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HUAWEI VP9050 Executive Video Terminal
User Guide
DGlossary
Issue 03 (2011-12-10) Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd
110
dual stream
During a conference, two channels of video streams can be sent or received
simultaneously. For example, one channel is used for transmitting video (such as
video captured by a camera) and the other channel is used for transmitting
presentation (such as a computer desktop). The two channels of videos can be
displayed on two displays.
G
G.711
G.711, also known as Pulse Code Modulation (PCM), is a very commonly used
waveform codec. G.711 uses a sampling rate of 8,000 samples per second, with the
tolerance on that rate 50 parts per million (ppm). Non-uniform quantization
(logarithmic) with 8 bits is used to represent each sample, resulting in a 64 kbit/s bit
rate. There are two slightly different versions; μ-law, which is used primarily in
North America, and A-law, which is in use in most other countries outside North
America.
G.722
G.722 is a ITU-T standard 7 kHz wideband speech codec operating at 48, 56 and 64
kbit/s. It was approved by ITU-T in November 1988. Technology of the codec is
based on sub-band ADPCM (SB-ADPCM).
G.728
G.728 is an ITU-T standard for speech coding operating at 16 kbit/s. It is officially
described as Coding of speech at 16 kbit/s using low-delay code excited linear
prediction.
give floor
After the chair site gives floor to a site, the other sites view and hear the site. All the
sites, except the chair site and the site that is given the floor, are muted.
H
H.239
H.239 is an ITU-T recommendation from the H.32x Multimedia Communications'
macrofamily of standards for multimedia communications over various networks.
The H.239 recommendation is titled "Role management and additional media
channels for H.3xx-series terminals". Practical importance of this recommendation is
its setting forth a way to have multiple video channels (for example, one for
conferencing, another for presentation) within a single session (call).
H.261
H.261 is a 1990 ITU-T video coding standard originally designed for transmission
over ISDN lines on which data rates are multiples of 64 kbit/s. It is one member of
the H.26x family of video coding standards in the domain of the ITU-T Video
Coding Experts Group (VCEG). The coding algorithm was designed to be able to
operate at video bit rates between 40 kbit/s and 2 Mbit/s. The standard supports two
video frame sizes: CIF (352x288 luma with 176x144 chroma) and QCIF (176x144
with 88x72 chroma) using a 4:2:0 sampling scheme. It also has a
backward-compatible trick for sending still picture graphics with 704x576 luma
resolution and 352x288 chroma resolution (which was added in a later revision in
1993).
H.263
H.263 is a video codec standard originally designed as a low-bitrate compressed
format for videoconferencing. It was developed by the ITU-T Video Coding Experts
Group (VCEG) in a project ending in 1995/1996 as one member of the H.26x family
of video coding standards in the domain of the ITU-T. H.263v2 (H.263+) added
support for flexible customized picture formats and custom picture clock frequencies.
Previously the only picture formats supported in H.263 had been Sub-QCIF, QCIF,
CIF, 4CIF, and 16CIF, and the only picture clock frequency had been 30000/1001
(approximately 29.97) clock ticks per second.