

signal. 

Video Bandwidth – The range between the lowest and highest signal frequency 

of a given video signal. In general, the higher the video bandwidth, 

the better the quality of the picture. Video bandwidths used in studio work 

typically vary between 3 and 12 MHz. Consumer VCRs are generally capable 

of 3 to 5.5 MHz. 

Video Buffering Verifier (VBV) – A hypothetical decoder that is conceptually 

connected to the output of the encoder. Its purpose is to provide a 

constraint on the variability of the data rate that an encoder or editing 

process may produce (ISO13818-2 Annex C). This postulates the existence 

of a buffer in the receiver and a prediction mechanism in the encoder. This 

mechanism will predict the buffer fullness due to the constant fill from the 

constant bit rate (CBR) stream and the variable empty due to the variation 

in decoder bit demand. This latter factor can be controlled at the encoder 

by varying the quality of the encoding process (quantization factor, mainly). 

Video Camera – A camera which contains an electronic image sensor 

rather than photographic film. The lens focuses an image on an electronic 

tube or CCD chip. A camera has electronic circuitry which generates color 

and sync pulses. Most portable consumer cameras are equipped with a full 

complement of audio circuitry, e.g., microphone, audio amplifier, and additional 

audio electronics. In order to obtain better quality images, a professional 

camera has three tubes or a triple CCD system, one for each basic 

color. Most professional cameras have a genlock input, which allows the 

camera to be synchronized to an external source. Some cameras also 

include basic character generators for titling purposes. 

Video Capture – The process of converting analog video to digital video. 

Video Compression (M-JPEG and MPEG) – Both these standards use 

special hardware and software to store video directly on a hard drive. Video 

compression is done in various ratios (e.g., 10:1, 5:1). The higher the ratio, 

the more video can be stored per meg, and conversely the lower the compression, 

the higher the video quality. See CODEC. 

Video Deck – An electronic component consisting of a video/audio head 

assembly, a system of transporting a videotape past the heads, and operational 

controls, used for recording and playback of videotape. 

Video Editing – A procedure for combining selected portions of video 

footage in order to create a new, combined version. A variety of editing 

consoles are available. During video editing, special effects such as wipes, 

dissolves, inserts, etc. can be added. Professional editing is done using 

time code recorded on every frame of the magnetic tape allowing single 

frame accuracy. Audio editing is often carried out simultaneously with video 



editing. The Thumbs Up offers a versatile solution for most editing 

applications. 

Video Enhancer – A general term used to describe a device used to correct 

video image problems. 

Video Fill – A video signal from a primary input or external input used to 

fill the hole made by a key signal. 

Video for Windows – Microsoft’s older multimedia environment for the 

Windows operating system. You use Video for Windows by installing several 

drivers and libraries in your Windows directories. 

Video Gain – Expressed on the waveform monitor by the voltage level of 

the whitest whites in the active picture signal. Defined as the range of 

light-to-dark values of the image which are proportional to the voltage difference 

between the black and white voltage levels of the video signal. 

Video gain is related to the contrast of the video image. 

Video Index – A data packet for carrying picture and program related 

source data in conjunction with the video signal. There are three classes of 

data to be included: Class 1 contains information that is required to know 

how to use the signal; Class 2 contains heritage information for better 

usage of the signal; Class 3 contains other information. The SMPTE 

Working Group on Video Index (P18.41) is developing the proposed recommended 

practice. 

Video Manager – Top-level menu linking multiple tiles from a common 

point. 

Video Mixer – A device used to combine video signals from two or more 

sources. Inputs are synchronized, then mixed along with various special 

effects patterns and shapes. A video mixer usually generates sync signals 

allowing genlocking of additional video sources to the first source. The 

Digital Video Mixer is capable of handling up to four video inputs. 

Video Noise – Poor quality video signal within the standard video signal. 

Also called Snow. 

Video On Demand (VOD) – True VOD implies completely random access 

to video. Users may access the video they want and when they want it. 

This is, in other words, synonymous with dialing a video from a data bank 

and not having to go to a video rental store. In contrast, near-VOD often 

implies a set of TV channels showing the same movie, but with shifted 

starting times. Owing to the demanding nature of the application in sense 

of data capacity, compression techniques are needed. The bit rates applied 

in some VOD projects are comparable to that of CD-based video, which 

provides a reasonable picture quality and makes delivery possible by 

means of ADSL over copper cables of a length commonly found in telephony. 

The Asymmetric Digital Subscriber Line (ADSL) technology is typically 

used on distances up to about 5 to 6 km at 2 Mbit/s. 

Video Path – The path that video takes through the switcher. 

Video Printer – A special device used to capture a single frame of video 

to create a hard-copy print. 

Video Processing Amplifier (Video Procamp) – A device that stabilizes 

the composite video signal, regenerates the synchronizing pulses, and can 

make other adjustments to the video signal. 




Video Program System (VPS) – Information is included in the video signal 

to automatically control VCRs. 

Video Projector – A display device which projects a video or computer 

image onto a large screen. The classic video projector has three primary 

color video tubes which converge on-screen to create the full-color image. 

Single tube projectors eliminate convergence problems but compared to 

three tube systems, project a relatively lower quality image. 

Video Sequence – a) A series of one or more pictures. b) In MPEG, the 

total, coded bit stream (the ES at system level). c) A video sequence is 

represented by a sequence header, one or more groups of pictures, and an 

end_of_sequence code in the data stream. 

Video Signal – The electrical signal produced by video components. 

Video Streaming – New technologies used to send video information over 

the internet. Rather than wait for the whole file to download, the video 

streaming technology lets the clip begin playing after only a few seconds. 

Video Switcher – A device that allows transitions between different video 

pictures. May contain special effects generators. Also called production 

switcher or switcher. 

Video Tape Recorder (VTR) – A device developed in Germany which permits 

audio and video signals to be recorded on magnetic tape. 

Video Time Base Error – Where all components of the video signal jitter 

(change in time) together in relation to another video signal. 

Video_TS – UDF filename used for the video directory on the disc volume. 

Files under this directory name contain pointers to the sectors on the disc 

that hold the program streams. 

Video Units – See IRE Units. 

Video Wall – A large array of several monitors, placed close to each other 

in the shape of a video screen or “wall.” Each monitor is fed only part of 

the original video image by using a video-wall generating unit. This device 

is a digitally-based processor which converts the original analog video signal 

to digital, rescans, resamples, and generates several individual analog 

video outputs for driving each array monitor separately. When viewed from 

a distance, the effect can be very dramatic. 

Video, Composite Signal – The electric signal that represents complete 

color picture information and all sync signals. Includes blanking and the 

deflection sync signals to which the color sync signal is added in the proper 

time relationship. 

Video, Peak – See White Clip, White Peak, White, Reference. 

Videocassette – A length of videotape wound around two reels and 

enclosed in a plastic shell. 

Videocassette Recorder (VCR) – An electronic component consisting of 

a tuner, an R modulator, and a video deck used for recording and playback 

of a videocassette. 

Videography – Operation of a video camera or camcorder in video 

production. 

Video-in-Black – A term used to describe a condition as seen on the 

waveform monitor when the black peaks extend through reference black 

level. 


Videotape – Oxide-coated plastic-based magnetic tape used for recording 

video and audio signals. 

Videotext – Two-way interactive service that uses either two-way cable or 

telephone lines to connect a central computer to a television screen. 

View Direction – This direction also requires three numbers, and specifies 

the direction in which the viewer is looking, and which direction is up. 

Viewfinder – Camera feature that allows the operator to view the image 

as it is being recorded. Video viewfinders typically depict the recorded 

image in black-and-white. 

Viewing Distance – Distance between image and a viewer’s eyes. In television, 

the distance is usually measured in picture heights. In film it is 

sometimes measured in picture widths. As a viewer gets closer to a television 

set from a long distance, the amount of detail perceptible on the 

screen continually increases until, at a certain point, it falls off rapidly. At 

that point, scanning line or triad visibility is interfering with the viewer’s 

ability to see all of the detail in the picture, sort of not being able to see 

the forest for the trees. The finer the triad or scanning structure, the closer 

to the screen this point can be (in picture heights). Therefore, high-definition 

screens allow either closer viewing for the same size screen or larger 

screens for the same physical viewing distance (not in picture heights). 

When the effects of scanning lines and triads are reduced, other artifacts 

(such as temporal alias of panning called strobing) may become more obvious. 

From far enough away, it is impossible to tell high-definition resolution 

from NTSC resolution. 

Viewpoint – Viewpoint defines the location of the viewer’s eye in the 3D 

world, as a (x, y, z) triplet of numbers. To define what is finally seen, the 

“view direction” must also be known. 

Viewport – A rectangular subregion of the video image that is displayed 

using local decode. See Local Decode. 

VIR – See Vertical Interval Reference. 

Visible Scanning Lines – Normally considered a defect that affects perception 

of fine vertical detail. Scanning line visibility can also have an 

apparent sharpness increasing effect, however. See also Sharpness and 

Viewing Distance. 

Visible Subcarrier – The most basic form of cross-luminance. 

VISION 1250 – The organization, headquartered in Brussels, investigates 

the ways of developing European widescreen production and seeks to contribute 

to the deployment of digital and widescreen broadcasting and high 

definition video production. Specifically, the organization helps European 

producers in the making of programs through provision of technical 

expertise. 

VISTA (Visual System Transmission Algorithm) – The NYIT ATV 

scheme. VISTA is based on the inability of the human visual system to perceive 

high temporal and high spatial resolution simultaneously. It combines 

low frame rate, high line rate information with normal frame rate, normal 

line rate information to create a channel-compatible, receiver-compatible 

signal plus a 3 MHz augmentation channel. Aspect ratio accommodation 

has been suggested by blanking adjustment, squeeze, and shoot and protect 

techniques. In spite of the relatively small size of NYIT’s research cen-

ter, VISTA was one of the first ATV schemes to actually be implemented in 

hardware. 

Visual Acuity – The amount of detail perceptible by the human visual system. 

It depends on many factors, including brightness, color, orientation, 

and contract. Optimum viewing distance depends upon visual acuity. 

VITC – See Vertical Interval Time Code. 

Viterbi Decoding – Viterbi decoding makes use of the predefined time 

sequence of the bits through convolutional coding (DVB-S). Thanks to a 

series of logic decisions, the most probable correct way is searched for 

through the trellis diagram and incorrectly transmitted bits are corrected. 

VITS – See Vertical Interval Test Signal. 

VITS Inserter – Device that produces a test signal in the video in the vertical 

interval so as not to be visible to the home viewer but allows the 

broadcasters to test signal quality during transmission. 

VL – See VESA Local Bus. 

VLC – See Variable Length Coding. 

VLSI – See Very Large Scale Integration. 

VM (Video Verification Mode) – The set of video coding algorithms that 

precedes the actual MPEG-4 video coding specification. 

VOB (Video Object) – Usually a group of pictures. 

VOD (Video On Demand) – A system in which television programs or 

movies are transmitted to a single consumer, and then, only when 

requested. 

Volatile Memory – Memory devices whose stored data is lost when power 

is removed. RAMs can be made to appear nonvolatile by providing them 

with back-up power sources. 



Volume Unit (VU) Meter – A device used for measuring the intensity of 

an audio signal. 

VP – Virtual Path. 

VPE – Virtual Path Entity. 

VPI – Virtual Path Identifier. 

VPME – Virtual Path Multiplexing Entity. 

VPS – See Video Program System. 

VPU (Video Presentation Unit) – A picture. 

VSAT – Very Small Aperture Terminal. 

VSB (Vestigial Sideband Modulation) – 8 VSB in ATSC system implies 

eight discrete amplitude levels. 

VSB-AM – See AM-VSB. 

VSYNC – See the definition of Sync. 

VTR – See Video Tape Recorder. 

VTS (Video Tile Set) – A maximum of 10 files (in ISO 9660 structure) 

may comprise a video tile set. Each video tile set is preceded by a 

Management File. Each file in turn is limited to 1 Gbyte. 

VU (Volume Units) – A unit of measure for complex audio signals, usually 

in dB. Zero VU is referenced to 1 milliwatt of power into a 600-ohm load. 

The reference level of –20 dB in this program is 0 VU. 




W 

Wait State – When a system processor is reading or writing a memory or 

peripheral device that cannot respond fast enough, one or more time intervals 

(typically on the order of tens of nanoseconds each) are inserted during 

which the processor does nothing but wait for the slower device. While 

this has a detrimental effect on system throughput, it is unavoidable. The 

number of wait states can be reduced using techniques such as CPU-bus 

caches or write FIFOs. 

Walking-Ones – Memory test pattern in which a single one bit is shifted 

through each location of a memory filled with 0s. A walking-zero pattern is 

the converse. 

Warp – A special effect created by ADO to distort (twist) video pictures. 

Warping – This video effect is related to morphing except that a warp 

consists of transforming one video image into one of a completely different 

type. For example, a scorebox might be twisted on and off a screen containing 

video action. Some examples of video transitions include flyons/offs, 

slide ons/offs, zoom in or out to/from a pinpoint, shattered glass 

transition, pixelization where on screen explodes into thousands of pixels, 

and fades out at a controlled rate. 

Wave – A continuous fluctuation in the amplitude of a quantity with 

respect to time. A wave will have a propagation velocity dependent on the 

medium through which it travels. For example, in air at 70° F, the propagation 

velocity of a sound pressure wave is 1130 feet per second. 

WAVE – A file format (.wav) used to represent digitized sound. 

Wave Velocity – The propagation velocity of a wave. The time it takes for 

one point of a waveform to travel a certain distance. Wave velocity is 

dependent on the medium through which the wave travels and the temperature 

of the medium. 

Waveform – The shape of an electro-magnetic wave. A graphical representation 

of the relationship between voltage or current and time. 

Waveform Coding – Coding that aims to reconstruct the waveform of the 

original (audio) signal as close as possible, independently of the material. 

Includes linear PCM, differential PCM, adaptive differential PCM, sub-band 

coding, adaptive transform coding, etc. 

Waveform Monitor – A piece of test equipment which displays waveforms 

(analog video signals) at a horizontal and/or vertical rate. A specialized 

oscilloscope for evaluating television signals. a) DC Restore – A circuit 

used in picture monitors and waveform monitors to clamp on point of the 

waveform to a fixed DC level. Typically the tip of the sync pulse or the back 

porch. This ensures the display does not move vertically with changes in the 

signal amplitude or average picture level (APL). The DC Restore speed can 

be set to SLOW or FAST DC. SLOW allows hums and other low-frequency 

distortions to be seen. FAST DC removes the effects of hum from the display 

so it will not interfere with other measurements. b) AFC/Direct – This 

selection allows the waveform monitor’s horizontal sweep to trigger on 

each individual horizontal sync pulse (direct mode). This will allow the user 

to see any jitter that might be in the signal. Or the waveform monitor can 

trigger horizontally in the AFC mode which causes the horizontal sweep to 


trigger on the average value of the horizontal sync pulses. The AFC mode 

eliminates jitter. 

Wavelength – In tape recording, the shortest distance between two peaks 

of the same magnetic polarity; also, the ratio of tape speed to recorded 

frequency. 

Wavelet – a) A transform in the basic function that is not of fixed length 

but that grows longer as frequency is reduced. b) A compression algorithm 

that samples the video image based on frequency to encode the information. 

This creates a series of bands representing the data at various levels 

of visual detail. The image is restored by combining bands sampled at low, 

medium, and high frequencies. 

Waveshape – The shape traced by the varying amplitude of the wave. See 

Waveform. 

WD – Working Draft. 

Wear Product – Any material that is detached from the tape during use. 

The most common wear products are oxide particles or agglomerates, portions 

of coating and material detached from the edges of the tape. 

Weighting – a) A method of changing the distribution of the noise that is 

due to truncation by premultiplying values. b) In a sound level meter, this is 

a filter that creates a response that corresponds to the ear’s varying sensitivity 

at different loudness levels. A weighting corresponds to the sensitivity 

of the ear at lower listening levels. The filter design weights or is more 

sensitive in certain frequency bands than others. The goal is to obtain 

measurements that correlate well with the subjective perception of noise. 

Weighting, ANSI A – The A-curve is a side bandpass filter centered at 

2.5 kHz with ~20 dB attenuation at 100 Hz, and ~10 dB attenuation at 

20 kHz. Therefore, it tends to heavily roll off the low end, with a more modest 

effect on high frequencies. It is essentially the inverse of the 30-phon 

(or 30 dB-SPL) equal-loudness curve of a Fletcher-Munson. 

Weighting, ANSI B – The B-weighting curve is used for intermediate level 

sounds and has the same upper corner as the C-weighting, but the lower 

amplitude corner is 120 Hz. 

Weighting, ANSI C – The C-curve is basically “flat,” with –3 dB corners of 

31.5 Hz and 8 kHz, respectively. 

Weighting, CCIR 468 – This filter was designed to maximize its response 

to the types of impulsive noise often coupled into audio cables as they 

pass through telephone switching facilities. The CCIR 468-curve peaks at 

6.3 kHz, where it has 12 dB of gain (relative to 1 kHz). From here, it gently 

rolls off low frequencies at a 6 dB/octave rate, but it quickly attenuates 

high frequencies at ~30 dB/octave (it is down –22.5 dB at 20 kHz, relative 

to +12 dB at 6.3 kHz). 

Weighting, CCIR ARM (or CCIR 2 kHz) – This curve is derived from the 

CCIR 468-curve. Dolby Laboratories proposed using an average-response 

meter with the CCIR 468-curve instead of the costly true quasi-peak 

meters used by the Europeans in specifying their equipment. They further 

proposed shifting the 0 dB reference point from 1 kHz to 2 kHz (in

essence, sliding the curve down 6 dB). This became known as the CCIR 

ARM (average response meter), as well as the CCIR 2 kHz-weighting curve. 

Wet Signal – The output of an effect device, especially a reverb unit. 

WG – Working Group. 

WGHDEP – SMPTE Working Group on High-Definition Electronic Production 

(N15.04). Now reformed as the SMPTE Committee on Hybrid Technology 

(H19). 

Whip Pan – A quick movement of the camera from left to right or right to 

left which creates a blurred image. Also called Swish Pan. 

White Balance – An electronic process used in camcorders and video 

cameras to calibrate the picture for accurate color display in different lighting 

conditions (i.e., sunlight vs. indoor incandescent). White balancing 

should be performed prior to any recording, typically by pointing the camera 

at a white object for reference. 

White Clip – The maximum video signal excursion in the white direction 

permitted by the system. 

White Compression – a) Amplitude compression of the signals corresponding 

to the white regions of the picture, thus modifying the tonal gradient. 

b) The reduction in gain applied to a picture signal at those levels 

corresponding to light areas in the picture, with respect to the gain at the 

level corresponding to the midrange light value in the picture. Note: The 

gain referred to in the definition is for a signal amplitude small in comparison 

with the total peak-to-peak picture signal involved. A quantitative evaluation 

of this effect can be obtained by a measurement of differential gain. 

The overall effect of white compression beyond bandwidth limiting is to 

reduce contrast in the highlights of the picture as seen on a monitor. 

White Level – Level which defines white for the video system. 

White Level Control – This is a name for the contrast or picture control. It 

describes a function that is otherwise not clearly spelled out in names of 

controls used on monitors. It is not a term found on a monitor control. (As 

“black level” clearly defines the brightness control function, “white level” 

more clearly defines the contrast or picture control function.) 

White Noise – A random signal having the same energy level at all frequencies 

(in contrast to pink noise which has constant power per octave 

band of frequency). 

White Peak – The maximum excursion of the picture signal in the white 

direction at the time of observation. 

White Point – That point on the chromaticity diagram having the tristimulus 

of a source appearing white under the viewing conditions; i.e., a 

spectrally nonselective sample under the illumination of viewing conditions. 

White, Reference – a) The light from a nonselective diffuse reflector (in 

the original scene) that is lighted by the normal illumination of the scene. 

That white with which the display device stimulates reference white of the 

original scene. b) In production context, reference white is defined as the 

luminance of a white card having 90% reflectance and subjected to scene 

illumination. It is expected that there will be the capability of some discrimination 

of surface texture or detail within that portion of the transfer function 

incorporating reference white. 



Wide Screen Signaling System (WSS) – It is used on (B, D, G, H, I) PAL 

line 23 and (M) NTSC lines 20 and 283 to specify the aspect ratio of the 

program and other information. ITU-R BT.1119 specifies the WSS signal for 

PAL and SECAM system. EIAJ CPX-1204 specifies the WSS signal for NTSC 

systems. 

Wide-Angle – Refers to camera lenses with short focal length and broad 

horizontal field of view. 

Wideband – Relatively wide in bandwidth. 

Widescreen – An image with an aspect ratio greater than 1.33:1 aspect 

ratio. 

Widescreen Panels – Additional sections of picture information that can 

be added to a 1.33:1 aspect ratio picture to create a widescreen image. 

Width – Refers to the width of recording tape, varying from 0.150" in cassette 

tape to 2.0" for video, mastering and instrumentation tapes. The size 

of the picture in a horizontal direction. 

Width Border – The 4100 series name for a Hard Border. 

Wind – The way in which tape is wound onto a reel. An A-wind is one in 

which the tape is wound so that the coated surface faces toward the hub; 

a B-wind is one in which the coated surface faces away from the hub. A 

uniform wind, as opposed to an uneven wind, is one giving a flat-sided 

tape pack free from laterally displaced, protruding layers. 

Winder/Cleaner – A device designed to wind and clean magnetic tape in 

order to restore it to a quality that approaches the condition of a new tape, 

providing the tape has not been physically damaged. 

Window – a) A portion of the screen that you can manipulate that contains 

text or graphics. b) Video containing information or allowing information 

entry, keyed into the video monitor output for viewing on the monitor 

CRT. c) A video test signal consisting of a pulse and bar. When viewed on a 

monitor, the window signal produces a large white square in the center of 

the picture. d) A graphical user interface that presents icons and tools for 

manipulating a software application. Most applications have multiple windows 

that serve different purposes. 

Window Dub – Copies of videotape with “burnt in” time-code display. 

Hours, minutes, seconds, and frames appear on the recorded image. 

Window dubs are used in off-line editing. 

Window Shades – See Side Panels. 

Windows, Analog – All analog windowing architectures multiplex graphics 

and video as analog signals rather than as digital information, but they vary 

widely in signal manipulation and digital processing capabilities. While they 

do offer some advantages, analog architectures fail to address certain 

problems. For example, the graphics pixel-clock frequency becomes the 

pixel clock for the video image. Therefore, the greater screen resolution, 

the smaller the video window. Since enlarging the image means losing 

graphics resolution, the end user may find himself changing display drivers 

several times a day to fit the immediate task. The simplest analog architecture 

is the genlocked video overlay. Composite video is decoded into its 

RGB components. Having no control over the video source, the graphics 

controller must be genlocked to the video source, operating at a resolution 

and timing characteristic compatible with the incoming video signal. The 

graphics signal is switched in and out at appropriate times so that the 




graphic appears in the desired place in the image. The multiplexed output 

is then encoded into a new composite signal. The analog multiplexer, currently 

the most popular architecture, is actually a group of slightly varied 

architectures. The most popular variation imports the graphics data and 

pixel clock from the graphics card feature connector across a ribbon cable, 

where it is fed to a DAC. 

The video signal is digitized, color-converted, and scaled, then is stored in 

a frame buffer similar to a FIFO which synchronizes the data. When the 

video data emerges from the frame buffer, it is fed to a second DAC. The 

two DACs are connected to an analog multiplexer that is controlled by a set 

of counters that keep track of the beam position on the graphics display. 

When the beam enters the video-window area, the mux is switched from 

the graphics signal to the video signal. 

Windows, Digital – Digital windowing offers a distinct advantage over 

analog. it digitizes the video image immediately, only converting it to analog 

as it is sent to the CRT. Incoming composite video is digitized and decoded 

to produce a YUV data stream, which then enters the video-processing 

pipeline (color-space and format conversion, scaling and/or zooming). After 

processing, the data is stored in the frame buffer. At the appropriate time, 

the data moves to the overlay controller, which serves as a digital multiplexer. 

Graphics data remains in digital form through the overlay controller; 

it is not converted to analog until the final DAC that drives the CRT. 

Wipe – a) A transition between two video signals that occurs in the shape 

of a selected pattern. b) Any pattern system effect that reveals a new 

video, and more specifically, one that does not have an enclosed boundary 

on the screen. c) Special effect in which two pictures from different video 

sources are displayed on one screen. Special effects generators provide 

numerous wipe patterns varying from simple horizontal and vertical wipes 

to multi-shaped, multi-colored arrangements. The Digital Video Mixer 

includes this effect. 

Wireframe – An image generated by displaying only the edges of all polygons 

or surfaces. 

Wireless Microphone System – A microphone system consisting of a 

microphone, an FM transmitter, and a tuned receiving station that eliminates 

the need for long runs of microphone cable. 

WMF (Windows Meta File) – The standard vector-based structure of the 

Windows operating system. Bitmapped images may be embedded in WMF 

files. 

Word – Set of characters that occupies one storage location and is treated 

by the computer circuits as a unit. Ordinarily a word is treated by the control 

unit as an instruction and by the arithmetic unit as a quantity. See 

Byte. 

Workspace – The main window for working with icons and customizing 

your view of the file system. You place files and directories from all over 

the file system here for easy access; placing them in the Workspace does 

not change their actual location in the file system. 

Workstation – The physical hardware that contains the CPU and graphics 

boards, a system disk, and a power supply. You connect it to a monitor, 

keyboard, and mouse to configure a working system. It is also sometimes 

referred to as the chassis. 


World Coordinate System – See World Reference. 

World Reference – The absolute coordinate system which is the root reference 

and upon which all other references are based. It cannot be 

animated. 

World Standard – A television standard accepted in all parts of the world. 

CCIR recommendation 601 is currently the closest there is to a world standard. 

It is accepted throughout the world, but can be used with either 525scanning 

line or 625-scanning line picture. HDTV 1125/60 Group is 

attempting to promote its system as a world HDEP standard, but Zenith 

suggests the same for 3XNTSC, and there are other candidates. 

World System Teletext (WST) – ITU-R BT.653 525-line and 625-line 

system B teletext. 

World Transmission Standards – For a definition of “TV” column codes. 

See Terrestrial Transmission Standards. 

Country TV Color Stereo Subtitles 

Albania B/G PAL 

Argentina N PAL-N 

Australia B/G PAL FM-FM TeleText 

Austria B/G PAL FM-FM TeleText 

Azores (Portugal) B PAL 

Bahamas M NTSC 

Bahrain B PAL 

Barbados N NTSC 

Belgium B/G PAL Nicam TeleText 

Bermuda M NTSC 

Brazil M PAL-M MTS 

Bulgaria D SECAM 

Canada M NTSC MTS CC 

Canary Islands B PAL 

China D PAL 

Colombia N NTSC 

Cyprus B PAL 

Czech Republic D/K SECAM/PAL 

Denmark B PAL Nicam TeleText 

Egypt B SECAM 

Faroe Islands (DK) B PAL 

Finland B/G PAL Nicam TeleText 

France E/L SECAM Antiope 

Gambia I PAL 

Germany B/G PAL FM-FM TeleText 

Germany (previously East) B/G SECAM/PAL 

Gibraltar B PAL 

Greece B/H SECAM 

Hong Kong I PAL Nicam


Hungary D/K SECAM 

Iceland B PAL 

India B PAL 

Indonesia B PAL 

Iran H SECAM 

Ireland I PAL Nicam TeleText 

Israel B/G PAL 

Italy B/G PAL FM/FM TeleText 

Jamaica M SECAM 

Japan M NTSC MTS 

Jordan B PAL 

Kenya B PAL 

Luxembourg B/G PAL TeleText 

Madeira B PAL 

Madagascar B SECAM 

Malaysia B PAL 

Malta B/G PAL 

Mauritius B SECAM 

Mexico M NTSC MTS CC 

Monaco L/G SECAM/PAL 

Morocco B SECAM 

Netherlands B/G PAL FM-FM TeleText 

New Zealand B/G PAL Nicam TeleText 

North Korea D/K? SECAM 

Norway B/G PAL Nicam 

Pakistan B PAL 

Paraguay N PAL 

Peru M NTSC 

Philippines M NTSC 

Poland D/K PAL TeleText 

Portugal B/G PAL Nicam TeleText 

Romania G PAL 

Russia D/K SECAM 

Saudi Arabia B SECAM 

Seychelles I PAL 

Singapore B PAL 

South Africa I PAL 

South Korea N NTSC 

Spain B/G PAL Nicam 

Sri Lanka B/G PAL 

Sweden B/G PAL Nicam TeleText 

Switzerland B/G PAL FM-FM TeleText 




Tahiti KI SECAM 

Taiwan M NTSC 

Thailand B PAL 

Trinidad M NTSC 

Tunisia B SECAM 

Turkey B PAL TeleText 

United Arab Emirates B/G PAL 

United Kingdom I PAL Nicam TeleText 

Uruguay N PAL 

United States M NTSC MTS CC 

Venezuela M NTSC 

Yugoslavia B/H PAL 

Zimbabwe B PAL 

WORM (Write Once, Read Many) – A WORM is an optical drive where 

the data is recorded once (usually with a laser) but may be read many 

times. CD ROMs are WORMs. 

Wow – Slow, periodic variations in the speed of the tape, characterized by 

its effect on pitch. A measure of non-uniform movement of magnetic tape 

or other recording parts. 

WPP (Wipe to Preset Pattern) – See Preset Pattern. 

Wrap – a) The length of the path along which tape and head are in intimate 

physical contact. b) A term used to signify the session (job) is 

finished. 

Wrist Strap – A coiled cable with a loop for your wrist at one end and an 

alligator clip at the other. You fasten the clip to a metal part of the workstation 

and place the loop around your wrist whenever you work with internal 

components of the workstation to avoid electrical shocks to yourself and 

the components. See also Static Electricity. 

Write – a) To transfer information, usually from a processor to memory or 

from main storage to an output device. b) To record data in a register, 

location, or other storage device. 

Write Buffer – A term used to denote the buffer that is logically positioned 

between the CPU interface and the display memory. 

Write-Through – A strategy where cache data is always written into main 

memory when data is written by the CPU. The write-through is done 

through the cache system. 

WRS – Wireless Relay Station. 

WSS – See Wide Screen Signaling System. 

WST – See World System Teletext. 

WYSIWYG (What You See Is What You Get) – Usually, but not always, 

referring to the accuracy of a screen display to show how the final result 

will look. For example, a word processor screen showing the final layout 

and typeface that will appear from the printer. 




X 

X.25 – A standard networking protocol suite approved by the CCITT and 

ISO. This protocol suite defines standard physical, link, and networking layers 

(OSI layers 1 through 3). X.25 networks are in use throughout the 

world. 

X.400 – The set of CCITT communications standards covering mail services 

provided by data networks. 


X-Axis – The horizontal axis of a graph. When a television signal is examined 

in one dimension, the x-axis is usually time. When it is examined in 

three dimensions, the x-axis is usually horizontal resolution. 

XLR – An audio connector characterized by three prongs covered by a 

metal sheath.

Y 

Y (Luminance) – a) An abbreviation or symbol for luminance, the black 

and white information in a television signal. b) Signal which is made up of 

0.59G + 0.3R + 0.11B. c) The y-axis of the chart of the spectral sensitivity 

of the human visual system. 

Y, C1, C2 – A generalized set of CAV signals: Y is the luminance signal, C1 

is the 1st color-difference signal, and C2 is the 2nd color-difference signal. 

Y, Cb, Cr – The international standard ITU-R BT.601-1 specifies eight-bit 

digital coding for component video, with black at luma code 16 and white 

at luma code 235, and chroma in 8-bit two’s complement form centered 

on 128 with a peak at code 224. This coding has a slightly smaller excursion 

for luma than for chroma: luma has 219 risers compared to 224 for 

Cb and Cr. The notation CbCr distinguishes this set from PbPr where the 

luma and chroma excursions are identical. For Rec. 601-1, coding is eight 

bits per component. 

Y_8b = 16 + 219 * 9 

Cb_8b = 128 + 112 * (0.5/0.866) * (Bgamma – Y) 

Cr_8b = 128 + 112 * (0.5/0.701) * (Rgamma – Y) 

Some computer applications place black at luma code 0 and white at luma 

code 255. In this case, the scaling and offsets above can be changed 

accordingly, although broadcast-quality video requires the accommodation 

for headroom and footroom provided in the CCIR-601-1 equations. ITU-R 

BT.601-1 Rec. calls for two-to-one horizontal subsampling of Cb and Cr, to 

achieve 2/3 the data rate of RGB with virtually no perceptible penalty. This 

is denoted 4:2:2. A few digital video systems have used horizontal subsampling 

by a factor of four, denoted 4:1:1. JPEG and MPEG normally subsample 

Cb and Cr two-to-one horizontally and also two-to-one vertically, to get 

1/2 the data rate of RGB. No standard nomenclature has been adopted to 

describe vertical subsampling. To get good results using subsampling you 

should not just drop and replicate pixels, but implement proper decimation 

and interpolation filters. YCbCr coding is employed by D1 component digital 

video equipment. 

Y, CR, CB – The three nonlinear video signals in which the information has 

been transformed into a luminance signal and two chrominance signals, 

each of which has been subject to nonlinear processing, and the chrominance 

signals at least have also been bandlimited. By convention, C'R, and 

C'B represent color-difference signals in digital format with typical excursion 

of values for 16 to 240. 

Y, I, Q – The human visual system has less spatial acuity for magentagreen 

transitions than it does for red-cyan. Thus, if signals I and Q are 

formed from a 123 degree rotation of U and V respectively, the Q signal 

can be more severely filtered than I (to about 600 kHz, compared to about 

1.3 MHz) without being perceptible to a viewer at typical TV viewing distance. 

YIQ is equivalent to YUV with a 33 degree rotation and an axis flip in 

the UV plane. The first edition of W.K. Pratt “Digital Image Processing,” and 

presumably other authors that follow that bible, has a matrix that erroneously 

omits the axis flip; the second edition corrects the error. Since an 

analog NTSC decoder has no way of knowing whether the encoder was 

encoding YUV or YIQ, it cannot detect whether the encoder was running at 



0 degree or 33 degree phase. In analog usage, the terms YUV and YIQ are 

often used somewhat interchangeably. YIQ was important in the early days 

of NTSC, but most broadcasting equipment now encodes equiband U and V. 

The D2 composite digital DVTR (and the associated interface standard) 

conveys NTSC modulated on the YIQ axes in the 525-line version and PAL 

modulated on the YUV axes in the 625-line version. The set of CAV signals 

specified for the NTSC system: Y is the luminance signal, I is the 1st colordifference 

signal and Q is the 2nd color-difference signal. 

Y, Pb, Pr – If three components are to be conveyed in three separate 

channels with identical unity excursions, then the Pb and Pr color difference 

components are used. These scale factors limit the excursion of EACH 

color difference component to –0.5 … +0.5 with respect to unity Y excursion: 

0.886 is just unity less the luma coefficient of blue. In the analog 

domain, Y is usually 0 mV (black) to 700 mV (white), and Pb and Pr are 

usually ±350 mV. YPbPr is part of the CCIR Rec. 709 HDTV standard, 

although different luma coefficients are used, and it is denoted E'Pb and 

E'Pr with subscript arrangement too complicated to be written here. YPbPr 

is employed by component analog video equipment such as M-II and 

Betacam; Pb and Pr bandwidth is half that of luma. A version of the (Y, R-Y, 

B-Y) signals specified for the SMPTE analog component standard. 

Pb = (0.5/0.866) * (Bgamma – Y) 

Pr = (0.5/0.701) * (Rgamma – Y) 

Y, PR, PB – The three nonlinear video signals in which the information has 

been transformed into a luminance signal and two chrominance signals, 

each of which has been subject to nonlinear processing, and the chrominance 

signals at least have also been bandlimited. By convention, P'R and 

P'B represent color-difference signals in analog format, with typical excursion 

between –350 mV and +350 mV. 

Y, R-Y, B-Y – The general set of CAV signals used in the PAL system as 

well as for some encoder and most decoder applications in the NTSC systems. 

Y is the luminance, R-Y is the 1st color-difference signal and B-Y is 

the 2nd color-difference signal. 

Y, U, V – Luminance and color difference components for PAL systems. Y, 

U, and V are simply new names for Y, R-Y, and B-Y. The derivation from 

RGB is identical. In composite NTSC, PAL or S-Video, it is necessary to 

scale (B-Y) and (R-Y) so that the composite NTSC or PAL signal (luma plus 

modulated chroma) is contained within the range –1/3 to +4/3. These limits 

reflect the capability of composite signal recording or transmission 

channel. The scale factors are obtained by two simultaneous equations 

involving both B-Y and R-Y, because the limits of the composite excursion 

are reached at combinations of B-Y and R-Y that are intermediate to primary 

colors. The scale factors are as follows: U = 0.493 * (B-Y); V = 

0.877 * (R-Y). U and V components are typically modulated into a chroma 

component: C = U * cos(t) + V * sin(t) where t represents the ~3.58 MHz 

NTSC color sub-carrier. PAL coding is similar, except that the V component 

switches Phase on Alternate Lines (±1), and the sub-carrier is at a different 

frequency, about 4.43 MHz. It is conventional for an NTSC luma signal 

in a composite environment (NTSC or S-Video) to have 7.5% setup: 




Y_setup = (3/40) + (37/40) * Y. A PAL signal has zero setup. The two signals 

Y (or Y_setup) and C can be conveyed separately across an S-Video 

interface, or Y and C can be combined (encoded) into composite NTSC or 

PAL: NTSC = Y_setup + C; PAL = Y + C. U and V are only appropriate for 

composite transmission as 1-wire NTSC or PAL, or 2-wire S-Video. The UV 

scaling (or the IQ set, described below) is incorrect when the signal is conveyed 

as three separate components. Certain component video equipment 

has connectors labeled YUV that in fact convey YPbPr signals. 

Y/C (Luminance and Chrominance) – A term used to describe the separation 

of video signal components used in systems such as Hi-8 and 

S-VHS. Generically called S-Video, all Videonics video products support the 

(Y/C) format. 

Y/C Connections – Connections between videotape recorders and 

between videotape recorders and cameras, monitors, and other devices 

that keep luminance and chrominance separate and thus avoid cross-color 

and cross-luminance. See also S-Video. 

Y/C Separator – Decoder used to separate luma and chroma in an (M) 

NTSC or (B, D, G, H, I) PAL system. 

Y/C Video – Shorthand for luma (Y) and chroma (C). 

Y-Axis – The vertical axis of a graph. When a television signal is examined 

in one dimension, the y-axis is usually signal strength. When it is examined 

in three dimensions, the y-axis is usually vertical resolution. 

YCC (Kodak PhotoCD) – Kodak’s Photo YCC color space (for PhotoCD) 

is similar to YCbCr, except that Y is coded with lots of headroom and no 

footroom, and the scaling of Cb and Cr is different from that of Rec. 601-1 

in order to accommodate a wider color gamut. The C1 and C2 components 

are subsequently subsampled by factors of two horizontally and vertically, 

186 

www.tektronix.com/video_audio 

but that subsampling should be considered a feature of the compression 

process and not of the color space. 

Y_8b = (255/1.402 * Y 

C1_8b = 156 + 111.40 * (Bgamma – Y) 

C2_8b = 137 + 135.64 * (Rgamma – Y) 

Yield Strength – The minimum force per unit cross-sectional area at 

which the tape or base film deforms without further increase in the load. 

Units are pounds per square inch (psi) or pounds per tape sample of given 

width and base film thickness. 

YUV – a) A video system employing luminance and two chroma components 

directly related to the red and blue components. This professional 

component video system is used in studios and requires special equipment. 

Interface devices are used to link the various component systems, 

i.e., RGB, Y/C, YUV, and YIQ (A system similar to YUV). b) A color model 

used chiefly for video signals in which colors are specified according to 

their luminance, the Y component, and their hue and saturation, the U and 

V components. See Hue, Luminance, Saturation. Compare RGB. 

YUV12 – Intel’s notation for compressed video. 

YUV9 – a) Intel’s notation for compressed Y, U, V format that provides a 

compression ratio of 3 to 1. b) A bitstream format that does not compress 

the video signal, but converts it from the RGB into the YUV color model and 

averages pixel colors so that the signal uses only nine bits per pixel. See 

Compress, Encode, RGB, YUV. Compare YUV9. 

YUV9C – A bitstream format that converts the video signal from RGB into 

the YUV color model, averages pixel colors so that the signal uses only nine 

bits per pixel, and then compresses the signal slightly. See Compress, 

Encode, RGB, YUV. Compare YUV9.

Z 

Z-Axis – An axis of a three-dimensional graph, which, when printed on a 

flat piece of paper, is supposed to be perpendicular to the plane of the 

paper. When a television signal is examined in three dimensions, the z-axis 

is usually time. 

Zenith – a) The tilt of the head relative to a direction perpendicular to the 

tape travel. b) Major U.S. consumer electronics manufacturer and proponent 

of the 3XNTSC ATV scheme, also possibly the first organization to 

suggest pre-combing for NTSC. 

Zero Carrier Reference – A 120 IRE pulse in the vertical interval which is 

produced by the demodulator to provide a reference for evaluating depth of 

modulation. 

Zero Modulation Noise – The noise arising when reproducing an erased 

tape with the erase and record heads energized as they would be in normal 

operation, but with zero input signal. This noise is usually 3 to 4 dB 



higher than the bulk erased noise. The difference between bulk erased and 

zero modulation noise is sometimes referred to as induced noise. 

Zero Timing Point – The point at which all video signals must be in synchronization 

(typically the switcher input). 

Zig-Zag Scan – Zig-zag scan of quantized DCT coefficient matrix. This 

gives an efficient run length coding (RLC). 

Zig-Zag Scanning Order – A specific sequential ordering of the DCT coefficients 

from (approximately) the lowest spatial frequency to the highest. 

Zoom – Type of image scaling. The process where a video picture is 

increased in size by processing pixels and lines through interpolation or 

replication. A 640 x 512 image will take up one quarter of a 1280 x 1024 

screen. To fill the screen, the 640 x 512 image must be zoomed. Zooming 

makes the picture larger so that it can be viewed in greater detail. 


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For other areas, contact: Tektronix, Inc. at 1 (503) 627-1924 

For Further Information 

Tektronix maintains a comprehensive, constantly expanding collection 

of application notes, technical briefs, and other resources to help engineers 

working on the cutting edge of technology. 

Please visit “Resources For You” at www.tektronix.com 

Copyright © 2001, Tektronix, Inc. All rights reserved. Tektronix products are 

covered by U.S. and foreign patents, issued and pending. Information in this 

publication supersedes that in all previously published material. Specification 

and price change privileges reserved. TEKTRONIX and TEK are registered 

trademarks of Tektronix, Inc. All other trade names referenced are the 

service marks, trademarks or registered trademarks of their respective 

companies. 

11/01 TD 25W-15215-0

Glossary of Video Terms and Acronyms - Isotest

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