Mode-specific method and apparatus for encoding signals containing speech

  • US 5,596,676 A
  • Filed: 10/11/1995
  • Issued: 01/21/1997
  • Est. Priority Date: 06/01/1992
  • Status: Expired due to Term
First Claim
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1. A method of encoding a signal having a speech component, the signal being organized as a plurality of frames, the method comprising the steps, performed for each frame, of:

  • analyzing a first linear prediction window to generate a first set of filter coefficients for a frame;

    analyzing a second linear prediction window to generate a second set of filter coefficients for the frame;

    analyzing a first pitch analysis window to generate a first pitch estimate for the frame;

    analyzing a second pitch analysis window to generate a second pitch estimate for the frame;

    determining whether the frame is one of a first mode, a second mode and a third mode, depending on measures of energy content of the frame and spectral content of the frame;

    encoding the frame, depending on the second set of filter coefficients and the first and the second pitch estimates, independently of the first set of filter coefficients, when the frame is determined to be the third mode;

    encoding the frame, depending on the first and the second sets of filter coefficients, independently of the first and the second pitch estimates, when the frame is determined to be the second mode; and

    encoding the frame, depending on the second set of filter coefficients, independently of the first set of filter coefficients and the first and the second pitch estimates, when the frame is determined to be the first mode.

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