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 Title: |
US5416847:
Multi-band, digital audio noise filter
[ Derwent Title ]
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| Country: |
US United States of America
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| Inventor: |
Boze, Steven E.; Valencia, CA
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| Assignee: |
The Walt Disney Company, Burbank, CA
other patents from WALT DISNEY COMPANY (617665) (approx. 101)
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| Published / Filed: |
1995-05-16
/ 1993-02-12
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| Application Number: |
US1993000017133
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| IPC Code: |
Advanced:
H04H 60/04;
IPC-7:
H04B 15/00;
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| ECLA Code: |
H04H60/04;
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| U.S. Class: |
Current:
381/094.3;
381/098;
Original:
381/094;
381/098;
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| Field of Search: |
381/098,68.2,94,68.4
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| Priority Number: |
| 1993-02-12 |
US1993000017133 |
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| Abstract: |
This disclosure provides a multi-band, digital audio noise filter that is especially useful in the restoration of motion picture film soundtracks. More particularly, the preferred embodiment presented herein utilizes a remote fader board having eight faders which permit a user to control thresholds for sixty-four frequency bins. These faders are monitored by a MOTOROLA 56000-series microprocessor, which accepts digitized audio input signals, performs a Fast Fourier Transform upon a 128 sample window to yield signal contribution for each of the sixty-four frequency bins, and derives FIR filter coefficients for noise attenuation. The digitized audio input signals, which have been stored in a circular input buffer, are convolved with the FIR filter and output as the digitized output signals of the restored motion picture soundtrack.
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| Attorney, Agent or Firm: |
Pretty, Schroeder, Brueggemann & Clark ;
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| Primary / Asst. Examiners: |
Isen, Forester W.;
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| INPADOC Legal Status: |
Show legal status actions
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| Family: |
None
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First Claim:
Show all 31 claims |
I claim:
1. A multi-band, digital audio noise filter that permits a user to convert a digital audio input signal into a digital audio output signal, the filter comprising:
- a signal processor that processes the digital audio input signal to obtain the digital audio output signal by multiplying each of a plurality of filter coefficients with each of a plurality of time-based digital samples which compose a finite-length window of the digital audio input signal and by summing the results to obtain a digital value that is an output value of the digital audio output signal;
- a user-interface that permits the user to vary contribution-thresholds for at least several of a plurality of frequency bins that correspond to composition frequencies of the digital audio input signal;
- a filter generator that repeatedly updates said filter coefficients in dependence upon current input values of each of said digital audio input signal and said contribution-threshold for said plurality of frequency bins, said filter generator including
- FFT means for receiving the digital audio input signal and applying thereto a Fast Fourier Transform to produce, in response thereto, at least one FFT value for each of the plurality of frequency bins, said FFT values each representing the contribution of harmonics to the digital audio input signal from frequencies within said frequency bins, index generating means for comparing, for each of said plurality of frequency bins, said FFT values which correspond to each frequency bin with a corresponding user-set signal threshold level, and for generating an attenuation index for each of said plurality of frequency bins in response thereto, said attenuation index representing an attenuation of harmonics within the frequency bin if said corresponding FFT value is less than said corresponding user-set signal threshold level, and,
- IFFT means coupled to said index generating means for generating and updating, in response to said attenuation index for each of said plurality of frequency bins, said plurality of filter coefficients.
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| Background / Summary: |
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| Drawing Descriptions: |
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| Description: |
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| Forward References: |
Show 86 U.S. patent(s) that reference this one
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