DYNAMIC CODEBOOK FOR EFFICIENT SPEECH CODING BASED ON ALGEBRAIC CODES

摘要

A method of encoding a speech signal isdisclosed. This method improves the excitationcodebook and search procedure of the conventional CodeExcited Linear Prediction (CELP) speech encoders. Useis made of a dynamic codebook based on a combinationof two modules: a sparse algebraic code generatorassociated to a filter having a transfer functionvarying in time. The generator is a structuredcodebook with codewords having very few non zerocomponents. The filter shapes the spectralcharacteristics whereby the resulting excitationcodebook exhibits favorable perceptual properties.The search complexity in finding the best codeword isgreatly reduced by bringing the search back to thealgebraic code domain thereby allowing the sparcity ofthe algebraic code to speed up the necessarycomputations.