Variable rate embedded ADPCM coding scheme for packet speech on ATM networks

A variable bit rate embedded ADPCM (adaptive differential PCM) coding scheme for packet speech, primarily for use in advanced private networks integrating ATM (asynchronous transfer mode) technology, is presented. The goal is to maintain high-quality speech even with the high percentage of information loss, anticipated in these networks. By varying the number of code bits of an embedded ADPCM coder from 6 bits per sample (48-kbits) for blocks of speech with high prediction gain, to 2 bits (16-kbits) for silent blocks, a good compromise between coding bit rate and speech quality with graceful degradation due to information loss was achieved.<<ETX>>

[1]  E. Fariello,et al.  A Novel Digital Speech Detector for Improving Effective Satellite Capacity , 1972, IEEE Trans. Commun..

[2]  Paul T. Brady,et al.  A technique for investigating on-off patterns of speech , 1965 .

[3]  E. Amada,et al.  A consideration on ATM technology in private networks , 1989, IEEE Global Telecommunications Conference, 1989, and Exhibition. 'Communications Technology for the 1990s and Beyond.

[4]  Man Mohan Sondhi,et al.  Enhancement of ADPCM speech coding with backward-adaptive algorithms for postfiltering and noise feedback , 1988, IEEE J. Sel. Areas Commun..