Adaptive sound source vector quantization device, adaptive sound source vector inverse quantization device, and method thereof

Abstract

Disclosed is an adaptive excitation vector quantization device capable of improving quantization accuracy of adaptive excitation vector quantization while suppressing increase of the calculation amount in CELP encoding which performs encoding in sub-frame units. An adaptive excitation vector generator cuts out an adaptive excitation vector of a frame length (n) from an adaptive excitation codebook. An impulse response matrix former forms a n×n impulse response matrix using impulse response matrixes of sub-frames inputted from a synthesis filter. A target vector generator adds a linear prediction residual vector of each sub-frame to form a target vector of frame length (n). An evaluation measure calculator calculates an evaluation measure of the adaptive excitation vector quantization by using the adaptive excitation vector, the impulse response matrix, and the target vector.