Predictive coding and decoding with error drift reduction

  • US 5,291,284 A
  • Filed: 07/23/1991
  • Issued: 03/01/1994
  • Est. Priority Date: 12/13/1988
  • Status: Expired due to Term
First Claim
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1. A predictive decoder comprising means for supplying a difference signal, means for supplying a prediction signal, and means for combining the said two signals to form an output signal dependent thereon, the prediction signal being derived from the output signal so as to depend upon previous portions of the difference signal, characterised in that means are provided for periodically alternating the operation of the decoder between first and second states, in which the cumulative effect of any time-averaged bias present in the difference signal is, respectively, to increase and to deplete the prediction signal, the respective lengths of the periods spent in the first and second states being such as to reduce the tendency of such time-averaged bias error to accumulate in the prediction signal.

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