Apparatus and method for speech coding
First Claim
1. A speech encoder comprising:
- an LPC synthesizer that obtains synthesized speech by filtering an adaptive excitation vector and a stochastic excitation vector stored in an adaptive codebook and in a stochastic codebook using LPC coefficients obtained from input speech;
a gain calculator that calculates gains of said adaptive excitation vector and said stochastic excitation vector and searches code of the adaptive excitation vector and code of the stochastic excitation vector by comparing distortions between said input speech and said synthesized speech obtained using said adaptive excitation vector and said stochastic excitation vector; and
a parameter coder that performs predictive coding of gains using said adaptive excitation vector and said stochastic excitation vector corresponding to the codes obtained, wherein said parameter coder comprises a prediction coefficient adjuster that adjusts at least one prediction coefficient used for said predictive coding according to at least one state of at least one previous subframe.
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Abstract
A speech encoder includes an LPC synthesizer that obtains synthesized speech by filtering an adaptive excitation vector and a stochastic excitation vector stored in an adaptive codebook and in a stochastic codebook using LPC coefficients obtained from input speech. A gain calculator calculates gains of the adaptive excitation vector and the stochastic excitation vector and searches code of the adaptive excitation vector and code of the stochastic excitation vector by comparing distortions between the input speech and the synthesized speech obtained using the adaptive excitation vector and the stochastic excitation vector. A parameter coder performs predictive coding of gains using the adaptive excitation vector and the stochastic excitation vector corresponding to the codes obtained. The parameter coder comprises a prediction coefficient adjuster that adjusts at least one prediction coefficient used for the predictive coding according to at least one state of at least one previous subframe.
18 Citations
6 Claims
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1. A speech encoder comprising:
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an LPC synthesizer that obtains synthesized speech by filtering an adaptive excitation vector and a stochastic excitation vector stored in an adaptive codebook and in a stochastic codebook using LPC coefficients obtained from input speech; a gain calculator that calculates gains of said adaptive excitation vector and said stochastic excitation vector and searches code of the adaptive excitation vector and code of the stochastic excitation vector by comparing distortions between said input speech and said synthesized speech obtained using said adaptive excitation vector and said stochastic excitation vector; and a parameter coder that performs predictive coding of gains using said adaptive excitation vector and said stochastic excitation vector corresponding to the codes obtained, wherein said parameter coder comprises a prediction coefficient adjuster that adjusts at least one prediction coefficient used for said predictive coding according to at least one state of at least one previous subframe. - View Dependent Claims (2, 3, 4, 5, 6)
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Specification