Efficient excitation quantization in a noise feedback coding system using correlation techniques
First Claim
1. A method of performing an efficient excitation quantization corresponding to a residual signal using a codebook in a speech or audio noise feedback coding (NFC) system, the NFC system including at least one noise feedback loop, the codebook including N vector quantization (VQ) codevectors, where N is an integer greater than one, the method comprising:
- (a) deriving N correlation values using the NFC system, each of the N correlation values corresponding to a respective one of the N VQ codevectors;
(b) combining each of the N correlation values with a corresponding one of N ZERO-STATE energies of the NFC system, thereby producing N minimization values each corresponding to a respective one of the N VQ codevectors; and
(c) selecting a preferred one of the N VQ codevectors based on the N minimization values, whereby the preferred VQ codevector is usable as an excitation quantization corresponding to a residual signal derived from a speech or audio signal.
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Accused Products
Abstract
A method of performing an excitation Vector Quantization (VQ) in a Noise Feedback Coding environment involves reorganizing a calculation of an energy of an error vector for each of a plurality of candidate excitation vectors of a codebook. The energy of the error vector is a cost function that is minimized during a search of the codebook for a best candidate excitation VQ vector. The reorganization includes expanding a Mean Squared Error (MSE) term of the error vector, excluding an energy term that is invariant to the candidate excitation vector, and pre-computing energy terms of ZERO-STATE responses of the candidate excitation vectors that are invariant to sub-vectors of a subframe. Another method searches a signed codebook. Both methods use correlation techniques.
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Citations
44 Claims
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1. A method of performing an efficient excitation quantization corresponding to a residual signal using a codebook in a speech or audio noise feedback coding (NFC) system, the NFC system including at least one noise feedback loop, the codebook including N vector quantization (VQ) codevectors, where N is an integer greater than one, the method comprising:
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(a) deriving N correlation values using the NFC system, each of the N correlation values corresponding to a respective one of the N VQ codevectors; (b) combining each of the N correlation values with a corresponding one of N ZERO-STATE energies of the NFC system, thereby producing N minimization values each corresponding to a respective one of the N VQ codevectors; and (c) selecting a preferred one of the N VQ codevectors based on the N minimization values, whereby the preferred VQ codevector is usable as an excitation quantization corresponding to a residual signal derived from a speech or audio signal. - View Dependent Claims (2, 3, 4, 5)
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6. A method of searching a codebook in a speech or audio coding system, the codebook including a plurality of shape codevectors each associated with a positive codevector and a negative codevector, comprising:
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(a) deriving a correlation term corresponding to one shape codevector by correlating a ZERO-STATE response of the coding system corresponding to the shape codevector, with a ZERO-INPUT response of the coding system; (b) deriving a first minimization value corresponding to the positive codevector associated with the one shape codevector when a sign of the correlation term is a first value; and (c) deriving a second minimization value corresponding to the negative codevector associated with the one shape codevector when the sign of the correlation term is a second value. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A method of searching a codebook in a speech or audio noise feedback coding (NFC) system, the NFC system including at least one noise feedback loop, the codebook including a plurality of shape codevectors each associated with a positive codevector and a negative codevector, comprising:
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for each shape codevector (a) deriving a correlation term corresponding to the shape codevector using at least one filter structure of the NFC system; (b) deriving a first minimization value corresponding to the positive codevector associated with the shape codevector when a sign of the correlation term is a first value; and (c) deriving a second minimization value corresponding to the negative codevector associated with the shape codevector when a sign of the correlation term is a second value; and (d) selecting a preferred codevector from among the positive and negative codevectors corresponding to minimization values derived in steps (b) and (c) based on the minimization values. - View Dependent Claims (18, 19, 20, 21, 22)
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23. A computer program product comprising a computer usable medium having computer readable program code means embodied in the medium for causing an application program to execute on a computer processor to perform an efficient excitation quantization corresponding to a residual signal using a codebook in a speech or audio noise feedback codec (NFC), the NFC including at least one noise feedback loop, the codebook including N vector quantization (VQ) codevectors, where N is an integer greater than one, the computer readable program code means comprising:
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a first computer readable program code means for causing the processor to derive N correlation values using the NFC, each of the N correlation values corresponding to a respective one of the N VQ codevectors; a second computer readable program code means for causing the processor to combine each of the N correlation values with a corresponding one of N ZERO-STATE energies of the NFC, thereby producing N minimization values each corresponding to a respective one of the N VQ codevectors; and a third computer readable program code means for causing the processor to elect a preferred one of the N VQ codevectors based on the N minimization values, whereby the preferred VQ codevector is usable as an excitation quantization corresponding to a residual signal derived from a speech or audio signal. - View Dependent Claims (24, 25, 26, 27)
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28. A computer program product comprising a computer usable medium having computer readable program code means embodied in the medium for causing an application program to execute on a computer processor to search a codebook in a speech or audio codec, the codebook including a plurality of shape codevectors each associated with a positive codevector and a negative codevector, the computer readable program code means comprising:
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a first computer readable program code means for causing the processor to derive a correlation term corresponding to one shape codevector by correlating a ZERO-STATE response of the codec corresponding to the shape codevector, with a ZERO-INPUT response of the codec; a second computer readable program code means for causing the processor to derive a first minimization value corresponding to the positive codevector associated with the one shape codevector when a sign of the correlation term is a first value; and a third computer readable program code means for causing the processor to derive a second minimization value corresponding to the negative codevector associated with the one shape codevector when the sign of the correlation term is a second value. - View Dependent Claims (29, 30, 31, 32, 33, 34, 35, 36, 37, 38)
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39. A computer program product comprising a computer usable medium having computer readable program code means embodied in the medium for causing an application program to execute on a computer processor to search a codebook in a speech or audio noise feedback codec (NFC), the NFC including at least one noise feedback loop, the codebook including a plurality of shape codevectors each associated with a positive codevector and a negative codevector, the computer readable program code means comprising:
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a first computer readable program code means for causing the processor to derive, for each shape codevector, a correlation term corresponding to the given shape codevector using at least one filter structure of the NFC; a second computer readable program code means for causing the processor to derive, for each shape codevector, a first minimization value corresponding to the positive codevector associated with the given shape codevector when a sign of the correlation term is a first value; and a third computer readable program code means for causing the processor to derive, for each shape codevector, a second minimization value corresponding to the negative codevector associated with the given shape codevector when a sign of the correlation term is a second value; and a fourth computer readable program code means for causing the processor to select a preferred codevector from among the positive and negative codevectors corresponding to minimization values derived by the first and second program code means based on the minimization values. - View Dependent Claims (40, 41, 42, 43, 44)
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Specification