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Vector-quantizing device having a capability of adaptive updating of code book

  • US 5,524,170 A
  • Filed: 06/15/1994
  • Issued: 06/04/1996
  • Est. Priority Date: 08/30/1991
  • Status: Expired due to Fees
First Claim
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1. A vector-quantizing device for coding an input signal by a vector-quantization process, comprising:

  • a first code book for storing a plurality of code vectors at respective addresses;

    first addressing means supplied with first index data for selecting a code vector stored only in said first code book in response to said first index data;

    synthesis means supplied with only said selected code vector from said first code book for producing a synthetic signal that simulates said input signal;

    evaluation means supplied with said input signal and further with said synthetic signal from said synthesis means for evaluating a difference therebetween, said evaluation means searching for a code vector that minimizes said difference in said first code book, transmitting said first index data that specifies a code vector wherein said difference is minimized as a coded output and producing a count signal each time a code vector in said first code book is selected;

    a second code book for storing a plurality of code vectors at respective addresses;

    second addressing means supplied with second index data for selecting a code vector stored in said second code book;

    counting means for counting a frequency of selection of the code vectors for each of said code vectors only stored in said first code book using said count signal; and

    update means for producing said second index data and replacing a code vector stored in said first code book and addressed by said first index data, when said frequency of selection of said code vector stored in said first code book and addressed by said first index data is below a predetermined threshold, with a code vector stored in said second code book and addressed by said second index data.

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