Methods and apparatus for compressing and quantizing signals
First Claim
1. A method for compressing digital input signals to provide compressed digital output signals, the method comprising the steps of:
- deriving plural spectral coefficients from a first digital input signal, and grouping the spectral coefficients into bands, each band having a band magnitude and a band frequency;
determining a level of correlation between the first digital input signal and a second digital input signal; and
adaptively allocating a number of spectrum-dependent quantizing bits among the bands to allocate to each band a number of spectrum-dependent quantizing bits for quantizing each spectral coefficient in the band, the number of spectrum-dependent quantizing bits allocated to each band being determined according to the level of correlation between the first digital input signal and the second digital input signal.
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Abstract
A high efficiency coding method and apparatus includes quantization which takes into account correlation of input signals of plural channels in coding the input signals of the respective channels simultaneously. In the high efficiency coding method and apparatus, spectrum data from MDCT circuits or coefficient data are transmitted to another channel via an other-channel transmission circuit, and data from another channel are transmitted to correlation adaption circuits. The data from correlation adaption on circuits are transmitted to adaptive bit allocation circuits, respectively, wherein bit allocation in coding of the input signals of one channel takes into account the input signals of another channel.
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Citations
32 Claims
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1. A method for compressing digital input signals to provide compressed digital output signals, the method comprising the steps of:
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deriving plural spectral coefficients from a first digital input signal, and grouping the spectral coefficients into bands, each band having a band magnitude and a band frequency; determining a level of correlation between the first digital input signal and a second digital input signal; and adaptively allocating a number of spectrum-dependent quantizing bits among the bands to allocate to each band a number of spectrum-dependent quantizing bits for quantizing each spectral coefficient in the band, the number of spectrum-dependent quantizing bits allocated to each band being determined according to the level of correlation between the first digital input signal and the second digital input signal. - View Dependent Claims (3, 4, 5, 6, 7)
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2. A method for compressing digital input speech signals to provide compressed digital output speech signals, the method comprising the steps of:
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deriving plural spectral coefficients from a first digital input signal, and grouping the spectral coefficients into bands, each band having a band magnitude and a band frequency; determining a level of correlation between the first digital input signal and a second digital input signal; and adaptively allocating a number of spectrum-dependent quantizing bits among the bands to allocate to each band a number of spectrum-dependent quantizing bits for quantizing each spectral coefficient in the band, the number of spectrum-dependent quantizing bits allocated to each band being determined according to human auditory sense characteristics, and the level of correlation between the first digital input signal and the second digital input signal.
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8. An apparatus for compressing digital input signals to provide compressed digital output signals, comprising:
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means for deriving plural spectral coefficients from a first digital input signal and for grouping the spectral coefficients into bands, each band having a band magnitude and a band frequency; means for determining a level of correlation between the first digital input signal and a second digital input signal; and means for adaptively allocating a number of spectrum-dependent quantizing bits for quantizing each spectral coefficient in the band, the number of spectrum-dependent quantizing bits allocated to each band being determined according to the level of correlation between the first digital input signal and the second digital input signal. - View Dependent Claims (10, 11, 12, 13, 14)
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9. An apparatus for compressing digital input speech signals to provide compressed digital output speech signals, comprising:
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means for deriving plural spectral coefficients from a first digital input signal, and for grouping the spectral coefficients into bands, each band having a band magnitude and a band frequency; means for determining a level of correlation between the first digital input signal and a second digital input signal; and means for adaptively allocating a number of spectrum-dependent quantizing bits among the bands to allocate to each band a number of spectrum-dependent quantizing bits for quantizing each spectral coefficient in the band, the number of spectrum-dependent quantizing bits allocated to each band being determined according to human auditory sense characteristics and the level of correlation between the first digital input signal and the second digital input signal.
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15. A method for compressing digital input signals to provide compressed digital output signals, the method comprising the steps of:
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dividing a first digital input signal into a plurality of critical bands; deriving plural spectral coefficients of each of the critical bands, and grouping the spectral coefficients into bands, each band having a band magnitude and a band frequency; determining a level of correlation between the first digital input signal and a second digital input signal; and adaptively allocating a number of spectrum-dependent quantizing bits among the bands to allocate to each band a number of spectrum-dependent quantizing bits for quantizing each spectral coefficient in the band, the number of spectrum-dependent quantizing bits allocated to each band being determined according to the level of correlation between the first digital input signal and the second digital input signal. - View Dependent Claims (17, 18, 19, 20, 21)
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16. A method for compressing digital input speech signals to provide compressed digital output speech signals, the method comprising the steps of:
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dividing a first digital input signal into a plurality of critical bands; deriving plural spectral coefficients of each of the critical bands, and grouping the spectral coefficients into bands, each band having a band magnitude and a band frequency; determining a level of correlation between the first digital input signal and a second digital input signal; and adaptively allocating a number of spectrum dependent quantizing bits among the bands to allocate to each band a number of spectrum-dependent quantizing bits for quantizing each spectral coefficient in the band, the number of spectrum-dependent quantizing bits allocated to each band being determined according to human auditory sense characteristics and the level of correlation between the first digital input signal and the second digital input signal.
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22. An apparatus for compressing digital input signals to provide compressed digital output signals, comprising:
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means for dividing a first digital input signal into a plurality of critical bands; means for deriving plural spectral coefficients of each of the critical bands, and for grouping the spectral coefficients into bands, each band having a band magnitude and a band frequency; means for adaptively allocating a number of spectrum-dependent quantizing bits among the bands to allocate to each band a number of spectrum-dependent quantizing bits for quantizing each spectral coefficient in the band, the number of spectrum-dependent quantizing bits allocated to each band being determined according to the level of correlation between the first digital input signal and the second digital input signal. - View Dependent Claims (24, 25, 26, 27, 28)
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23. An apparatus for compressing digital input speech signals to provide compressed digital output signals, comprising:
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means for dividing a first digital input signal into a plurality of critical bands; means for deriving plural spectral coefficients of each of the critical bands, and for grouping the spectral coefficients into bands, each band having a band magnitude and a band frequency; means for adaptively allocating a number of spectrum-dependent quantizing bits among the bands to allocate to each band a number of spectrum-dependent quantizing bits, quantizing each spectral coefficient in the band, the number of spectrum-dependent quantizing bits allocated to each band being determined according to human auditory sense characteristics and according to a level of correlation between the first digital input signal and the second digital input signal.
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29. An apparatus for compressing digital input signals to provide compressed digital output signals, comprising:
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means for dividing a first digital input signal into a plurality of critical bands; block decision means for generating floating information from each of the plurality of critical bands, the floating information including information of the normalization of the first digital input signal and information of the bit length of the first digital input signal; means for deriving plural spectral coefficients of each of the critical bands and for grouping the plural spectral coefficients into bands, each band having a band magnitude and a band frequency based in part upon the floating information; level correction means for correcting data levels within each critical band; adaptive bit allocation means for determining the number of bits to be allocated to each critical band; means for determining a level of correlation between the first digital input signal and a second digital input signal; correlation adaption means for adjusting the number of bits to be allocated by the adaptive bit allocation means based upon the level of correlation between the first digital input signal and a simultaneously coded second digital input signal; and means for re-quantizing the level corrected data within each critical band in response to the determination of the adaptive bit allocation means. - View Dependent Claims (30)
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31. A method for compressing digital input signals to provide compressed digital output signals, the method comprising the steps of:
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dividing a first digital input signal into a plurality of critical bands; generating floating information from each of the plurality of critical bands, the floating information including information of a normalization of the first digital input signal and information of a bit length of the first digital input signal; deriving plural spectral coefficients of each of the critical bands based in part upon the floating information; correcting data levels within each critical band; determining the number of bits to be allocated to the derived plural spectral coefficients of each critical band; determining a level of correlation between the first digital input signal and a second digital input signal; adjusting the determined number of bits to be allocated to the derived plural spectral coefficients of each critical band based upon the level of correlation between the first digital input signal and a second digital input signal; and re-quantizing the level corrected data within each critical band in response to the determination of the number of bits to be allocated to the derived plural spectral coefficients of each critical band. - View Dependent Claims (32)
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Specification