Method for generating filter for audio signal, and parameterization device for same

• US 9,832,589 B2
• Filed: 12/23/2014
• Issued: 11/28/2017
• Est. Priority Date: 12/23/2013
• Status: Active Grant

• Current Assignee: GCOA Company Limited, WILUS Inc.
• Original Assignee: WILUS Inc.
• Inventors: Lee, Taegyu, Oh, Hyunoh
• Primary Examiner(s): Laekemariam, Yosef K
• Application Number:
  US15/107,462
• Publication Number:
  US 20160323688A1
• Time in Patent Office: 1,071 Days
• Field of Search: 381 1, 381 17, 381 18, 381 23, 381 61, 381 63, 381306, 381307, 381309
• CPC Class Codes: G10L 19/008 Multichannel audio signal coding or decoding using interchannel correlation to reduce redundancy, e.g. joint-stereo, intensity-coding or matrixing
• CPC Class Codes: G10L 19/0204 using subband decomposition
• CPC Class Codes: H04S 2400/01 Multi-channel, i.e. more than two input channels, sound reproduction with two speakers wherein the multi-channel information is substantially preserved
• CPC Class Codes: H04S 2400/03 Aspects of down-mixing multi-channel audio to configurations with lower numbers of playback channels, e.g. 7.1 -> 5.1 H04S2400/01 takes precedence
• CPC Class Codes: H04S 2420/01 Enhancing the perception of the sound image or of the spatial distribution using head related transfer functions [HRTF's] or equivalents thereof, e.g. interaural time difference [ITD] or interaural level difference [ILD]
• CPC Class Codes: H04S 2420/03 Application of parametric coding in stereophonic audio systems
• CPC Class Codes: H04S 2420/07 Synergistic effects of band splitting and sub-band processing
• CPC Class Codes: H04S 3/008 in which the audio signals are in digital form, i.e. employing more than two discrete digital channels data reduction aspects thereof based on psychoacoustics G10L19/02
• CPC Class Codes: H04S 7/305 Electronic adaptation of stereophonic audio signals to reverberation of the listening space H04S7/301 takes precedence
• CPC Class Codes: H04S 7/307 Frequency adjustment, e.g. tone control H04S7/301 takes precedence

Abstract

The present invention relates to a method for generating a filter for an audio signal and a parameterization device for the same, and more particularly, to a method for generating a filter for an audio signal, to implement filtering of an input audio signal with a low computational complexity, and a parameterization device therefor.

To this end, provided are a method for generating a filter for an audio signal, including: receiving at least one binaural room impulse response (BRIR) filter coefficients for binaural filtering of an input audio signal; converting the BRIR filter coefficients into a plurality of subband filter coefficients; obtaining average reverberation time information of a corresponding subband by using reverberation time information extracted from the subband filter coefficients; obtaining at least one coefficient for curve fitting of the obtained average reverberation time information; obtaining flag information indicating whether the length of the BRIR filter coefficients in a time domain is more than a predetermined value; obtaining filter order information for determining a truncation length of the subband filter coefficients, the filter order information being obtained by using the average reverberation time information or the at least one coefficient according to the obtained flag information and the filter order information of at least one subband being different from filter order information of another subband; and truncating the subband filter coefficient by using the obtained filter order information and a parameterization device therefor.

Claims

1. A method for generating a filter for an audio signal, comprising:

receiving at least one binaural room impulse response (BRIR) filter coefficients for binaural filtering of an input audio signal;

converting the BRIR filter coefficients into a plurality of subband filter coefficients;

obtaining average reverberation time information of a corresponding subband by using reverberation time information extracted from the subband filter coefficients;

obtaining at least one coefficient for curve fitting of the obtained average reverberation time information;

obtaining flag information indicating whether the length of the BRIR filter coefficients in a time domain is more than a predetermined value;

obtaining filter order information for determining a truncation length of the subband filter coefficients, the filter order information being obtained by using the average reverberation time information or the at least one coefficient according to the obtained flag information, and the filter order information of at least one subband being different from filter order information of another subband; and

truncating the subband filter coefficients by using the obtained filter order information.

2. The method of claim 1, wherein when the flag information indicates that the length of the BRIR filter coefficients is more than a predetermined value, the filter order information is determined based on a curve-fitted value by using the obtained at least one coefficient.

3. The method of claim 2, wherein the curve-fitted filter order information is determined as a value of power of 2 using an approximated integer value in which a polynomial curve-fitting is performed by using the at least one coefficient as an index.

4. The method of claim 1, wherein when the flag information indicates that the length of the BRIR filter coefficients is not more than the predetermined value, the filter order information is determined based on the average reverberation time information of the corresponding subband without performing the curve fitting.

5. The method of claim 4, the filter order information is determined as a value of power of 2 using a log-scaled approximated integer value of the average reverberation time information as an index.

6. The method of claim 1, wherein the filter order information is determined as a smaller value of a reference truncation length of the corresponding subband determined based on the average reverberation time information and an original length of the subband filter coefficients.

7. The method of claim 6, wherein the reference truncation length is a value of power of 2.

8. The method of claim 1, wherein the filter order information has a single value for each subband.

9. The method of claim 1, wherein the average reverberation time information is an average value of reverberation time information of each channel extracted from at least one subband filter coefficients of the same subband.

10. A parameterization device for generating a filter for an audio signal, the parameterization device further configured to:

receive at least one binaural room impulse response (BRIR) filter coefficients for binaural filtering of an input audio signal;

convert the BRIR filter coefficients into a plurality of subband filter coefficients;

obtain average reverberation time information of a corresponding subband by using reverberation time information extracted from the subband filter coefficients;

obtain at least one coefficient for curve fitting of the obtained average reverberation time information;

obtain flag information indicating whether the length of the BRIR filter coefficients in a time domain is more than a predetermined value;

obtain filter order information for determining a truncation length of the subband filter coefficients, the filter order information being obtained by using the average reverberation time information or the at least one coefficient according to the obtained flag information, and the filter order information of at least one subband being different from filter order information of another subband; and

truncates the subband filter coefficients by using the obtained filter order information.