Apparatus and method for data compression using signal-weighted quantizing bit allocation
First Claim
1. An apparatus for compressing a digital input signal to provide a compressed digital output signal, the apparatus comprising:
- a means for deriving plural spectral coefficients from the digital input signal, and for grouping the spectral coefficients into bands, each band having a band magnitude and a band frequency; and
an adaptive bit allocation 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 band magnitude, weighted depending on the band frequency.
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Abstract
A data compression apparatus for compressing a digital input signal to provide a compressed digital output signal. In the apparatus, a circuit derives plural spectral coefficients from the digital input signal, and groups the spectral coefficients into bands. An adaptive bit allocation circuit adaptively allocates 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 of the spectral coefficients in the band. The number of spectrum-dependent quantizing bits allocated to each band by the adaptive bit allocation circuit is determined according to the band magnitude, weighted depending on the band frequency.
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Citations
65 Claims
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1. An apparatus for compressing a digital input signal to provide a compressed digital output signal, the apparatus comprising:
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a means for deriving plural spectral coefficients from the digital input signal, and for grouping the spectral coefficients into bands, each band having a band magnitude and a band frequency; and an adaptive bit allocation 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 band magnitude, weighted depending on the band frequency. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A method for compressing a digital input signal to provide a compressed digital output signal, the method comprising the steps of:
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deriving plural spectral coefficients from the digital input signal, and grouping the spectral coefficients into bands, each band having a band magnitude and a band frequency; 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 band magnitude, weighted depending on the band frequency. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38)
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39. A medium whereon is stored a compressed digital signal derived from a digital input signal by a data compressing method comprising the steps of:
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deriving plural spectral coefficients from the digital input signal, and grouping the spectral coefficients into bands, each band having a band magnitude and a band frequency; 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 band magnitude, weighted depending on the band frequency; quantizing each spectral coefficient in each band using a number of quantizing bits including the number of spectrum-dependent quantizing bits allocated for quantizing each spectral coefficient in the band; and including the quantized spectral coefficients in the compressed digital signal. - View Dependent Claims (40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52)
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53. An expander for expanding a compressed digital signal derived from a digital input signal by a data compressing method comprising the steps of:
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deriving plural spectral coefficients from the digital input signal, and grouping the spectral coefficients into bands, each band having a band magnitude and a band frequency, 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 band magnitude, weighted depending on the band frequency, quantizing each spectral coefficient in each band using a number of quantizing bits including the number of spectrum-dependent quantizing bits allocated for quantizing each spectral coefficient in the band, and including in the compressed digital signal, for each band, the quantized spectral coefficients and data indicating the number of quantizing bits, the expander including; a means for separating from the compressed digital signal, for each band, the quantized spectral coefficients and the data indicating the number of quantizing bits; a means for dequantizing, for each band, the quantized spectral coefficients in response to the data indicating the number of quantizing bits; and a means for deriving the output signal from the dequantized spectral coefficients. - View Dependent Claims (54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65)
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Specification