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G.722.2 uses a wideband audio band of 50 - 7000 Hz instead of 200 - 3400 Hz for wideband HD VoIP applications. The increased bandwidth improves the intelligibility and naturalness of speech significantly. G.722.2 describes the detailed mapping from input blocks of 320 speech samples in 16 bit uniform PCM format to encoded blocks of 132, 177, 253, 285, 317, 365, 397, 461 and 477 bits and from encoded blocks of 132, 177, 253, 285, 317, 365, 397, 461 and 477 bits to output blocks of 320 reconstructed speech samples.
The coding scheme for the multi-rate coding modes is the so called Algebraic Code Excited Linear Prediction Coder, hereafter referred to as ACELP. The multi-rate wideband ACELP coder is referred to as AMR-WB. G.722.2 also utilizes an integrated Voice Activity Detector (VAD). The sampling rate is 16 000 samples/s leading to a bit rate for the encoded bit stream of 6.60, 8.85, 12.65, 14.25, 15.85, 18.25, 19.85, 23.05 or 23.85 kbit/s.
Annexes A and B and Appendix I provide supplemental functionalities allowing interoperability with GSM and 3GPP wireless systems. These functionalities have originally been developed for these systems, but their use is not limited to mobile applications. Two other Annexes D and E describe test vectors and frame structure respectively.
G.722 is used for Voice over IP (VoIP) and Internet (IP) applications, Mobile Communications, PSTN applications, ISDN wideband telephony, ISDN videotelephony and video-conferencing.
ITU Recommendation G.722.2 3GPP TS 26.171 Adaptive Multi-Rate Wideband