ITU-T Standard Vocoders
G.729A/G.729AB
The algorithms implemented are
the ITU-T G.729A and G.729AB recommendations, fixed rate speech coders for
internet and multimedia communications. G.729A is a reduced complexity version
of G.729 with similar audio performance in most circumstances with the additional
option of Annex B.
Annex B implements silence compression
techniques to reduce the transmitted bit rate during the silent intervals
of speech and conforms to Recommendation V.70 silence compression. Systems
allowing discontinuous transmission (DTX) are based on Voice Activity Detection
(VAD) algorithms and Comfort Noise Generator (CNG) algorithms that allows
the insertion of Silence Insertion Descriptor (SID) frames during the silence
intervals. This also provides the additional advantage of using lower processing
loads and DSP bandwidth resource during silence frames.
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