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System for predictive coding/decoding of a digital speech signal by embedded-code adaptive transform

  • US 5,583,963 A
  • Filed: 01/21/1994
  • Issued: 12/10/1996
  • Est. Priority Date: 01/21/1993
  • Status: Expired due to Term
First Claim
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1. System for predictive coding of a digital signal as an embedded-code digital signal, coded by embedded-code adaptive transformation, in which the coded digital signal comprises a coded speech signal and, if appropriate, an auxiliary data signal inserted into the coded speech signal after coding said digital speech signal, said system comprising:

  • a perceptual weighting filter driven by a short-term prediction loop delivering a perceptual signal;

    ;

    a long-term prediction circuit delivering an estimated perceptual signal P1n, said long-term prediction circuit forming a long-term prediction loop delivering, from said perceptual signal and from an estimated past excitation signal POn, a modelled perceptual excitation signal Pn ;

    adaptive transform and quantization means for receiving said modelled perceptual excitation signal, and for generating said coded speech signal, said perceptual weighting filter including a filter, driven by a short-term prediction loop for providing short-term prediction of a speech signal to be coded, for producing a frequency distribution of quantization noise; and

    means for subtracting said past excitation signal P0n, from said perceptual signal to deliver an updated modelled perceptual signal Pn,said long-term prediction circuit being formed, as a closed loop, from a dictionary updated by a modelled past excitation corresponding to the lowest throughput and delivering a waveform, and an estimated gain associated therewith, which make up the estimated perceptual signal,said adaptive transform and quantization means including an orthonormal transform module including an adaptive orthogonal transformation module and a module for progressive modelling by orthogonal vectors, said means of progressive modelling and said long-term prediction circuit making it possible to deliver indices representing the coded speech signal, said system further including means for inserting auxiliary data, coupled to a transmission channel.

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