Hierarchical adaptive multistage vector quantization
First Claim
1. An hierarchical adaptive multistage vector quantizer to supply compressed video signals to a transmission line, said hierarchical adaptive multistage vector quantizer comprising:
- means for receiving a vector I having a particular magnitude reflective of a portion of a video signal;
mean removal means for performing mean removal on vector I to provide a mean removed vector IM ;
an vector quantizer having "N" stages in which N equals 3 or more, the first stage performing vector quantization (VQ) and inverse vector quantization (YQ-1) of the vector IM to obtain a residual vector E1-, the (N-1)th second stage performing VQ and inverse vector quantization (VQ-1) of the residual vector E1 to obtain a residual vector EN-1 and the Nth stage performing vector quantization (VQ) and inverse vector quantization (VQ-1) of the residual vector ENN-1 to obtain residual vector EN ;
comparison means for comparing each vector(IM, E1, EN-1, . . . EN) to a threshold when each such vector is generated; and
vector reduction means connected to be operative when residual vector EN is greater than said threshold for selecting a subsection of vector I for processing by the vector quantizer and for processing the comparison means until a residual vector (rs), is equal to or less than said threshold; and
means to generate and transmit to a transmission line an address representing said residual vector rs when said residual vector (rs) is equal to or less than said threshold.
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Abstract
An N-stage vector quantizer in which increasingly smaller portions of a vector are compared to a threshold until the quantization error is less than the threshold. The threshold may be adaptive to insure a constant bit rate. The first stage performs VQ and inverse VQ on an input vector. The difference between the inverse VQ and the input vector is determined to create a first stage residual error. If the first stage residual error is less than a threshold, no further stages of the multistage vector quantizer are used and the input vector or first stage residual is passed on to the output stage. However, if the first stage residual error is not less than the threshold, the residual error is passed to stage two of the multistage vector quantizer where VQ and inverse VQ are performed on the first stage residual error. The process is continued until the residual is less than the threshold. If the Nth stage is reached without the residual being less than the threshold, the process is repeated on a smaller portion of the original input vector. For example, if the original input vector were a 16×16 vector, the smaller section could be a 16×8 vector.
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Citations
6 Claims
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1. An hierarchical adaptive multistage vector quantizer to supply compressed video signals to a transmission line, said hierarchical adaptive multistage vector quantizer comprising:
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means for receiving a vector I having a particular magnitude reflective of a portion of a video signal; mean removal means for performing mean removal on vector I to provide a mean removed vector IM ; an vector quantizer having "N" stages in which N equals 3 or more, the first stage performing vector quantization (VQ) and inverse vector quantization (YQ-1) of the vector IM to obtain a residual vector E1-, the (N-1)th second stage performing VQ and inverse vector quantization (VQ-1) of the residual vector E1 to obtain a residual vector EN-1 and the Nth stage performing vector quantization (VQ) and inverse vector quantization (VQ-1) of the residual vector ENN-1 to obtain residual vector EN ; comparison means for comparing each vector(IM, E1, EN-1, . . . EN) to a threshold when each such vector is generated; and vector reduction means connected to be operative when residual vector EN is greater than said threshold for selecting a subsection of vector I for processing by the vector quantizer and for processing the comparison means until a residual vector (rs), is equal to or less than said threshold; and means to generate and transmit to a transmission line an address representing said residual vector rs when said residual vector (rs) is equal to or less than said threshold. - View Dependent Claims (2, 3, 4, 5)
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6. An hierarchical adaptive multistage vector quantizer to supply compressed video signals to a transmission line, said hierarchical adaptive multistage vector quantizer comprising:
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means for receiving a vector I having a particular magnitude reflective of a portion of a video signal; mean removal means for performing mean removal on vector I to provide a mean removed vector IM ; an vector quantizer having "N" stages in which N equals 3 or more with each of said N stages having its own vector codebook, the first stage performing vector quantization (VQ) and inverse vector quantization (VQ-1) of the vector IM to obtain a residual vector E1-, the (N-1)th stage performing VQ and inverse vector quantization (VQ-1) of the residual vector E1- to obtain a residual vector EN-1 and the Nth stage performing vector quantization (VQ) and inverse vector quantization (VQ-1) of the residual vector EN-1 to obtain residual vector EN ; comparison means for comparing each vector(IM, EI, EN-1, . . . EN) to a threshold when each such vector is generated; and vector reduction means connected to be operative when residual vector EN is greater than said threshold for selecting a subsection of vector I for processing by the vector quantizer and for processing the comparison means until a residual vector (rs) is equal to or less than said threshold; and selection means for selecting the first residual vector that is equal to or less than the threshold and for passing an address reflective of said residual vector to a transmission line.
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Specification