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Encoding method, encoder, periodic feature amount determination method, periodic feature amount determination apparatus, program and recording medium

  • US 9,711,158 B2
  • Filed: 01/18/2012
  • Issued: 07/18/2017
  • Est. Priority Date: 01/25/2011
  • Status: Active Grant
First Claim
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1. A computer-implemented encoding method for encoding a sample string in a frequency domain that is derived from an audio signal in frames, executing on a processor, the method comprising:

  • a step of receiving the sample string of the audio signal in the time-domain;

    a step of transforming the audio signal in the time-domain to the frequency-domain;

    an interval determination step of determining an interval T between samples from a set S of candidates for the interval T, the interval T corresponding to a periodicity of the audio signal or to an integer multiple of a fundamental frequency of the audio signal;

    a side information generating step of encoding the interval T determined at the interval determination step to obtain side information;

    outputting the side information to a decoder;

    a sample string encoding step of encoding a rearranged sample to obtain a code string, the rearranged sample string(1) including all of the samples in the sample string, and(2) being a sample string in which at least some of the samples are rearranged so that all or some of one or a plurality of successive samples including a sample corresponding to the periodicity or the fundamental frequency of the audio signal in the sample string and one or a plurality of successive samples including a sample corresponding to an integer multiple of the periodicity or the fundamental frequency of the audio signal in the sample string are gathered together into a cluster on the basis of the interval T determined by the interval determination step;

    wherein the interval determination step determines the interval T from a set S of candidates for the interval T, the set S being made up of Y candidates among Z candidates for the interval T, the Y candidates including Z2 candidates selected without depending on a previous candidate for the interval T corresponding to a periodicity of the audio signal or to an integer multiple of a fundamental frequency of the audio signal, the previous candidate subjected to the interval determination step in a previous frame a predetermined number of frames before the current frame and including the previous candidate subjected to the interval determination step in the previous frame the predetermined number of frames before the current frame, the Z candidates being representable with the side information, where Z2<

    Z and Y<

    Z; and

    outputting the code string to the decoder, wherein the code string has a compressed amount of data compared to the received sample string of the audio signal, and the decoder is configured to reproduce a sample string of an audio signal in the time-domain based on the code string and the side information.

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