Adaptive transform coding by selecting optimum block lengths according to variatons between successive blocks
First Claim
1. An adaptive transform coding method comprising:
- a) storing subblocks of input digital samples representing an audio-frequency signal in a buffer at predetermined intervals, reading the stored samples from the buffer and segmenting the samples from the buffer into a plurality of blocks each having an integral multiple of length of said subblock;
b) encoding each of said blocks into corresponding transform coefficients and storing said transform coefficients in a memory;
c) squaring each of said transform coefficients;
d) summing those of said squared transform coefficients which correspond to high-frequency components of said input digital samples to produce squared sums;
e) detecting a minimum of said squared sums as corresponding to an optimum block length;
g) selecting those of said transform coefficients which correspond to said optimum block length from said memory; and
h) multiplexing the selected transform coefficients with a block length signal representative of said optimum block length.
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Accused Products
Abstract
Subblocks of input digital samples are stored into a buffer at frame intervals and segmented into blocks having an integral multiple of the length of the subblock. Each block is encoded into transform coefficients and stored into a memory. Each coefficient is squared and those of the squared transform coefficients which correspond to high-frequency components of the input digital samples are summed and a minimum value is detected therefrom as corresponding to an optimum block length. Those transform coefficients which correspond to the optimum block length are selected from the memory and multiplexed with a signal representative of the optimum block length. In a modification, interblock differences are detected between successive transform coefficients of equal block length and squared. Those of the squared interblock differences which correspond to equal block length are summed, producing a set of squared sums for each block length. A variation is detected between a representative squared sum of a given set and a representative squared sum of a successive set to identify a block length which corresponds to the variation as an optimum block length.
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Citations
53 Claims
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1. An adaptive transform coding method comprising:
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a) storing subblocks of input digital samples representing an audio-frequency signal in a buffer at predetermined intervals, reading the stored samples from the buffer and segmenting the samples from the buffer into a plurality of blocks each having an integral multiple of length of said subblock; b) encoding each of said blocks into corresponding transform coefficients and storing said transform coefficients in a memory; c) squaring each of said transform coefficients; d) summing those of said squared transform coefficients which correspond to high-frequency components of said input digital samples to produce squared sums; e) detecting a minimum of said squared sums as corresponding to an optimum block length; g) selecting those of said transform coefficients which correspond to said optimum block length from said memory; and h) multiplexing the selected transform coefficients with a block length signal representative of said optimum block length. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An adaptive transform coding method comprising:
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a) storing subblocks of input digital samples representing an audio-frequency signal into a buffer at frame intervals, reading the stored samples from the buffer and segmenting the samples from the buffer into a plurality of blocks each having an integral multiple of the length of said subblock; b) encoding each of said blocks into corresponding transform coefficients and storing said transform coefficients into a memory; c) detecting interblock differences between successive transform coefficients of equal block length; d) squaring each of said interblock differences; e) summing those of said squared interblock differences which correspond to equal block length to produce a set of squared sums of said interblock differences for each block length; f) detecting representative values of the squared sums from successive ones of said sets, detecting a variation between said representative values and identifying a block length corresponding to said variation as an optimum block length; g) selecting those of said transform coefficients which correspond to said optimum block length from said memory; and h) multiplexing the selected transform coefficients with a block length signal representative of said optimum block length. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. An adaptive transform coding method comprising:
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a) storing subblocks of input digital samples representing an audio-frequency signal in a buffer at frame intervals, reading the stored samples from the buffer and segmenting the samples from the buffer into a plurality of blocks each having an integral multiple of the length of said subblock; b) storing said blocks in a memory and detecting interblock differences between successive blocks of equal length; c) squaring each of said interblock differences; d) summing those of said squared interblock differences which correspond to equal block length to produce a set of squared sums of said interblock differences for each block length; e) detecting representative values of the squared sums from successive ones of said sets, detecting a variation between said representative values and identifying a block length corresponding to said variation as an optimum block length; f) selecting those of said blocks having said optimum block length from said memory; g) linearly encoding the selected blocks into corresponding transform coefficients; and h) multiplexing said transform coefficients with a block length signal representative of said optimum block length. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26)
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27. A data compression system comprising:
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a buffer; buffer control means for storing subblocks of input digital samples representing an audio-frequency signal in said buffer at predetermined intervals, reading the stored samples from the buffer and segmenting the samples from the buffer into a plurality of blocks each having an integral multiple of the length of said subblock; a transform encoder for encoding each of said blocks into corresponding transform coefficients; a memory for storing said transform coefficients therein; optimum block length determination means for squaring each of said transform coefficients, summing those of said squared transform coefficients which correspond to high-frequency components of said input digital samples to produce squared sums, detecting a minimum of said squared sums as corresponding to an optimum block length, and selecting those of said transform coefficients which correspond to said optimum block length from said memory; multiplexer means for multiplexing the selected transform coefficients with a signal representative of said optimum block length into a multiplex signal; demultiplexer means for demultiplexing the multiplex signal into said transform coefficients and said block length signal; and a transform decoder coupled to said demultiplexer means for decoding said demultiplexed transform coefficients in a process inverse to said transform encoder at intervals corresponding to the block length indicated by said demultiplexed block length signal. - View Dependent Claims (28, 29, 30, 31, 32, 33)
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34. A data compression system comprising:
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a buffer; buffer control means for storing subblocks of input digital samples representing an audio-frequency signal in said buffer at frame intervals, reading the stored samples from the buffer and segmenting the samples from the buffer into a plurality of blocks each having an integral multiple of the length of said subblock; a transform encoder for encoding said blocks into respective transform coefficients; a memory for storing said transform coefficients therein; optimum block length determination means for detecting interblock differences between successive transform coefficients of equal block length, squaring each of said interblock differences, summing those squared interblock differences corresponding to equal block length to produce a set of said squared sums for each block length, detecting representative values of the squared sums from successive ones of said sets, detecting a variation between said representative values and identifying a block length corresponding to said variation as an optimum block length, and selecting those of the transform coefficients having said optimum block length from said memory; multiplexer means for multiplexing the selected transform coefficients with a signal representative of said optimum block length into a multiplex signal; demultiplexer means for demultiplexing the multiplex signal into said transform coefficients and said block length signal; and a transform decoder coupled to said demultiplexer means for decoding said demultiplexed transform coefficients in a process inverse to said transform encoder at intervals corresponding to the block length indicated by said demultiplexed block length signal. - View Dependent Claims (35, 36, 37, 38, 39, 40, 41, 42, 43)
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44. A data compression system comprising:
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a buffer; buffer control means for storing subblocks of input digital samples representing an audio-frequency signal into said buffer at predetermined intervals, reading the stored samples from the buffer and segmenting the samples from the buffer into a plurality of blocks each having an integral multiple of the length of said subblock; a memory for storing said blocks therein; optimum block length determination means for detecting interblock differences between successive blocks of equal block length, squaring each of said interblock differences, summing those squared interblock differences corresponding to equal block length to produce a set of said squared sums for each block length, detecting representative values of the squared sums from successive ones of said sets, detecting a variation between said representative values and identifying a block length corresponding to said variation as an optimum block length, and selecting those of the blocks having said optimum block length from said memory; a transform encoder for encoding said selected blocks into respective transform coefficients; multiplexer means for multiplexing the transform coefficients with a signal representative of said optimum block length into a multiplex signal; demultiplexer means for demultiplexing the multiplex signal into said transform coefficients and said block length signal; and a transform decoder coupled to said demultiplexer means for decoding said demultiplexed transform coefficients in a process inverse to said transform encoder at intervals corresponding to the block length indicated by said demultiplexed block length signal. - View Dependent Claims (45, 46, 47, 48, 49, 50, 51, 52, 53)
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Specification