Encoding method, decoding method, encoder apparatus, decoder apparatus, and recording medium for processing pitch periods corresponding to time series signals
First Claim
1. An encoding method comprising:
- (A) a step of obtaining pitch periods corresponding to time series signals included in a predetermined time interval; and
(B) a step of outputting a code corresponding to the pitch periods;
wherein the step (B) comprises a step of outputting the code obtained by encoding the pitch periods expressed at a first quantization resolution when an index that indicates a level of stationarity of the time series signals does not satisfy the condition that indicates high stationarity, andof outputting the code obtained by encoding the pitch periods expressed at a second quantization resolution when the index satisfies the condition that indicates high stationarity; and
the second quantization resolution is higher than the first quantization resolution.
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Abstract
In encoding, pitch periods for time series signals in a predetermined time interval are calculated, and a code corresponding thereto is output. In that encoding, the resolutions for expressing the pitch periods and/or a pitch period encoding mode are switched according to whether an index indicating a periodicity and/or stationarity level of the time series signals satisfies a condition indicating high or low in periodicity and/or stationarity. In that decoding, according to whether an index indicating a periodicity and/or stationarity level, the index being included in or obtained from an input code corresponding to the predetermined time interval, satisfies a condition indicating high periodicity and/or stationarity, a decoding mode for a code, included in the input code, corresponding to pitch periods is switched to decode the code corresponding to the pitch periods to obtain the pitch periods corresponding to the predetermined time interval.
30 Citations
24 Claims
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1. An encoding method comprising:
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(A) a step of obtaining pitch periods corresponding to time series signals included in a predetermined time interval; and (B) a step of outputting a code corresponding to the pitch periods; wherein the step (B) comprises a step of outputting the code obtained by encoding the pitch periods expressed at a first quantization resolution when an index that indicates a level of stationarity of the time series signals does not satisfy the condition that indicates high stationarity, and of outputting the code obtained by encoding the pitch periods expressed at a second quantization resolution when the index satisfies the condition that indicates high stationarity; and the second quantization resolution is higher than the first quantization resolution. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A decoding method comprising:
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receiving of a code corresponding to a predetermined time interval; and decoding a pitch code included in the code to obtain the pitch periods corresponding to the predetermined time interval; wherein the pitch code corresponding to the pitch periods is decoded with a decoding mode that obtains each of the pitch periods expressed at a first quantization resolution, when an index that indicates a level of stationarity, the index being included in or obtained from the code corresponding to the predetermined time interval, does not satisfy the condition that indicates high stationarity; the pitch code corresponding to the pitch periods is decoded with a decoding mode that obtains each of the pitch periods expressed at a second quantization resolution, when the index satisfies the condition that indicates high stationarity; and the second quantization resolution is higher than the first quantization resolution. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. An encoder which obtains pitch periods corresponding to time series signals included in a predetermined time interval;
- and outputs a code corresponding to the pitch periods;
wherein the code obtained by encoding the pitch periods expressed at a first quantization resolution is output when an index that indicates a level of stationarity of the time series signals does not satisfy the condition that indicates high stationarity, and the code obtained by encoding the pitch periods expressed at a second quantization resolution is output when the index satisfies the condition that indicates high stationarity; and the second quantization resolution is higher than the first quantization resolution.
- and outputs a code corresponding to the pitch periods;
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22. A decoder which receives of a code corresponding to a predetermined time interval;
- and decodes a pitch code included in the code to obtain the pitch periods corresponding to the predetermined time interval;
wherein the pitch code corresponding to the pitch periods is decoded with a decoding mode that obtains each of the pitch periods expressed at a first quantization resolution, when an index that indicates a level of stationarity, the index being included in or obtained from the code corresponding to the predetermined time interval, does not satisfy the condition that indicates high stationarity; the pitch code corresponding to the pitch periods is decoded with a decoding mode that obtains each of the pitch periods expressed at a second quantization resolution, when the index satisfies the condition that indicates high stationarity; and the second quantization resolution is higher than the first quantization resolution.
- and decodes a pitch code included in the code to obtain the pitch periods corresponding to the predetermined time interval;
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23. A non-transitory computer readable recording medium having stored therein a program causing a computer to execute processing of the encoding method comprising:
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(A) a step of obtaining pitch periods corresponding to time series signals included in a predetermined time interval; and (B) a step of outputting a code corresponding to the pitch periods; wherein the step (B) comprises a step of outputting the code obtained by encoding the pitch periods expressed at a first quantization resolution when an index that indicates a level of stationarity of the time series signals does not satisfy the condition that indicates high stationarity, and of outputting the code obtained by encoding the pitch periods expressed at a second quantization resolution when the index satisfies the condition that indicates high stationarity; and
the second quantization resolution is higher than the first quantization resolution.
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24. A non-transitory computer readable recording medium having stored therein a program causing a computer to execute processing of the decoding method comprising:
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receiving of a code corresponding to a predetermined time interval; and decoding a pitch code included in the code to obtain the pitch periods corresponding to the predetermined time interval; wherein the pitch code corresponding to the pitch periods is decoded with a decoding mode that obtains each of the pitch periods expressed at a first quantization resolution, when an index that indicates a level of stationarity, the index being included in or obtained from the code corresponding to the predetermined time interval, does not satisfy the condition that indicates high stationarity; the pitch code corresponding to the pitch periods is decoded with a decoding mode that obtains each of the pitch periods expressed at a second quantization resolution, when the index satisfies the condition that indicates high stationarity; and
the second quantization resolution is higher than the first quantization resolution.
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Specification