The Adaptive Multi-Rate Wideband Codec (AMR-WB) is a speech coder standard introduced by the 3rd Generation Partnership Project (3GPP), which is a partnership project of various standards organizations, for compressing the toll quality speech (16,000 samples/second). The AMR-WB Codec has been approved by the ITU-T standards body and is referred to as G.722.2.This speech coder is mainly used for speech compression in the 3rd generation mobile telephony.

This codec has nine basic bit rates, 23.85, 23.05, 19.85, 18.25, 15.85, 14.25, 12.65, 8.85 and 6.6 kbit/s. This codec works on the principle of Algebraic Code Excited Linear Prediction (ACELP) for all bit rates. To reduce average bit rate, this codec supports the discontinuous transmission (DTX), using Voice Activity Detection (VAD) and Comfort Noise Generation (CNG) algorithms.

The coder works on a frame of 320 speech samples (20 msec), and a look ahead of 5 msec is required. So the algorithmic delay for the coder is 25 msec.

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