Image Processing Reference
In-Depth Information
Topic
Description
Frame
A single picture within a video sequence.
G.711
An audio codec supporting 3.4-KHz speech at 56 and 64 Kbps.
G.722
An audio codec supporting 7-KHz speech at 48, 56, and 64
Kbps.
G.728
An audio codec supporting 3.4-KHz speech at 16 Kbps.
Genlock
Generator locking describes the technique of synchronizing the
film shutter in a camera with an external electronic source. This
generator locking is also used to sync any two arbitrary video
systems together. Studio and production environments typically
provide genlock signals via a distribution amplifier so that all
the equipment can be synchronized to the same timing.
Global motion
A spatial transform applied to the whole picture in order to
compensation
reduce the residual motion vectors required in each macroblock.
H.221
A standard that describes the transmission frame structure. This
is based on frame multiplexing for a 64- to 1920-Kbps ISDN
channel.
H.231
Describes a Multipoint Control Unit (MCU) for video-
conferencing systems with more than 2 end-points.
H.243
A system for establishing communication between three or more
terminals with circuits that have a capacity of up to 2 Mbps.
This is sometimes called multi-point conferencing.
H.261
An ITU standard codec for video-conferencing video streams.
H.261 uses the Discrete Cosine Transform (DCT) algorithm to
compress video so it can be accommodated within a bandwidth
of 64 Kbps to 2 Mbps. This standard also defines the CIF and
QCIF image formats. This is a legacy codec.
H.263
Another ITU video-conferencing standard codec; offers better
compression than H.261. This is particularly well suited to
compression down to the low bit rate available through dial-up
modems. Probably not an optimal choice these days. Used to be
a good codec for use on low-powered playback hardware.
H.264
The newest and most advanced codec. This is the one codec to
rule them all. It is a modern codec developed for consumer
applications at much better bit rate/performance trade-offs than
MPEG-2. Although not technically a video-conferencing
standard, some telecommunications companies are looking at
deploying this for delivery of video content to mobile phones.
H.26L
Early trials of the H.264 standard were tested under the H.26L
nomenclature.
Continued
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