Apparatus and method for speech encoding based on short-term prediction valves
First Claim
1. A speech encoding method comprising the steps of:
- generating short-term prediction coefficients based on an input speech signal;
providing first and second codebooks formed of assorted parameters representing said short-term prediction coefficients, said first and second codebooks relating to at least one of a plurality of characteristic parameters of said input speech signal;
selecting one of said first and second codebooks based on a pitch value of said input speech signal; and
quantizing said short-term prediction coefficients using said selected codebook.
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Abstract
Foe executing the code excitation linear prediction (CELP) coding, for example, α-parameters are taken out from the input speech signal by a linear prediction coding (LPC) analysis circuit 12. The α-parameters are then converted by an α-parameter to LSP converting circuit 13 into linear spectral pair (LSP) parameters and a vector of these line spectral pair (LSP) parameters is vector-quantized by a quantizer 14. The changeover switch 16 is controlled depending upon the pitch value detected by a pitch detection circuit 22 for selecting and using one of the codebook 15M for male voice and the codebook 15F for female voice for improving quantization characteristics without increasing the transmission bit rate.
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Citations
19 Claims
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1. A speech encoding method comprising the steps of:
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generating short-term prediction coefficients based on an input speech signal; providing first and second codebooks formed of assorted parameters representing said short-term prediction coefficients, said first and second codebooks relating to at least one of a plurality of characteristic parameters of said input speech signal; selecting one of said first and second codebooks based on a pitch value of said input speech signal; and quantizing said short-term prediction coefficients using said selected codebook. - View Dependent Claims (2, 3, 4, 5)
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6. A speech encoding method comprising the steps of:
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generating short-term prediction errors based on an input speech signal; providing first and second codebooks formed of assorted parameters representing said short-term prediction errors, said first and second codebooks relating to at least one of a plurality of characteristic parameters of said input speech signal; selecting one of said first and second codebooks based on a pitch value of said input speech signal; and quantizing said short-term prediction errors using said selected codebook. - View Dependent Claims (7, 8, 9)
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10. A speech encoding apparatus comprising:
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short-term prediction means for generating short-term prediction coefficients based on an input speech signal; first and second codebooks formed of assorted parameters representing said short-term prediction coefficients, said first and second codebooks relating to one or more of a plurality of characteristic parameters of said input speech signal; selection means for selecting one of said first and second codebooks based on a pitch value of said input speech signal; and quantization means for quantizing said short-term prediction coefficients using said selected codebook. - View Dependent Claims (11, 12, 13)
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14. A speech encoding apparatus comprising:
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short-term prediction means for generating short-term prediction coefficients based on an input speech signal; a first plurality of codebooks formed of assorted parameters representing said short-term prediction coefficients, said first plurality of codebooks relating to reference parameters of said input speech signal, said reference parameters including at least one of a plurality of characteristic parameters of said input speech signal; selecting means for selecting one of said first plurality of codebooks based on said reference parameters of said input speech signal; quantization means for quantizing said short-term prediction coefficients based on said codebook selected from said first plurality of codebooks; a second plurality of codebooks formed on the basis of training data corresponding to said reference parameters; and synthesis means for synthesizing an excitation signal which relates to an output of a codebook selected from said second plurality of codebooks based on a quantized value from said quantization means. - View Dependent Claims (15, 16, 17, 18, 19)
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Specification