Fujitsu Corporation

Mark A Johnson

Tomohiko Taniguchi

Yoshinori Tanaka

Hideaki Kurihara

Yasuji Ohta

Yoshihiro Sakai

A speech coding and decoding system, where the system is operated under a known code-excited linear prediction (CELP) coding method. The CELP coding is achieved by selecting an optimum pitch prediction residual vector P from an adaptive codebook and the corresponding first gain, and at the same time, selecting an optimum code vector C from a white-noise stochastic codebook and the corresponding second gain. The system of the present invention is implemented by a weighted orthogonalization transforming unit introduced therein. The perceptually weighted code vector AC is not used as in the prior art. Rather, the weighted orthogonalization transformation unit transforms the code vector into a perceptually weighted reproduced code vector AC' being made orthogonal to the optimum perceptually weighted pitch prediction vector AP.

Speech coding and decoding system

Speech coding system having codebook storing differential vectors

A speech coding system operated under a known code-excited linear prediction (CELP) coding method. The CELP coding is achieved by selecting an optimum pitch vector P from an adaptive codebook and the corresponding first gain and, at the same time, selecting an optimum code vector from a sparse-stochastic codebook and the corresponding second gain. Special code vectors are loaded in the sparse-stochastic codebook, which code vectors are hexagonal lattice code vectors each consisting of a zero vector with one sample set to +1 and another sample set to -1.

Speech coding system

A CELP type speech coding system is provided with an arithmetic processing unit which transforms a perceptual weighted input speech signal vector AX to a vector .sup.t AAX, a sparse adaptive codebook which stores a plurality of pitch prediction residual vectors P sparsed by a sparse unit, and a multiplying unit which multiplies the successively read out vectors P and the output .sup.t AAX from the arithmetic processing unit. In addition, the CELP type speech coding system includes a filter operation unit which performs a filter operation on the vectors P, and an evaluation unit which finds the optimum vector P based on the output from the filter operation unit, so as to enable reduction of the amount of arithmetic operations.

Growing community of inventors

Cambridge, MA, United States of America

Mark A Johnson