EP0473367A1
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Digital signal encoders
Assignee: Sony Corp
•
Filing: 1991-08-22
•
Granted: —
•
Expires: 2011-08-22
Abstract
Abstract In a digital signal encoder for analyzing an input digital signal by frequency analysis means (10) of the non-block type and frequency analysis means (20, 40, 60) of the block type to quantize outputs obtained, a quantization characteristic (29, 49, 69) is set in the basis of an allowable noise level based on an energy within a predetermined time period of an output from the block type frequency analysis means (10) and an allowable noise level based on an energy of at least one of data preceding and succeeding in time within the predetermined time period, thereby to provide a real time processing.
Inventors
- 👤 Kenzo c/o Patents Div. Akagiri
- 👤 Kyoya c/o Patents Div. Tsutsui
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-02 22:37
CPC Classifications
H; H03; H03M; H03M7/00; H03M7/30; H03M7/3053; H04; H04B; H04B1/00; H04B1/66; H04B1/665
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
202 words
A digital signal encoder comprising: first frequency analysis means (10) of the non-block type for carrying out frequency analysis of an input digital signal; second frequency analysis means (20, 40, 60) of the block type for further carrying out frequency analysis of frequency components analyzed by said first frequency analysis means (10) ; first noise level setting means (75) for setting a first allowable noise level on the basis of the energy of each frequency component within a predetermined time period of outputs from said second frequency analysis means (20, 40, 60); second noise level setting means (23, 43, 63, 50, 70, 51, 71, 72, 73, 52, 74, 22, 44, 64) for setting a second allowable noise level of each frequency component within said predetermined time period on the basis of the energy of at least one of data preceding in time and data succeeding in time outputs from said second frequency analysis means (20, 40, 60); and quantization means (29, 49, 69) for quantizing an output from said second frequency analysis means (20, 40, 60); a quantization characteristic of said quantization means being set on the basis of outputs from said first and second noise level setting means (75, 23, etc.).
Claim 2
Dependent Claim
64 words
An encoder according to claim 1 wherein said first frequency analysis means (10) comprises band division means for dividing said input digital signal into signal components in a plurality of frequency bands, including at least one filter (11, 12), and said second frequency analysis means (20, 40, 60) comprises fast Fourier transform means for carrying out fast Fourier transformation of signal components every block.
Claim 3
Dependent Claim
63 words
An encoder according to claim 2 wherein said band division means carries out a division such that the bandwidth becomes large as the frequency band shifts to a higher frequency, said fast Fourier transform means carrying out processing such that the block time length where said fast Fourier transform processing is conducted becomes small as the frequency band shifts to a higher frequency.
Claim 4
Dependent Claim
31 words
An encoder according to claim 1, claim 2 or claim 3 wherein said at least one datum at said second noise level setting means (23, etc.) is data preceding in time.
Claim 5
Dependent Claim
46 words
An encoder according to any one of the preceding claims wherein said second noise level setting means (23, etc.) sets said second allowable noise level on the basis of energies of data which are the same in terms of frequency components for periods different in time.
Claim 6
Dependent Claim
43 words
An encoder according to any one of the preceding claims which comprises a critical band division circuit (21, 41, 61) for further dividing as a whole an output from said second frequency analysis means (20, 40, 60) into signal components in critical bands.
Claim 7
Dependent Claim
43 words
An encoder according to claim 6 wherein said first noise level setting means (23, etc. ) sets said first allowable noise level on the basis of an energy determined by a sum total of amplitude values in respective bands of said critical bands.
Claim 8
Dependent Claim
25 words
An encoder according to claim 6 wherein said second noise level setting means (23, etc.) sets said second allowable noise level every said critical band.
Claim 9
Dependent Claim
37 words
An encoder according to claim 6 wherein said second allowable noise level in an arbitrary band of said critical bands is set on the basis of said second allowable noise level in another of said critical bands.
Claim 10
Dependent Claim
42 words
An encoder according to claim 8 wherein the quantization characteristic of said quantization means (29, 49, 69) is set in dependence upon level differences between said energies in every band of said critical bands, and said first and second allowable noise levels.
Claim 11
Dependent Claim
40 words
An encoder according to any one of the preceding claims wherein the quantization characteristic of said quantization means (29, 49, 69) is such that as the frequency band shifts to a higher frequency, the number of bits allocated becomes smaller.
Claim 12
Dependent Claim
28 words
An encoder according to any one of the preceding claims wherein said first allowable noise level is a masking level on the frequency axis based on human hearing.
Claim 13
Dependent Claim
28 words
An encoder according to any one of the preceding claims wherein said second allowable noise level is a masking level on the time axis based on human hearing.
Claim 14
Dependent Claim
37 words
An encoder according to claims 12 and 13 wherein said first and second allowable noise levels are obtained by synthesizing masking levels on said frequency and time bases and a minimum audible curve based on human hearing.
Claim 15
Dependent Claim
28 words
An encoder according to any one of the preceding wherein said at least one filter of said first frequency analysis means (20, 40, 60) is a mirror filter.
Claim 16
Dependent Claim
30 words
An encoder according to any one of claims 1 to 14 wherein said at least one filter of said first frequency analysis means (20, 40, 60) is a band-pass filter.
References Cited (Backward Citations)
EP0193143B1
Cited
EP0400473A2
Cited
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.