Bandwidth
In casual use, the amount of information that can be transmitted in an information channel. High bandwidth Internet access means those web graphics load quickly on Netscape. High bandwidth videoconferencing means that the picture and the sound will be clear.
In computers, the speed at which data can be transmitted on a communications frequency.
In telecommunication, the maximum frequency (spectrum) measured in Hertz or cycles per second, between the two limiting frequencies of a channel.

Broadband
A high-capacity communications circuit/path. It usually implies a speed greater than 1.544 Mbps. (Contrast with wideband and narrowband).

BRI – Basic Rate Interface (ISDN)
3 digital signals over a single pair of copper wires: 2 voice (B) channels and 1 signal (D) channel. (e.g. voice and fax on a single pair of wires)

Camera presets
Allows pre-defined camera angles to be programmed into a videoconferencing system.

Codec
Coder-Decoder. Videoconferencing hardware that codes the outgoing video and audio signals and decodes the incoming signals. Prior to transmission, the codec converts analog-signals to digital signals and compresses the digital signals. Incoming audio and video must be decompressed and converted from digital back to analog.

Compressed video
When the vast amount of information in a normal tv transmission is squeezed into a fraction of its former bandwidth by a codec, the resulting compressed video can be transmitted more econmically over a smaller carrier. Some information is dacrificed in the process, which may result in diminished picture and sound quality.

Desktop videoconferencing
Videoconferencing on a personal computer. Most appropriate for small groups or individuals (compare with room-based videoconferencing). Many desktop videoconferencing systems support document sharing.

Document sharing
A feature supported by many desktop videoconferencing systems that allows participants at both ends of a videoconference to view and edit the same computer document.

Echo-cancellation
Process of eliminating acoustic echo in a videoconferencing room.

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

Frame Rate
Frequency in which video frames are displayed on a monitor, typically described in frames-per-second (fps). Higher frame rates improve the appearance of video motion. Broadcast TV (full motion video) is 30 frames-per-second.

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 30fps. Images are sent in real time and motion is continous.

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

H.323 standard
The H.323 protocol is the International Telecommunications Union - Telecommunications (ITU-T) standard for real-time multimedia communications and conferencing over packet-based networks.

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.

ISDN
Stands for Integrated Services Digital Network. ISDN is essentially a digital network that will provide seamless communcations of voice, video, and text between individual desktop videoconferencing systems and group videoconferencing systems. ISDN is expected to replace current telephone lines.

Multipoint videoconference
Videoconference with more than two sites. The sites must connect via a video bridge. (Compare with point-to-point videoconference.)

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

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 propietary 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.

Standard compression algorithm
An algorithm convention for compression of a video signal. Adherance to standards allows communication among a wide variety of videoconferencing systems, though not with the same clarity as two similar systems using a proprietary algorithm. H320 is the most widely accepted standard in use today.

Video bridge
Computerized switching system which allows multipoint videoconferencing.

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