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.
Currently Encore’s G.711 is available on
TI’s TMS320C64x (c64x), TMS320C62x (c62x), TMS320C54x (c54x),
ZSP400 and ARM platforms.
GSM-AMR-WB Product Brief - Download PDF
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