Vector quantization device, vector inverse-quantization device, and methods of same

Abstract

An LSP vector quantization device able to improve the precision of quantization in vector quantization where a codebook for first stage vector quantization is switched according to the type of a feature that has a correlation with the quantization target vector. In this device, a classifier () selects, from a plurality of code vectors for classifying, the code vector for classifying that indicates the type of the feature that has a correlation with the quantization target vector; a switch () selects, from among a plurality of first codebooks, the first codebook corresponding to the abovementioned type; an error minimizing unit () selects, from the plurality of first code vectors constituting the selected first codebook, the first code vector closest to the quantization target vector; a matrix determining unit () selects, from a plurality of matrices, the matrix corresponding to the abovementioned type; and the error minimizing unit () uses the selected matrix to select, from a plurality of second code vectors, the one that is closest to the residual vector between the selected first code vector and the quantization target vector.