An International Telecommunications Union (
ITU) standard for
for audio (speech)
compression and
decompression that is used in digital transmission systems, and in
particular, used for the coding of
analog signals into digital signals.
G.729 is an ITU-T audio data compression standard that operates at
8 kbit/s using a conjugate-structure
algebraic-code-excited
linear-prediction (CS-ACELP). This algorithm for voice compresses voice
audio in 10 millisecond frames. G.729 is commonly used in in Voice over IP
(VoIP) applications because of its inherently low bandwidth requirement.
Extensions to the G.729 standard include the following;
- G.729a (G.729 Annex A) - Compatible with G.729 Annex A
specifies a coder with several simplifications, including code book
search routines. These modifications are known to often result in a
slightly lower voice quality.
- G.729b (G.729 Annex B) - Compatible with G.729, Annex B
specifies a coder that uses Discontinuous Transmission (DTX), Voice
Activity Detection (VAD), and Comfort Noise Generation (CNG) to reduce
bandwidth usage. Bandwidth is reduced by preventing the transmission of
non-voice during periods of silence.
See G.7xx for more information on how these standards are used in telephony
networks.
