Glossary of Video Terms

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Glossary

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A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Numeric

AAL
Shorthand for ATM Adaptation Layer.

ABCD Sequence
Referring to the "pull down" identification cadence of field/frame rate conversion between 24 and 30 frame video. In 24 frame progressive video or film sources, four consecutive frames A, B, C, D will relate to 30 frame video interlaced fields as AA - BB - BC- CD -DD, an 8 Field cycle that actually takes up 5 full frames of 30 frame interlaced (or segmented frame) video before it repeats, where an "A" frame is predetermined in SMPTE recommended practice to be at every Non-Drop Time Code frame ending in zero. This requires precise synchronization to achieve. Because the ABCD cycle repeats in 30Hz operation after 5 frames, and using non-drop frame time code numbers, one can relate the timing of 24Hz end of frame D or start of frame number 5 at the same point of vertical sync of the start of the 6th 30hz frame. This pattern repeats 6 times per second in 30Hz, resulting in a difference of 6 frames per second more information (or 12 fields) than 24Hz. In the conversion to 30 frames from 24, the additional information is merely a repetition of some of the frames of the 24 frame material as extra fields (extra half frames) which are mostly unnoticed except in editing, or slow motion. Having the extra half frames may serve to cause inefficiencies in compression, temporal bandwidth, and storage.

AC Resistance
Also referred to as impedance, a measurement of electric resistance to current flow such as in an alternating-current circuit.

AC-3 Digital Audio
A Dolby Laboratory third generation multi-channel compression and decompression (codec) system (audio coding and decoding algorithm) capable of storing and recovering 5.1 channel surround sound for DVD, laser disc, and digital TV (DTV) transmissions, renamed Dolby Digital. To store AC-3 in a digital audio track of a digital videotape, for example, as the native AC-3 digital data is already compressed, it needs to be sampled and stored as though it were uncompressed data. Dolby AC-3, also referred to as Dolby D or Dolby Digital uses approximately a 13:1 compression of six discrete audio channels: Left, Center, Right, Left Rear (or side) Surround, Right Rear (or side) Surround, and a subwoofer (considered the ".1" with limited low frequency bandwidth). The recorded bit rate ranges from 56 Kbps to 640 Kbps.

Active Circuit
A circuit containing amplification. For example, an active throughput circuit on a monitor would provide amplification to compensate for the loss in voltage of the returned signal "split off" of the input for the monitor. If the active circuit is not self terminating (either by a switch to a load, or already terminated but self-sensing to pass throughput amplification), a "terminator" rated to the proper load should be used to close the circuit. A passive circuit in the same circumstances would "tap" the input voltage.

ADR
Shorthand for Automatic Dialogue Re-recording or Automatic Dialogue Replacement, a process of using performers and a synchronous system in post production to listen to production track dialogue (sometimes not correctly recorded) and replace it with new (properly recorded) dialogue. If done synchronously (matching the correct sync reference of the playback and recording standards used) and if done skillfully, the original voices of performers (say recorded with a cold) can be replaced without noticeable difference to the viewer.

AES/EBU
Digital audio standard established jointly by the Audio Engineering Society (AES) and the European Broadcasting Union (EBU).

AFD
Shorthand for Active Format Description used in DVB Europe, descriptive format display data carried in the user data portion of the MPEG-2 video elementary stream for a 4-bit field notating the active aspect ratio format.

AIT
Shorthand for Advanced Intelligent Tape.

AIT2
Shorthand for Advanced Intelligent Tape 2nd Generation, with 50/100 GB capacities (native/compressed) and supporting up to 6/12 MBps (native/compressed) data transfer rates.

ALS
Shorthand for Automated Library System.

Analog
A term that generally describes an artificial electrical signal that is continuously variable in signal level or electrical energy. In terms of video, a group of sine waves called an analog waveform are used to represent the electrical phosphor values of an image that has been "captured" on a CCD (charge-coupled device) that turns values of light energy into voltage so that when properly displayed as scan lines on a television receiver or monitor, the waveform will create a similar image on the television tube phosphors by causing them to "excite" (respond to beams of electrical current) by glowing with approximately the same values of the original image. Analog signals can be turned back and forth into digital signals and digital signals can be turned back and forth into analog signals, but the process may degrade the quality of the converted signal compared to the original signal and may likely do so after repeated generations. Since motion picture film captures an approximation of visual spectrum light energy values through a chemically responsive process, and can allow the light values to be represented through a projection display process as visual energy, some people refer to the film process as "analog" when comparing film to digital television. It is also important to note that analog signals are not necessarily resolution limited compared to digital signals (analog signals can carry less, the same, or more resolution than digital signals depending upon the frequencies of the signal capture, storage, and display process). Display CRT (cathode ray tube) computer monitors, video monitors, and televisions are all actually analog devices for which a digital signal must be decoded internally or externally into an analog signal prior to the beam phosphor display process. In the case of a television to receive off-air analog television signals, the signals must first be separated from their transmitted RF (radio frequency) carrier and demodulated (separating analog video and analog audio) through a frequency agile (or fixed frequency) demodulator (also known as a TV tuner).

Anamorphic Lens
A special lens which squeezes the width of an image onto the normal limits of a frame during photography. A reversing anamorphic lens is used in projection to bend back the image at the point of projection. Anamorphic lenses enable such cinematic aspect ratios as 2.85:1. It is not recommended, but Anamorphic Lenses can theoretically work with video whereby an optically distorted image is presented to the video imaging system, resulting in a squeezed pixel. There are many reasons to avoid doing this, including the fact that the camera imager may already not be capable of adequately representing the increase in horizontal bandwidth for which it was originally designed (e.g., some cameras with 16:9 capability may not have true 16:9 CCDs, already pushing the limits of adequately representing an image out of their 4:3 CCD chips). In another use of the anamorphic concept, standard definition television camcorders with 16:9 (1.77:1) aspect ratio capability already employ a digital "squeeze" when recording 16:9 within the boundaries of standard definition television's 4:3 (1.33:1) active picture area. In this case, the image is recovered in its original aspect ratio in display only with a 16:9 capable monitor, projector, or television, by upconversion to high definition 16:9, or by conversion to 1.77:1 aspect ratio film. Where projection is concerned, due to the substantial curvature in the matching recovering anamorphic lens, distortions may be more apparent and occur on the sides of the image.

Anastigmat Lens
An old term for a corrected lens that focuses vertical and horizontal lines with equal brightness and definition and which is also free of other common aberrations.

Antenna
In the context of television or radio, a structure or physical path that can radiate or capture radio frequency energy. High Definition Television and Digital Television is transmitted in the UHF Band (Ultra-High Frequency). An interesting point is that cables and physical structures can also act as antennas, as can something as simple as a metal paperclip. There are many specialized ways to prevent cables from acting like antennas and limiting the effect of unwanted frequencies from interfering with signals sent across them. Some of these specialized ways include different types of signal circuits at the send and receive ends of the cables, shielding, grounding, and filtering.

API
Shorthand for Application Program Interface.

Apochromatic Lens
An old term for a lens that can focus rays of all colors on virtually the same plane.

ASA
American Standards Association film emulsion speed rating system. ASA film emulsion numbers are commonly used to express the factor which determines the exposure necessary to produce a satisfactory image.

ASI
Shorthand for Asynchronous Serial Interface.

ASI-TS
Shorthand for Asynchronous Serial Interface Transport Stream.

Aspect Ratio
Refers to the mathematical ratio of the width to height of an image, such as 16:9 (also expressed as 1.77:1) or 4:3 (also expressed as 1.33:1).

Asynchronous
Meaning non-synchronous, referring to an analog signal or digital signal lacking synchronization or requiring buffering to recover.

ATC
Shorthand for Ancillary Time Code.

ATM
Asynchronous Transfer Mode. ATM protocol includes its own error correction.

ATSC
Advanced Television Systems Committee.

Attenuate
To reduce the strength of a signal, such as in the use of a "pad" circuit. Signal passing through a length cable will be reduced in strength. One of the measurements of the signal reduction loss is the Attenuation Loss rating of the cable.

ATV
Advanced digital television, including standard, enhanced and high-definition television.

Audio Breakaway
Term typically used to describe a separate signal routing path for Audio from Video. A router with audio breakaway capability can be said to provide a choice of switching (at least a specific group of channels of audio independently from the way video is switched within different levels of control circuits of the same router frame versus switching audio to or from the same source or destination at the same time as video is switched.

Audio Normalling
Term used to describe a wiring pattern in a patch panel in which a circuit path is established from one point of contact to another separate point of contact (usually above or below the first point of contact) without the use of a patch cord. If a patch cord is inserted, then the established path is interrupted and rerouted along the patch cord to a different circuit path. "Normalled" patch panels allow a "normal" commonly used circuit path to remain connected without the use of a patch cord, yet provide flexibility in connecting either the sending (source) circuit or the receiving (destination) circuit to a different circuit entirely, or through the use of a terminating patch plug, or a self terminating patch panel, to end the signal path of the sending circuit. Through the use of cables with patch cord ends, a source or a destination may also be entirely off the patch panel altogether.

Auto Timing
Certain digital video equipment automatic phasing circuits which can automatically adjust input video timing to match a reference video input, usually within a specific range of lines (or expressed as within a specific multiple or sub-multiple range of the vertical reference line frequency, such as in standard definition plus or minus one line, 63.5 microseconds), and if falling within the correctable range, can eliminate the need for manual timing adjustments.

Axis
With respect to a two dimensional picture "plane", the X axis refers to a horizontal line across the center of the plane, the Y axis refers to a vertical line, and the Z axis refers to spatial depth and distance in the third dimension, perpendicular to the X and Y axes. The term Axis can apply to person, place, or thing, for which there may be multiple Axis lines. The term Axis can also be associated with an imaginary "stage" line between one object and another corresponding with the location of a camera lens (or view) with respect to both objects. In motion picture photography, television, or video, "crossing the line" without properly orienting the audience to the change in camera position relative to the "stage" line axis between two objects can create a disorienting "jump" cut where the objects appear to have switched places (like a football game changing directions at the end of a quarter). Each object may also have its own additional axis (of direction) also called "stage presence", and "crossing the line" with a camera position in this case also can create disorientation to an audience.

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Baseband Signal
Original analog or digital video signal used to modulate a carrier.

BAT
Shorthand for Bouquet Association Table.

BCD
Shorthand for Binary Coded Decimal.

B frames
Refers to one type of MPEG-2 digital signal video frame compression method whereby two successively alternate complete video frames (each with two fields of information like normal digital video frames) which are called "I" frames (shorthand for "Information" frames) are compared to compress redundant data from the frame in between (thereby reducing the amount of data used to store a series of frames in a video sequence and as such "B frame" is a shorthand abbreviation for a "Bi-directional" or "Bi-directionally" compressed frame). To decode a B frame, both fields of the successive frames used before and after are used in a special multiple frame memory buffer system in conjunction with MPEG-2 decompression software/decoder chip hardware to reconstruct the special Bi-directionally compressed data.

BER
Shorthand for Basic Encoding Rules, for encoding an object identifier as specified in ISO/IEC 8825-1.

Bit Rate
The number of bits of a digital signal or any specific portion of a digital signal expressed in the context of a time measurement, such as the rate of 172Mb/sec for the active picture payload of 8-bit uncompressed 4:2:2 sampled component digital video recorded onto or played back from a D-1 videotape recorder operating at normal playback speed.

Black Burst
A type of video reference signal (typically a standard definition analog video signal) that contains the combined sync timing elements of a video signal, such as horizontal and vertical sync and blanking, along with the color burst signal, and that when viewed, will appear as a "black" picture. Multiple devices that accept a Black Burst reference will use the timing information to alter their specific performance, such as in recording, editing, and playback operations, to assist in the common synchronous interchange of signals between any two or more such devices (meaning in more simple terms, so the pictures don’t jump when switching from device to device, and so the audio doesn’t click, pop, loose phase, or lag behind the picture). Depending upon the devices involved, Black Burst is usually referenced to a power frequency (such as 60Hz or 50Hz), and can also be locked to another reference signal, such as word clock reference. By the same token, depending upon the sophistication of the devices, word clock or super word clock can be referenced to Black Burst. Although NTSC and PAL use different frequencies of Black Burst, some devices can generate simultaneous NTSC and PAL Black Burst while locked to a common power frequency. Expensive Master Sync Generators with low drift crystals (and the ability to hold precise timing phase and frequency) are used in broadcast operations along with automatic changeover units (in case of a single Sync Generator failure) to create the master system reference timing.

BMP
Shorthand for Basic Multilingual Plane.

bslbf
Shorthand for Bit String Left Bit First.

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C

CA
Shorthand for Conditional Access, such as scrambled data or scrambled satellite digital broadcasts.

CAS
Shorthand for Conditional Access System or Consumer Conditional Access System, such as Nagra Vision by Nagra, Irdeto "Mcrypt", Viaccess by France Telecom, Crypto Works, Canal+, Conax, etc.

CAP
Shorthand for Carrierless Amplitude Phase Modulation, a modulation scheme similar to QAM Quadrature Amplitude Modulation method of modulating digital signals onto an RF (Radio Frequency) carrier which involves both amplitude and phase coding, but CAP has no carrier frequency.

Caption Vision
Refers to receiver/monitor access to 2 closed caption channels and 2 text channels (where service is available).

Capture Card
Also known as a still or motion video and audio I/O or interface card for computer CPU interface. Different capture cards are available for just PC, just Mac, for both, and for SGI (and some other computers). Different capture cards also provide for still video capture only, audio capture only, and motion video and audio, and are available in analog only, analog and firewire digital, analog and component serial digital video, component serial digital only, firewire digital only, and other forms of high speed data exchange such as on SGI systems for high definition analog and/or high definition component digital video/data.
Carbon
With reference to motion picture production, the "stick like" filament that when burned created a high output light source in a carbon arc lamp housing, such as found in an old carbon arc film projector or Molarc "Brute" light. As the carbon burned, the carbon stick got shorter and shorter.

CAT
Shorthand for Conditional Access Table.

CC
Shorthand for Closed Caption. In NTSC or PAL, EIA608 closed caption data may be employed. In ATSC digital formats, EIA708 closed caption data is employed. In ATSC High Definition, Line 9 is used for closed captioning.

CD
Shorthand for Compact Disk (also spelled "Compact Disc"). CD-DA was the original Compact Disk audio application developed by Philips and Sony Corporation and expanded under Red Book ISO 10149 standard. CD-I (Compact Disc-Interactive) was developed by Philips as a hardware and software standard for bringing together text, sound, and video on a single disk and was expanded under Green Book Standard. CD-ROM (Compact Disc Read Only Memory) was expanded under Yellow Book ISO 9660 Standard and includes CD-XA compressed audio information. CD-R (Compact Disc Recordable) was expanded under Orange Book. MMCD was developed for hand-held Compact Disc players developed by Sony Corporation. PhotoCD was developed by the Eastman Kodak Company for storing high-quality photographic still images. PhotoCD players were originally designed to also play back audio discs. Base level consumer PhotoCD resolution is set at 768x512 pixels, and professional PhotoCD with 64base resolution is set at 6144x4096 pixels.

Cell Side
Shorthand for "cellulose acetate shiny (also called cell or base or backing) side" of motion picture film as opposed to the dull (emulsion) side.

CEMA
Consumer Electronics Manufacturers Association.

Channel Caption
Refers to the receiver/monitor on-screen display identification of channel call letters.

CLUT
Shorthand for Color Lookup Table.

Color Subcarrier
Composite analog signal carrier display frequency (in NTSC of 3.58 MHz) on which the color signal information is stored in successive field ninety degree phase alternating positions requiring a four field sequence to complete color framing cycle, and which can vary in degree no more than 2.6% or the result will be loss of color on a monitor.

Color-Under Recording
Separating the standard NTSC signal into luminance and modulated chrominance with sidebands. In �" U-Matic recordings, the luminance frequency is used to modulate an FM carrier signal to hold a 3.58 MHz to 688 kHz downconverted (heterodyned) chrominance signal with the FM carrier acting as bias (maintaining linearity in tape response), as similarly achieved in VHS and SVHS video format recording, and 8-mm video format recording (yet each with different incompatible tape formats and FM carrier frequencies). U-Matic SP recordings use a higher frequency FM carrier and a different tape formulation than the old standard U-Matic format. In each of these formats, the narrow bandwidth luminance signal requires time base correction prior to broadcast and/or mixing with other video sources, or prior to conversion into a digital signal.

Component Analog Video
Component Analog Video is comprised of sync, and three related linear combination "channels" of picture information, representing weighted sampling of the three primary colors (RGB) while maintaining respective frequency and timing relationships. Component Analog Video is subject to linear distortions, nonlinear distortions, and noise. Y is the weighted designation for the "luma" signal and is the designation for the Green signal; R-Y is a weighted color difference process and is the designation for the Red signal; and B-Y is a weighted color difference process and is for the designation of the Blue signal. Also noted as the designation Y', Pb, Pr, or Y', Cb, Cr. If the signal The Y' "Luma" signal generally carries sync information (sync on green) and has a nominal distribution bandwidth of 5 MHz. In component VTR’s, the bandwidth of the "Luma" signal is limited to 4MHz, and the color difference channels are limited to 1.25 MHz.

Constant Linear Velocity Recording
Generally used to maximize the storage available on a disc. With reference to CD recording, for example, when the CD disc spins faster for its inner tracks than it does for its outer tracks so that the same length of track appears under the read/write head every second.

Control-L
Control-L is a consumer-level bi-directional editing protocol developed by Sony with a sophisticated command set for transport commands, monitoring device status, and tape time information (first introduced using a 5-pin connector with 8mm and Hi8 formats, later switching to a stereo three conductor minijack). Control-L is only accurate to +/- 5 frames.

Control-M
Control-M is a bi-directional semi-professional editing protocol developed by Panasonic with a sophisticated command set for transport commands, monitoring device status, and tape time counter information (introduced using a proprietary Panasonic 5-pin connector). Because the equipment that supports Control-M does not generally support internal time code (nor reporting to the command set), Control-M is only accurate to +/- 5 frames.

Control-S
Control-S is a consumer-level or semi-professional one-directional protocol developed by Sony with a transport, command, and special record command set (an altered infrared IR Remote protocol set sent by wire), used mainly for wired remote device control. Control-S has been replaced by Control-L, and is not used for editing (crash recording commands if device supported are not accurate).

CRC
Shorthand for Cyclic Redundancy Check (code).

CRI
Color Reversal Inter-negative film (stock).

CRT
Cathode Ray Tube.

CS
Close Shot.

CU
Close Up.

Cue Tracks
With reference to video, some digital videotape recorders cue tracks to allow for the monitoring of audio during high-speed search and slow jogging for cueing up tapes and finding edit points. Ideally, 2 cue channels would be available to mirror each AES/EBU digital pair, while a third cue channel might provide a mix.

CVCT
Shorthand for Cable Virtual Channel Table.

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D

D-1
A standard definition digital 8-bit uncompressed 4:2:2 13.5 MHz sampled 172Mb/sec (picture payload) component digital tape format developed by Sony, which has become a general interchange format for standard definition post production, and a mastering format for telecine and broadcast and cable network program delivery.
D-2
A standard definition composite digital 4fsc 14.3 MHz sampled and bandwidth filtered 94Mb/sec (picture payload) composite digital tape format manufactured by Sony and Ampex (execpt for some cassette size incompatibilities, recordings made on either are playable on each).

D-3
A standard definition 1/2" MP composite digital fsc 14.3 MHz sampled and bandwidth filtered 94Mb/sec (picture payload) composite digital tape format manufactured by Panasonic (not compatible with Sony D-2 or Ampex D-2).

D-5
A standard definition 1/2" MP digital 10-bit uncompressed 4:2:2 13.5 MHz sampled 220Mb/sec (picture payload) component digital tape format developed by Panasonic, also capable of 8-bit 4:2:2 18MHz sampled 16:9 recording and playback. The D-5 VTR has become the basis for modification for Panasonic High Definition VTRs.

DA (D A)
Shorthand for distribution amplifier, which can be either analog or digital, and for audio or video, and may require a power frame or may be designed to work as a stand-alone unit for desktop applications (such as in a small AC powered box enclosure). Video distribution amplifiers differ greatly in performance and capabilities. In addition to a wide band frequency response, the more expensive and more complex distribution amplifiers offer base cable equalization correction, additional adjustable gain settings, circuit clamping, a small adjustable line delay, and peak white level clipping. Some digital distribution amplifiers offer reclocking.

D/A (D to A)
Shorthand for Digital to Analog path and/or conversion.

DASE
Shorthand for Digital TV Application Software Environment. DASE Level 1 is Local Interaction/Enhanced TV; DASE Level 2 is Remote Interaction/Interactive TV, DASE Level 3 is Internet Enabled/Internet TV.

DBS
Shorthand for Direct Broadcast Satellite.

DBS Band
Shorthand for Direct Broadcast Satellite Band, 11.70-12.40ghz frequency.

DCCSCT
Shorthand for Directed Channel Change Selection Code Table.

DCCT
Shorthand for Directed Channel Change Table.

DCT
Shorthand for Discrete Cosine Transform, used as part of the compression schemes (but used differently) in JPEG, MJPEG, MPEG1, MPEG2, Digital Betacam, Ampex DCT, Digital-S, DV, DVCam, all DVCPro formats, Panasonic D-5 HD, and Sony HDCam formats. Coincidentally also the name of the Ampex 2:1 8-bit switchable 525/60 and 625/50 compressed 4:2:2 component digital tape format developed by Ampex.

Delay
The amount of time necessary for an analog or digital signal to pass through a device or circuit conductor or wire. A complex facility or a simple editing facility may share the same types of problems trying to overcome the effects of unwanted delay, especially where precise timing (phasing) is required not only between audio tracks but in relation to multiple video channels, such as mixing and recording AC-3 audio for DVD. It is important to know that there is always a delay when passing any signal, and that the delay will increase depending upon the amount of processing of the signal that may be involved, however the delay (or cumulative delay through multiple devices, circuits, and cables) may not be relevant to your application if it is minimal, and if in reference to video and audio and time code, the delays are all the same. A circuit or wire delay is also called a "Propagation Delay". Digital devices tend to create more delay than analog devices. New generation digital video synchronizers with auto-tracking audio and time code delays are used to correct for minor video to audio delays in standard definition video. If the video delay is severe, a new generation video time/memory cache may be employed. The concept of adding a delay can also be beneficial to live event or delayed broadcast coverage (helping to insure that station breaks are properly inserted, adding profanity delay, etc.) and may involve a multiple channel video server whereby an input channel is used to live record, and an output channel with access to the same disk storage for recall outputs the delayed feed (sometimes after editing). In the past, profanity broadcast delay was made possible by placing two tape machines near each other, recording on one, and stretch feeding the tape across the room to the playback machine.

DENS
Density (of film negative or inter-negative). Many old television shows from the 1960's filmed in color negative tended to be carefully "overexposed" and photographed with high light intensity, low (even) lighting ratios, and significant depth of field to help reproduce bright colored images for the newly available color home television receivers.

Depth of Focus
An infinitely small range behind the lens at the focal plane within a film camera within which the film is positioned as it is exposed, or within a video camera relating to the distance from the back of the lens to the light prism, and the spatial offset between the light prism and the CCD.

Deserializer
A device that converts serial digital data (or digital video) information to parallel digital data (or digital video) information. The opposite of the deserializer is the serializer. There are different video deserializers for 4fsc, and for 4:2:2 component digital, and for the different line rates of high definition.

Dichroic Prism
A transparent optical light bending block that divides incoming light into red, green, and blue primary color components in an analog or digital camera for precision image sampling (or sub-sampling).

Digital Betacam
A standard definition 1/2" MP digital 2:1 8-bit or 10-bit compressed 4:2:2 13.5MHz sampled 95Mb/sec (picture payload) component digital tape format that uses proprietary DCT compression, and developed by Sony, which has become a general mastering format for standard definition telecine and broadcast and cable network program delivery. Units are manufactured for either PAL Standard or for NTSC Standard. NTSC characteristics are 30 frames/second field interlaced with an active picture area of 720x486 (NTSC) active lines.

Digital-S (also known as D-9)
A standard definition digital 3:1 8-bit compressed 4:2:2 sampled 50Mb/sec (picture payload) component digital tape format that uses non-proprietary DCT compression on a proprietary (but licensed) tape format developed by JVC. Units are manufactured for either PAL Standard or for NTSC Standard. NTSC characteristics are 30 frames/second field interlaced with an active picture area of 720x480 (NTSC) active lines (select new units may allow for some increase of the active line count by allowing special storage of data for several lines).

DISS (Dissolve)
Shorthand for Dissolve, a blending of images, usually from just one image into another, achieved optically, and/or electronically (as in a video mixer with analog hardware circuits and frame/field memory circuits or with digital hardware data processing and digital frame buffers), or through digital processing hardware and software (as in a computer system). The time rate of the blending can theoretically be mathematical or logarithmic, and sometimes a third image (or more) is used subtly within the dissolve to direct attention during the dissolve, or to produce a desired effect. Morphing, a term used to describe a blending transformation of an object (or person, or image) into another can also involve a dissolve (or series of dissolves) between successive frames.

DIT
Shorthand for Discontinuity Information Table.

DLT
Shorthand for (Quantum) Digital Linear Tape.

DSLAM
Shorthand for Digital Subscriber Line Access Multiplexer.

DSM-CC
Shorthand for Digital Storage Media-Command and Control specifications (ISO/IEC 13818-6).

DSS
Shorthand for Digital Satellite System, used in the U.S. for DirectTV.

DTA
Shorthand for Digital Turn Around.

DTS
Shorthand for Digital Theatre Systems audio 5.1 channel encoding alternative to Dolby Digital AC-3 audio 5.1 channel encoding. Also shorthand for Decode Time Stamp.

DTV
Shorthand for Digital Television, the over-the-air broadcast standards include ATSC Table 3 format compliance and compliance with SMPTE310M.

DV
A standard definition 1/4" ME consumer digital 10 micron track pitch 5:1 8-bit compressed 4:1:1 (NTSC) 4:2:0 (PAL) sampled 25Mb/sec (picture payload) 30 frame/second field interlaced component digital recording format that uses unlocked digital audio and non-proprietary DCT based DV compression on a Metal Evaporated tape format, and joint manufacturer developed codec hardware and/or software. Common interchange of playback signals between DV devices and with other manufacturer's standard definition equipment is through analog interfaces, although professional equipment is available for allowing for DV playback with a 270Mb/s SDI interface. Common exchange of files between DV devices is possible through 4 or 6 pin (depending upon the devices) I-Link IEEE 1394 "Firewire" with DV driver sets (and DV protocol) and DV software codecs. NTSC characteristics are 30 frames/second field interlaced with an active picture area of 720x480 (NTSC) active lines.

DVB
Shorthand for Digital Video Broadcast. There are three sub-sections. DVB-C for cable, DVB-T for terrestrial, and DVB-S for satellite.

DVB-ASI
Shorthand for Digital Video Broadcast Asynchronous Serial Interface commonly used in Europe for video-based MPEG II transport stream interfacing via electrical copper (BNC) cabling or optical (fiber). Decoding DVB transport streams include FEC (forward error correction) decoding, and de-interleaving, and the transport stream may or may not have to be frequency demodulated, decrypted and de-muxed from other channels as part of the RF modulation passing to and from the L Band frequency bounced off a satellite.

DVB-CI
Shorthand for Digital Video Broadcast Common Interface.

DVCam
A standard definition 1/4" ME digital 15 micron track pitch 5:1 8-bit compressed 4:1:1 (NTSC) 4:2:0 (PAL) sampled 25Mb/sec (picture payload) 30 frame/second field interlaced component digital recording format that uses locked digital audio, field flags, and non-proprietary DCT based DV compression on a Metal Evaporated tape format, and joint manufacturer developed codec hardware and/or software. Common interchange of playback signals between Sony devices and with other manufacturer's standard definition equipment is through a 270Mb/s SDI Interface or through analog interfaces. Common exchange of files between DVCam devices is possible through 4 or 6 pin (depending upon the devices) I-Link IEEE 1394 "Firewire" with DVCam driver sets (and DVCam protocol) and DVCam software codecs, or through two different types of SDI-type DVCam Data Interfaces. NTSC characteristics are 30 frames/second field interlaced with an active picture area of 720x480 (NTSC) active lines.

DVCPro (DVCPro 25)
A standard definition 1/4" MP digital 18 micron track pitch 5:1 8-bit compressed 4:1:1 (NTSC) 4:2:0 (PAL) sampled 25Mb/sec (picture payload) 30 frame/second field interlaced component digital recording format that uses locked digital audio, an analog audio cue track, and non-proprietary DCT based DV compression on a proprietary (but licensed) Metal Particle tape format, and/or proprietary (but licensed) codec hardware developed by Panasonic. Common interchange of playback signals between Panasonic devices and with other manufacturer's standard definition equipment is through a 270Mb/s SDI Interface, or through analog interfaces. Common exchange of files between DVCPro devices is possible through 4 or 6 pin (depending upon the devices) I-Link IEEE 1394 "Firewire" with DVCPro driver sets (with DVCPro protocol) and DVCPro software codecs, or through two different types of SDI-type DVCPro Data Interfaces. NTSC characteristics are 30 frames/second field interlaced with an active picture area of 720x480 (NTSC) active lines.

DVCPro 50
A standard definition 1/4" MP digital 3:1 8-bit compressed 4:2:2 sampled 50Mb/sec (picture payload) 30 frame/second field interlaced component digital recording format that uses non-proprietary DCT based DV compression on a proprietary (but licensed) Metal Particle tape format, and/or proprietary (but licensed) codec hardware developed by Panasonic. Common interchange of playback signal between Panasonic devices and with other manufacturer's standard definition equipment is through a 270Mb/s SDI Interface or through analog interfaces. Camera Units are generally manufactured for either PAL Standard or for NTSC Standard, although some VTRs are manufactured for dual standard recording and playback (dual standard analog video decoding may not be possible without swapping out decoder board options, however). NTSC characteristics are 30 frames/second field interlaced with an active picture area of 720x480 (NTSC) active lines (it is possible but unconfirmed at this time that select VTR units may allow for some increase of the active line count by allowing special storage of data for several lines).

DVCPro 50P (Progressive Mode)
An ATSC table compliant 480p 60 frame/second progressive component digital 1/4" MP 8-bit compressed 4:2:0 sampled 50Mb/sec (picture payload) recording format that uses non-proprietary DCT based DV compression on a proprietary (but licensed) Metal Particle tape format, and/or proprietary (but licensed) codec hardware developed by Panasonic. Common interchange of playback signal between 480p Panasonic devices and with other manufacturer's 480p equipment is through a 360Mb/s dual SDI Interface or through 480p analog interfaces (note: no exchange of signals is possible with standard definition equipment or with 1080i, 1080p, or 720p without format conversion).

DVCPro 100
A "High Definition" 16:9 digital 8-bit 1/4" MP compressed 100Mb/sec (picture payload) 30 frame/second field interlaced component digital recording format that uses non-proprietary DCT based DV compression on a proprietary (but licensed) Metal Particle tape format, and/or proprietary (but licensed) codec hardware developed by Panasonic. Common interchange of recorded signal between Panasonic devices and with other manufacturer's standard definition equipment is through HDSDI or HD analog.

DWDM
Shorthand for Dense Wavelength Division Multiplexing.

E

EDH
Shorthand for Error Detection and Handling, a digital signal error detection data insertion and monitoring standard developed by Tektronix for an in-service test (meaning at the same time the equipment is being used in a system) to pinpoint in EDH monitoring and test equipment, system data recovery failures upstream of the EDH monitor.
EFX or FX (Effects)
Shorthand for Effects.

EIT
Shorthand for Event Information Table.

Emissions Limits
In television, "emissions limits" refers to regulatory governmental agency tolerance levels established which limit or do not cause interference to radio or television reception when one or more wall and 30 feet separate the emitting device and the television set or radio. With respect to digital electronic devices, radiation emissions are generally monitored in the United States by the FCC and are expressed in frequency of emission levels (MHz levels) with conductive limits for conductive emissions sent through wires in the power cord (expressed in millivolts) for different classifications of devices (typically Class A or Class B). Class A devices emit up to 10 times or more interference than Class B devices.

EMM
Shorthand for Element Management Message.

EMS
Shorthand for Element Management System.

EPG
Shorthand for Electronic Program Guide.

Equalization for cable loss
In television and video, correcting for the high frequency and low frequency signal attenuation losses introduced by coaxial cable (a loss of up to 45dB at 270MHz for a typical 300 meter long coaxial cable).

ESCR
Shorthand for Elementary Stream Clock Reference.

ETM
Shorthand for Encoded Text Message.

ETT
Shorthand for Encoded Text Table.

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F

Field
In NTSC interlaced video, one field is half of one video frame equal to 262.5 horizontal lines with a horizontal line frequency of 63.5 microseconds per line at 59.94 Hz vertical frequency, where the odd field is displayed first, followed by the even field. The persistence of vision, line averaging, filtering, and the latent image retention characteristics of interlaced circuit phosphor display CRT tubes allows the image of one field to "overlap" onto the next field, resulting in a seemingly complete picture, yet in interlaced video displays, only one half of the vertical resolution of an interlaced video picture is seen at a time. Today’s progressive scan images may employ segmented frames in which the allocated space to record odd and even fields is used to record successive fields of picture information that had been obtained with a progressive scanning process, bypassing the normal line averaging and filtering processes to produce a complete frame ready for progressive display and simultaneously compatible with interlaced field display.
Field of View
The dimensions of the photographed area at the plane of focus (which will be slightly different at the same distance if the lens is not focused on this plane).

FCC
Shorthand for Federal Communications Commission, which regulates frequencies from 9000 Herz to 300 billion Herz including emission limits for different classifications of devices.

FDDI
Shorthand for Fiber Distributed Data Interface.

Footcandle
The intensity of light falling on a surface placed 1 foot away from a point light source of 1 candle power.

FSS Band
Part of the KU Band 10.70-18ghz.

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G

Gain
In television terms, the strength or amplitude of an analog or digital video or audio signal. Input amplifiers on certain devices help "range in" signals that lose strength through long signal paths. A digital signal will have a steep "cliff" effect of no recovery at the point where the gain is no longer sufficient to recover the signal.
Gamma Correction
In electronic display, refers to a compensating nonlinearity correction to overcome the nonlinear electrooptical transfer characteristics of any given display device (individual device power transfer characteristics can differ greatly). In NTSC television, the assumed receiver gamma is 2.2, and in PAL and SECAM, the assumed receiver gamma is 2.8. Television and video have a linear transfer curve. Film has a log transfer curve. In the use of film, gamma correction applies to correcting for either negative or reversal exposure characteristics or correcting for the reversal exposure characteristics of a print. In film projection, projection print gamma is affected by the light source and ambient light. Different film stocks whether used in a film camera or as projection prints have a different gamma response. A camera negative film stock may have a gamma of 2.048, for example, but the projected film print made of the same negative may have a gamma of 1.5.

GPS
Shorthand for Global Positioning System.

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H

HAD
Shorthand for Hole Accumulation Diode. A Sony Term for Advanced HAD Technology which significantly reduces noise in CCD imaging when photographing dark objects or in low light conditions.

HANC
Shorthand for Horizontal Ancillary data stored in the unused space between the EAV and SAV of all active video lines of a digital HDTV signal as part of SMPTE 292M. Time code is stored in this area in HDTV digital formats.

HD SDI
Shorthand for High Definition Serial Digital Interface or commonly referring to a 1.5Gb/sec SMPTE 292M Interface of High Definition 1080 Interlaced Component Digital signal.
Horizontal Pixels
Refers in digital video to the number of discrete elements per scanning line (interlaced or progressive scan) used to generate and display an image in the horizontal screen direction, which are derived from the multiple of the horizontal scanning or subcarrier frequency. Digitized NTSC and CCIR-601 signals will produce non square pixel displays.

Hz (abbreviation for Hertz)
A unit of measurement which refers to the frequency or repetition rate (or in the case of display, correlated with the expression of the "retrace" or "vertical refresh" rate) per second of an electrical energy signal, and is also commonly expressed as cycles per second. NTSC Television is currently referenced to 59.94Hz for its vertical frequency scan rate, but has a horizontal frequency scan rate many times greater of approximately 15.75 kHz (15,750 Hz). In another use of the term Hertz for measurement, power line frequency in the United States is set at 60Hz.

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I

Image Size
Not to be confused with Image Resolution, Image Size generally refers to the displayed spatial resolution of a picture, e.g.: a still image captured on a digital consumer video camera may have an image size of 640x480 pixels when displayed on a computer monitor, but the actual resolution of the image from a depth of modulation measurement test is significantly less.

Interlaced Video
A television scanning process in which two fields of video (an odd line field and an even line field) are "interlaced" to represent one whole video frame image upon display. If Adaptive Frame Interpolation image processing is used, the two video fields will be filtered and combined into one frame upon display with smoother "jagged" stair step transitions between the original interlaced lines.
I/O
Shorthand for Input/output.

IRD
Shorthand for Integrated Receiver Decoder, a satellite receiver with a built-in decoder for unscrambling conditional access (scrambled) programs. The decoder may require permissions to be granted by access codes or even by constant bi-directional scrambled communication with the sender.

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J

Jitter
Jumping or instability in an analog or digital signal.
JPEG
Shorthand for Joint Photographic Experts Group DCT (Discrete Cosine Transform) based compression used for still images and derived from specialized software/hardware encoding and decoding.

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K

kbps
Shorthand for Kilobits per second.
kHz (abbreviation for Kilohertz)
A unit of measurement 1000 times greater than Hertz (i.e., 1 Kilohertz = 1,000 Hertz) which refers to the frequency or repetition rate (or in the case of display, often correlated with the expression of the "horizontal scan rate") per second of an electrical energy signal, and is also commonly expressed as cycles per second. NTSC Television is currently referenced to 59.94Hz for its vertical frequency scan rate, but has a horizontal frequency scan rate many times greater of approximately 15.734.26 kHz (15,734 Hz).

KLV
Shorthand for Key Length Value octet-level 8-bit word data encoding protocol, a part of the data infrastructure for the encoding and processing of media content for representing data items and data groups as defined in SMPTE 336M, where data can be coded in either full form - universal sets - or in one of four other groups referred to as global sets, local sets, variable-length packs or fixed-length packs.

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L

LNBF
Shorthand for Low Noise Blockdown Feedhorn, which sits at the focus point of a satellite dish and amplifies received microwave signals and then converts them to a lower frequency to be sent along a cable to a satellite receiver.

Lossless Compression
Fully-reversible compression when the regenerated image is exactly the same as the original image.
Lossy Compression
Non-reversible compression when the regenerated image is different from the original image.

LSB
Shorthand for Least Significant Bit.

LTC
Shorthand for Longitudinal Time Code, a type of audible audio pulse SMPTE Drop Frame or Non-Drop Frame time code that is recorded on the audio track of a videotape. Address track time code used on old Broadcast �" U-Matic SP machines is a form of a different type of vertical interval time code, but it is written in the vertical interval longitudinally.

LTO
Shorthand for Linear Tape Open IBM digital tape cartridge archive.

Lumen
A measurement of light equal to the amount of light falling on a foot square surface which is 1 foot away from a point light source of 1 candlepower.

Lux
An international photometric term representing a metre-candle as a unit of intensity of illumination. A Lux level of 10.764 metre-candles equals 1 footcandle. A Lux level of 2000 metre-candles equals 186.2 foot candles. A standard definition television CCD camera with a sensitivity of 2000 Lux at f11.0 would respond to the value of 186.2 foot candles of reflectance under 3200 Kelvin color temperature light from a specified reflective white surface (e.g., 89.9% reflectance) with the corresponding lens opening of f11.0 at 0 gain to represent white at peak 100 IRE voltage exposure. Operating such a camera with 0 dB gain could correlate with the response of approximately an 800 ASA exposure index.

Line Frequency
Refers in television/video to the number of horizontal line scans per second. Refers in electrical terms to power line frequency (in the United States, power line frequency is set at 60Hz, in Europe, it is set at 50 Hz).

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M

Mbps or Mb/Sec
Shorthand for Megabits per second.
MBps or MB/Sec
Shorthand for Megabytes per second, one Megabyte equals 8 Megabits, or 1,048,576 bites.

MCPC
Shorthand for Multi Channel Per Carrier.

MGT
Shorthand for Master Guide Table.

MHP
Shorthand for Media Home Platform, the European equivalent of digital video broadcast (DVB).

MHz
Shorthand for Megahertz. One million hertz cycles per second.

MIC
Shorthand for Microphone, also for (Sony) Memory In Cassette, a 16kb memory chip for storing data about the data, reducing seek time.

MJPEG
Shorthand for Motion JPEG (Joint Photographic Experts Group) DCT (Discrete Cosine Transform) based JPEG compression derived from specialized software and/or hardware encoding and decoding.

MMDS
Shorthand for Multi-channel Multi-point Distribution Service commonly used in cable television for analog or digital signals within a short range of about 30 miles.

Monitor/Receiver
Display device (typically CRT or LCD) with a built-in RF tuner to display either pictures within the scan range capabilities of the display circuits, and/or broadcast television (and/or cable television) RF modulated signals.

MOS
Shorthand for "Media Object Server" Protocol and also "Mid-Out Sound" (silent).

MPEG
Shorthand for Motion Picture Experts Group and many different but related MPEG compression algorithms derived from specialized software and/or hardware encoding and decoding. There are some exchange issues relative to the MPEG file format used for proprietary applications data. There are also MPEG Program Streams, such as derived from and between file format compatible storage systems, and MPEG Transport Streams (which also may be multiplexed) for digital broadcast. MPEG uses different types of frames, such as I (identifying), B (bi-directional), and P (predicted) frames. A GOP is a Group of Pictures related to the I frame for compression decoding.

MPTS
Shorthand for Multi-Program Transport Stream.

MSB
Shorthand for Most Significant Bit.

MTBF
Shorthand for Mean Time Between Failures.

MTF
Shorthand for Modulation Transfer Function.

MVPD
Shorthand for Multichannel Video Program Distributor.

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N

NABTS
Shorthand for North American Basic TeleText Specification, the open standard for transmission of data over the television vertical blanking interval.

NAS
Shorthand for Network Attached Storage.

NIT
Shorthand for Network Information Table, which contains details of the bearer network and RF carrier frequency used to transmit an MPEG TS multiplex.

NMS
Shorthand for Network Management System.

NVOD
Shorthand for Near Video On Demand.

Nyquist Sampling Theorem
Suggests that intervals between successive samples should be equal to or less than one half the period of highest frequency, meaning that the sample frequency must be at least double the frequency of the sample.

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O

OOB
Shorthand for Out Of Band.

Orthogonal Sampling
Related to the repetitive sampling of video lines in which during the process the horizontal samples of any one line are in the same fixed horizontal position.

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P

Parallel Cable
A multi-conductor data cable that carries simultaneous transmission of data bits.
PAT
Shorthand for Program Association Table, lists the PIDs of tables describing each program within an MPEG multiplex.

Patch Cable
A wire jumper (or wire jumper set) to manually connect like signal source and destination on a patch panel. Patch Cables and Patch Panels can be designed to carry analog and digital signals, including digital data.

Patch Panel
A manual method of using wire jumpers (or wire jumper sets) to connect like signal sources and destinations using a panel of receptacles.

PCM
Shorthand for Pulse Code Modulation, used to modulate audio channels.

PCMCIA
Shorthand for Personal Computer Memory Card International Association peripheral interface memory card, available in three different card types for IBM, Mac, and other computers. Type 1 cards are generally used for memory expansion. Type 2 cards specify I/O circuitry and connections for networks. Type 3 cards may contain a hard disk drive.

PCR
Shorthand for Program Clock Reference.

PDC
Shorthand for Program Devilery Control.

PDH Network
Shorthand for Plesiochronous Digital Hierarchy (Network) form of multiplexing data at rates of from 2 Mb/s to 565 Mb/s with optical fiber connectivity developed for Telco applications but can be used for digital video.

Peak to Peak
The amplitude voltage difference between the most positive and the most negative peak levels of an electrical signal.

Peak White
Brightest possible level of a video signal.

Pedestal
Reference black level of the video signal, set for 7.5 ire for NTSC, 0 ire Japan standard.

PES
Shorthand for Packetized Elementary Stream.

PID
Shorthand for Packet Identifyer.

Pixel (or subpixel)
Derived from Picture (Pix) Element (el) and determined from software and hardware and bandwidth to be the smallest distinguishable and resolvable horizontal/vertical element area of a digital image, and in combination with the number of bits used to represent the pixel value, can also be (but is not necessarily) indicative by pixel count of the horizontal and vertical pixels of the two-dimensional resolution of an image.

Pixel Aspect Ratio
Refers in digital video or computer graphics to the ratio of the horizontal pixel spacing to the vertical pixel spacing, also called "dot spacing", but does not refer to the actual shape of the pixel (changing the pixel aspect ratio in display will "overlap" pixels).

Plate
Term used to describe the act of or temporary result of isolated image creation or photography (such as of image elements of objects, backgrounds, effects, people) or temporary combination of image elements used in image compositing to produce a new image (e.g., a background plate, a foreground plate, an element plate, a shadow plate, and a matte plate are all combined in a special order in the image compositing process to produce a desired effect or another image). Complex images can require the production of and special combination of hundreds of "plates".

PMT
Shorthand for Program Map Table.

PSI
Shorthand for Program Specific Information.

PSIP
Shorthand for Program and System Information Protocol as defined by the ATSC A/65 Standard, for carring progam names, netword ID's, channel numbers, V-Chip ratings, and other informational data in Digital Television Broadcasting.

PPV
Shorthand for Pay-per-view conditional access.

Proc Amp
Shorthand for Processing Amplifier, an analog or a digital device that is sometimes built in to videotape recorders and players to rebuild and stabilize signals, such as the otherwise jittery luma signal from VHS sources. If the proc amp is also capable of rebuilding the sync portion of the signal, than it would be more appropriately referred to as a Time Base Corrector (see Time Base Corrector).

Protocol
A set of standards specific to manufacturer, to device, to software, and/or to interface for the common exchange of electrical data values including data format, data order, timing, and error checking method. Examples of Fiber Channel supported protocol types are SCSI, ATM, IPI, HIPPI, TCP/IP, and Ethernet. As another example, different videotape recorders have their own protocol variant for optimum performance with respect to timing and feature sets, but also share Sony BVW-75 protocol emulation.

PTC
Shorthand for Physical Transmission Channel.

PTS
Shorthand for Presentation Time Stamp.

PVR
Shorthand for Personal Video Recorders such as TIVO.

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Q

QAM
Shorthand for Quadrature Amplitude Modulation method of modulating digital signals onto an RF (Radio Frequency) carrier which involves both amplitude and phase coding, used by dial up modems and broadband networks.

QPSK
Shorthand for Quadrature Phase Shift Keying method of modulating digital signals used by dial up modems and for digital delivery of television from DBS (Direct Broadcast) satellite.

Quantization
Process of converting an analog input into a set of discrete output levels.

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R

RAID
Shorthand for Redundant Arrays of Inexpensive Disks, a standard with different levels (0, 1, 3, 5, 6, and 7). Raid controllers typically operate under proprietary (to a particular manufacturer and/or performance device) disk control protocols.
RAID 0
Raid controller(s) spread(s) data across all disks.

RAID 1
Raid controller(s) put(s) duplicate copy of the incoming data on a separate disk.

RAID 3
Raid controller(s) spread(s) data across all disks, an extra drive is added and used for parity storage. Maintains performance in single drive failure and recovery.

RAID 5
Parity information spread across all drives. Higher performance than Raid 3 except during single drive failure and recovery.

RAID 6
Allows for dual drive failure and recovery, or a second drive to fail during recovery.

RAID 7
Proprietary system developed by Storage Computer Corporation in 1991 using an embedded operating system, independent control, and data paths, and supports multiple host interfaces.

Reclocking
With respect to a digital signal, the process of regenerating the original data with a regenerated clock with the same integer value before sending the digital signal through the circuit. Device inputs may provide a range of reclocking capabilities, as may device outputs. If the data clock value is not common between the send and the receive side, reclocking should be turned off or the signal will not properly pass. Data is reclocked in order to assist the next receiving device or the next circuit in line with the data path to help recover the digital signal should the path or circuit be overly long or otherwise out of the range of the input amplifier.

RRT
Shorthand for Rating Region Table.

RST
Shorthand for Running Status Table.

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S

Sampling
Process where analog signals are measured.
Sampling Frequency
The number of sample measurements made in a given period of time.

SAN
Shorthand for Storage Area Network.

SAV
Shorthand for Start of Active Video, a timing reference signal consisting of a four-word sequence using 10-bit hexadecimal values to identify line sync information, field identification, state of vertical blanking, and state of horizontal blanking in a digital video signal.

SCSI
Shorthand for Small Computer System Interface, a type of parallel bus interface between devices requiring a host with SCSI port hardware, specific addressing, appropriately rated cabling, and often different software protocol drivers to implement. SCSI is available in different levels, requiring different support hardware, cabling, and software. SCSI 3 can be implemented over firewire, SSA (Serial Storage Architecture) and FC-AL (Fiber Channel-Arbitrated Loop).

SDI
Shorthand for Serial Digital Interface or commonly referring to a 270 Mb/sec SMPTE 259M Component Digital signal.

SDT
Shorthand for Service Description Table.

SDTI-CP
Shorthand for Serial Data Transport Interface Content Protocol or commonly referring to an exchange standard under SMPTE 326M for native video data and metadata including file format information used in a storage system. Certain DVCAM VTR units with SDTI-CP codecs can connect to other similarly equipped DVCAM units to exchange native compressed video data provided the file information can also be exchanged (such as NTSC to NTSC, but not NTSC to PAL or PAL to NTSC, or not DVCAM to Betacam SX).

SDH Network
Shorthand for Synchronous Digital Hierarchy (Network) form of multiplexing data with optical fiber connectivity, developed for Telco applications but can be used for digital video.

Serial Digital
Digital information (or digital video) transmitted (or sent from one device to others) in serial form.

Serializer
A device that converts parallel digital data (or digital video) information to serial digital data (or digital video) information. The opposite of the serializer is the deserializer. There are different video serializers for 4fsc, and for 4:2:2 component digital, and for the different line rates of high definition.

SI
Shorthand for Service Information.

SIT
Shorthand for Selection Information Table.

SMI
Shorthand for Storage Media Interoperability.

SNMP
Shorthand for Simple Network Management Protocol.

SoIP
Shorthand for Storage over Internet Protocol (SoIP).

Sonet Telecom Standards
Includes DS-3 and OC-3.

Spatial Uniformity
A measure of the uniformity of the reproduction of brightness on a screen or display device or monitor.

SPI
Shorthand for Synchronous Parallel Interface, part of the DVB Digital Video Broadcast specification for moving MPEG transport streams through a 25-pin parallel interface at data rates of up to 70 Mb/s over a few meters.

SPTS
Shorthand for Single Program Transport Stream.

SSI
Shorthand for Synchronous Serial Interface, part of the SMPTE 310 specification for supporting clocked data rates of 19.39 Mb/s (8-VSB) and 38.78 DVB (16-VSB) and recommended only for ATSC modulators.

SSP
Shorthand for Storage Service Providers.

ST
Shorthand for (bit) Stuffing Table.

STD
Shorthand for System Target Decoder.

Still Store
Typically refers to a specially designed high performance device and/or high performance software specifically designed for the rapid capture of, storage of, manipulation of, and recall of specific frames of video and associated graphic key signals.

STT
Shorthand for System Time Table.

SuperDLT
Shorthand for Super Digital Linear Tape, for storing up to 200 MB and allowing for up to 20 MBps data throughput.

SVGA
Shorthand for Super Video Graphics Array, and progressive scan resolution of 640x480 with a display color depth of 256 colors, 800x600 16 colors, 800x600 256 colors, 1024x768 16 colors, 1024x768 256 colors, 1280x1024 16 colors, or 1280x1024 256 colors.

Synchronous
Generally, synchronous means "at the same time as something else", or "with consistent reference to a commonality". In motion pictures and television, audio is generally noticed to be out of synchronization when it is delayed or advanced by more than 2 frames. With respect to digital information, synchronous refers to digital information transmitted (or sent from one device or buffer to others) with the bit stream and character stream slaved to accurately synchronized clocks, both at the receiving and sending end. However, when multiple signals of digital information are transmitted and also must be sent and must arrive at the same moment, other factors determine if the end result is in fact desirable, and, there may be "asynchronous"-type data (in simple terms meaning data out of context) sent with the synchronous data. For example, due to the fact that there are not an exact number of digital audio samples in the 525/60 video system per frame (not an integer number but rather a fractional number), digital audio signal to video frame alignment must also include "phasing" to a five-frame sequence, or when sending digital audio through a device or router, an audio sample is injected or dropped depending upon the switching point. Another example is the use of firewire to send digital video and digital audio signals from one device to another, where the audio signal may not be "locked" (phased) even though the digital send was synchronous, with the end effect resulting in audio clicks, pops, or drift at the receive side.

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T

TBC (Time Base Corrector)
A type of analog video stabilizing device with multiple layers of processing amplifiers (Proc Amps) for video signals that replaces the original signal timing references with newly generated timing references at the expense of increasing the signal to noise ratio of the original recording, but to help recover the signal stability lost from a VTR mechanical system. Typically, Time Base Correctors compare the sync and color jitter from a tape source to a stable sync and color reference. Analog TBCs had an input to output delay of less than 1 field. If the TBC employs digital sampling of the analog input signal, as most do today, the signal input to output delay from the additional digital sampling process forces the manufacturer to fix input to output delay to a fixed value, such as a 1 frame delay. The TBC is then advertised as a TBC and (Video) Frame Synchronizer. To overcome the fact that matching audio input to output delay and time code is not addressed when sending signal through the TBC Frame Synchronizer, and that correcting the audio delay precisely for all conditions under which a TBC Frame Synchronizer might be used in a facility was complicated, a new generation of TBC and Video/Audio Frame Synchronizers was developed which generally allow for a fixed delay to be set and an automatic tracking delay to be introduced on top of the fixed delay with respect to input timing reference.

TDT
Shorthand for Time Date Table.

Telecine
Refers to any number of specially designed high-performance analog or digital capture devices for transferring and manipulating the gama, aspect ratio, and speed of motion picture film negative or positive into either an analog video stream, analog color component signals, and/or digital data.

Telecom Standards
Standards for passing data at high speed over optical and electrical copper paths within the telecommunications industry. Sonet North American (Synchronous Optical Network) Telecom standards include DS-3 and OC-3. SDH International (Synchronous Digital Hierarchy) Telecom Standards include E1, E2, E3 and STM-1 network architectures.
THD
Shorthand for Total Harmonic Distortion.

Throw Ratio
Refers to the distance between the center of a projection lens and the screen it is projecting on, divided by the screen width.

TOT
Shorthand for Time Offset Table.

TPS
Shorthand for Transmission Parameter Signaling.

TS
Shorthand for Transport Stream.

TSID
Shorthand for Transport Stream Identifier used in one form with MPEG-2 ATSC subset Transport Streams, or shorthand for optional (non-required) analog NTSC Transmission Signal Identifier, for using NTSC signals with the DTV program guide, inserted into the Extended Data Services (XDS) portion of the NTSC Line 21 signals.

TTL
Shorthand for Transistor to Transistor Logic, refers to an analog pulse sync code with a voltage swing range from high to low used to drive or "gate" another device capable of responding to the TTL pulse, such as in driving a progressive scan video tap camera to clock out images to detected shutter impulses from a film camera.

TVCT
Shorthand for Terrestrial Virtual Channel Table.

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U

UHF
Shorthand for Ultra-High Frequency.

UL
Shorthand for Universal Label, as described in SMPTE 298M, a universal unique authoring labeling mechanism that aids in describing the origin, type, and encoding protocol of data within a general-purpose bitstream.

UMID
Shorthand for Unique Material Identifier, for production and broadcast environments detailed in the recommended practices (SMPTE RP 205-2000).
Underscan
Refers to the decreasing of the display raster so that the entire (or virtually entire) active picture area can be seen on a monitor or display device regardless of the displayed picture aspect ratio. The underscan image is useful for editing purposes to insure that the complete frame is seen and understood (such as verifying that microphone booms are not in the picture at the edge, and that people have actually exited the frame). Many monitors or display devices can not underscan. This typically involves special capabilities in the monitor or display device circuits, such as minus 8% to minus 10% scaling.

UTC
Shorthand for coordinated Universal Time.

UTP
Shorthand for Unshielded Twisted Pair wire.

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V

VANC
Shorthand for Vertical Ancillary as in data stored between the SAV and EAV of the 12 unused active video line spaces (lines 9-20) of a digital HDTV signal as part of SMPTE 292M.

VBI
Shorthand for Vertical Blanking Interval.

VCR
Shorthand for Video Tape Recorder.

VCT
Shorthand for Virtual Channel Table (such as CVCT or TVCT).
Vectorscope
Special form of an oscilloscope used in part to monitor chroma levels and chroma phase in video signals.

Vertical Scan Frequency
A video industry term referring to the process and amount of time it takes by which an image capture device, a display device, or a monitor is refreshed with information in the vertical dimension. Also referred to as the "frame rate" in the video industry, and the "refresh rate" in the computer industry.

VITC
Shorthand for Vertical Interval Time Code, stored on specific scan lines during the vertical blanking interval of a video signal.

VGA
Shorthand for Video Graphics Adapter, or Video Graphics Array. The Video Graphics Array would support progressive scan resolution of 640x480 with a color display depth of 16 colors.

VLAN
Shorthand for Virtual Local Area Network.

VOD
Shorthand for Video On Demand.

VPS
Shorthand for Vectors Per Sceond.

VSB
Shorthand for Vestigial Sideband.

VTR
Shorthand for Video Tape Recorder.

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W

Waveform
The shape of an electromagnetic wave, which can be viewed in an oscilloscope or a specially designed oscilloscope called a waveform monitor as a graphical representation of the relationship between voltage or current and time.
Waveform Monitor
A specially designed oscilloscope designed to measure the shape of an electromagnetic wave of a video signal.

WSS
Shorthand for Wide Screen Signaling. On 525 digital formats, it is a flag bit inserted by the camera or a data inserter box on/in line 20 and 283, and in 625 digital format on/in line 23 to enable monitors and receivers to switch orientation of their display aspect ration to 16:9, although per EIA 608B for NTSC analog the aspect ratio data is (or could be) carried in the extended data services packets of Line 21.

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X

XDS
Shorthand for Extended Data Service receiver/monitor display of current time, channel time, and program time (where service is available) stored/transmitted on the extended data service portion of NTSC Line 21.

XGA
Shorthand for Extended Video Graphics Array, and progressive scan resolution of 640x480 with a color display depth of 16 colors, 640x480 256 colors, 640x480 65,535 colors, 1024x768 16 colors, and 1024x768 256 colors.

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Y

YUV
Shorthand for Pal luma and weighted chrominance color difference components (the NTSC equivalent is Y/R-Y/B-Y, and also refers to the unmodulated storage channels of digital video disk recorders sampling standard definition video at 4:2:2 (technically, PAL receivers have a different gamma).
Y’,Cb,Cr
Shorthand for luma and weighted chrominance color difference components in ITU-R BT.601 color space.

Y’,Pb,Pr
Shorthand for luma and weighted chrominance color difference components derived from a digital source.

Y, R-Y, B-Y (Y/R-Y/B-Y)
Shorthand for luma and weighted chrominance color difference components derived from an analog source.

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Z

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Numeric

4fsc
Shorthand for an NTSC or PAL D-2 composite digital recording format meaning the sampling rate of signal is set at Four times the Frequency of SubCarrier. The 4fsc sampling frequency is 14.3 MHz (4 times the NTSC subcarrier frequency of 3.58 MHz) in NTSC and 17.7 MHz in PAL (4 times the PAL subcarrier frequency of 4.43 MHz).
4:1:1
Shorthand for digital luma frequency sampling rate of four times that of each of two color difference signals in the 4/3 aspect ratio, resulting in four times as many luma samples per active line (720 in 525/60 scanning standard versus 180 color difference samples per active line). In 525/60 standard, the value of 1 equals 3.375 MHz, and the value of 4 equals 13.5 MHz. In the 525/60 standard, consumer DV, DVC Pro, and DVCam are considered 4:1:1 digital formats.

4:2:2
Shorthand for digital luma frequency sampling rate of four times the frequency of 3.375 MHz compared to that of each of two color difference signals in the 4/3 aspect ratio sampling at two times the frequency of 3.375 MHz each (each channel of color difference sampling equals 6.75 MHz, or a combined color difference sampling frequency of 13.5 MHz) resulting in a ratio of 13.5:6.75:6.75 or twice as many luma samples per active line (720 in 525/60 scanning standard versus 360 color difference samples per active line). In the 525/60 standard, D-1, D-5, Digital Betacam, Digital-S, Betacam SX, and DVC Pro50 are considered 4:2:2 digital formats.

4:2:2:4
Shorthand for 4:2:2 with the addition of a key channel with a frequency sampling rate of four times the frequency of 3.375 MHz.

4:4:4
Shorthand for digital luma frequency sampling rate of four times the frequency of 3.375 MHz compared to full bandwidth color difference signals in the 4/3 aspect ratio also sampling at four times the frequency of 3.375 MHz each, resulting in a ratio of 13.5:13.5:13.5 or the same number of luma samples per active line (720 in 525/60 scanning standard) as color difference samples per active line. The 4:4:4 sampling is transmitted (sent) through parallel digital interfaces or through dual serial component digital interfaces (4:2:2 and 0:2:2 for a combined effect after reconstruction from the receiving buffer to be 4:4:4). D-1 format machines can be operated in parallel "tandem-like" fashion with special encoding and decoding buffer devices to support 4:4:4 recording and playback. New generation disk recorders can also support 4:4:4 standard definition recordings through the dual serial component digital interface.

4:4:4:4
Shorthand for 4:4:4 with the addition of a key channel with a frequency sampling rate the same as the luma frequency of 13.5 MHz.

8-VSB
Shorthand for Eight discrete amplitude level Vestigial Side-Band digital transmission.

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Updated 05/26/02