Apparatus and method for speech coding
First Claim
1. A CELP-based speech encoder that performs encoding by decomposing one frame into a plurality of subframes, 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;
a parameter coder that performs vector quantization of the adaptive excitation vector and the stochastic excitation vector obtained by comparing distortions between said input speech and said synthesized speech;
a pitch analyzer that calculates correlation values by performing pitch analyses of the plurality of subframes before performing an adaptive codebook search for a first subframe and finds a value most approximate to a pitch period using said correlation values; and
a search range setter that determines a lag search range using at least one of said correlation values and a value calculated using said correlation values.
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Accused Products
Abstract
CELP-based speech encoder that performs encoding by decomposing one frame into a plurality of subframes, 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 an stochastic codebook using LPC coefficients obtained from input speech. A gain calculator calculates gains of the adaptive excitation vector and the stochastic excitation vector. A parameter coder performs vector quantization of the adaptive excitation vector and the stochastic excitation vector obtained by comparing distortions between the input speech and the synthesized speech. A pitch analyzer performs pitch analyses of a plurality of subframes in the frame respectively, before performing an adaptive codebook search for the first subframe, calculating correlation values and finding a value most approximate to the pitch period using the correlation values.
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Citations
8 Claims
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1. A CELP-based speech encoder that performs encoding by decomposing one frame into a plurality of subframes, 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; a parameter coder that performs vector quantization of the adaptive excitation vector and the stochastic excitation vector obtained by comparing distortions between said input speech and said synthesized speech; a pitch analyzer that calculates correlation values by performing pitch analyses of the plurality of subframes before performing an adaptive codebook search for a first subframe and finds a value most approximate to a pitch period using said correlation values; and a search range setter that determines a lag search range using at least one of said correlation values and a value calculated using said correlation values. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A computer-readable recording medium that stores a speech encoding program, an adaptive codebook storing part used for synthesizing an excitation vector signal and a stochastic codebook storing a plurality of stochastic excitation vectors, said speech encoding program comprising:
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code for obtaining a synthesized speech by filtering an adaptive excitation vector and a stochastic excitation vector stored in said adaptive codebook and said stochastic codebook using decoded LPC coefficients obtained from an input speech; code for calculating gains of said adaptive excitation vector and said stochastic excitation vector; code for performing vector quantization on the adaptive excitation vector and the stochastic excitation vector determined by comparing distortions between said input speech and said synthesized speech; code for calculating correlation values by performing pitch analyses of a plurality of subframes in a processing frame before performing an adaptive codebook search of a first subframe and calculating a value most approximate to a pitch period using said correlation values; and code for determining a lag search range using at least one of said correlation values and a value calculated using said correlation values.
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8. A CELP-based speech encoding method for performing encoding by decomposing one frame into a plurality of subframes, comprising:
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obtaining a synthesized speech by filtering an adaptive excitation vector and by filtering a stochastic excitation vector stored in an adaptive codebook and in a stochastic codebook using decoded LPC coefficients obtained from an input speech; calculating gains of said adaptive excitation vector and said stochastic excitation vector; performing vector quantization on the adaptive excitation vector and the stochastic excitation vector obtained by comparing distortions between said input speech and said synthesized speech; calculating correlation values by performing pitch analyses of the plurality of subframes before performing an adaptive codebook search for a first subframe, and finding a value most approximate to the pitch period using said correlation values; and determining a lag search range using at least one of said correlation values and a value calculated using said correlation values.
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Specification