SPECTRAL MAGNITUDE QUANTIZATION FOR A SPEECH CODER

摘要

An amplitude quantization scheme for low-bit-rate speech coders includes the first step of extracting a vector of spectral information from a frame. The energy of the vector is normalized to generate gain factors. The gain factors are differentially vector quantized. The normalized gain factors are non-uniformly downsampled to generate a fixed-dimension vector with elements associated with a set of non-uniform frequency bands. The fixed-dimension vector is split into two or more sub-vectors. The sub-vectors are differentially quantized, to best advantage with a harmonic cloning process.