METHOD AND APPARATUS FOR SEARCHING FIXED CODEBOOK, AND METHOD AND APPARATUS ENCODING/DECODING SPEECH SIGNAL USING METHOD AND APPARATUS FOR SEARCHING FIXED CODEBOOK

摘要

A method and an apparatus for searching for a fixed code book, and an apparatus and a method for encoding/decoding a voice signal are provided to reduce a bit rate without the degradation of the performance in an enhancement layer based on a CELP(Code Exited Linear Prediction) by searching for plural spaces of the enhancement layer and a core layer. An apparatus for searching for a fixed code book includes a core layer code book, a core layer searching module, an enhancement code book, and an enhancement layer searching module. The core layer code book is provided by classifying the combination of pulse positions into a plurality of spaces. The spaces of the core layer code book are searched, and a space having smaller distortion is determined. The enhancement layer code book has spaces corresponding to the core layer code book. The enhancement layer searching module searches for the spaces of the enhancement layer except for the determined space.