Encoding method for acquiring codes corresponding to prediction residuals, decoding method for decoding codes corresponding to noise or pulse sequence, encoder, decoder, program, and recording medium
First Claim
1. A computer-implemented encoding method executing on a processor, the method comprising acquiring codes corresponding to prediction residuals obtained according to prediction analysis applied to time series signals included in a predetermined time interval of input time series signals which are speech or acoustic signals, with the number of bits to be assigned to the codes corresponding to the prediction residuals being switched according to whether an index that indicates a level of periodicity and/or stationarity corresponding to the time series signals in the predetermined time interval or time series signals in an interval before the predetermined time interval of the input time series signals satisfies a condition that indicates high periodicity and/or high stationarity or a condition that indicates low periodicity and/or low stationarity,wherein the number of bits of the codes corresponding to the prediction residuals, obtained when the index that indicates the level of periodicity and/or stationarity satisfies the condition that indicates high periodicity and/or high stationarity, is smaller than the number of bits of the codes corresponding to the prediction residuals, obtained when the index that indicates the level of periodicity and/or stationarity does not satisfy the condition that indicates high periodicity and/or high stationarity;
- orthe number of bits of the codes corresponding to the prediction residuals, obtained when the index that indicates the level of periodicity and/or stationarity satisfies the condition that indicates low periodicity and/or low stationarity, is larger than the number of bits of the codes corresponding to the prediction residuals, obtained when the index that indicates the level of periodicity and/or stationarity does not satisfy the condition that indicates low periodicity and/or low stationarity,wherein a predetermined total number of bits is assigned to codes corresponding to a time interval that includes the predetermined time interval and a second predetermined time interval after the predetermined time interval; and
the number of bits to be assigned to codes corresponding to second prediction residuals obtained according to prediction analysis applied to time series signals included in the second predetermined time interval is determined according to the number of unassigned bits determined from the total number of bits and the number of bits to be assigned to the codes corresponding to the prediction residuals obtained according to the prediction analysis applied to the time series signals included in the predetermined time interval, to acquire, with the determined number of bits, the codes corresponding to the second prediction residuals.
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Abstract
In encoding, the number of bits to be assigned to codes corresponding to noise or a pulse sequence obtained according to prediction analysis applied to time series signals included in a predetermined time interval is switched according to whether an index that indicates a level of periodicity and/or stationarity of input time series signals satisfies a condition that indicates high periodicity and/or high stationarity or a condition that indicates low periodicity and/or low stationarity, to acquire the codes corresponding to the noise and the pulse sequence. In decoding, a decoding mode for codes corresponding to noise or a pulse sequence included in codes corresponding to a predetermined time interval is switched according to the same criterion as that described above to decode the codes corresponding to the noise or the pulse sequence to acquire noise or a pulse sequence corresponding to the predetermined time interval.
18 Citations
24 Claims
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1. A computer-implemented encoding method executing on a processor, the method comprising acquiring codes corresponding to prediction residuals obtained according to prediction analysis applied to time series signals included in a predetermined time interval of input time series signals which are speech or acoustic signals, with the number of bits to be assigned to the codes corresponding to the prediction residuals being switched according to whether an index that indicates a level of periodicity and/or stationarity corresponding to the time series signals in the predetermined time interval or time series signals in an interval before the predetermined time interval of the input time series signals satisfies a condition that indicates high periodicity and/or high stationarity or a condition that indicates low periodicity and/or low stationarity,
wherein the number of bits of the codes corresponding to the prediction residuals, obtained when the index that indicates the level of periodicity and/or stationarity satisfies the condition that indicates high periodicity and/or high stationarity, is smaller than the number of bits of the codes corresponding to the prediction residuals, obtained when the index that indicates the level of periodicity and/or stationarity does not satisfy the condition that indicates high periodicity and/or high stationarity; - or
the number of bits of the codes corresponding to the prediction residuals, obtained when the index that indicates the level of periodicity and/or stationarity satisfies the condition that indicates low periodicity and/or low stationarity, is larger than the number of bits of the codes corresponding to the prediction residuals, obtained when the index that indicates the level of periodicity and/or stationarity does not satisfy the condition that indicates low periodicity and/or low stationarity, wherein a predetermined total number of bits is assigned to codes corresponding to a time interval that includes the predetermined time interval and a second predetermined time interval after the predetermined time interval; and the number of bits to be assigned to codes corresponding to second prediction residuals obtained according to prediction analysis applied to time series signals included in the second predetermined time interval is determined according to the number of unassigned bits determined from the total number of bits and the number of bits to be assigned to the codes corresponding to the prediction residuals obtained according to the prediction analysis applied to the time series signals included in the predetermined time interval, to acquire, with the determined number of bits, the codes corresponding to the second prediction residuals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 23)
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11. A computer-implemented decoding method executing on a processor, the method comprising decoding codes corresponding to noise or a pulse sequence included in inputted codes corresponding to a speech or acoustic signal sampled in a predetermined time interval to acquire noise or a pulse sequence corresponding to the predetermined time interval, with a decoding mode for the codes corresponding to the noise or the pulse sequence being switched according to whether an index that indicates a level of periodicity and/or stationarity corresponding to the predetermined time interval or an interval before the predetermined interval, the index being included in input codes or obtained from the codes, satisfies a condition that indicates high periodicity and/or high stationarity or a condition that indicates low periodicity and/or low stationarity,
wherein codes having a first number of bits, corresponding to the noise or the pulse sequence are decoded when the index that indicates the level of periodicity and/or stationarity satisfies the condition that indicates high periodicity and/or high stationarity, and codes having a second number of bits, corresponding to the noise or the pulse sequence are decoded when the index that indicates the level of periodicity and/or stationarity does not satisfy the condition that indicates high periodicity and/or high stationarity; - or
codes having the second number of bits, corresponding to the noise or the pulse sequence are decoded when the index that indicates the level of periodicity and/or stationarity satisfies the condition that indicates low periodicity and/or low stationarity, and codes having the first number of bits, corresponding to the noise or the pulse sequence are decoded when the index that indicates the level of periodicity and/or stationarity does not satisfy the condition that indicates low periodicity and/or low stationarity; and the first number of bits is smaller than the second number of bits, wherein a predetermined total number of bits is assigned to codes corresponding to a time interval that includes the predetermined time interval and a second predetermined time interval after the predetermined time interval; and a decoding mode for codes corresponding to second noise or a second pulse sequence included in codes corresponding to the second predetermined time interval is switched according to the number of bits assigned to the second predetermined time interval, determined from the total number of bits and the number of bits of the codes corresponding to the noise or the pulse sequence included in the codes corresponding to the predetermined time interval, to decode the codes corresponding to the second noise or the second pulse sequence to acquire second noise or a second pulse sequence corresponding to the second predetermined time interval. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20, 24)
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21. A computer-implemented encoder for acquiring codes corresponding to prediction residuals obtained according to prediction analysis applied to time series signals included in a predetermined time interval of input time series signals which are speech or acoustic signals, with the number of bits to be assigned to the codes corresponding to the prediction residuals being switched according to whether an index that indicates a level of periodicity and/or stationarity corresponding to the time series signals in the predetermined time interval or time series signals in an interval before the predetermined time interval of the input time series signals satisfies a condition that indicates high periodicity and/or high stationarity or a condition that indicates low periodicity and/or low stationarity,
wherein the number of bits of the codes corresponding to the prediction residuals, obtained when the index that indicates the level of periodicity and/or stationarity satisfies the condition that indicates high periodicity and/or high stationarity, is smaller than the number of bits of the codes corresponding to the prediction residuals, obtained when the index that indicates the level of periodicity and/or stationarity does not satisfy the condition that indicates high periodicity and/or high stationarity; - or
the number of bits of the codes corresponding to the prediction residuals, obtained when the index that indicates the level of periodicity and/or stationarity satisfies the condition that indicates low periodicity and/or low stationarity, is larger than the number of bits of the codes corresponding to the prediction residuals, obtained when the index that indicates the level of periodicity and/or stationarity does not satisfy the condition that indicates low periodicity and/or low stationarity, wherein a predetermined total number of bits is assigned to codes corresponding to a time interval that includes the predetermined time interval and a second predetermined time interval after the predetermined time interval; and the number of bits to be assigned to codes corresponding to second prediction residuals obtained according to prediction analysis applied to time series signals included in the second predetermined time interval is determined according to the number of unassigned bits determined from the total number of bits and the number of bits to be assigned to the codes corresponding to the prediction residuals obtained according to the prediction analysis applied to the time series signals included in the predetermined time interval, to acquire the codes, with the determined number of bits, corresponding to the second prediction residuals.
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22. A computer-implemented decoder for decoding codes corresponding to noise or a pulse sequence included in inputted codes corresponding to a speech or acoustic signal sampled in a predetermined time interval to acquire noise or a pulse sequence corresponding to the predetermined time interval, with a decoding mode for the codes corresponding to the noise or the pulse sequence being switched according to whether an index that indicates a level of periodicity and/or stationarity corresponding to the predetermined time interval or an interval before the predetermined interval, the index being included in input codes or obtained from the codes, satisfies a condition that indicates high periodicity and/or high stationarity or a condition that indicates low periodicity and/or low stationarity,
wherein codes having a first number of bits, corresponding to the noise or the pulse sequence are decoded when the index that indicates the level of periodicity and/or stationarity satisfies the condition that indicates high periodicity and/or high stationarity, and codes having a second number of bits, corresponding to the noise or the pulse sequence are decoded when the index that indicates the level of periodicity and/or stationarity does not satisfy the condition that indicates high periodicity and/or high stationarity; - or
codes having the second number of bits, corresponding to the noise or the pulse sequence are decoded when the index that indicates the level of periodicity and/or stationarity satisfies the condition that indicates low periodicity and/or low stationarity, and codes having the first number of bits, corresponding to the noise or the pulse sequence are decoded when the index that indicates the level of periodicity and/or stationarity does not satisfy the condition that indicates low periodicity and/or low stationarity; and the first number of bits is smaller than the second number of bits, wherein a predetermined total number of bits is assigned to codes corresponding to a time interval that includes the predetermined time interval and a second predetermined time interval after the predetermined time interval; and a decoding mode for codes corresponding to second noise or a second pulse sequence included in codes corresponding to the second predetermined time interval is switched according to the number of bits assigned to the second predetermined time interval, determined from the total number of bits and the number of bits of the codes corresponding to the noise or the pulse sequence included in the codes corresponding to the predetermined time interval, to decode the codes corresponding to the second noise or the second pulse sequence to acquire second noise or a second pulse sequence corresponding to the second predetermined time interval.
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Specification