Pitch cycle search range setting apparatus and pitch cycle search apparatus
First Claim
1. A pitch cycle search range setting apparatus comprising:
- a pitch cycle indicating section that, in pitch cycle search processing that searches for a pitch cycle included in a linear predictive residual on a subframe basis, sequentially indicates pitch cycle candidates within a preset pitch cycle search range with integral accuracy to an adaptive sound source vector generating section;
an adaptive sound source vector generating section that extracts an adaptive sound source vector that has a pitch cycle indicated by said pitch cycle indicating section from an adaptive code book that stores past drive sound sources; and
a last subframe integral pitch cycle storage section that stores the integral component of a pitch cycle finally selected in pitch cycle search processing of a previous subframe;
wherein said pitch cycle search range setting apparatus sets as a pitch cycle search object, in processing subframe section pitch cycle search processing, both or one of an integral-accuracy pitch cycle candidate indicated by said pitch cycle indicating section and a fractional-accuracy pitch cycle search candidate that covers with fractional-accuracy a pitch cycle in the vicinity of an integral-accuracy pitch cycle read from said last subframe integral pitch cycle storage section.
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Abstract
An Adaptive Sound Source Vector Generator (ASSVG) 103 sets preceding and succeeding pitch cycles centered on an integral-accuracy pitch cycle T0 selected in the previous subframe as a range for searching for a fractional-accuracy pitch frequency, and extracts an adaptive sound source vector P(T-frac) that has fractional-accuracy pitch cycle T-frac within this range from an Adaptive Code Book (ACB) 102. A Last Sub Frame Integral Pitch Cycle Storage (LSFIPCS) 108 stores integral component T0 of the optimal pitch cycle selected by a Distortion Comparator (DC) 107, and when a pitch cycle of the next subframe is searched for, outputs this optimal pitch cycle integral component T0 to the Adaptive Sound Source Vector Generator (ASSVG) 103. An Optimal Pitch Cycle Accuracy Judge Section (OPCAJS) 109 judges whether the optimal pitch cycle is of integral accuracy or fractional accuracy. A Comparison Judge Section (CJS) 110 restricts the number of times fractional-accuracy pitch information is selected in an optimal pitch cycle.
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Citations
19 Claims
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1. A pitch cycle search range setting apparatus comprising:
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a pitch cycle indicating section that, in pitch cycle search processing that searches for a pitch cycle included in a linear predictive residual on a subframe basis, sequentially indicates pitch cycle candidates within a preset pitch cycle search range with integral accuracy to an adaptive sound source vector generating section; an adaptive sound source vector generating section that extracts an adaptive sound source vector that has a pitch cycle indicated by said pitch cycle indicating section from an adaptive code book that stores past drive sound sources; and a last subframe integral pitch cycle storage section that stores the integral component of a pitch cycle finally selected in pitch cycle search processing of a previous subframe; wherein said pitch cycle search range setting apparatus sets as a pitch cycle search object, in processing subframe section pitch cycle search processing, both or one of an integral-accuracy pitch cycle candidate indicated by said pitch cycle indicating section and a fractional-accuracy pitch cycle search candidate that covers with fractional-accuracy a pitch cycle in the vicinity of an integral-accuracy pitch cycle read from said last subframe integral pitch cycle storage section. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A decoding adaptive sound source vector generating apparatus comprising:
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a last subframe integral pitch cycle storage section that has a function that stores a pitch cycle selected in a previous subframe section; a pitch cycle judging section that has a function that finds an optimal adaptive sound source vector pitch cycle using a pitch cycle selected in a previous subframe received from said last subframe integral pitch cycle storage section and an index received as input, and passes that optimal adaptive sound source vector pitch cycle to an adaptive sound source vector generating section; an adaptive sound source vector generating section that has a function that extracts from an adaptive code book an adaptive sound source vector that has a pitch cycle received from said pitch cycle judging section, outputs that extracted adaptive sound source vector if a pitch cycle is of integral accuracy, or outputs that extracted adaptive sound source vector to a fractional pitch cycle adaptive sound source vector generating section if a pitch cycle is of fractional accuracy; and a fractional pitch cycle adaptive sound source vector generating section that has a function that generates and outputs an adaptive sound source vector that has a fractional-accuracy pitch cycle from an adaptive sound source vector received from said adaptive sound source vector generating section. - View Dependent Claims (16, 17, 18, 19)
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Specification