Method and system for audio filtering
AssigneeKind of Loud Technologies, LLC
InventorsJonathan S. Abel, David P. Berners
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Abstract
A system and method for graphic equalization of audio signals is disclosed. Traditional graphic equalizers provide control over the gains in each of a set of frequency bands. However, the actual band gains vary from the desired gains due to crosstalk between bands. Prior art methods for addressing this difficulty include applying a correction filter to the equalizer, and adjusting the shape of the individual band filters, both of which increase the computational cost. In an embodiment of the present invention, the input gains are processed to produce a set of adjusted gains which take into account the crosstalk, and result in an equalization interpolating the input band gains.
Claims14
A method for equalizing a signal comprising:
- accepting a set of frequency bands and a corresponding set of band gains;
- processing the band gains to form filter gains for, and interference between, each of a plurality of infinite impulse response (IIR) filters, such that a combined gain comprising a sum of the filter gains of the plurality of IIR filters in all of the frequency bands due to the interference between filters in adjacent bands is approximately equal to the band gains.
A method for equalizing a signal comprising:
- accepting a transfer function magnitude;
- accepting a set of frequency bands;
- forming a set of band gains corresponding to the set of frequency bands;
- processing the band gains to form filter gains for, and interference between, at least one of a plurality of infinite impulse response (IIR) filters, such that a combined transfer function magnitude comprising a sum of the filter gains of a cascade of the plurality of IIR filters due to the interference between filters in adjacent bands is approximately equal to the accepted transfer function magnitude.
A method for equalizing a signal according to at least one time-varying control, comprising:
- forming a table of sets of filter gains corresponding to sets of respective frequency bands, the table being indexed by at least one of said time-varying controls, and wherein at least one set of filter gains and associated interference between filters is such that a sum of gains due to the interference between a cascade of a plurality of infinite impulse response (IIR) filters having said filter gains and said interference is approximately equal to a set of desired band gains in the respective frequency bands;
- producing a set of interpolated filter gains in response to the time-varying control.
Dependencies are inferred from the claim text.