Coding and decoding a sound signal by adapting coefficients transformable to linear predictive coefficients and/or adapting a code book

Abstract

A linear predictive coding apparatus is provided that performs linear predictive analysis using a pseudo correlation function signal sequence obtained by performing inverse Fourier transform regarding the η-th power of the absolute values of the frequency domain sample sequence corresponding to the time-series signal as a power spectrum to obtain coefficients transformable to linear predictive coefficients. The apparatus further adapts values of η for a plurality of candidates for coefficients transformable to linear predictive coefficients stored in a code book and the coefficients transformable to linear predictive coefficients are obtained by the linear predictive analysis. The apparatus further obtains a linear predictive coefficient code corresponding to the coefficients transformable to linear predictive coefficients obtained by the linear predictive analysis, using the plurality of candidates for coefficients transformable to linear predictive coefficients and the coefficients transformable to linear predictive coefficients for which the values of η have been adapted.