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Software or hardware that is promised or talked about but is not yet completed-and may never be released.  Vaporware is sometimes marketed, but has proven to be more profitable to the manufacturer than the purchaser. Caveat Emptor.

Variable Bit Rate Reduction:

See: Compression. 

Variable Focal Length Lens

See Zoom Lens.

VBR  (Variable Bit Rate) 

Operation where the bit rate varies with time during the decoding of a compressed bit stream. MPEG video compression where the amount of compression can be varied to allow for minimum degradation of the image in scenes that are harder to compress.

VBV  (Video Buffering Verifier) 

A hypothetical decoder that is conceptually connected to the output of an encoder.  Its purpose is to provide a constraint on the variability of the data rate that an encoder can produce. 

VCC  (Versatile Cart Controller) 

Generic term for group of CPU and interface boards mounted internally to a cart machine that function being to control devices internal and external to a cart machine.  See Flexicart and LMS. 

VCR  (Videocassette Recording or Recorder) 

VDC  (Versatile Device Controller) 

An external configuration of the VCC. 


Video Disk Recorder. Similar to a VTR except that it records to and plays from a magnetic disk rather than videotape. 


Refers to a special-purpose oscilloscope used to examine and measure the color burst and chrominance portion of a composite video signal.  The vectorscope offers a unique portrayal of the chrominance component of a video signal as vectors.  Radial distance from the center of the display equates to color saturation (the chrominance amplitude) and the angular distance counterclockwise equates to color hue (the chrominance phase).  The reference color burst is displayed on the vectorscope as a vector in the west (9 o'clock) direction..

Vertical Interval 

Refers to the synchronization information of the video signal in the first 21 lines of each video field.  This causes the electron beam in a monitor to return to the top of the display to commence another vertical scan.  Vertical blanking is defined as a pulse that spans the width of the entire vertical interval.  The vertical interval contains pre- and post-equalization pulses, vertical sync pulses, serration pulses, horizontal pulses, and possibly VITS, VIRS and VITC signals and codes. 

Vertical Interval Switcher

A device which can select between several video sources for viewing or signal routing. A switcher of this type makes the transition between sources during the vertical blanking interval of the two video signals. When both sources are in sync and the switch occurs at this time, the transition will appear smooth without any glitches or picture breakup.

Vertical Resolution

For television signals, the specification of resolution in the vertical direction. The ability to reproduce closely spaced horizontal lines. The maximum number of alternating white-and-black horizontal lines that can be counted from the top of the picture to the bottom, or the amount of detail that can be perceived in the vertical direction. Vertical resolution is only roughly equivalent to the number of horizontal scanning lines in a picture.

Vertical Retrace

The action taken by the beam-scanning circuitry in a monitor to return to the top of the display to commence another vertical scan. 

Vertical Scan Rate

The speed at which the electron beam scans down the entire screen of a monitor.

Vertical Sync

Synchronizing pulses used to define the end of one television field and the start of the next, occurring at a rate of approximately 59.94 Hz (color), and 60 Hz (black & white) in NTSC.

Vertical Sync Pulse

A pulse that is found on lines 4, 5 and 6 of a video field (in NTSC) and is used to trigger the start of each vertical scan. 

VGA  (Video Graphics Array) 

Refers to the standard Video Graphics Array adapter card or function of your computer. Standard VGA resolution is 320x240 pixels, while Super VGA resolutions are 640x480, 800x600, and 1024x768 


Video Home System - A consumer video cassette format 

Video Clip 

This is usually a part of some other program material.  It normally does not have an introduction or ending, but could.  A clip is "normally" intended to be used within other program material.  Its origin can be film, video or whatever. 

Video Distribution Amplifier  (VDA)

A device which provides multiple video outputs from one video source. VDAs are used to distribute the video signal to several pieces of equipment often over multiple locations.

Video Equalization Amplifier

A device used to maintain video signal quality and to compensate for signal losses in especially long cable runs.

Video for Windows:

Microsoft's system-level Windows software architecture that is similar to Apple Computer's QuickTime.


When video can be requested at any time and is available at the discretion of the end-user, it is then video-on-demand.

Video Loss Detectors

A device which can trigger an alarm when an unmonitored camera loses its output. The loss detector alerts the operator to a camera monitoring problem for prompt correction. Especially important in CCTV security applications.

Video Server 

A very large, super-fast hard drive, or a combination of hard drives, used to store digitized video. 

Video Sequence

A video sequence, which is represented by a sequence header, one or more groups of pictures, and an end-of-sequence code in the data stream. 

Video Signal

A waveform carrying video information.


The practice of connecting two or more people at two or more locations through analog or digital video transmission. Cameras, monitors, microphones, speakers, and computers create sound, data, and images that are transmitted. Videoconferencing rooms can be connected in point-to-point or multipoint configurations. (Also called video teleconferencing).


A disc medium for the storage of video and audio information. Laserdiscs store information on a spiral track of pits pressed into the surface of the disc and read by a laser. Discs are manufactured in CLV and CAV formats. Laservision discs are read only. Other types of videodisc (see WORM) can be recorded by the user. The term videodisc can also be applied to non-laser media such as the defunct RCA Selectavision format or to magnetic disc media. (See CAV and CLV).

Video Shading,

Shading is a term that goes back to the time of black and white. The video operator would have the ability to not only address the amplitude (white levels) but the black levels (pedestal). In some instances, there were parabolic controls that would permit the change of the gray scale areas between white levels and black levels. In color, this operations is performed by a colorist and involves all three color signals - Red, Blue and Green.


Oxide-coated or evaporated, metal-particle, plastic-based magnetic tape used for recording video and audio signals.


One of the earliest pick-up tube designs, and the first imager used in CCTV, the Vidicon is the forerunner of most pick-up tube designs. Vidicon imagers are still the most common tube-type imagers in CCTV primarily because they are inexpensive. However, they are not as sensitive as other tube types and exhibit more problems with burn-in and lag.

Viewing Angle

The maximum perceived resolution of a picture viewed when the eye subtends its limit of angular discrimination of 1 minute of arc on the front surface of the screen, and captures, or recognizes a single pixel.

At the minimum viewing angle the observer will see maximum unimpaired resolution, no pixels, scan lines or normal picture artifacts will be seen from this position. When moving closer to the display, pixels, scan lines and normal picture artifacts will now become progressively visible. When moving farther away from the display, perceived horizontal and vertical resolution will diminish progressively.


VIRS (Vertical Interval Reference) 

This signal is optionally transmitted on line 19 (NTSC) and is used as a reference for resetting black level, white-to-black gain, chrominance and amplitude at reference phase. 

Virtual Channel 

An aggregation of elementals, which can be recombined to suit particular viewers.


A program which replicates itself on computer systems by incorporating itself into other programs that are shared among computer systems.  Viruses vary, and can be harmless or completely debilitating to a computer system.

Vision Mixer

(British) Vision Switcher. Device with a series of input selectors that permits one or more selected inputs to be combined, manipulated and sent out on the program line.  see switcher

VITC (Vertical Interval Time Code) 

Often stored in non-adjacent lines (e.g. lines 13 and 15) of the vertical interval, VITC is a version of time code stored in each video field.  It offers precise video frame identification during stopped or slow motion viewing and does not make use of an audio channel as in Longitudinal Time Code. 

Viterbi Decoding

Makes use of the predefined time sequence of the bits through convolution coding (DVB-S).  Incorrectly transmitted bits are corrected through a series of logic decisions by way of the trellis diagram. 


Optional signals stored in the vertical interval often used in broadcast transmissions.  Typical VITS signals in NTSC as specified by the FCC include a Multiburst test signal (line 17, field 1), a Color Bar test signal (line 17, field 2), and others. 

VLC  (Variable Length Coding) 

Coding of data with variable number of bits (also see RLC). 

VMD  (Video Motion Detector)

A device that is used in conjunction with CCTV cameras to detect movement within a specified area covered by the relevant camera. Motion detectors often are used to simultaneously trigger an alarm, turn on additional lights, and automatically switch the camera on for viewing and recording.

Voice Activation

A long-sought-after capability to “talk to” your computer instead of inputting commands on a keyboard or mouse. New products that take advantage of improved voice recognition software, such as Voice Navigator from Articulate Systems, show the reality of these systems growing closer.

Voice-Activated Cameras

In full-motion videoconferencing, refers to a control system which uses the voice of the participant who is talking to turn on the camera which is pointed toward that speaker.


A spoken message delivered off-camera. This is the opposite of Lip Sync recording which is done live as the actors are being photographed. An off-screen narration would be considered a “voice-over.”


A teleconferencing device or system which switches control of certain functions based on which individual is speaking. Some audio and video teleconferencing bridges use voice switches to select the single speaker who will be heard and seen by all other sites.

VRML  (Virtual reality modeling language)

An ISO standard for 3-D multimedia and shared virtual worlds on the Internet.  An open, extensible, industry-standard scene description language for 3-D scenes, or worlds, on the Internet. With VRML and certain software tools, you can create and view distributed, interactive 3-D worlds that are rich with text, images, animation, sound, music and video.

VSB  (Vestigial Sideband Modulation) 

Vestigial side band. VSB is a digital frequency modulation technique used to send data over a coaxial cable network. Used by Hybrid Networks for upstream digital transmissions, VSB is faster than the more commonly used QPSK, but it's also more susceptible to noise. 

·8 VSB has 8 discrete amplitude levels 

·16 VSB has 16 discrete amplitude levels 

n VSB Modulation 

Transmission of n discrete amplitude values using the vestigial sideband method on normal terrestrial (DVB-T) channels and conventional IF modulators.  The most common variant is 8-VSB transmission, which has already been tested in the US.  With 8 VSB, 3 bits (23 = 8) of the data stream are transmitted per amplitude value. 


Visual Scene Representation. An option for the da Vinci DUI that creates a small interactive thumbnail image for each event in the TDL. The VSR option also provides an interface for capturing and accessing full resolution images automatically for use as a reference store. 

VSR Plus

Visual Scene Representation. An option for the da Vinci 2K that creates a small thumbnail image for each event in the TDL. The VSR Plus option includes two extra Browsers and an interface for capturing and accessing full resolution images automatically for use as a resolution independent reference store.


The ratio between RF power from the transmitter and the non-transmitted power reflected back to the transmitter caused by discontinuities in the transmission line or miss-match at the antenna. The reflected power must be as small as possible to avoid transmitter damage. Too high VSWR usually caused a controlled decrease of output RF power and could launch a VSWR alarm.

Video Tape Recorder

VU Meter

A meter calibrated in Volume Units and percentage of modulation used to measure the amplitude (signal strength) of audio signals for recording, monitoring or playback.

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