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Decoding method, apparatus and recording medium

  • US 10,643,631 B2
  • Filed: 10/15/2019
  • Issued: 05/05/2020
  • Est. Priority Date: 04/24/2014
  • Status: Active Grant
First Claim
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1. A decoding method, implemented by a decoding apparatus having processing circuitry, comprising:

  • where p is an integer equal to or greater than 1,decoding, by the processing circuitry, input adjusted LSP codes to obtain a decoded adjusted LSP parameter sequence {circumflex over ( 

    )}θ

    γ

    [1], {circumflex over ( 

    )}θ

    γ

    [2], . . . , {circumflex over ( 

    )}θ

    γ

    [p];

    with a frequency domain parameter sequence ω

    [1], ω

    [2], . . . , ω

    [p] being the decoded adjusted LSP parameter sequence {circumflex over ( 

    )}θ

    γ

    [1], {circumflex over ( 

    )}θ

    γ

    [2], . . . , {circumflex over ( 

    )}θ

    γ

    [p], executing, by the processing circuitry, a parameter sequence conversion step of determining a converted frequency domain parameter sequence ˜

    ω

    [1], ˜

    ω

    [2], . . . , ˜

    ω

    [p] using the frequency domain parameter sequence ω

    [1], ω

    [2], . . . , ω

    [p] as input to thereby generate the converted frequency domain parameter sequence ˜

    ω

    [1], ˜

    ω

    [2], . . . , ˜

    ω

    [p] as a decoded approximate LSP parameter sequence {circumflex over ( 

    )}θ

    app[1], {circumflex over ( 

    )}θ

    app[2], . . . , {circumflex over ( 

    )}θ

    app[p];

    generating, by the processing circuitry, a decoded adjusted linear prediction coefficient sequence {circumflex over ( 

    )}aγ

    [1], {circumflex over ( 

    )}aγ

    [2], . . . , {circumflex over ( 

    )}aγ

    [p] by converting the decoded adjusted LSP parameter sequence {circumflex over ( 

    )}θ

    γ

    [1], {circumflex over ( 

    )}θ

    γ

    [2], . . . , {circumflex over ( 

    )}θ

    γ

    [p] into linear prediction coefficients;

    calculating, by the processing circuitry, a decoded smoothed power spectral envelope series {circumflex over ( 

    )}W65[1], {circumflex over ( 

    )}Wγ

    [2], . . . , {circumflex over ( 

    )}Wγ

    [N] which is a series in frequency domain corresponding to the decoded adjusted linear prediction coefficient sequence {circumflex over ( 

    )}aγ

    [1], {circumflex over ( 

    )}aγ

    [2], . . . , {circumflex over ( 

    )}aγ

    [p];

    generating, by the processing circuitry, decoded sound signals using a frequency domain signal sequence resulting from decoding of input frequency domain signal codes and the decoded smoothed power spectral envelope series {circumflex over ( 

    )}Wγ

    [1], {circumflex over ( 

    )}Wγ

    [2], . . . , {circumflex over ( 

    )}Wγ

    [N];

    decoding, by the processing circuitry, input LSP codes to obtain a decoded LSP parameter sequence {circumflex over ( 

    )}θ

    [1], {circumflex over ( 

    )}θ

    [2], . . . , {circumflex over ( 

    )}θ

    [p]; and

    decoding, by the processing circuitry, input time domain signal codes, and generating decoded sound signals by synthesizing the time domain signal codes using either the decoded LSP parameter sequence for a preceding time segment or the decoded approximate LSP parameter sequence for the preceding time segment, and the decoded LSP parameter sequence for the predetermined time segment,whereinthe processing circuitry determines a value of each converted frequency domain parameter ˜

    ω

    [i] (i=1, 2, . . . , p) in the converted frequency domain parameter sequence ˜

    ω

    [1], ˜

    ω

    [2], . . . , ˜

    ω

    [p] through linear transformation which is based on a relationship of values between ω

    [i] and one or more frequency domain parameters adjacent to ω

    [i].

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