Adaptive method and apparatus for coding speech

  • US 4,790,016 A
  • Filed: 11/14/1985
  • Issued: 12/06/1988
  • Est. Priority Date: 11/14/1985
  • Status: Expired due to Term
First Claim
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1. A speech coding system comprising:

  • transform means for performing a discrete transform of a window of speech to generate a discrete transform spectrum of coefficients;

    envelope defining and encoding means for defining an approximate envelope of the discrete spectrum in each of a plurality of subbands of coefficients and for encoding the defined envelope of each subband of coefficients;

    means for scaling each spectrum coefficient relative to the defined envelope of the respective subband of coefficients; and

    coefficient encoding means for encoding the scaled spectrum coefficients within each subband in a number of bits determined by the defined envelope of the subband.

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