G.729a
From Wikipedia, the free encyclopedia
G.729a is an audio data compression algorithm for voice that compresses voice audio in chunks of 10 milliseconds. G.729a is compatible with G.729, but requires less computation. This lower complexity is not free since speech quality is marginally worsened.
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[edit] Development
The codec was developed by a consortium of organisations: France Telecom, Mitsubishi Electric Corporation, Nippon Telegraph and Telephone Corporation (NTT), and Université de Sherbrooke.
The intellectual property rights (IPR) for this codec are maintained by SIPRO (http://www.sipro.com/).
[edit] Features
- Sampling frequency 8 kHz/16-bit (80 samples for 10 ms frames)
- Fixed bit rate (8 kbit/s 10 ms frames)
- Fixed frame size (10 bytes for 10 ms frame)
- Algorithmic delay is 15 ms per frame, with 5 ms look-ahead delay
- G.729a is a hybrid speech coder which uses Algebraic Code Excited Linear Prediction (ACELP)
- The complexity of the algorithm is rated at 15, using a relative scale where G.711 is 1 and G.723.1 is 25.
- G.729 Annex B defines 2 byte Silence Insertion Descriptor (SID) frame for Comfort Noise Generation
- PSQM testing under ideal conditions yields Mean Opinion Scores of 4.04 for G.729a, compared to 4.45 for G.711 (u-law)
- PSQM testing under network stress yields Mean Opinion Scores of 3.51 for G.729a, compared to 4.13 for G.711 (u-law)
[edit] See also
- G.711 (a-law and mu-law/u-law)
- G.722
- G.722.1
- G.723
- G.723.1
- G.726
- G.728
- G.729
- G.729.1
- List of codecs
- AMR
- AMR-WB
- EFR
- FR
- iLBC
[edit] External links
- Tables of PSQM/PSQM+ derived MOS values for different speech codecs
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