Systems, methods, apparatus, and computer-readable media for coding of harmonic signals
First Claim
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1. A method of audio signal processing, said method comprising:
- in a frequency domain, locating a plurality of peaks in a reference audio signal;
selecting a number Nf of candidates for a fundamental frequency of a harmonic model, each based on the location of a corresponding one of the plurality of peaks in the frequency domain;
based on the locations of at least two of the plurality of peaks in the frequency domain, calculating by a communications device a number Nd of candidates for a spacing between harmonics of the harmonic model;
for each of a plurality of different pairs of the fundamental frequency and harmonic spacing candidates, selecting by the communications device a set of at least one subband of a target audio signal, wherein a location in the frequency domain of each subband in the set is based on the pair of candidates;
for each of the plurality of different pairs of candidates, calculating an energy value from the corresponding set of at least one subband of the target audio signal; and
based on at least a plurality of the calculated energy values, selecting a pair of candidates from among the plurality of different pairs of candidates,wherein at least one among the numbers Nf and Nd has a value greater than one.
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Abstract
A scheme for coding a set of transform coefficients that represent an audio-frequency range of a signal uses a harmonic model to parameterize a relationship between the locations of regions of significant energy in the frequency domain.
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Citations
58 Claims
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1. A method of audio signal processing, said method comprising:
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in a frequency domain, locating a plurality of peaks in a reference audio signal; selecting a number Nf of candidates for a fundamental frequency of a harmonic model, each based on the location of a corresponding one of the plurality of peaks in the frequency domain;
based on the locations of at least two of the plurality of peaks in the frequency domain, calculating by a communications device a number Nd of candidates for a spacing between harmonics of the harmonic model;for each of a plurality of different pairs of the fundamental frequency and harmonic spacing candidates, selecting by the communications device a set of at least one subband of a target audio signal, wherein a location in the frequency domain of each subband in the set is based on the pair of candidates; for each of the plurality of different pairs of candidates, calculating an energy value from the corresponding set of at least one subband of the target audio signal; and based on at least a plurality of the calculated energy values, selecting a pair of candidates from among the plurality of different pairs of candidates, wherein at least one among the numbers Nf and Nd has a value greater than one. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method of constructing a decoded audio frame, said method comprising:
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placing by a communications device a first one of a plurality of decoded subband vectors according to a fundamental frequency value; placing by the communications device the rest of the plurality of decoded subband vectors according to the fundamental frequency value and a harmonic spacing value; and inserting a decoded residual signal at locations of the frame that are not occupied by the plurality of decoded subband vectors. - View Dependent Claims (16, 17, 18, 19)
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20. An apparatus for audio signal processing, said apparatus comprising:
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means for locating a plurality of peaks in a reference audio signal in a frequency domain; means for selecting a number Nf of candidates for a fundamental frequency of a harmonic model, each based on the location of a corresponding one of the plurality of peaks in the frequency domain; means for calculating a number Nd of candidates for a spacing between harmonics of the harmonic model, based on the locations of at least two of the plurality of peaks in the frequency domain; means for selecting, for each of a plurality of different pairs of the fundamental frequency and harmonic spacing candidates, a set of at least one subband of a target audio signal, wherein a location in the frequency domain of each subband in the set is based on the pair of candidates; and means for calculating, for each of the plurality of different pairs of candidates, an energy value from the corresponding set of at least one subband of the target audio signal; and means for selecting a pair of candidates from among the plurality of different pairs of candidates, based on at least a plurality of the calculated energy values, wherein at least one among the numbers Nf and Nd has a value greater than one. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33)
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34. An apparatus for audio signal processing, said apparatus comprising:
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a frequency-domain peak locator configured to locate a plurality of peaks in a reference audio signal in a frequency domain, wherein the frequency-domain peak locator is implemented by the apparatus, and wherein the apparatus comprises hardware; a fundamental-frequency candidate selector configured to select a number Nf of candidates for a fundamental frequency of a harmonic model, each based on the location of a corresponding one of the plurality of peaks in the frequency domain; a distance calculator configured to calculate a number Nd of candidates for a spacing between harmonics of the harmonic model, based on the locations of at least two of the plurality of peaks in the frequency domain; a subband placement selector configured to select, for each of a plurality of different pairs of the fundamental frequency and harmonic spacing candidates, a set of at least one subband of a target audio signal, wherein a location in the frequency domain of each subband in the set is based on the pair of candidates; an energy calculator configured to calculate, for each of the plurality of different pairs of candidates, an energy value from the corresponding set of at least one subband of the target audio signal; and a candidate pair selector configured to select a pair of candidates from among the plurality of different pairs of candidates, based on at least a plurality of the calculated energy values, wherein at least one among the numbers Nf and Nd has a value greater than one. - View Dependent Claims (35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47)
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48. A non-transitory computer-readable storage medium having tangible features that when read by a machine cause the machine to:
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locate, in a frequency domain, a plurality of peaks in a reference audio signal; select a number Nf of candidates for a fundamental frequency of a harmonic model, each based on the location of a corresponding one of the plurality of peaks in the frequency domain; based on the locations of at least two of the plurality of peaks in the frequency domain, calculate a number Nd of candidates for a spacing between harmonics of the harmonic model; for each of a plurality of different pairs of the fundamental frequency and harmonic spacing candidates, select a set of at least one subband of a target audio signal, wherein a location in the frequency domain of each subband in the set is based on the pair of candidates; for each of the plurality of different pairs of candidates, calculate an energy value from the corresponding set of at least one subband of the target audio signal; and based on at least a plurality of the calculated energy values, select a pair of candidates from among the plurality of different pairs of candidates, wherein at least one among the numbers Nf and Nd has a value greater than one.
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49. An apparatus for constructing a decoded audio frame, said apparatus comprising:
a subband placer configured to place a first one of a plurality of decoded subband vectors according to a fundamental frequency value, to place the rest of the plurality of decoded subband vectors according to the fundamental frequency value and a harmonic spacing value, and to insert a decoded residual signal at locations of the frame that are not occupied by the plurality of decoded subband vectors. - View Dependent Claims (50, 51, 52, 53)
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54. An apparatus for constructing a decoded audio frame, said apparatus comprising:
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means for placing a first one of a plurality of decoded subband vectors according to a fundamental frequency value; means for placing the rest of the plurality of decoded subband vectors according to the fundamental frequency value and a harmonic spacing value; and means for inserting a decoded residual signal at locations of the frame that are not occupied by the plurality of decoded subband vectors. - View Dependent Claims (55, 56, 57, 58)
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Specification