Method and apparatus for identifying frequency bands to compute linear phase shifts between frame prototypes in a speech coder
First Claim
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1. A method of partitioning the frequency spectrum of a prototype of a frame, comprising the steps of:
- dividing the frequency spectrum into a plurality of segments;
assigning a plurality of bands to each segment;
establishing, for each segment, a set of bandwidths for the plurality of bands, wherein the establishing step comprises the step of allocating variable bandwidths to the plurality of bands in a particular segment, and wherein the allocating step comprises the steps of;
setting a target bandwidth;
searching, for each band, an amplitude vector of the prototype to determine the maximum harmonic number in the band, excluding from the search ranges covered by any previously established band edges;
positioning, for each hand, the band edges around the maximum harmonic number such that the total number of harmonics located between the band edges is equal to the target bandwidth divided by the fundamental frequency; and
removing gaps between adjacent band edges.
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Abstract
A method and apparatus for identifying frequency bands to compute linear phase shifts between frame prototypes in a speech coder includes partitioning the frequency spectrum of a prototype of a frame by dividing the frequency spectrum into segments, assigning one or more bands to each segment, and establishing, for each segment, a set of bandwidths for the bands. The bandwidths may be fixed and uniformly distributed in any given segment. The bandwidths may be fixed and non-uniformly distributed in any segment. The bandwidths may be variable and non-uniformly distributed in any given segment.
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Citations
18 Claims
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1. A method of partitioning the frequency spectrum of a prototype of a frame, comprising the steps of:
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dividing the frequency spectrum into a plurality of segments;
assigning a plurality of bands to each segment;
establishing, for each segment, a set of bandwidths for the plurality of bands, wherein the establishing step comprises the step of allocating variable bandwidths to the plurality of bands in a particular segment, and wherein the allocating step comprises the steps of;
setting a target bandwidth;
searching, for each band, an amplitude vector of the prototype to determine the maximum harmonic number in the band, excluding from the search ranges covered by any previously established band edges;
positioning, for each hand, the band edges around the maximum harmonic number such that the total number of harmonics located between the band edges is equal to the target bandwidth divided by the fundamental frequency; and
removing gaps between adjacent band edges. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A speech coder configured to partition the frequency spectrum of a prototype of a frame, comprising:
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means for dividing the frequency spectrum into a plurality of segments;
means for assigning a plurality of bands to each segment; and
means for establishing, for each segment, a set of bandwidths for the plurality of bands, wherein the means for establishing comprises means for allocating variable bandwidths to the plurality of bands in a particular segment, and wherein the means for allocating comprises;
means for setting a target bandwidth;
means for searching, for each band, an amplitude vector of the prototype to determine the maximum harmonic number in the band, excluding from the search ranges covered by any previously established band edges;
means for positioning, for each band, the band edges around the maximum harmonic number such that the total number of harmonics located between the band edges is equal to the target bandwidth divided by the fundamental frequency; and
means for removing gaps between adjacent band edges. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A speech coder comprising:
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a prototype extractor configured to extract a prototype from a frame being processed by the speech coder; and
a prototype quantizer coupled to the prototype extractor and configured to divide the frequency spectrum of the prototype into a plurality of segments, assign a plurality of bands to each segment, and establish, for each segment, a set of bandwidths for the plurality of bands, wherein the prototype quantizer is further configured to establish the set of bandwidths as variable bandwidths for the plurality of bands in a particular segment, and wherein the prototype quantizer is further configured to set the variable bandwidths by setting a target bandwidth, searching, for each band, an amplitude vector of the prototype to determine the maximum harmonic number in the band, excluding from the search ranges covered by any previously established band edges, positioning, for each band, the band edges around the maximum harmonic number such that the total number of harmonics located between the band edges is equal to the target bandwidth divided by the fundamental frequency, and removing gaps between adjacent band edges. - View Dependent Claims (14, 15, 16, 17, 18)
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Specification