Voice cover and a method for searching codebooks

Claim 2

A voice coder comprising: masking calculating means for calculating masking threshold values from supplied discrete voice signals based on auditory sense masking characteristics; auditory sense weighting means for calculating filter coefficients based on said masking threshold values and weighting input signals based on said filter coefficients; a codebook which includes a plurality of code vectors; and searching means for searching for a code vector in the codebook that minimizes error signal power between an output signal of said auditory sense weighting means and the code vectors in said codebook.

Claim 3

The voice coder of claim 1, wherein said codebook is an excitation codebook.

Claim 4

The voice coder of claim 1, wherein said codebook is an adaptive codebook.

Claim 5

The voice coder of claim 1, further comprising a subbanding means for subbanding said voice signals, wherein said auditory sense weighting means performs weighting to signals that have been subbanded with said subbanding means.

Claim 6

The voice coder of claim 4, further comprising: a bit allocating means for allocating quantization bits to the subbanded signals; and switching means for switching a number of bits of said codebook according to bits allocated with said bit allocating means.

Claim 7

The voice coder of claim 1, further comprising a subframe generating means for dividing said voice signals into frames of a first pre-set time length and generating subframes by dividing said frames into second pre-set time length divisions, wherein searching of said codebook is performed for each said subframe.

Claim 8

A voice coder comprising: dividing means for dividing supplied discrete voice signals into first pre-set time length frames; subframe generating means for generating subframes by dividing said frames into second pre-set time length divisions; regenerating means for regenerating said voice signals for said subframes based on an adaptive codebook; masking calculating means for calculating masking threshold values for each of said subframes from said voice signals based on auditory sense masking characteristics; an auditory sense weighting means for calculating filter coefficients based on said masking threshold values and performing auditory sense weighting to a difference signal formed as a difference between a signal regenerated with said regenerating means and said voice signal based on said filter coefficients; an excitation codebook which includes a plurality of code vectors; and searching means for searching for a code vector in said excitation codebook that minimizes an error signal power between said auditory sense weighting means and the code vectors in said excitation codebook.

Claim 9

A voice coder comprising: dividing means for dividing supplied discrete voice signals into first pre-set time length frames; subframe generating means for generating subframes by dividing said frames into second pre-set time length divisions; regenerating means for regenerating said voice signals for said subframes based on an adaptive codebook; masking calculating means for calculating masking threshold values for each of said subframes from said voice signals based on auditory sense masking characteristics; an auditory sense weighting means for calculating filter coefficients based on said masking threshold values and performing auditory sense weighting to a difference signal formed as a difference between a signal regenerated with said regenerating means and said voice signal based on said filter coefficients; an excitation codebook which includes a plurality of code vectors; and searching means for searching for a code vector in said excitation codebook that minimizes an error signal power between said auditory sense weighting means and the code vectors in said excitation codebook.

Claim 10

The voice coder of claim 7, further comprising a subbanding means for subbanding said voice signals, wherein said auditory sense weighting means performs weighting to a signal that has been subbanded with said subbanding means.

Claim 11

The voice coder of claim 8, further comprising: bit allocating means for allocating quantization bits to the subbanded signals; and switching means for switching a number of bits of said excitation codebook according to bits allocated with said bit allocating means.

Claim 12

The voice coder of claim 7, further comprising spectral parameter calculating means for calculating and outputting a spectral parameter representing a spectral envelope of said voice signal for each frame.

Claim 13

The voice coder of claim 7, wherein said regenerating means calculates, for each of said subframes, a pitch parameter so that a signal regenerated based on said adaptive codebook which includes past excitation signals approximates said voice signal.

Claim 14

The voice coder of claim 7, wherein said adaptive codebook means calculates, for each of said subframes, a pitch parameter so that a signal regenerated based on said adaptive codebook which includes past excitation signals approximates said voice signal.

Claim 15

A voice coder comprising: dividing means for dividing supplied discrete voice signals into pre-set time length frames; subframe generating means for generating subframes by dividing said frames into pre-set time length divisions; masking calculating means for calculating masking threshold values for each of said subframes form said voice signals based on auditory sense masking characteristics; auditory sense weighting means for calculating filter coefficients based on said masking threshold values and performing auditory sense weighting to said voice signals based on said filter coefficients; adaptive codebook means for calculating an adaptive code vector that minimizes power of a difference signal formed as a difference between a response signal and a voice signal weighted with said auditory sense weighting means; an excitation codebook which includes a plurality of excitation code vectors; and searching means for searching for a code vector in said excitation codebook that minimizes an error signal power between an output signal generated from said adaptive codebook means and said difference signal.

Claim 16

A voice coder comprising: dividing means for dividing supplied discrete voice signals into pre-set time length frames; subframe generating means for generating subframes by dividing said frames into pre-set time length divisions; masking calculating means for calculating masking threshold values for each of said subframes form said voice signals based on auditory sense masking characteristics; auditory sense weighting means for calculating filter coefficients based on said masking threshold values and performing auditory sense weighting to said voice signals based on said filter coefficients; adaptive codebook means for calculating an adaptive code vector that minimizes power of a difference signal formed as a difference between a response signal and a voice signal weighted with said auditory sense weighting means; an excitation codebook which includes a plurality of excitation code vectors; and searching means for searching for a code vector in said excitation codebook that minimizes an error signal power between an output signal generated from said adaptive codebook means and said difference signal.

Claim 17

The voice coder of claim 13, further comprising a subbanding means for subbanding said voice signals, wherein said auditory sense weighting means performs weighting to signals subbanded with said subbanding means.

Claim 18

The voice coder of claim 14, further comprising: bit allocating means for allocating quantization bits to the subbanded signals; and switching means for switching a number of bits of said excitation codebook according to bits allocated with said bit allocating means.

Claim 19

The voice coder of claim 13, further comprising spectral parameter calculating means for calculating and outputting, for each of said frames, a spectral parameter representing a spectral envelope of said voice signals.

Claim 20

The voice coder of claim 13, comprising a spectral parameter calculating means for calculating and outputting, for each of said frames, a spectral parameter representing spectral envelope of said voice signals.

Claim 21

A voice coder comprising: dividing means for dividing supplied discrete voice signals into pre-set time length frames; subframe generating means for generating subframes by dividing said frames into pre-set time length divisions; regenerating means for regenerating said voice signals for each of said subframes based on an adaptive codebook; masking calculating means for calculating masking threshold values from said voice signals based on auditory sense masking characteristics; auditory sense weighting means for calculating filter coefficients based on said masking threshold values and performing auditory sense weighting to an error signal formed as a difference between said voice signal and a signal regenerated with said regenerating means based on said filter coefficients; and calculating means for calculating a multi-pulse that minimizes an error signal power between an output signal of said auditory sense weighting means and said code vectors in said adaptive codebook.

Claim 22

A voice coder comprising: dividing means for dividing supplied discrete voice signals into pre-set time length frames; subframe generating means for generating subframes by dividing said frames into pre-set time length divisions; regenerating means for regenerating said voice signals for each of said subframes based on an adaptive codebook; masking calculating means for calculating masking threshold values from said voice signals based on auditory sense masking characteristics; auditory sense weighting means for calculating filter coefficients based on said masking threshold values and performing auditory sense weighting to an error signal formed as a difference between said voice signal and a signal regenerated with said regenerating means based on said filter coefficients; and calculating means for calculating a multi-pulse that minimizes an error signal power between an output signal of said auditory sense weighting means and said code vectors in said adaptive codebook.

Claim 23

The voice coder of claim 18, further comprising a subbanding means for subbanding said voice signals, wherein said auditory sense weighting means performs weighting to a signal subbanded with said subbanding means.

Claim 24

The voice coder of claim 19, further comprising: a bit allocating means for allocating quantization bits to subbanded signals; and a switching means for switching a number of bits of said excitation codebook according to bits allocated with said allocating means.

Claim 27

The method for searching a codebook of claim 21, further comprising the step of: (g) calculating a multi-pulse that minimizes the error signal power weighted in the step (e), instead of the step (f).

Claim 28

The method for searching a codebook of claim 21, further comprising the step of: (g) subbanding said voice signals, wherein the step (d) performs weighting to the subbanded signals.

Claim 29

The method for searching a codebook of claim 23, further comprising the step of: (h) allocating quantization bits to the subbanded signals; and (i) switching a number of bits of said excitation codebook according to bits allocated in the step (h).

Claim 32

The method for searching a codebook of claim 25, further comprising the step of: (7) calculating a multi-pulse that minimizes the error signal power weighted in the step (5), instead of the step (6).

Claim 33

The method for searching a codebook of claim 25, further comprising the step of: (7) subbanding said voice signals, wherein the step (4) performs weighting to the subbanded signals.

Claim 34

The method for searching a codebook of claim 27, further comprising the step of: (8) allocating quantization bits to the subbanded signals; and (9) switching a number of bits of said excitation codebook according to bits allocated in the step (8).

Claim 35

A voice coder comprising: dividing means for dividing supplied discrete voice signals into frames of a first pre-set time length and further dividing said frames into subframes of a second pre-set time length smaller than said first pre-set time length; masking calculating means for calculating masking threshold values from said voice signals based on auditory sense masking characteristics; a plurality of codebooks of which bit numbers are different from each other; bit number allocating means for allocating a number of bits of said codebooks based on said masking threshold values; and searching means for searching a code vector by switching said codebooks for each of said subframes based on the allocated number of bits.

Claim 36

A voice coder comprising: dividing means for dividing supplied discrete voice signals into frames of a first pre-set time length and further dividing said frames into subframes of a second pre-set time length smaller than said first pre-set time length; masking calculating means for calculating masking threshold values from said voice signals based on auditory sense masking characteristics; a plurality of codebooks of which bit numbers are different from each other; bit number allocating means for allocating a number of bits of said codebooks based on said masking threshold values; and searching means for searching a code vector by switching said codebooks for each of said subframes based on the allocated number of bits.

Claim 37

The voice coder of claim 29, wherein said codebooks are excitation codebooks.

Claim 38

The voice coder of claim 29, wherein said codebooks are gain codebooks.

Claim 39

The voice coder of claim 29, further comprising a subbanding means for subbanding said voice signals.

Claim 40

The voice coder of claim 32, wherein impulse responses of subbanding filters are convoluted in each of said codebooks.

Claim 41

The voice coder of claim 29, further comprising an auditory sense weighting means for calculating filter coefficients based on said masking threshold values and conducting auditory sense weighting to said voice signals based on said filter coefficients.

Claim 42

A voice coder comprising: dividing means for dividing supplied discrete voice signals into frames of a preset time length; masking calculating means for calculating masking threshold values from said voice signals based on auditory sense masking characteristics; pitch calculating means for calculating pitch parameters so as to make signals regenerated based on said adaptive codebooks made of past excitation signals approximate, for each of said subframes, said voice signals; auditory sense weighting means for calculating filter coefficients based on said masking threshold values and conducting auditory sense weighting to error signals between signals regenerated with said pitch calculating means and said voice signals based on said filter coefficients; a plurality of excitation codebooks of which bit numbers are different from each other; bit allocating means for allocating a bit number of said excitation codebooks for each of said subframes based on said masking threshold values; and searching means for switching said excitation codebooks for each of said subframes based on the allocated number of bits and searching for an excitation code vector minimizing an error signal power between an output signal generated from said auditory sense weighting means and code vectors in a switched excitation codebook.

Claim 43

A voice coder comprising: dividing means for dividing supplied discrete voice signals into frames of a preset time length; masking calculating means for calculating masking threshold values from said voice signals based on auditory sense masking characteristics; pitch calculating means for calculating pitch parameters so as to make signals regenerated based on said adaptive codebooks made of past excitation signals approximate, for each of said subframes, said voice signals; auditory sense weighting means for calculating filter coefficients based on said masking threshold values and conducting auditory sense weighting to error signals between signals regenerated with said pitch calculating means and said voice signals based on said filter coefficients; a plurality of excitation codebooks of which bit numbers are different from each other; bit allocating means for allocating a bit number of said excitation codebooks for each of said subframes based on said masking threshold values; and searching means for switching said excitation codebooks for each of said subframes based on the allocated number of bits and searching for an excitation code vector minimizing an error signal power between an output signal generated from said auditory sense weighting means and code vectors in a switched excitation codebook.

Claim 44

The voice coder of claim 35, further comprising subbanding means for subbanding said voice signals, wherein said bit allocating means allocates a bit number to subbanded signals.

Claim 45

The voice coder of claim 36, wherein impulse responses of subbanding filters are convoluted in said codebooks.

Claim 46

A voice coder comprising: dividing means for dividing supplied discrete voice signals into frames of a first pre-set time length and further dividing said frames into subframes of a second pre-set time length smaller than said first pre-set time length; masking calculating means for calculating masking threshold values from said voice signals based on auditory sense masking characteristics; deciding means for deciding a number of multipulses for each of said subframes based on said masking threshold values; and means for representing excitation signals of said voice signals in a form of multipulse using the number of multipulses decided for each of said subframes.

Claim 47

A voice coder comprising: dividing means for dividing supplied discrete voice signals into frames of a first pre-set time length and further dividing said frames into subframes of a second pre-set time length smaller than said first pre-set time length; masking calculating means for calculating masking threshold values from said voice signals based on auditory sense masking characteristics; deciding means for deciding a number of multipulses for each of said subframes based on said masking threshold values; and means for representing excitation signals of said voice signals in a form of multipulse using the number of multipulses decided for each of said subframes.

Claim 48

The voice coder of claim 38, further comprising subbanding means for subbanding said voice signals, wherein said deciding means decides the number of multipulses for each subbanded signal.

Claim 49

The voice coder of claim 38, further comprising an auditory sense weighting means for calculating filter coefficients based on said masking threshold values and conducting auditory sense weighting to said voice signals based on said filter coefficients.

Claim 50

A voice coder comprising: dividing means for dividing supplied discrete voice signals into frames of a first pre-set time length; means for generating subframes by dividing said frames into divisions of a second pre-set time length; masking calculating means for calculating masking threshold values form said voice signals based on auditory sense masking characteristics; pitch calculating means for calculating pitch parameters so as to make signals regenerated based on said adaptive codebooks made of past excitation signals approximate, for each of said subframes, said voice signals; auditory sense weighting means for calculating filter coefficients based on said masking threshold values and conducting auditory sense weighting to error signals between signals regenerated with said pitch calculating means and said voice signals based on said filter coefficients; deciding means for deciding a number of multipulses for each of said subframes based on said masking threshold values; and means for calculating a multipulse minimizing said error signal power using the number of multipulses decided for each of said subframes and representing excitation signals of said voice signals using said multipulse.

Claim 51

A voice coder comprising: dividing means for dividing supplied discrete voice signals into frames of a first pre-set time length; means for generating subframes by dividing said frames into divisions of a second pre-set time length; masking calculating means for calculating masking threshold values form said voice signals based on auditory sense masking characteristics; pitch calculating means for calculating pitch parameters so as to make signals regenerated based on said adaptive codebooks made of past excitation signals approximate, for each of said subframes, said voice signals; auditory sense weighting means for calculating filter coefficients based on said masking threshold values and conducting auditory sense weighting to error signals between signals regenerated with said pitch calculating means and said voice signals based on said filter coefficients; deciding means for deciding a number of multipulses for each of said subframes based on said masking threshold values; and means for calculating a multipulse minimizing said error signal power using the number of multipulses decided for each of said subframes and representing excitation signals of said voice signals using said multipulse.

Claim 54

The method of searching codebooks of claim 42, wherein said codebooks are excitation codebooks.

Claim 55

The method of searching codebooks of claim 42, wherein said codebooks are gain codebooks.

Claim 56

The method of searchign codebooks of claim 42, wherien the step (a) is a step of dividing and subbanding supplied discrete voice signals into frames of the first pre-set time length and further dividing said frames into subframes of the second pre-set time length, and the steps (b) to (d) are conducted in each band.

Claim 57

The method of searching codebooks of claim 45, wherein impulse responses of subbanding filters are convoluted in advance.

Claim 58

A multipulse calculating method comprising the steps of: (a) dividing and subbanding supplied discrete voice signals into frames of a first pre-set time length and further dividing said frames into subframes of a second pre-set time length; (b) calculating masking threshold values from said voice signals based on audtory sense masking characteristics, and dividing supplied discrete voice signals into frames of the first pre-set time length and further dividing said frames into subframes of the second pre-set time length; (c) deciding a number of multipulses for each of said subframes based on said masking threshold values; and (d) calculating a multipulse minimizing said error signal power usign a number of multipulses decided for each of said subframes and representing excitation signals of said voice signals using said multipulse.

Claim 59

A multipulse calculating method comprising the steps of: (a) dividing and subbanding supplied discrete voice signals into frames of a first pre-set time length and further dividing said frames into subframes of a second pre-set time length; (b) calculating masking threshold values from said voice signals based on audtory sense masking characteristics, and dividing supplied discrete voice signals into frames of the first pre-set time length and further dividing said frames into subframes of the second pre-set time length; (c) deciding a number of multipulses for each of said subframes based on said masking threshold values; and (d) calculating a multipulse minimizing said error signal power usign a number of multipulses decided for each of said subframes and representing excitation signals of said voice signals using said multipulse.

Claim 60

The multipulse calculating method of claim 47, wherein the step (a) is a step of dividing and subbanding supplied discrete voice signals into frames of the first pre-set time length and further dividing said frames into subframes of the second pre-set time length, and the steps (b) to (d) are conducted in each band.