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Tonal analysis for perceptual audio coding using a compressed spectral representation

  • US 7,333,930 B2
  • Filed: 03/14/2003
  • Issued: 02/19/2008
  • Est. Priority Date: 03/14/2003
  • Status: Active Grant
First Claim
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1. A method for performing perceptual audio encoding on an input audio signal, the method comprising:

  • (a) sampling the input audio signal to generate multiple sampled frames;

    (b) performing a first frequency transformation of each sampled frame into a frequency do main representation of the sample frame;

    (c) applying a magnitude compression operation to the frequency domain representation of each sampled frame to form a magnitude-compressed representation of the sample frame;

    (d) performing a second frequency transformation of the magnitude-compressed representation of each sampled frame to form a compressed spectral representation of the sample frame;

    (e) determining tonality of each sampled frame from a peak magnitude and an average magnitude of the compressed spectral representation of the sampled frame to distinguish tone-like components in the input audio signal from noise-like components in the input audio signal;

    (f) selecting a masked threshold for each sampled frame corresponding to the determined tonality of the sampled frame, wherein masked thresholds selected for the tone-like components in the input audio signal are different from masked thresholds selected for the noise-like components in the input audio signal; and

    (g) performing perceptual audio encoding on the sampled frames based on the selected masked thresholds to compress the tone-like features in the input audio signal at a different level of compression from the noise-like features in the input audio signal.

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