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Chapter 19 –
Appendix C: Glossary
19-2
19
Appendix C: Glossary
Abbreviation/Term
Explanation
Bandwidth
Defines the information-carrying capacity of a channel. In
analog systems, it is the difference between the highest
frequency that a channel can carry and the lowest,
measured in hertz. In digital systems, bandwidth is
measured in bits per second. The larger a connection's
bandwidth, the more data can be transmitted in a given
amount of time, allowing for greater video resolution and
more sites in a conference.
Coder-decoder.
A device that converts voice and video into digital code and
vice versa. Refers to the endpoint video camera and video
board that are used for videoconferencing.
Conference
Connection between two or more endpoints exchanging
video and audio information. If only two endpoints are
involved, a conference is called point-to-point and no MCU
is required. If more than two endpoints are involved, it is
called a multipoint conference, and a Multipoint Control
Unit (MCU) is required as the management system.
Endpoint
A hardware device, or set of devices, that can call, and be
called by an MCU or another endpoint. For example, an
endpoint can be a phone, a camera, or microphone
connected to a computer or conferencing system.
Frame
A group of bits that make up an elementary block of video
data for transmission by certain protocols.
Frame Rate
The number of video frames displayed on-screen during
one second, measured in fps (frames per second).
Gatekeeper
A type of server that performs two main functions:
translates LAN alias addresses of terminals and gateways
to IP addresses and provides bandwidth management.
Line rate
The amount of bandwidth used by a communication
device, measured in Kbps (kilobits per second).
Participant
A person using an endpoint to connect to a conference.
High Definition (HD)
HD refers to the ultra-high quality video resolution. An
HD-compliant endpoint can connect to a conference at a
resolution of 1280x720 (720p) and at a bit rate of 384kbp~
4Mb. When setting up an HD video conference, all
participants connected to the conference are required to
use the same conference bit rate and same HD settings.
Those endpoints unable to meet the above requirements
will be treated as secondary connections (audio only).
Bps, Kbps
Bits and kilobits per second a unit of bandwidth--that is the