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Audio classification based on perceptual quality for low or medium bit rates

  • US 9,589,570 B2
  • Filed: 09/13/2013
  • Issued: 03/07/2017
  • Est. Priority Date: 09/18/2012
  • Status: Active Grant
First Claim
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1. A method for encoding signals, the method comprising:

  • receiving, by an audio encoder, a digital signal comprising audio data, wherein the audio data includes data of speech and non-speech sounds;

    classifying, by the audio encoder, the digital signal as an AUDIO signal based on the audio data in the digital signal;

    determining, by the audio encoder, whether classifying conditions are satisfied, wherein the classifying conditions include;

    pitch differences between sub-frames in the digital signal are less than a first threshold, a coding rate of the digital signal is below a second threshold, an average normalized pitch correlation value for the sub-frames in the digital signal is greater than a third threshold and a smoothed pitch correlation obtained according to the average normalized pitch correlation value is greater than a fourth threshold, wherein each of the pitch differences is an absolute value of the difference between two pitch values corresponding to two sub-frames respectively;

    re-classifying, by the audio encoder, the digital signal as a VOICED signal when the classifying conditions are satisfied;

    encoding, by the audio encoder, the digital signal in the time-domain if the digital signal is classified as a VOICED signal; and

    encoding, by the audio encoder, the digital signal in the frequency-domain if the digital signal is classified as an AUDIO signal.

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