Method and apparatus for vector quantization
First Claim
1. A method of compressing an original signal convertible into a plurality of binary signal vectors, each signal vector containing a plurality of data elements of the original signal to be compressed, the method comprising the steps of:
- hashing a first signal vector converted from the original signal to identify one of at least three different subsets of a first set of code words, each code word of the first set having a unique, associated binary code, each code associated with the first set of code words having a first predetermined length less than the length of the first signal vector;
storing a first code associated with one of the code words from the one identified subset of the first set as a compressed representation of the first signal vector;
hashing a second signal vector converted from the original signal to identify one of at least three different subsets of a second set of code words, each code word of the second set having a unique, associated binary code, each code associated with the second set of code words having a second predetermined length less than the length of the second signal vector and the second set of code words differing from the first set of code words; and
storing a second code associated with one of the code words from the one selected subset of the second set as a compressed representation of the second signal vector.
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Abstract
A method of and apparatus for vector quantizaiton operates on binary signal vectors. Each signal vector contains a plurality of sample elements of a signal to be compressed. Each of the signal vectors is hashed to generate a value identifying one of at least three different subsets of code words collectively constituting a set of binary code words. Each of the signal vectors is hashed a second time to generate a value identifying one of at least three different subsets of code words collectively constituting a second different set of binary code words. Each code word is equal in length to the length of each of the signal vectors and has associated with it a unique binary code of a lesser length. The vector quantizer performs a distortion comparison search through the code words of the selected subset to identify the one code word and its uniquely associated code which has the least distortion of all of the code words of the one subset with respect to the hashed signal vector. That one code is outputted to represent the hashed signal vector. The subsets may be mutually exclusive and include a plurality of code words.
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Citations
16 Claims
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1. A method of compressing an original signal convertible into a plurality of binary signal vectors, each signal vector containing a plurality of data elements of the original signal to be compressed, the method comprising the steps of:
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hashing a first signal vector converted from the original signal to identify one of at least three different subsets of a first set of code words, each code word of the first set having a unique, associated binary code, each code associated with the first set of code words having a first predetermined length less than the length of the first signal vector; storing a first code associated with one of the code words from the one identified subset of the first set as a compressed representation of the first signal vector; hashing a second signal vector converted from the original signal to identify one of at least three different subsets of a second set of code words, each code word of the second set having a unique, associated binary code, each code associated with the second set of code words having a second predetermined length less than the length of the second signal vector and the second set of code words differing from the first set of code words; and storing a second code associated with one of the code words from the one selected subset of the second set as a compressed representation of the second signal vector. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An apparatus for compressing an original signal convertible into a plurality of binary signal vectors, each signal vector comprising a plurality of data elements of the original signal to be compressed, the apparatus comprising:
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first data storage means for storing sets of binary code words; first and second different sets of binary code words stored in the first data storage means; means for hashing signal vectors of the plurality to identify uniquely for each hashed signal vector one subset of code words from one of the different sets of code words stored in the first storage means; and second data storing means for storing as a compressed representation of the data of the original signal, a plurality of binary codes, each stored code being associated with one code word from the one subset of code words identified by the hashing means uniquely for each hashed signal vector. - View Dependent Claims (12)
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13. A method of decompressing data compressed from an original signal and represented by a plurality of binary codes comprising the steps of:
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identifying a first binary code word uniquely associated with a first code of the plurality, the first code word being longer than the first code; identifying a second binary code word uniquely associated with a second code of the plurality, the second code word being longer than the second code and the second code being different in length from the first code; and storing in a data storage device, a decompressed binary approximation of the data of the original signal using a combination of the first and second binary code words. - View Dependent Claims (14, 15)
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16. An apparatus for decompressing data compressed from an original signal represented by a plurality of binary codes of at least two different lengths comprising:
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first data storage means for storing sets of binary code words; at least first and second different sets of binary code words stored in the first data storage means, the first set having a first number of code words and the second set having a second number of code words different from the first, each stored code word having a length longer than an associated binary code; and means for identifying for each code one of the different sets of code words from the first data storage means containing the one code word associated with the code and identifying the one code word of the one identified set associated with the code and for converting the identified code words into decompressed data elements approximating data of the original signal.
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Specification