LSP markov model for reducing the complexity of vector quantization

International audienceIn this paper the vector quantization (VQ) of the LSP (Line Spectrum Pairs) coefficients of the CELP (Code Excited Linear Predictive) coder is addressed. Methods to reduce the complexity of VQ are proposed. First a method, which determines the search zone for the input vector's nearest neighbour in the codebook by comparing the norm of the vectors, is presented. This is followed by the description of a method based on the correlation of consecutive quantized LSP vectors. Here the transition matrix of the n states Markov model is used to reduce the searching zone for the nearest neighbour. The experimental results show that the combination of these two methods is an effective way of reducing the complexity of the vector quantization