August 1999
Intermediate to advanced
328 pages
8h 50m
English
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CODEC REQUIREMENTS
H.323 establishes the requirements for speech codecs; the video codec is optional. A summary of the requirements follows.
Speech Codecs
All H.323 terminals must have a voice codec. The minimum requirement is the support of recommendation G.711 (the A-law and μ-law). Other speech encoding/decoding standards cited by H.323 are G.722, G.723, G.728, G.729, and MPEG-1 audio.
H.245 is used during an initial handshake between the machines to determine the audio encoding algorithm. The terminal should be capable of sending and receiving different audio streams. After H.245 has completed the agreements on the terminals' capabilities, H.225 is used to format the audio stream.
Video Codecs
If video is supported, the H.323 terminal must ...