Vector quantization codebook generation method

摘要

A CELP speech coder or decoder comprising an adaptive codebook; a random codebook; a synthesis filter for receiving a random code vector generated from the random codebook so as to perform LPC synthesis; wherein said random codebook is formed by an excitation vector generator comprising fixed waveform arranging means for arranging one or more fixed waveforms (v1,v2,v3) stored in a fixed waveform storage means in accordance with the positions (P1,P2,P3) and polarities of an input impulse vector. The CELP speech coder/decoder further comprising means for determining a voiced/unvoiced characteristic of the input speech and that the random codebook generates the random code vector in accordance with the determined voiced/unvoiced characteristic.