Glossary of Videoconferencing
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A | B | C
| D | E | F
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X | Y |Z
16:9 Aspect Ratio
Aspect ratio most commonly known as widescreen (letterbox). It is wider than
the standard definition 4:3 aspect ratio. 16:9 aspect ratio is associated with
the most popular HDTV formats.
An algorithm is a specified, usually mathematical, way
of doing something. For example, in a videoconference system, the
"audio algorithm" defines exactly how audio such as the
speakers voice will be converted to a string of ones and zeros (binary
data) and then compressed for transmission to the other conference
ATM (Asynchronous Transfer Mode)
A new communications standard that is currently in the later stages
of development. ATM is designed to transfer voice, video and other
multimedia data that requires short bursts of large quantities of
data that can survive small losses but must be broadcast in real
Bandwidth defines the amount of information that can be sent and
received in a certain time frame. In Videoconferencing, the higher
the bandwidth, the higher the quality of the picture and sound during
the Videoconference. Lower bandwidths result in more choppy pictures
A numbering system that uses strings of ones and zeros to represent
A basic unit of binary (digital) data. This is a single One or Zero
that is transmitted. Collections of bits can be used to represent
more complex values. A bit is the smallest unit of binary data that
you can have.
BRI - Basic Rate Interface (ISDN)
A type of ISDN phone line. A BRI line allows up to 128kpbs of information
to be transported (using two B-Channels). This is the type of ISDN
connection that a person might have at home.
In videoconferencing vernacular, a bridge connects three or more
conference sites so they can simultaneously communicate.
A generic term applied to networks having bandwidth significantly
greater than traditional telephone networks (DSL, Cable Modem, T1,
etc.). Broadband systems are capable of carrying a vast quantity
of data simultaneously.
A hook up to your cable TV system that allows you to transmit
computer information and access the internet through your
Allows predefined camera angles to be programmed into a videoconferencing
Coder-Decoder. A codec is the core (or "engine")
of a videoconference system and is responsible for all of
the encoding and decoding of information (audio, video). Before
the 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.
The codec compresses the information into smaller pieces for
easier and faster transmission. This allows the information
to be transmitted faster over smaller capacity lines. Due
to the compression and decompression of information some of
the original quality of the video and sound are lost which
results in diminished picture and sound quality.
Videoconferencing on a personal computer. This is the most
economical type of Videoconferencing systems. It is most useful
for individuals and smaller groups.
A camera used during a videoconference for taking pictures
of still images, pictures, graphics, pages of text, and 3-D
objects. All images can be sent stand alone to a TV monitor
or as part of a videoconference.
Allows users on both sides of the videoconference to view
and edit the same computer document.
A digital signal can only have a certain number of defined
values (like, 0 or 1). This is different from an Analog signal
that could have any value within a given range. In general,
because of having only a certain number of defined possible
values, a digital signal provides better performance than
E, F, G
Process of eliminating acoustic echo in a videoconferencing
A Local Area Network (LAN) running on coaxial or twisted pair
wiring at 10 or 100 Mbps. (Large Bit Ethernet is slowly becoming
Frequency that the video frames are displayed on a monitor,
typically described in frames-per-second (fps). The higher
the frame rate the better the quality of the video.
Sending audio data in both directions at the same time. Usually
higher quality, but requires more bandwidth. Provides much
more natural and useable audio to a videoconference because
people on either end of the conference can speak at the same
The interface between two opposing protocols, typically h.320
and h.323. By means of software and hardware, a gateway allows
connection between otherwise incompatible networks.
H, I, J, K
ITU Standard for sending data long as a dual stream in a videoconference.
ITU Standard for video compression sometimes referred to as MPEG 4 part 10.
A commonly used video compression standard for videoconferencing
over networks that provide fixed communication paths (such
as the ISDN phone network). By defining standardized ways
of performing all of the processing that has to be done by
a videoconference system, systems from different vendors can
communicate with each other as long as they all comply with
the standards. H.320 references many other standards for specific
tasks (such as audio coding or video coding).
This is also a top-level standard, like H.320, for videoconference
systems. The difference is that H.323 defines methods to be
used on what are called packet-based networks (which are also
called IP (Internet Protocol) networks) like a typical business,
school LAN or the Internet.
The standards used to specify voice and video transmission
over traditional analog phone lines.
A telecommunication system where data can only flow in one
direction at a time. For example, a half duplex speakerphone
only allows one person to speak at a time.
High Definition 720p - 720p
720p - 720p is the designated name for one of the HDTV video modes. 720
represents 720 lines of vertical resolution, and the letter p stands for progressive
scan (non-interlaced). The horizontal resolution of 1280 dots across and a frame
resolution of 1280 x 720 with an aspect ratio of 16:9.
High Definition 1080i - 1080i
1080i - 1080i is the designated name for one of the HDTV video modes.
1080 stands for 1080 lines of vertical resolution, while the letter "I"
stands for interlaced or non-progressive scan. The horizontal resolution
of 1920 dots across and a frame resolution of 1920 × 1080 or over two million
pixels with an aspect ratio of 16:9. In addition a field resolution of 1920 × 1080/2
(interlaced) or about 1.04 million pixels.
High Definition 1080p - 1080p
1080p - 1080p is the designated name for one of the HDTV video modes. 1080
represents 1,080 lines of vertical resolution, and the letter p stands for
progressive scan (non-interlaced). The horizontal resolution of 1920 dots across
and a frame resolution of 1920 × 1080 or over two million pixels with an aspect
ratio of 16:9.
The Internet Protocol. IP is the basic language of the Internet.
A technique for "many to many" communications over an IP network.
Multicast is scalable and gets to a larger viewer population by not
requiring prior knowledge of who or how many viewers there are. Multicast
utilizes network infrastructure efficiently by requiring the source to send
the information only once, even if it needs to be delivered to a large number
of viewers. The network nodes will replicate packets as needed to reach multiple
viewers as necessary.
A technique where a IP network distributes packets of information to
a single destination. Each viewer would have their own separate stream
of the same information sent through the network.
Stands for "Integrated Services Digital Network".
A type of telephone network that uses digital service right
up to the end user's equipment (like an ISDN modem). This
type of telephone network also uses separate paths or channels
for signaling so that the signaling information does not interfere
with the data being sent by the user. It provides seamless
communications of voice, video, and text between individual
desktop videoconferencing systems and group videoconferencing
systems. It allows for faster data transfer rates than existing
It stands for "kilobits per second". The "kilo"
means "thousand". This term is used when talking
about the speed that a device (or circuit) can transport data.
For example, a 56kbps modem could transmit 56,000 bits in
LAN (Local Area Network)
A computer network linking workstations, file servers, printers
and other devices within a local area, such as an office.
LANs allow the sharing of resources and the exchange of both
video and data.
Allows the transmission of digital information over an analog
Multipoint Videoconference (via MCU)
Videoconference with more than two sites. The sites
must connect via a video bridge, which is also called a Multipoint
Control Unit (MCU).
Packet Based Network
A network where data is sent in small chunks, called packets.
There is not a fixed path from the sender to the receiver,
so each packet (chunk of data) has to identify the source
and destination. Most corporate LANs (and the Internet) are
Videoconference between two sites.
POTS (Plain Old Telephone System)
This is the traditional analog system for voice we use at
PRI (Primary Rate Interface)
Another type of ISDN phone line with much higher capacity
(23 B-Channels that can carry up to a total of 1472kbps).
This type of circuit might be used by schools or businesses
and may be shared between several users or devices.
PTZ (Pan, Tilt, and Zoom)
Remote control features that typically come with high-quality
cameras that are used in room-sized videoconferencing systems.
A transmission that occurs right away, without any perceptible
Videoconferencing using a larger and more sophisticated system.
These systems can be mobile stand-alone systems or customized
for the needs of the user. These systems are more appropriate
for large groups and more sophisticated techniques.
Standard Compression Algorithm
This is a standard algorithm convention for compressing the
video signal. This allows different videoconferencing systems
to communicate with each other successfully. This does not
always provide the same clarity as two similar systems using
a proprietary algorithm. H.320 is the most commonly used standard.
Sending video or audio over a network as needed, instead of
forcing the user to download the entire file before using
it. Typically a few seconds of data is sent ahead and buffered
in case of network transmission delays. (Although some data
is buffered to the hard drive, it is written to a temporary
storage and is gone once viewing is complete.)
Another standard. This one defines the way in which data and
computer applications can be shared between two or more users.
Network link used on the Internet allowing speeds of up to
Higher speed (45 megabits/second) network link used on the
TCP (Transmission Control Protocol)
works in conjunction with IP to ensure that packets reach
their intended destinations.
TCP/IP (Transmission Control Protocol/Internet Protocol)
The suite of networking protocols that let different types
of equipment communicate over the Internet or other packet
V, W, X, Y, Z
Computerized switching system (also known as MCU - Multipoint
Control Unit), which allows more than two sites to communicate
using videoconferencing. Many companies now offer bridging
services for a set fee.
Interactive communication using video and audio to communicate
over long distances. It combines the interactivity of the
telephone with the visual stimulation of the television. Videoconferencing
may also include graphics and data exchange.
WAN (Wide Area Network)
A communications network that services a geographic area larger
than that served by a local area network or metropolitan area
network. WANs include commercial or educational dial-up networks
such as CompuServe, Janet, and BITNET.