An implementation of a variable rate codec based on ADPCM with multi-quantizer (ADPCM-MQ)
Y. Tomita, Kohei Iseda, T. Taniguchi, Shigeyuki Unagami · 2003
Discusses an implementation of an experimental variable bit rate codec (VRC) based on adaptive differential pulse code modulation with a multiquantizer (ADPCM-MQ) that processes speech signals at 16 kb/s to 48 kb/s. The authors propose a method for the combined use of constant SNR (signal/noise ratio) and constant noise to determine optimum bit/rate control of the VRC. This algorithm was implemented using six digital signal processor chips. The average bit rate of the prototype codec for the telephone voice channel was about 23 kb/s, including supplementary information, and a quality better than that specified in G.721 (32 kb/s ADPCM) was observed.>