Method of converting codes between speech coding and decoding systems, and device and program therefor
First Claim
1. A speech communication code conversion method of converting a first code string of a speech signal into a second code string of the speech signal, said method comprising the steps of:
- a first step of obtaining a first line spectral pair from a code corresponding to a linear prediction coefficient out of said first code string, said first code string codable in a first coding and decoding system,a second step of storing and holding said first line spectral pair as a second line spectral pair,a third step of calculating, from said first line spectral pair, said second line spectral pair, a third line spectral pair sequentially read from a table in which a plurality of line spectral pairs are stored in advance, and a fourth line spectral pair selected, and stored and held among the third line spectral pairs read in the past from said table, an evaluation value for each said third line spectral pair, anda fourth step of selecting said third line spectral pair for which said evaluation value is the minimum from said table to output a code corresponding to said selected third line spectral pair as a converted code corresponding to a linear prediction coefficient in the second code string, anda fifth step of storing and holding said selected third line spectral pair as the fourth line spectral pair,wherein said converted code is decodable by a linear prediction coefficient decoding method in a second coding and decoding system such that the speech signal is interpretable by said first coding and decoding system and said second coding and decoding system.
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Abstract
A second evaluation value calculation circuit calculates an evaluation value from a first linear prediction coefficient, a second linear prediction coefficient stored and held, a third linear prediction coefficient read from a table in which a plurality of linear prediction coefficients are stored in advance, and a fourth linear prediction coefficient selected, stored and held among the third linear prediction coefficients read from the table in the past, while a second evaluation value minimizing circuit selects the third linear prediction coefficient with which the evaluation value is the minimum and outputs a code corresponding to the selected third linear prediction coefficient as a code decodable by a second coding and decoding system.
6 Citations
55 Claims
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1. A speech communication code conversion method of converting a first code string of a speech signal into a second code string of the speech signal, said method comprising the steps of:
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a first step of obtaining a first line spectral pair from a code corresponding to a linear prediction coefficient out of said first code string, said first code string codable in a first coding and decoding system, a second step of storing and holding said first line spectral pair as a second line spectral pair, a third step of calculating, from said first line spectral pair, said second line spectral pair, a third line spectral pair sequentially read from a table in which a plurality of line spectral pairs are stored in advance, and a fourth line spectral pair selected, and stored and held among the third line spectral pairs read in the past from said table, an evaluation value for each said third line spectral pair, and a fourth step of selecting said third line spectral pair for which said evaluation value is the minimum from said table to output a code corresponding to said selected third line spectral pair as a converted code corresponding to a linear prediction coefficient in the second code string, and a fifth step of storing and holding said selected third line spectral pair as the fourth line spectral pair, wherein said converted code is decodable by a linear prediction coefficient decoding method in a second coding and decoding system such that the speech signal is interpretable by said first coding and decoding system and said second coding and decoding system. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A code conversion device for converting a first code string of a speech signal into a second code string of the speech signal, said device comprising:
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a linear prediction coefficient decoding circuit for obtaining a first line spectral pair from a code corresponding to a linear prediction coefficient out of said first code string codable in a first coding and decoding system, a storage circuit for storing and holding said first line spectral pair as a second line spectral pair, an evaluation value calculation circuit for calculating, from said first linear spectral pair, said second linear spectral pair, a third linear spectral pair sequentially read from a table in which a plurality of line spectral pairs are stored in advance, and a fourth linear spectral pair stored and held, an evaluation value for each said third line spectral pair, and an evaluation value minimizing circuit for selecting said third linear spectral pair for which said evaluation value is the minimum from said table to output a code corresponding to said selected third linear spectral pair as a converted code corresponding to a linear prediction coefficient in a second code string, and a second storage circuit for storing and holding said selected third linear spectral pair as the fourth linear spectral pair, wherein a linear prediction coefficient decoding method in a second coding and decoding system decodes said converted code such that the speech signal is interpretable by said first coding and decoding system and said second coding and decoding system. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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20. A code conversion program embedded and implemented in a computer readable medium for conducting code conversion by controlling a computer which forms a code conversion device for converting a first code string of a speech signal into a second code string of the speech signal, said program comprising the functions of:
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a) obtaining a first line spectral pair from a code corresponding to a linear prediction coefficient out of said first code string codable in a first coding and decoding system, b) storing and holding said first line spectral pair as a second line spectral pair, c) calculating, from said first linear spectral pair, said second linear spectral pair, a third liner spectral pair sequentially read from a table in which a plurality of line spectral pairs are stored in advance, and a fourth linear spectral pair stored and held, an evaluation value for each said third line spectral pair, and d) selecting said third linear spectral pair with which said evaluation value is the minimum from said table to output the converted code corresponding to selected third linear spectral pair as a code corresponding to the linear prediction coefficient in the second code string, and e) storing and holding said selected third linear spectral pair as the fourth linear spectral pair, wherein said converted code being decodable by a linear prediction coefficient decoding method in a second coding and decoding system such that the speech signal is interpretable by said first coding and decoding system and said second coding and decoding system. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28)
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29. A code conversion method of converting a first code string of a speech signal into a second code sting of the speech signal, comprising the steps of:
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a first step of obtaining a first gain from a code corresponding to a gain out of said first code string codable in a first coding and decoding system, a second step of storing and holding said first gain as a second gain, a third step of calculating, from said first gain, said second gain, a third gain sequentially read from a table in which a plurality of gains are stored in advance, and a fourth gain selected, stored and held among third gains read from said table in the past, an evaluation value for each said third gain, and a fourth step of selecting said third gain with which said evaluation value is the minimum from said table and the code corresponding to said selected third gain is output as a converted code corresponding to a gain in the second code string, and a fifth step of storing and holding said selected third gain as the fourth gain, wherein said converted code being decodable by a linear prediction coefficient decoding method in a second coding and decoding system such that the speech signal is interpretable by said first coding and decoding system and said second coding and decoding system. - View Dependent Claims (30, 31, 32, 33, 34, 35, 36, 37)
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38. A code conversion device for converting a first code string of a speech signal into a second code string of the speech signal, said device comprising:
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a gain decoding circuit for obtaining a first gain from a code corresponding to a gain out of said first code string codable in a first coding and decoding system, a storage circuit for storing and holding said first gain as a second gain, an evaluation value calculation circuit for calculating, from said first gain, said second gain, said third gain sequentially read from a table in which a plurality of gains are stored in advance, and a fourth gain stored and held, and an evaluation value minimizing circuit for selecting said third gain with which said evaluation value is the minimum from said table to output a code corresponding to said selected third gain as a converted code corresponding to a gain in the second code string, and a second storage circuit for storing and holding said selected third gain as the fourth gain, wherein said converted code being decodable by a linear prediction coefficient decoding method in a second coding and decoding system such that the speech signal is interpretable by said first coding and decoding system and said second coding and decoding system. - View Dependent Claims (39, 40, 41, 42, 43, 44, 45, 46)
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47. A code conversion program embedded and implemented in a computer readable medium for conducting code conversion by controlling a computer which forms a code conversion device for converting a first code string of a speech signal into a second code string of the speech signal, said program comprising the functions of:
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(a) obtaining a first gain from a code corresponding to a gain out of said first code string codable in a first coding and decoding system, (b) storing and holding said first gain as a second gain, (c) calculating, from said first gain, said second gain, said third gain sequentially read from a table in which a plurality of gains are stored in advance, and a fourth gain stored and held, an evaluation value for each said third gain, and (d) selecting said third gain with which said evaluation value is the minimum from said table and outputting a code corresponding to said selected third gain as a converted code corresponding to a gain in the second code string, and (e) storing and holding said selected third gain as the fourth gain, wherein said converted code being decodable by a linear prediction coefficient decoding method in a second coding and decoding system such that the speech signal is interpretable by said first coding and decoding system and said second coding and decoding system. - View Dependent Claims (48, 49, 50, 51, 52, 53, 54, 55)
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Specification