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Audio encoding apparatus, audio decoding apparatus, audio encoding method, and audio decoding method

  • US 9,786,292 B2
  • Filed: 10/12/2012
  • Issued: 10/10/2017
  • Est. Priority Date: 10/28/2011
  • Status: Active Grant
First Claim
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1. A speech encoding apparatus, comprising:

  • a memory that stores instructions;

    a processor that executes the instructions;

    a time-frequency domain transformer that transforms a time domain input speech signal to a frequency domain signal;

    a calculator; and

    a parameter encoder,wherein, when executed by the processor, the instructions cause the processor to perform operations comprising;

    dividing the frequency domain signal into a plurality of sub-vectors and quantizing spectral coefficients of each of the resultant sub-vectors;

    encoding codebook indication values of all of the sub-vectors, the codebook indication values being obtained by the quantization, the codebook indication values representing codebook numbers in which larger numbers are given according to an energy amount of the plurality of sub-vectors, wherein the larger the codebook numbers, the larger a number of bits are used by each of the codebook indication values;

    identifying, of the entire band, a band of a sub-vector with a codebook indication value having a largest used bit count among all of the codebook indication values; and

    estimating a number of bits used by the codebook indication value having the largest used bit count, based on a total number of bits available in transmission units of the input speech signal and a number of used bits of a codebook indication value other than the codebook indication value having the largest used bit count;

    wherein the calculator calculates, with respect to a number of bits necessary for encoding a codebook indication value of the band, a difference between an actual value and an estimated value, the actual value being an actual number of used bits of the codebook indication value having the largest used bit count, which is obtained by encoding the codebook indication value having the largest used bit count, and the estimated value being the estimated number of used bits of the codebook indication value having the largest used bit count, and the estimated value is obtained as the number of bits obtained by subtracting the total number of bits required for encoding a codebook indication value, other than that of the band, from the total number of bits usable for a codebook indication value of the entire band; and

    wherein the parameter encoder encodes the identified position information of the sub-vector and the calculated difference information.

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