Method for processing an audio signal, signal processing unit, binaural renderer, audio encoder and audio decoder

Patent metadata

Field	Value
Publication number	US-9955282-B2
Application number	US-201615002177-A
Country	US
Kind code	B2
Filing date	Jan 20, 2016
Priority date	Jul 22, 2013
Publication date	Apr 24, 2018
Grant date	Apr 24, 2018

Abstract

A method for processing an audio signal in accordance with a room impulse response is described. The audio signal is processed with an early part of the room impulse response separate from a late reverberation of the room impulse response, wherein the processing of the late reverberation has generating a scaled reverberated signal, the scaling being dependent on the audio signal. The processed early part of the audio signal and the scaled reverberated signal are combined.

First claim

The invention claimed is:

1. A method, comprising:
receiving an audio signal;
separately processing the audio signal with an early part and a late reverberation of a room impulse response, wherein processing the audio signal with the late reverberation of the room impulse response yields a reverberated signal and further comprises scaling the reverberated signal to obtain a scaled reverberated signal; and
combining the audio signal processed with the early part of the room impulse response and the scaled reverberated signal,
wherein the audio signal comprises a plurality of input channels,
wherein the scaling is dependent on a fixed correlation measure of the input channels of the audio signal or is dependent on a calculated correlation measure of the input channels of the audio signal, and
wherein scaling the reverberated signal comprises applying a gain factor to the audio signal processed with the late reverberation of the room impulse response, the gain factor being determined based on the fixed correlation measure or on the calculated correlation measure,
wherein the gain factor is determined as follows:
g=c u +ρ·( c c −c u )

where
ρ=fixed correlation measure of the input channels of the audio signal or calculated correlation measure of the input channels of the audio signal,
c u , c c =factors indicative of the condition of the plurality of input channels of the audio signal, with c u referring to totally uncorrelated channels, and c c relating to totally correlated channels.

2. The method of claim 1 , wherein scaling the reverberated signal is dependent on a condition of the plurality of input channels of the audio signal, wherein the condition of the plurality of input channels of the audio signal comprises one or more of the number of input channels, the number of active input channels, and an activity in the one or more of the plurality of input channels.

3. The method of claim 1 , wherein the fixed correlation measure of the input channels of the audio signal has a fixed value of 0.1 to 0.9.

4. The method of claim 1 , wherein:
c u and c c are determined as follows:

c
u

=

10

10
·
lo

⁢

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g
10

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(

K

i
⁢

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n

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20

=

K

i
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c
c

=

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20
·
lo

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g
10

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(

K

i
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20

=

K

i
⁢

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n

where
K in =number of active input channels of the audio signal.

5. The method of claim 1 , wherein a correlation analysis of the audio signal comprises determining for an audio frame of the audio signal a combined correlation measure, and wherein the combined correlation measure is calculated by combining correlation coefficients for a plurality of channel combinations of one audio frame, each audio frame comprising one or more time slots.

6. The method of claim 5 , wherein combining the correlation coefficients comprises averaging a plurality of correlation coefficients of the audio frame.

7. The method of claim 5 , wherein determining the combined correlation measure comprises:
calculating an overall mean value for every channel of the audio frame,
(ii) calculating a zero-mean audio frame by subtracting the overall mean value from every channel,
(iii) calculating for the plurality of channel combinations the correlation coefficient, and
(iv) calculating the combined correlation measure as the mean of the plurality of correlation coefficients.

8. The method of claim 5 , wherein a correlation coefficient for a channel combination is calculated as follows:

ρ
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m
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n

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=

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Assignees

• Fraunhofer Ges Forschung

Inventors

• Fueg Simone
• Plogsties Jan

Classifications

• H04S2400/13

  Aspects of volume control, not necessarily automatic, in stereophonic sound systems · CPC title

• H04S7/30

  Control circuits for electronic adaptation of the sound field · CPC title

• G10K15/12

  using electronic time-delay networks · CPC title

• H04S2420/01

  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 title

• H04S2400/03

  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 title