Single stage spectral quantization at 20 bits

Efficient coding of spectral parameters constitutes a major concern for speech compression. It is generally agreed that a single-stage vector quantizer, operating in the log-spectral domain would give superior performance, as compared to any other block coding procedure. Such a coder has, however, been considered impractical due to its complexity. The authors demonstrate that high quality encoding of speech spectra is feasible around 20 bits/spectrum with a single-stage approach. The experimental results are accurately predicted by a theoretical performance analysis. The author suggests a straightforward tree-based procedure that can be employed for the codebook search such that the computational complexity is acceptable