A variable rate coding by APC with maximum likelihood quantization from 4.8 kbits/s to 16 kbits/s

This paper presents a variable rate APC coding with Maximum Likelihood Quantization (MLQ) and noise-shaping filtering which covers a wide range of coding rates from 4.8 kbit/s to 16 kbit/s. At a rate lower than 8.0 kbit/s a new hybrid coding based on the ACP-MLQ and a new high-frequency regeneration are proposed. Simulation results indicate that the APC-MLQ having noise-shaping filters is very effective for achieving a high quality of speech in variable rate coding.