EP0458645A2
Expired / Lapsed
EP
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Subband digital signal encoding apparatus
Assignee: Sony Corp
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Filing: 1991-05-23
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Granted: —
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Expires: 2011-05-23
Abstract
Abstract In a digital signal encoding apparatus an input digital signal has its frequency range divided (13) into a number of frequency bands so that the bandwidths will be broader towards the frequency bands of higher frequencies, a first allowable noise level (14 to 18) based on the energies on the band-by-band basis, and a second allowable noise level (51 to 55) based on the energies of the signals temporally adjacent to the signals of the frequency band under consideration, are set, and signal components of each frequency band are quantized with the number of bits corresponding to the level of the difference between an output synthesized from the first and the second noise levels and the energy of each frequency band.
Inventors
- 👤 Kenzo c/o Patents Div. Akagiri
- 👤 Kyoya c/o Patents Div. Tsutsui
- 👤 Yoshihito c/o Patents Div. Fujiwara
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-01 06:35
CPC Classifications
H; H03; H03M; H03M9/00; H04; H04B; H04B1/00; H04B1/66; H04B1/667; G; G06; G06T; G06T9/00; G06T9/007
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
139 words
A digital signal encoding apparatus for encoding an input digital signal, the apparatus comprising: dividing means (13) supplied with said input digital signal for dividing the frequency range of said input digital into a plurality of frequency bands; first noise level setting means (14 to 18) for setting a first allowable noise level of each frequency band based on the energy of each frequency band; second noise level setting means (51 to 55) for setting a second allowable noise level of each frequency band based on the energies of signals in the temporally adjacent corresponding frequency band; synthesizing means (55,56) for synthesizing said first and second allowable noise levels, for generating a synthesized allowable noise level; and quantizing means (24) for quantizing signal components of each frequency band with the bit number conforming to said synthesized allowable noise level.
Claim 2
Dependent Claim
47 words
Apparatus according to claim 1 wherein said dividing means (13) divides the frequency range of said input digital signal into a plurality of frequency bands so that the bandwidth of each frequency band is selected to be broader towards the side of frequency bands of higher frequencies.
Claim 3
Dependent Claim
31 words
Apparatus according to claim 1 wherein said dividing means (13) includes transform coding means for transform coding a predetermined number of samples of said input digital signal for generating co-efficient data.
Claim 4
Dependent Claim
18 words
Apparatus according to claim 3 wherein each of said plurality of frequency bands corresponds to a critical band.
Claim 5
Dependent Claim
22 words
Apparatus according to claim 1 wherein said input digital signal is the coefficient data obtained upon orthogonal transform of an audio signal.
Claim 6
Dependent Claim
28 words
Apparatus according to claim 1 wherein said input digital signal is the amplitude value information based on the coefficient data obtained upon orthogonal transform of said audio signal.
Claim 7
Dependent Claim
31 words
Apparatus according to claim 5 or claim 6 wherein said audio signal to be processed by orthogonal transform is the audio signal divided into predetermined frequency ranges by a band-dividing filter.
Claim 8
Dependent Claim
36 words
Apparatus according to any one of claims 1 to 7 wherein said first allowable noise level is found on the basis of the energy of each frequency band on which a predetermined weighting function is convolved.
Claim 9
Dependent Claim
31 words
Apparatus according to any one of claims 1 to 7 wherein said first and second allowable noise levels are found on the basis of the masking effect for each frequency band.
Claim 10
Dependent Claim
27 words
Apparatus according to any one of claims 1 to 7 wherein said first allowable noise level has been corrected on the basis of an equal loudness curve.
References Cited (Backward Citations)
No citation records indexed.
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