A fast adaptive codebook search method for speech coding

Abstract

This paper presents an algorithm for fast codebook search of code excited linear prediction (CELP) coders and its descendants. The problem of reducing the bit rate of speech while preserving the quality of speech reconstructed from such a representation has received continuous attention. Real time implementation of adaptive codebook search in code excited linear prediction (CELP) and CELP based speech coders is identified as the computationally most complex module. Thus in this work, we propose a new method of using one bit computation instead of the 16 bit computation in the codebook search part of the speech codec. The simulation results show that effective codebook size and hence the computational time is reduced by 50%.