Multi-channel decorrelator, multi-channel audio decoder, multi-channel audio encoder, methods and computer program using a premix of decorrelator input signals

Patent metadata

Field	Value
Publication number	US-10448185-B2
Application number	US-201615138176-A
Country	US
Kind code	B2
Filing date	Apr 25, 2016
Priority date	Jul 22, 2013
Publication date	Oct 15, 2019
Grant date	Oct 15, 2019

Abstract

A multi-channel decorrelator for providing a plurality of decorrelated signals on the basis of a plurality of decorrelator input signals is configured to premix a first set of N decorrelator input signals into a second set of K decorrelator input signals, wherein K<N. The multi-channel decorrelator is configured to provide a first set of K′ decorrelator output signals on the basis of the second set of K decorrelator input signals. The multi-channel decorrelator is further configured to upmix the first set of K′ decorrelator output signals into a second set of N′ decorrelator output signals, wherein N′>K′. The multi-channel decorrelator can be used in a multi-channel audio decoder. A multi-channel audio encoder provides complexity control information for the multi-channel decorrelator.

First claim

The invention claimed is:

1. A multi-channel decorrelator apparatus for providing a plurality of decorrelated audio signals on the basis of a plurality of decorrelator input audio signals, comprising;
a premixer configured to premix, using a premixing matrix, a first set of N decorrelator input audio signals into a second set of K decorrelator input audio signals, wherein K<N;
a multi-channel decorrelator configured to decorrelate the second set of K decorrelator input audio signals and to provide a first set of K′ decorrelator output audio signals on the basis of the second set of K decorrelator input audio signals, wherein the decorrelating performed by the multi-channel decorrelator is performed on the K decorrelator input audio signals of the second set of K decorrelator input audio signals; and
an upmixer configured to upmix the first set of K′ decorrelator output audio signals into a second set of N′ decorrelator output audio signals, to thereby obtain N′ decorrelated audio signals, wherein N′>K′;
wherein the multi-channel decorrelator is further configured to receive a complexity information describing a number K of decorrelator input audio signals of the second set of decorrelator input audio signals, and wherein the multi-channel decorrelator is configured to select the premixing matrix in dependence on the complexity information, such that, for a given N and for a given N′, three or more different numbers K of decorrelator input audio signals of the second set of K decorrelator input audio signals can be chosen by the multi-channel decorrelator in dependence on the complexity information; and
wherein K=K′;
wherein the multi-channel decorrelator is implemented using a hardware apparatus, or using a computer, or using a combination of a hardware apparatus and a computer.

2. The multi-channel decorrelator apparatus according to claim 1 , wherein N=N′.

3. The multi-channel decorrelator apparatus according to claim 1 , wherein N>=3 and N′>=3.

4. The multi-channel decorrelator apparatus according to claim 1 , wherein the premixer is configured to combine channel signals of the first set of N decorrelator input audio signals which are associated with spatially adjacent positions of an audio scene when performing the premixing.

5. The multi-channel decorrelator apparatus according to claim 4 , wherein the premixer is configured to combine channel signals of the first set of N decorrelator input audio signals which are associated with vertically spatially adjacent positions of the audio scene when performing the premixing.

6. The multi-channel decorrelator apparatus according to claim 1 , wherein the premixer is configured to combine channel signals of the first set of N decorrelator input audio signals which are associated with a horizontal pair of spatial positions comprising a left side position and a right side position.

7. The multi-channel decorrelator apparatus according to claim 1 , wherein the premixer is configured to combine at least four channel signals of the first set of N decorrelator input audio signals, wherein at least two of said at least four channel signals are associated with spatial positions on a left side of an audio scene, and wherein at least two of said at least four channel signals are associated with spatial positions on a right side of the audio scene.

8. The multi-channel decorrelator apparatus according claim 7 , wherein the at least two left-sided channel signals to be combined are associated with spatial positions which are symmetrical, with respect to a center plane of the audio scene, to the spatial positions associated with the at least two right-sided channel signals to be combined.

9. The multi-channel decorrelator apparatus according to claim 1 , wherein the multi-channel decorrelator is configured to step-wisely increase a number of decorrelator input audio signals of the first set of decorrelator input audio signals which are combined to acquire the decorrelator input audio signals of the second set of decorrelator input audio signals with a decreasing value of the complexity information.

10. The multi-channel decorrelator apparatus according to claim 1 , wherein the premixer is configured to combine only channel signals of the first set of N decorrelator input audio signals which are associated with vertically spatially adjacent positions of an audio scene when performing the premixing for a first value of the complexity information, and
wherein the premixer is configured to combine at least two channel signals of the first set of N decorrelator input audio signals which are associated with vertically spatially adjacent positions on a left side of the audio scene and at least two channel signals of the first set of N decorrelator input audio signals which are associated with vertically spatially adjacent positions on a right side of the audio scene in order to acquire a given signal of the second set of decorrelator input audio signals when performing the premixing for a second value of the complexity information.

11. The multi-channel decorrelator apparatus according to claim 1 , wherein the premixer is configured to combine at least four channel signals of the first set of N decorrelator input audio signals, wherein at least two of said at least four channel signals are associated with spatial positions on a left side of an audio scene, and wherein at least two of said at least four channel signals are associated with spatial positions on a right side of an audio scene, in order to acquire a given signal of the second set of decorrelator input audio signals when performing the premixing for a second value of the complexity information.

12. The multi-channel decorrelator apparatus according to claim 1 , wherein the premixer is configured to combine at least two channel signals of the first set of N decorrelator input audio signals which are associated with vertically spatially adjacent positions on a left side of the audio scene, in order to acquire a first decorrelator input audio signal of the second set of decorrelator input audio signals, and to combine at least two channel signals of the first set of N decorrelator input audio signals which are associated with vertically spatially adjacent positions on a right side of the audio scene, in order to acquire a second decorrelator input audio signal of the second set of decorrelator input audio signals for a first value of the complexity information, and
wherein the premixer is configured to combine the at least two channel signals of the first set of N decorrelator input audio signals which are associated with vertically spatially adjacent positions of the left side of the audio scene and the at least two channel signals of the first set of N decorrelator input audio signals which are associated with vertically spatially adjacent positions on the right side of the audio scene, in order to acquire a decorrelator input audio signal of the second set of decorrelator input audio signals for a second value of the complexity information,
wherein a number of decorrelator input audio signals of the second set of decorrelator input audio signals is larger for the first value of the complexity information than for the second value of the complexity information.

13. A multi-channel audio decoder for providing at least two output audio signals on the basis of an encoded representation,
wherein the multi-channel audio decoder comprises the multi-channel decorrelator apparatus according to claim 1 .

14. The multi-channel audio decoder according to claim 13 ,
wherein the multi-channel audio decoder is configured to render a plurality of decoded audio signals, w

Assignees

• Fraunhofer Ges Forschung

Inventors

• Disch Sascha
• Fuchs Harald
• Hellmuth Oliver
• Herre Juergen
• Murtaza Adrian
• Paulus Jouni
• Ridderbusch Falko
• Terentiv Leon

Classifications

• H04S2420/03

  Application of parametric coding in stereophonic audio systems · CPC title

• G10L19/032

  Quantisation or dequantisation of spectral components · CPC title

• G10L19/22

  Mode decision, i.e. based on audio signal content versus external parameters · CPC title

• H04S3/008

  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 title

• G10L19/008 Primary

  Multichannel audio signal coding or decoding using interchannel correlation to reduce redundancy, e.g. joint-stereo, intensity-coding or matrixing · CPC title