Half-rate vocoder
First Claim
1. A speech coder configured to encode a sequence of digital speech samples into a bit stream, the speech coder being operable to:
- divide the digital speech samples into one or more frames;
compute model parameters for a frame;
quantize 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;
combine 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;
encode the first parameter codeword with an error control code to produce a first FEC (“
forward error control”
) codeword; and
include the first FEC codeword in a bit stream for the frame.
1 Assignment
0 Petitions
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
80 Claims
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1. A speech coder configured to encode a sequence of digital speech samples into a bit stream, the speech coder being operable to:
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divide the digital speech samples into one or more frames; compute model parameters for a frame; quantize 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; combine 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; encode the first parameter codeword with an error control code to produce a first FEC (“
forward error control”
) codeword; andinclude 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 speech decoder configured to decode digital speech samples from a bit stream, the speech decoder being operable to:
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divide the bit stream into one or more frames of bits; extract a first FEC (“
forward error control”
) codeword from a frame of bits;error control decode the first FEC codeword to produce a first parameter codeword; extract 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; use the extracted pitch bits to at least in part reconstruct pitch information for the frame; use the extracted voicing bits to at least in part reconstruct voicing information for the frame; use the extracted gain bits to at least in part reconstruct signal level information for the frame; and use 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)
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53. A speech decoder configured to decode digital speech samples from a bit stream, the speech decoder being operable to:
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divide the bit stream into one or more frames of bits; extract a first FEC (“
forward error control”
) codeword from a frame of bits;error control decode the first FEC codeword to produce a first parameter codeword; use the first parameter codeword to determine whether the frame of bits corresponds to a tone signal; extract tone amplitude bits from the first parameter codeword if the frame of bits is determined to correspond to a tone signal, otherwise extract 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 use either the tone amplitude bits or the pitch bits, voicing bits and gain bits to compute digital signal samples. - View Dependent Claims (54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64)
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65. A speech decoder configured to decode a frame of bits into speech samples, the speech decoder being operable to:
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determine the number of bits in the frame of bits; extract spectral bits from the frame of bits; use 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; reconstruct spectral information using the spectral codebook index; and compute speech samples using the reconstructed spectral information. - View Dependent Claims (66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80)
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Specification