Vector-quantizing device having a capability of adaptive updating of code book
First Claim
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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Abstract
A vector-quantizing device comprises a first code book for storing a plurality of code vectors at respective addresses; a first addressing unit for selecting a code vector stored in the first code; a synthesis unit supplied with the code vector from the first code book for producing a synthetic signal that simulates an input signal; an evaluation unit supplied with the input signal and further with the synthetic signal from the synthesis means for evaluating a difference therebetween and searching for a code vector that minimizes the difference. There, the evaluation unit produces the first index data that specifies a code vector wherein the difference is minimized as a coded output. In addition, the vector-quantizing device includes a second code book for storing a plurality of code vectors at respective addresses; a second addressing unit for selecting a code vector stored in the second code book: and an update unit for counting the frequency of selection of the code vectors for each of the code vectors stored in the first code book. There, the update unit is for replacing a code vector in the first code book, when the frequency of use of the code vector is below a predetermined threshold, with a code vector in the second code book.
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Citations
12 Claims
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1. A vector-quantizing device for coding an input signal by a vector-quantization process, comprising:
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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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A coder that uses a vector-quantizing device comprising:
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an encoder; and a decoder; said encoder 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 only with 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 the 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 the 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; andsaid decoder comprising; a third code book for storing a plurality of code vectors at respective addresses; third addressing means supplied with said coded output from said evaluation means as third index data for selecting a code vector stored in said third code book in response to said third index data; second synthesis means supplied with said selected code vector from said third code book for producing a synthetic signal that simulates said input signal as a reproduced signal; a fourth code book for storing a plurality of code vectors at respective addresses; fourth addressing means supplied with fourth index data for selecting a code vector stored in said fourth code book; and second update means for counting the frequency of selection of the code vectors for each of said code vectors stored in said third code book, said update means producing said third index data and said fourth index data for replacing a code vector stored in said third code book and addressed by said third index data, when the frequency of use of said code vector is below a predetermined threshold, with a code vector stored in said fourth code book and addressed by said fourth index data. - View Dependent Claims (10, 11)
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12. A method for encoding an input signal with a vector-quantizing process, comprising the steps of:
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quantizing the input signal usinq only a code vector in a first code book; detecting a count frequency of use of the code vector stored in the first code book; identifying code vectors of the first code book of which a frequency of use is smaller than a predetermined threshold; and replacing the code vectors of the first code book thus identified with another code vector stored in a second code book.
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Specification