Adaptive Multi-Rate audio codec: Difference between revisions

Revision as of 15:31, 19 July 2006

Revision as of 11:16, 14 August 2006

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'''Adaptive Multi-Rate (AMR)''' is an [[audio data compression]] scheme optimized for [[speech coding]]. AMR is adopted as the standard speech codec by [[3GPP]] in Octomber 1998.

The codec has eight bit rates, 12.2, 10.2, 7.95, 7.40, 6.70, 5.90, 5.15 and 4.75 kbit/s. The bitstream is based on frames which contain 160 samples and are 20 milliseconds long. AMR uses different techniques, such as [[Algebraic Code Excited Linear Prediction]] (ACELP), [[Discontinuous Transmission]] (DTX), [[voice activity detection]] (VAD) and [[comfort noise]] generation (CNG).