Speech encoding method and apparatus including a codebook storing a plurality of code vectors for encoding a speech signal
First Claim
1. A speech encoding method comprising the steps of:
- preparing a codebook storing a plurality of code vectors for encoding a speech signal;
producing a reconstruction speech vector by using the code vectors extracted from said codebook, and an error vector representing an error of the reconstruction speech vector with respect to a target vector corresponding to an input speech signal to be encoded;
passing the error vector through a perceptual weighting filter having a transfer function including an inverse characteristic of a transfer function of a filter for emphasizing a spectrum of the reconstruction speech signal, to generate a weighted error vector; and
searching said codebook for a code vector that minimizes the weighted error vector, and outputting an index corresponding to the code vector found as an encoding parameter.
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Abstract
A speech encoding method including generating a reconstruction speech vector by using a code vector extracted from a codebook storing a plurality of code vectors for encoding a speech signal. In addition an input speech signal to be encoded is used as a target vector to generate an error vector representing the error of the reconstruction speech vector with respect to the target vector, and the error vector is passed through a perceptual weighting filter having a transfer function including the inverse characteristics of the transfer function of a filter for emphasizing the spectrum of a reconstructed speech signal. Thus a weighted error vector is generated, the codebook for a code vector that minimizes the weighted error vector is searched, and an index corresponding to the code vector found as an encoding parameter is output.
38 Citations
20 Claims
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1. A speech encoding method comprising the steps of:
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preparing a codebook storing a plurality of code vectors for encoding a speech signal; producing a reconstruction speech vector by using the code vectors extracted from said codebook, and an error vector representing an error of the reconstruction speech vector with respect to a target vector corresponding to an input speech signal to be encoded; passing the error vector through a perceptual weighting filter having a transfer function including an inverse characteristic of a transfer function of a filter for emphasizing a spectrum of the reconstruction speech signal, to generate a weighted error vector; and searching said codebook for a code vector that minimizes the weighted error vector, and outputting an index corresponding to the code vector found as an encoding parameter. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A speech encoding apparatus comprising:
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a codebook storing a plurality of code vectors for encoding a speech signal; a reconstruction speech vector generator for generating a reconstruction speech vector by using a code vector extracted from said codebook; an error vector generator for generating, using an input speech signal to be encoded as a target vector, an error vector representing an error of the reconstruction speech vector with respect to the target vector; a perceptual weighting filter which has a transfer function including an inverse characteristic of a transfer function of a filter for emphasizing a spectrum of a reconstruction speech signal, and receives the error vector and outputs a weighted error vector; a search searcher for searching said codebook for a code vector that minimizes the weighted error vector; and an output circuit for outputting an index corresponding to the code vector found by said searcher as an encoding parameter. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. A speech encoding method comprising the steps of:
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preparing a codebook storing a plurality of code vectors for encoding a speech signal; generating a reconstruction speech vector by using the code vector extracted from said codebook, and an error vector representing an error of the reconstruction speech vector with respect to a target vector corresponding to a speech signal obtained by performing spectrum emphasis for an input speech signal to be encoded; and searching said codebook for a code vector that minimizes a weighted error vector obtained by passing the error vector through a perceptual weighting filter, and outputting an index corresponding to the code vector found as an encoding parameter.
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20. A speech encoding apparatus comprising:
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a codebook storing a plurality of code vectors for encoding a speech signal; a reconstruction speech vector generator for generating a reconstruction speech vector by using a code vector extracted from said codebook; a pre-filter for performing spectrum emphasis for an input speech signal to be encoded; an error vector generator for generating, using a speech signal having undergone spectrum emphasis by said pre-filter as a target vector, an error vector representing an error of the reconstruction speech vector with respect to the target vector; a perceptual weighting filter for receiving the error vector and outputting a weighted error vector; a searcher for searching said codebook for a code vector that minimizes the weighted error vector; and an output circuit for outputting an index corresponding to the code vector found by said searcher as an encoding parameter.
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Specification