Method and apparatus for performing bit-allocation coding for an acoustic signal of frequency region and time region correction for an acoustic signal and method and apparatus for decoding a decoded acoustic signal
First Claim
1. An acoustic signal coding method, comprising the steps of:
- dividing a digital acoustic signal of time region information supplied as an original signal into one or more pieces of sub-band data for each of a plurality of sub-bands to change the digital acoustic signal of the time region information to a digital acoustic signal of frequency region information;
combining the pieces of sub-band data of all sub-bands to produce a band combined signal as a reproduced digital acoustic signal of time region information;
producing a residual signal from the digital acoustic signal of the time region information and the reproduced digital acoustic signal of the time region information as time region correcting information; and
multiplexing the digital acoustic signal of the frequency region information and the time region correcting information to produce a bit stream as an output signal.
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Accused Products
Abstract
A digital acoustic signal of a time region information is divided into a plurality of sub-band groups, and the number of bits allocated to each data of the sub-band groups is reduced by a reducing number Nr in a quantizing unit according to a maximum value selected among energy values of pieces of data in each sub-band group, so that the digital acoustic signal of a frequency region information is produced. Thereafter, Nr bits are added to each data of the digital acoustic signal of the frequency region information in the inversely quantizing unit, and the data of all sub-bands are combined to produce a reproduced digital acoustic signal of the time region information. Thereafter, a residual signal indicating a difference between the digital-acoustic signal of the time region information and the reproduced digital acoustic signal of the time region information is produced, and the residual signal and the reproduced digital acoustic signal of the frequency region information are multiplexed. Therefore, when a reproduced digital acoustic signal of the time region information is produced from the reproduced digital acoustic signal of the frequency region information and is corrected according to the residual signal in a decoding operation, the digital acoustic signal can be efficiently coded and decoded while maintaining the redundancy.
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Citations
19 Claims
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1. An acoustic signal coding method, comprising the steps of:
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dividing a digital acoustic signal of time region information supplied as an original signal into one or more pieces of sub-band data for each of a plurality of sub-bands to change the digital acoustic signal of the time region information to a digital acoustic signal of frequency region information; combining the pieces of sub-band data of all sub-bands to produce a band combined signal as a reproduced digital acoustic signal of time region information; producing a residual signal from the digital acoustic signal of the time region information and the reproduced digital acoustic signal of the time region information as time region correcting information; and multiplexing the digital acoustic signal of the frequency region information and the time region correcting information to produce a bit stream as an output signal. - View Dependent Claims (2, 3, 4)
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5. An acoustic signal coding and decoding method, comprising the steps of:
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dividing a digital acoustic signal of time region information supplied as an original signal into one or more pieces of sub-band data for each of a plurality of sub-bands to change the digital acoustic signal of the time region information to a digital acoustic signal of frequency region information; combining the pieces of sub-band data of all sub-bands to produce a band combined signal as a first reproduced digital acoustic signal of the time region information; producing a residual signal from the first reproduced digital acoustic signal of the time region information and the digital acoustic signal of the time region information as time region correcting information; multiplexing the digital acoustic signal of the frequency region information and the time region correcting information to a bit stream; demultiplexing the bit stream to separate the digital acoustic signal of the frequency region information from the time region correcting information; combining the pieces of sub-band data of all sub-bands included in the digital acoustic signal of the frequency region information to produce a second reproduced digital acoustic signal of the time region information; and correcting the second reproduced digital acoustic signal of the time region information according to the time region correcting information demultiplexed. - View Dependent Claims (6, 7)
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8. An acoustic signal coding apparatus comprising:
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a band dividing filter for dividing a digital acoustic signal of time region information supplied as an original signal into one or more pieces of sub-band data for each of a plurality of sub-bands to change the digital acoustic signal of the time region information to a digital acoustic signal of frequency region information; a maximum value selecting unit for selecting a maximum value among the pieces of sub-band data divided by the band dividing filter for each of the sub-bands, each piece of sub-band data being expressed at a fixed quantization bit precision; a bit allocating information producing unit for producing bit allocating information indicating a minimum bit number required to express the maximum value selected by the maximum value selecting unit among the pieces of sub-band data of one sub-band for each of the sub-bands; a quantizing unit for reducing the number of bits used in each piece of sub-band data divided by the band dividing filter by a reducing number Nr according to the bit allocating information produced by the bit allocating information producing unit for each sub-band to produce the digital acoustic signal of the frequency region information composed of the pieces of sub-band data, the pieces of sub-band data of the digital acoustic signal of the frequency region information being respectively expressed by an allowed number of bits indicated by the bit allocating information for each sub-band; an inversely quantizing unit for adding Nr bits to each piece of sub-band data of one sub-band, in which the number of bits is reduced by the reducing number Nr by the quantizing unit, for each sub-band on condition that values of the Nr bits added to each piece of sub-band data are the same as that of a sign bit of the niece of sub-band data; a band combining filter for combining the pieces of sub-band data of all sub-bands produced by the inversely quantizing unit to produce a band combined signal as a reproduced digital acoustic signal of time region information; a residual signal producing unit for producing a residual signal from the digital acoustic signal of the time region information and the reproduced digital acoustic signal of the time region information produced by the band combining filter and outputting the residual signal as time region correcting information; and a multiplexing unit for multiplexing the digital acoustic signal of the frequency region information produced by the quantizing unit and the time region correcting information produced by the residual signal producing unit to produce a bit stream as an output signal. - View Dependent Claims (9)
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10. An acoustic signal coding and decoding apparatus comprising:
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a band dividing filter for dividing a digital acoustic signal of time region information supplied as an original signal into one or more pieces of sub-band data for each of a plurality of sub-bands to change the digital acoustic signal of the time region information to a digital acoustic signal of frequency region information; a maximum value selecting unit for selecting a maximum value among the pieces of sub-band data divided by the band dividing filter for each of the sub-bands, each piece of sub-band data being expressed at a fixed quantization bit precision; a bit allocating information producing unit for producing bit allocating information indicating a minimum bit number required to express the maximum value selected by the maximum value selecting unit among the pieces of sub-band data of one sub-band for each of the sub-bands; a quantizing unit for reducing the number of bits used in each piece of sub-band data divided by the band dividing filter by a reducing number Nr according to the bit allocating information produced by the bit allocating information producing unit for each sub-band to produce the digital acoustic signal of the frequency region information composed of the pieces of sub-band data, the pieces of sub-band data of the digital acoustic signal of the frequency region information being respectively expressed by an allowed number of bits indicated by the bit allocating information for each sub-band; a first inversely quantizing unit for adding Nr bits to the pieces of sub-band data of one sub-band, in which the number of bits is reduced by the reducing number Nr by the quantizing unit, for each sub-band on condition that values of the Nr bits added to each piece of sub-band data are the same as that of a sign bit of the piece of sub-band data; a first band combining filter for combining the pieces of sub-band data of all sub-bands produced by the first inversely quantizing unit to produce a band combined signal as a first reproduced digital acoustic signal of time region information; a residual signal producing unit for producing a residual signal from the digital acoustic signal of the time region information and the first reproduced digital acoustic signal of the time region information produced by the first band combining filter and outputting the residual signal as time region correcting information; a multiplexing unit for multiplexing the digital acoustic signal of the frequency region information produced by the quantizing unit and the time region correcting information produced by the residual signal producing unit to produce a bit stream as an output signal; a demultiplexing unit for demultiplexing the bit stream produced by the multiplexing unit to separate the digital acoustic signal of the frequency region information from the time region correcting information; a second inversely quantizing unit for adding Nr bits to the pieces of sub-band data of the digital acoustic signal of the frequency region information demultiplexed by the demultiplexing unit for each sub-band on condition that a value of the Nr bits added to each piece of sub-band data is the same as that of a sign bit of the piece of sub-band data; a second band combining filter for combining the pieces of sub-band data of all sub-bands in the digital acoustic signal of the frequency region information produced by the second inversely quantizing unit to produce a second reproduced digital acoustic signal of the time region information; and a residual correcting unit for correcting the second reproduced digital acoustic signal of the time region information produced by the second band combining filter according to the time region correcting information demultiplexed by the demultiplexing unit. - View Dependent Claims (11)
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12. An acoustic signal coding method, comprising the steps of:
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receiving a digital acoustic signal of time region information as an original signal; dividing the digital acoustic signal of time region information into one or more pieces of sub-band data for each of a plurality of sub-bands to change the digital acoustic signal of the time region information to a digital acoustic signal of frequency region information; combining the pieces of sub-band data of all sub-bands to produce a band combined signal as a reproduced digital acoustic signal of time region information; producing a residual signal composed of pieces of residual data from the digital acoustic signal of the time region information received as the original signal and the reproduced digital acoustic signal of the time region information as time region correcting information; producing a piece of pulse data according to the residual signal on condition that a residual value of one piece of having an absolute value higher than a maximum value, which is expressed by a prescribed number of bits determined according to an average of absolute values of the pieces of residual data of the residual signal, is made lower than the maximum value in cases where the residual signal is again produced from a new digital acoustic signal of time region information obtained by adding the pulse data to the digital acoustic signal of time region information; adding the pulse data to the digital acoustic signal of time region information to produce an adjusted digital acoustic signal of frequency region information from the digital acoustic signal of time region information; producing an adjusted reproduced digital acoustic signal of time region information from the adjusted digital acoustic signal of frequency region information; producing an adjusted residual signal from the adjusted reproduced digital acoustic signal of time region information as adjusted time region correcting information; and multiplexing the digital acoustic signal of the frequency region information and the adjusted time region correcting information to produce a bit stream as an output signal. - View Dependent Claims (13, 14, 15, 16, 17)
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18. An acoustic signal coding apparatus, comprising:
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a band dividing filter for dividing a digital acoustic signal of time region information supplied as an original signal into one or more pieces of sub-band data for each of a plurality of sub-bands to change the digital acoustic signal of the time region information to a digital acoustic signal of frequency region information; a maximum value selecting unit for selecting a maximum value among the pieces of sub-band data divided by the band dividing filter for each of the sub-bands; a bit allocating information producing unit for producing bit allocating information indicating a minimum bit number required to express the maximum value selected by the maximum value selecting unit among the pieces of sub-band data of one sub-band according to the maximum value selected by the maximum value selecting unit for each of the sub-bands; a quantizing unit for reducing the number of bits used in each piece of sub-band data divided by the band dividing filter by a reducing number Nr according to the bit allocating information produced by the bit allocating information producing unit for each sub-band to produce the digital acoustic signal of the frequency region information composed of the pieces of sub-band data, the pieces of sub-band data of the digital acoustic signal of the frequency region information being respectively expressed by an allowed number of bits indicated by the bit allocating information for each sub-band; an inversely quantizing unit for adding Nr bits to the pieces of sub-band data of one sub-band, in which the number of bits is reduced by the reducing number Nr by the quantizing unit, for each sub-band on condition that values of the Nr bits added to each piece of sub-band data are the same as that of a sign bit of the piece of sub-band data; a band combining filter for combining the pieces of sub-band data of all sub-bands produced by the inversely quantizing unit to produce a band combined signal as a reproduced digital acoustic signal of time region information; a residual signal producing unit for producing a residual signal composed of pieces of residual data from the digital acoustic signal of the time region information and the reproduced digital acoustic signal of the time region information produced by the band combining filter, each piece of residual data having a residual value; a pulse data producing unit for producing a piece of pulse data according to the residual signal produced by the residual signal producing unit on condition that a residual value of one piece of residual data having an absolute value higher than a maximum value, which is expressed by a prescribed number of bits determined according to an average of absolute values of the pieces of residual data of the residual signal, is made lower than the prescribed value in cases where the residual signal is again produced from a new digital acoustic signal of time region information obtained by adding the pulse data to the digital acoustic signal of time region information; an acoustic signal adjusting unit for adding the pulse data produced by the pulse data producing unit to the digital acoustic signal of time region information to produce an adjusted digital acoustic signal of time region information and produce an adjusted residual signal from the adjusted reproduced digital acoustic signal of time region information as adjusted time region correcting information in the residual signal producing unit through the band dividing filter, the quantizing unit, the inversely quantizing unit and the band combining filter; and a multiplexing unit for multiplexing the digital acoustic signal of the frequency region information produced by the quantizing unit and the adjusted time region correcting information produced by the residual signal producing unit to produce a bit stream as an output signal. - View Dependent Claims (19)
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Specification