High efficiency encoding method
First Claim
1. A high efficiency encoding method, comprising the steps of:
- determining an M-dimensional vector by dividing an input audio signal on a block-by-block basis and performing time domain to frequency domain conversion on at least one block of the signal;
determining an S-dimensional vector from the M-dimensional vector, where S<
M, by dividing the components of the M-dimensional vector into plural groups and finding a representative value for each of said groups;
processing the S-dimensional vector in accordance with a first vector quantization;
finding a corresponding S-dimensional code vector by inversely quantizing output data of the first vector quantization;
generating an expanded M-dimensional vector by expanding the S-dimensional code vector;
determining data expressing a relation between the expanded M-dimensional vector and the original M-dimensional vector, and performing a second vector quantization on said data.
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Abstract
A high efficiency encoding method for encoding data on frequency axis obtained by dividing an input audio signal on block-by-block basis and converting the signal onto the frequency axis, wherein V bands are searched for a band BVH with the highest center frequency if it is decided that there are one or more shift points of voiced (V)/unvoiced (UV) decision data of all bands on the frequency axis, and wherein the number of V bands NV up to the band BVH is found, so as to decide whether proportion of the V bands is equal to or higher than a predetermined threshold Nth, thereby deciding one V/UV boundary point. Thus, it is possible to replace the V/UV decision data for each band by information on one demarcation in all bands, thereby to reduce data volume and to reduce bit rate. Also, by using two-stage hierarchical vector quantization in quantizing the data on the frequency axis, operation volume for codebook search and memory capacity of the codebook are reduced.
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Citations
28 Claims
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1. A high efficiency encoding method, comprising the steps of:
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determining an M-dimensional vector by dividing an input audio signal on a block-by-block basis and performing time domain to frequency domain conversion on at least one block of the signal; determining an S-dimensional vector from the M-dimensional vector, where S<
M, by dividing the components of the M-dimensional vector into plural groups and finding a representative value for each of said groups;processing the S-dimensional vector in accordance with a first vector quantization; finding a corresponding S-dimensional code vector by inversely quantizing output data of the first vector quantization; generating an expanded M-dimensional vector by expanding the S-dimensional code vector; determining data expressing a relation between the expanded M-dimensional vector and the original M-dimensional vector, and performing a second vector quantization on said data. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A high efficiency encoding method comprising the steps of:
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determining an M-dimensional vector on the basis of data obtained by dividing an input audio signal on a block-by-block basis thus generating blocks each comprising a variable number of parameter data, performing time domain to frequency domain conversion on one of the blocks of the signal to generate frequency domain data, and generating from the frequency domain data a fixed number of data determining the M-dimensional vector; and processing the M-dimensional vector in accordance with vector quantization. - View Dependent Claims (18, 19, 20, 21)
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22. A high efficiency encoding method comprising the steps of:
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determining an M-dimensional vector for each block of an input audio signal by dividing the input audio signal on a block-by-block basis, performing time domain to frequency domain conversion on each block of the signal to generate frequency domain data, and performing an inter-block difference operation on the frequency domain data; and processing each said M-dimensional vector in accordance with vector quantization. - View Dependent Claims (23, 24, 25, 26)
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27. A high efficiency encoding method comprising the steps of:
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determining an M-dimensional vector by dividing an input voice signal on block-by-block basis, performing time domain to frequency domain conversion on at least one block of the signal thus generating frequency domain data, and performing non-linear compression on the frequency domain data; determining an S-dimensional vector from the M-dimensional vector, where S<
M, by dividing the data of the M-dimensional vector into plural groups and finding an average value for each of the groups;processing the S-dimensional vector in accordance with a first vector quantization; finding a corresponding S-dimensional code vector by inversely quantizing output data of the first vector quantization; expanding the S-dimensional code vector to an expanded M-dimensional vector; and processing, in accordance with second vector quantization, data indicative of a difference between the expanded M-dimensional vector and the M-dimensional vector.
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28. A high efficiency encoding method comprising the steps of:
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determining M-dimensional vectors by dividing an input audio signal on a block-by-block basis and performing time domain to frequency domain conversion on each block of the audio signal to generate frequency domain data for said each block, wherein the audio signal is a voice signal; and performing quantization, by using a vector quantizer having plural codebooks according to a state of the input audio signal to process each said M-dimensional vector in accordance with vector quantization, and by changing over the plural codebooks in accordance with a parameter indicating characteristics of said each block of the voice signal, wherein a first one of the codebooks is employed to process at least one of the M-dimensional vectors for which the parameter indicates that a corresponding portion of the voice signal is voiced, and a second one of the codebooks is employed to process at least one of the M-dimensional vectors for which the parameter indicates that a corresponding portion of the voice signal is unvoiced.
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Specification