EP0331405A2
Expired / Lapsed
EP
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Method and apparatus for processing a digital signal
Assignee: Sony Corp
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Filing: 1989-02-27
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Granted: —
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Expires: 2009-02-27
Abstract
Abstract A method and an apparatus for processing a digital signal by calculating a predictive error, then requantizing the predictive error thus obtained, and correcting the spectral form of requantization noise generated in quantizing the predictive error, wherein the spectral form of such requantization noise is approximated to that of the input signal while being suppressed in the lower frequency band thereof. In particular, there is disclosed a digital signal processing apparatus comprising a predictive filter with a feedback loop, a requantizer for requantizing a difference signal between an input signal and the output signal of the predictive filter, and an inverse requantizer for requantizing the output signal of the requantizer with an inverse characteristic thereto and supplying the inversely requantized signal to the predictive filter, wherein the input signal of the requantizer and the output signal of the inverse requantizer supplied to the predictive filter are each weighted by a predetermined amount individually and then are outputted to the predictive filter.
Inventors
- 👤 Naoto Iwahashi
- 👤 Kenzo Akagiri
- 👤 Hiromi Setoguchi
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-27 21:10
CPC Classifications
H; H03; H03H; H03H9/00; H04; H04B; H04B14/00; H04B14/02; H04B14/04; H04B14/046
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
58 words
A method of processing a digital signal, comprising the steps of: calculating a predictive error; requantizing said predictive error; and correcting the spectral form of requantization noise generating in requantizing said predictive error; wherein the spectral form of said requantization noise is approximated to that of the input signal while being suppressed in the lower frequency band thereof.
Claim 2
Independent Claim
58 words
A method of processing a digital signal, comprising the steps of: calculating a predictive error; requantizing said predictive error; and correcting the spectral form of requantization noise generating in requantizing said predictive error; wherein the spectral form of said requantization noise is approximated to that of the input signal while being suppressed in the lower frequency band thereof.
Claim 3
Independent Claim
100 words
An apparatus for processing a digital signal, comprising: a predictive filter with a feedback loop; requantizer means for requantizing a difference signal between an input signal and the output signal of said predictive filter; and inverse requantizer means for requantizing the output signal of said requantizer means with an inverse characteristic thereto and supplying the inversely requantized signal to said predictive filter; wherein the input signal of said requantizer means and the output signal of said inverse requantizer means supplied to said predictive filter are each weighted by a predetermined amount individually and then are outputted to said predictive filter.
Claim 4
Independent Claim
100 words
An apparatus for processing a digital signal, comprising: a predictive filter with a feedback loop; requantizer means for requantizing a difference signal between an input signal and the output signal of said predictive filter; and inverse requantizer means for requantizing the output signal of said requantizer means with an inverse characteristic thereto and supplying the inversely requantized signal to said predictive filter; wherein the input signal of said requantizer means and the output signal of said inverse requantizer means supplied to said predictive filter are each weighted by a predetermined amount individually and then are outputted to said predictive filter.
Claim 5
Independent Claim
145 words
An apparatus for processing a digital signal, comprising: a predictive filter with a feedback loop; requantizer means for requantizing a difference signal between an input signal and the output signal of said predictive filter; and inverse requantizer means for requantizing the output signal of said requantizer means with an adverse characteristic thereto and supplying the inversely requantized signal to said predictive filter; wherein the input signal of said requantizer means and the output signal of said inverse requantizer means supplied to said predictive filter are each weighted by a predetermined amount individually and then are outputted to said predictive filter; and both the output signal of said inverse requantizer means and the input signal of said requantizer means are weighted by a predetermined amount and then are fed back to said predictive filter and said requantizer means via a filter having a predetermined frequency characteristic.
Claim 6
Independent Claim
145 words
An apparatus for processing a digital signal, comprising: a predictive filter with a feedback loop; requantizer means for requantizing a difference signal between an input signal and the output signal of said predictive filter; and inverse requantizer means for requantizing the output signal of said requantizer means with an adverse characteristic thereto and supplying the inversely requantized signal to said predictive filter; wherein the input signal of said requantizer means and the output signal of said inverse requantizer means supplied to said predictive filter are each weighted by a predetermined amount individually and then are outputted to said predictive filter; and both the output signal of said inverse requantizer means and the input signal of said requantizer means are weighted by a predetermined amount and then are fed back to said predictive filter and said requantizer means via a filter having a predetermined frequency characteristic.
Claim 7
Dependent Claim
15 words
An apparatus according to claim 2, wherein said filter consists of a plurality of filters.
Claim 8
Independent Claim
64 words
An apparatus for processing a digital signal, comprising: a predictive filter; requantizer means for requantizing the output signal of said predictive filter; and noise shaping means for correcting the spectral form of requantization noise generated in requantizing said output signal; wherein the spectral form of said requantization noise is approximated to that of the input signal while being suppressed in the lower frequency band.
Claim 9
Independent Claim
64 words
An apparatus for processing a digital signal, comprising: a predictive filter; requantizer means for requantizing the output signal of said predictive filter; and noise shaping means for correcting the spectral form of requantization noise generated in requantizing said output signal; wherein the spectral form of said requantization noise is approximated to that of the input signal while being suppressed in the lower frequency band.
Claim 10
Independent Claim
109 words
An apparatus for processing a digital signal, comprising: a plurality of predictive filters; and predictive error detection means for producing differential signals between an input signal and the individual output signals of said plurality of predictive filters, said input signal being supplied to said predictive filters and encoded by selectively requantizing the difference signal; wherein said predictive filters are so designed as to render one of the difference signals equal in frequency characteristic to the input signal, and in the stage of selectively requantizing the difference signal obtained from the relevant predictive filter, the lower frequency component of the requantization error signal generated due to such requantization is suppressed.
Claim 11
Independent Claim
109 words
An apparatus for processing a digital signal, comprising: a plurality of predictive filters; and predictive error detection means for producing differential signals between an input signal and the individual output signals of said plurality of predictive filters, said input signal being supplied to said predictive filters and encoded by selectively requantizing the difference signal; wherein said predictive filters are so designed as to render one of the difference signals equal in frequency characteristic to the input signal, and in the stage of selectively requantizing the difference signal obtained from the relevant predictive filter, the lower frequency component of the requantization error signal generated due to such requantization is suppressed.
Claim 12
Independent Claim
76 words
An apparatus for processing a digital signal, comprising: a predictive filter; predictive error detection means for outputting a difference signal between the input signal and the output signal of said predictive filter; requantizer means for requantizing said difference signal; and a noise filter for feeding back to said requantizer means the requantization error signal generated during the requantization; wherein the order of said noise filter is set to be higher than that of said predictive filter.
Claim 13
Independent Claim
76 words
An apparatus for processing a digital signal, comprising: a predictive filter; predictive error detection means for outputting a difference signal between the input signal and the output signal of said predictive filter; requantizer means for requantizing said difference signal; and a noise filter for feeding back to said requantizer means the requantization error signal generated during the requantization; wherein the order of said noise filter is set to be higher than that of said predictive filter.
Claim 14
Independent Claim
124 words
An apparatus for processing a digital signal, comprising: a predictive filter for selectively switching the filtering characteristic in accordance with the spectral form of an input signal; predictive error detection means for outputting a difference signal between the input signal and the output signal of said predictive filter; requantizer means for requantizing said difference signal; and a noise filter for feeding back to said requantizer means the requantization error signal generated during the requantization; wherein, when the characteristic of said predictive filter is switched to the other characteristic for selecting a small predictive gain in the mid and lower frequency bands, the characteristic of said noise filter is also switched to raise the distribution of said requantization error signal to the higher frequency band.
Claim 15
Independent Claim
124 words
An apparatus for processing a digital signal, comprising: a predictive filter for selectively switching the filtering characteristic in accordance with the spectral form of an input signal; predictive error detection means for outputting a difference signal between the input signal and the output signal of said predictive filter; requantizer means for requantizing said difference signal; and a noise filter for feeding back to said requantizer means the requantization error signal generated during the requantization; wherein, when the characteristic of said predictive filter is switched to the other characteristic for selecting a small predictive gain in the mid and lower frequency bands, the characteristic of said noise filter is also switched to raise the distribution of said requantization error signal to the higher frequency band.
References Cited (Backward Citations)
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