Very low rate speech encoder and decoder
First Claim
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1. A speech encoder, comprising:
- a segmenter for segmenting speech information into frames, each having a predetermined time period;
means for computing a quantized energy vector of speech information using a scalar energy parameter for each said frame;
means for computing a quantized voice vector of speech information using a scalar voice parameter for each said frame;
means for computing a quantized pitch vector of speech information using a scalar pitch parameter for each said frame; and
means for arranging bits associated with said quantized vectors in a block to provide a profile of speech information over said block.
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Abstract
A speech encoder is disclosed quantizing speech information with respect to energy, voicing and pitch parameters to provide a fixed number of bits per block of frames. Coding of the parameters takes place for each N frames, which comprise a block, irrespective of phonemic boundaries. Certain frames of speech information are discarded during transmission, if such information is substantially duplicated in an adjacent frame. A very low data rate transmission system is thus provided which exhibits a high degree of fidelity and throughput.
80 Citations
25 Claims
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1. A speech encoder, comprising:
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a segmenter for segmenting speech information into frames, each having a predetermined time period; means for computing a quantized energy vector of speech information using a scalar energy parameter for each said frame; means for computing a quantized voice vector of speech information using a scalar voice parameter for each said frame; means for computing a quantized pitch vector of speech information using a scalar pitch parameter for each said frame; and means for arranging bits associated with said quantized vectors in a block to provide a profile of speech information over said block. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A fixed data rate speech transmission system, comprising:
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means for segmenting speech information into a plurality of frames defining a block; means for quantizing a voice profile of speech information into a fixed number of bits per block; means for quantizing a pitch profile of speech information into a fixed number of bits per block; means for quantizing an energy profile of speech information into a fixed number of bits per block; means for quantizing a spectrum profile of speech information into a fixed number of bits per block; and means for transmitting said bits as a fixed number of bits for each said block. - View Dependent Claims (12, 13)
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14. A method of encoding speech information, comprising the steps of:
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segmenting speech information into a number of predetermined time periods defining frames; computing a quantized energy vector of speech information for each said frame using a scalar energy parameter; computing a quantized voice vector of said speech information of each said frame using a scalar voice parameter; computing a quantized pitch vector of the speech information of each said frame using a scalar pitch parameter; and arranging bits associated with said quantized vectors in a block to provide a profile of speech information over said block of frames. - View Dependent Claims (15, 16, 17, 18, 19, 20)
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21. A method of encoding and transmitting speech information at a fixed data rate, comprising the steps of:
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segmenting speech information into a plurality of frames defining a block; quantizing a voice profile of speech information into a fixed number of bits per block; quantizing a pitch profile of speech information into a fixed number of bits per block; quantizing an energy profile of speech information into a fixed number of bits per block; quantizing a spectrum profile of speech information into a fixed number of bits per block; and transmitting a fixed number of said bits for each said block. - View Dependent Claims (22, 23, 24)
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25. A method of encoding and processing speech information for transmission at a low data rate, comprising the steps of:
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converting the speech information in corresponding digital signals segmented into frame intervals; performing an LPC analysis on each said frame to produce corresponding LPC coefficients; converting said LPC coefficients into principal spectral components; vector quantizing different parameters of the speech information associated with a plurality of said frames to produce a vector quantized time profile of said parameters; comparing adjacent frames of said speech information for informativeness and discarding speech information in frames found to be similar to the speech information of adjacent frames; correlating the vector quantized parameters into other data using a codebook having principal spectral component vectors; and transmitting an index of a correlated principal spectral component vector at a low data rate.
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Specification