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AT&T - Videoconferencing Glossary
Category: Film and Animation > Videoconferencing
Date & country: 12/09/2008, US
Words: 18


bit
Comes from binary digit. The smallest unit of information with 2 possible states. Computers use a series of 1's and 0's called the binary system to work with data. All data is stored in binary code as 1's (1 means yes or on) and 0's (0 means no or off). There are eight bits in one byte.

circuit
The complete path between two points or terminals over which one-way or two-way communications may be provided with capabilities for a number of channels. A simple dial-up connection is a circuit that is reserved only for the duration of the call. A dedicated circuit is reserved in advance or leased for a period of time and can only be used by the owner/renter.

continuous presence
The screen is split into quadrants and allows multiple sites to be viewed simultaneously on the same screen. Check out this cool demonstration at the AT&T Videoconferencing Services site.

echo-cancellation
Process of eliminating acoustic echo in a videoconferencing room. Automatically built-in most systems nowadays.

FCIF/QCIF
Standards-based formats for communicating between videoconferencing systems from different vendors. QCIF is one quarter of the resolution of FCIF.

full duplex audio
2-way audio simultaneously transmitted and received without any interference or 'clipping.' A common feature of room-based videoconferencing systems. Contrast with half duplex audio.

full motion video
Full motion video is equivalent to broadcast television video with a frame rate of 30 fps. Images are sent in real time and motion is continuous.

H.243 standard
An advanced feature that is increasingly being used to control multipoint videoconferences. See Chair Control mode.

H.320 standard
A widely-used video compression standard that allows a wide variety of videoconferencing systems to communicate. Usually associated with ISDN.

H.323 standard
A rapidly growing video compression standard that allows videoconferencing systems to communicate over the internet using IP. Here is a pretty indepth overview from Northwest University.

H.324 standard
A less popular standard that uses the regular POTS (plain old telephone service) to videoconference.

half duplex audio
2-way audio transmitted and received in turn (rather than simultaneously) so only one site can speak at a time. Contrast with full duplex audio.

narrowband
A low-capacity communications circuit/path. It usually implies a speed of 56Kbps or less. (Contrast with wideband and broadband)

PAL
Standard for scanning television signals. Used in most European countries.

point-to-point videoconference
Videoconference between two sites. (Compare with multipoint videoconference.)

proprietary compression algorithm
A vendor-specific algorithm for compression of a video signal. A videoconferencing system using a proprietary algorithm can only communicate with a remote site using the same algorithm. Many vendors also adhere to standard compression algorithms to facilitate communication across platforms.

public room
Videoconferencing service offered to the public on a fee-for-usage basis.

videoconferencing
Communication across long distances with video and audio contact that may also include graphics and data exchange.