Coding apparatus having adaptive coding at different bit rates and pitch emphasis
First Claim
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1. A coding apparatus comprising:
- an input terminal to which an input signal is supplied;
an adaptive codebook for storing excitation signals as vectors;
a synthesis filter for forming a synthesis signal from the vectors stored in the adaptive codebook;
similarity calculation means for calculating a similarity between the synthesis signal obtained by the synthesis filter and an input signal;
coding scheme determining means for determined one coding scheme from a plurality of coding schemes respectively having coding bit rates different from each other, on the basis of the similarity obtained by the similarity calculation means; and
coding means for coding the input signal in accordance with the coding scheme determined.
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Abstract
The coding apparatus comprises an adaptive codebook storing excitation signals as vectors, a synthesis filter for forming a synthesis signal, referring to the vectors stored in the adaptive codebook, a similarity computation circuit for computing a similarity between the synthesis signal obtained by the synthesis filter and a target signal, and a coding scheme determining circuit for deciding one coding scheme from a plurality of coding schemes respectively having coding bit rates different from each other, on the basis of the similarity obtained by the similarity computation circuit.
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Citations
13 Claims
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1. A coding apparatus comprising:
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an input terminal to which an input signal is supplied; an adaptive codebook for storing excitation signals as vectors; a synthesis filter for forming a synthesis signal from the vectors stored in the adaptive codebook; similarity calculation means for calculating a similarity between the synthesis signal obtained by the synthesis filter and an input signal; coding scheme determining means for determined one coding scheme from a plurality of coding schemes respectively having coding bit rates different from each other, on the basis of the similarity obtained by the similarity calculation means; and coding means for coding the input signal in accordance with the coding scheme determined. - View Dependent Claims (2, 3, 4, 5)
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6. A coding apparatus comprising:
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pitch analysis means for analyzing an input signal to detect a pitch period and a pitch gain; emphasis means for emphasizing the input signal to emphasize signal components contained in the input signal in units of the pitch period, using the detected pitch period and pitch gain; and coding means for coding the input signal emphasized by said emphasis means. - View Dependent Claims (7, 8)
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9. A coding apparatus comprising:
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LPC analysis means for LPC-analyzing an input signal to detect a pitch period and a LPC coefficient; a prediction filter arranged on the basis of the LPC coefficient to obtain a prediction residual signal from the input signal; pitch emphasis means for emphasizing the prediction residual signal in units of the pitch period; a synthesis filter arranged on the basis of the LPC coefficient for forming an input signal emphasized in units of the pitch period from the prediction residual signal; and coding means for coding the input signal emphasized in units of the pitch period. - View Dependent Claims (10, 11)
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12. A coding method comprising the steps of:
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analyzing an input signal to detect a pitch period and a pitch gain; emphasizing the input signal in units of the pitch period, using the pitch period and pitch gain; and coding the input signal emphasized in units of the pitch period.
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13. A coding method comprising the steps of:
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analyzing an input signal to obtain a LPC coefficient and a pitch period; obtaining a prediction residual signal, using a prediction filter arranged on the basis of the LPC coefficient; emphasizing the prediction residual signal in units of the pitch period to obtain a pitch-emphasized prediction residual signal; forming an input signal emphasized in units of the pitch period from the pitch-emphasized prediction residual signal, using a synthesis filter arranged on the basis of the LPC coefficient; and coding the input signal emphasized in units of the pitch period.
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Specification