Speech and waveform coding based on vector quantization
Guillermo Rebolledo-Cortizo · 1981
Three new techniques for designing and simulating low rate speech compression systems based on vector quantization (VQ) are described. The first is a rate-distortion speech coder that resembles a linear predictive coded (LPC) speech compression system, but has much lower rate (under 800 bits per second (bps)) and a much larger memory requirement. The encoder performs a minimum distortion rule using the Itakura-Saito distortion measure. The speech quality provided at such low rate is comparable to that of 2400 bps and 4800 bps standard LPC systems. The second system is a waveform coder consisting of a minimum (weighted and unweighted) mean-square error VQ of one or two bits per sample (6500 and 13000 bps, respectively). It can be considered as a multidimensional pulse code modulation (PCM) system. The speech quality provided is considered at least as good as that of other standard waveform coders. The third system combines ideas from the first two to obtain a residual-excited linear predictive (RELP) speech compression system using VQ in both model selection and residual digitization. The working rates of our RELP system are 7000 and 13500 bps providing, among the RELP systems that we know of, the best speech quality.