G.729 is an 8 Kpbs audio codec, standardized by ITU , and called also CS-ACELP: Coding of Speech using Coniugate-Structure Algebraic-Code-Excited Linear Prediction , as that’s the algorithm used for audio compression. It has two extended versions: G.729A (optimized algorithm, slightly lower quality) and G.729B (extended features, higher quality), and it's popular in the VoIP world because combines very low bitrate with good quality (but alas is not royalty-free). G.729A takes as input frames of voice of 10 msec of duration, sampled at 8KHz and with each sample having 16 bit : This gives a frame size of 80 samples: 8000 sample/sec * 10 * 10e-3 sec/frame = 80 samples/frame The output is 8 Kbps, so each encoded frame is represented by 10 Bytes: 8000 bit/sec * 10 * 10e-3 sec/frame = 80 bit/frame = 10 Bytes/frame Quality Considering its bit rate, G.729 has an excellent perceived quality ( MOS ). Under normal network conditions G.729A has MOS 4.04 (while G.711 u-law, 64 kbps, has 4.4...