Half-rate vocoder
First Claim
1. A method of encoding a sequence of digital speech samples into a bit stream, the method comprising:
- dividing the digital speech samples into one or more frames;
computing model parameters for a frame;
quantizing the model parameters to produce pitch bits conveying pitch information, voicing bits conveying voicing information, and gain bits conveying signal level information, wherein the pitch bits, the voicing bits and the gain bits are included in quantizer bits for the frame;
combining one or more of the pitch bits with one or more of the voicing bits and one or more of the gain bits to create a first parameter codeword that includes less than all of the quantizer bits for the frame;
encoding the first parameter codeword with an error control code to produce a first FEC (“
forward error control”
) codeword; and
including the first FEC codeword in a bit stream for the frame.
1 Assignment
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Accused Products
Abstract
Encoding a sequence of digital speech samples into a bit stream includes dividing the digital speech samples into one or more frames, computing model parameters for a frame, and quantizing the model parameters to produce pitch bits conveying pitch information, voicing bits conveying voicing information, and gain bits conveying signal level information. One or more of the pitch bits are combined with one or more of the voicing bits and one or more of the gain bits to create a first parameter codeword that is encoded with an error control code to produce a first FEC codeword that is included in a bit stream for the frame. The process may be reversed to decode the bit stream.
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Citations
87 Claims
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1. A method of encoding a sequence of digital speech samples into a bit stream, the method comprising:
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dividing the digital speech samples into one or more frames; computing model parameters for a frame; quantizing the model parameters to produce pitch bits conveying pitch information, voicing bits conveying voicing information, and gain bits conveying signal level information, wherein the pitch bits, the voicing bits and the gain bits are included in quantizer bits for the frame; combining one or more of the pitch bits with one or more of the voicing bits and one or more of the gain bits to create a first parameter codeword that includes less than all of the quantizer bits for the frame; encoding the first parameter codeword with an error control code to produce a first FEC (“
forward error control”
) codeword; andincluding the first FEC codeword in a bit stream for the frame. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41)
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42. A method for decoding digital speech samples from a bit stream, the method comprising:
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dividing the bit stream into one or more frames of bits; extracting a first FEC (“
forward error control”
) codeword from a frame of bits;error control decoding the first FEC codeword to produce a first parameter codeword; extracting pitch bits, voicing bits and gain bits from the first parameter codeword, the extracted pitch bits, voicing bits and gain bits including less than all of a set of quantizer bits for the frame; using the extracted pitch bits to at least in part reconstruct pitch information for the frame; using the extracted voicing bits to at least in part reconstruct voicing information for the frame; using the extracted gain bits to at least in part reconstruct signal level information for the frame; and using the reconstructed pitch information, voicing information and signal level information for one or more frames to compute digital speech samples. - View Dependent Claims (43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59)
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60. A method for decoding digital signal samples from a bit stream, the method comprising:
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dividing the bit stream into one or more frames of bits; extracting a first FEC (“
forward error control”
) codeword from a frame of bits;error control decoding the first FEC codeword to produce a first parameter codeword; using the first parameter codeword to determine whether the frame of bits corresponds to a tone signal; extracting tone amplitude bits from the first parameter codeword if the frame of bits is determined to correspond to a tone signal, otherwise extracting pitch bits, voicing bits, and gain bits from the first codeword if the frame of bits is determined to not correspond to a tone signal, the extracted pitch bits, voicing bits and gain bits including less than all of a set of quantizer bits for the frame; and using either the tone amplitude bits or the pitch bits, voicing bits and gain bits to compute digital signal samples. - View Dependent Claims (61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71)
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72. A method for decoding a frame of bits into speech samples, the method comprising:
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determining the number of bits in the frame of bits; extracting spectral bits from the frame of bits; using one or more of the spectral bits to form a spectral codebook index, wherein the index is determined at least in part by the number of bits in the frame of bits; reconstructing spectral information using the spectral codebook index; and computing speech samples using the reconstructed spectral information. - View Dependent Claims (73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87)
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Specification