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Distortion detecting device, distortion correcting device, and distortion correcting method for digital audio signal

  • US 6,587,984 B1
  • Filed: 09/17/1999
  • Issued: 07/01/2003
  • Est. Priority Date: 03/18/1997
  • Status: Expired due to Fees
First Claim
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1. A digital audio signal distortion correcting device comprising:

  • storage means (2) for storing a digital audio signal converted to code by an analog/digital converter;

    occurrence frequency detecting means (3) for extracting a plurality of samples from said digital audio signal stored in said storage means (2) and counting an occurrence frequency of said samples for every code expressing a quantization level of the samples to obtain a level distribution;

    normalizing means (34) for generating, by applying a low-pass filtering process on the original level distribution detected by said occurrence frequency detecting means (3), an ideal level distribution approximating an ideal case where said analog/digital converter has no error, dividing said original level distribution by said ideal level distribution, and setting the division result thereof as a normalized level distribution;

    conversion table calculating means (35) for calculating, based on said normalized level distribution, a conversion table in which data bit lengths are extended to make a correction with respect to a conversion error of said analog/digital converter for all of said quantization levels of said digital audio signal; and

    data substituting means (36) for substituting said quantization level of said digital audio signal with level data according to said conversion table for output.

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