Multi-channel audio decoder, multi-channel audio encoder, methods and computer program using a residual-signal-based adjustment of a contribution of a decorrelated signal

1. A multi-channel audio encoder for providing an encoded representation of a multi-channel audio signal, comprising:

a processor configured to:

acquire a downmix signal on the basis of the multi-channel audio signal;

provide parameters describing dependencies between channels of the multi-channel audio signal; and

provide a residual signal; and

a residual signal processor configured to vary an amount of residual signal included into the encoded representation in dependence on the multi-channel audio signal, the residual signal processor configured to selectively include the residual signal into the encoded representation for frequency bands for which the multi-channel audio signal is tonal, and to omit the inclusion of the residual signal into the encoded representation for frequency bands in which the multi-channel audio signal is non-tonal.

2. The multi-channel audio encoder according to claim 1 , wherein the residual signal processor is configured to vary a bandwidth of the residual signal in dependence on the multi-channel audio signal.

3. The multi-channel audio encoder according to claim 1 ,

wherein the residual signal processor is configured to select frequency bands for which the residual signal is included into the encoded representation in dependence on the multi-channel audio signal.

4. The multi-channel audio encoder according to claim 1 ,

wherein the residual signal processor is configured to selectively include the residual signal into the encoded representation for time portions and/or for frequency bands in which a formation of the downmix signal results in a cancellation of signal components of the multi-channel audio signal.

5. The multi-channel audio encoder according to claim 4 ,

wherein the residual signal processor is configured to detect a cancellation of signal components of the multi-channel audio signal in the downmix signal, and wherein the residual signal processor is configured to activate a provision of the residual signal in response to the result of the detection.

6. The multi-channel audio encoder according to claim 1 ,

wherein the residual signal processor is configured to compute the residual signal using a linear combination of at least two channel signals of the multi-channel audio signal and in dependence on upmix coefficients to be used at a side of a multi-channel decoder.

7. The multi-channel audio encoder according to claim 6 , wherein the multi-channel audio encoder is configured to determine and encode the upmix coefficients,

or to derive the upmix coefficients from the parameters describing dependencies between the channels of the multi-channel audio signal.

8. The multi-channel audio encoder according to claim 1 ,

wherein the residual signal processor is configured to time-variantly determine the amount of residual signal included into the encoded representation using a psychoacoustic model.

9. The multi-channel audio encoder according to claim 1 ,

wherein the residual signal processor is configured to time-variantly determine the amount of residual signal included into the encoded representation in dependence on a currently available bitrate.

10. A method for providing an encoded representation of a multi-channel audio signal, comprising:

acquiring a downmix signal on the basis of the multi-channel audio signal,

providing parameters describing dependencies between channels of the multi-channel audio signal;

providing a residual signal; and

varying an amount of residual signal included into the encoded representation in dependence on the multi-channel audio signal;

wherein the residual signal is selectively included into the encoded representation for frequency bands for which the multi-channel audio signal is tonal, and omitted from the encoded representation for frequency bands in which the multi-channel audio signal is non-tonal.

11. A non-transitory computer-readable storage medium storing instructions that, when executed by a processor, cause the processor to perform the method according to claim 10 .

12. A multi-channel audio encoder for providing an encoded representation of a multi-channel audio signal, comprising:

a processor configured to:

acquire a downmix signal on the basis of the multi-channel audio signal;

provide parameters describing dependencies between the channels of the multi-channel audio signal; and

provide a residual signal; and

a residual signal processor configured to vary an amount of residual signal included into the encoded representation in dependence on the multi-channel audio signal, wherein the residual signal processor is configured to:

detect a cancellation of signal components of the multi-channel audio signal in the downmix signal; and

selectively include the residual signal into the encoded representation for time portions and/or for frequency bands in which a formation of the downmix signal results in the cancellation of signal components of the multi-channel audio signal.

13. A multi-channel audio encoder for providing an encoded representation of a multi-channel audio signal, comprising:

a processor configured to:

acquire a downmix signal on the basis of the multi-channel audio signal;

provide parameters describing dependencies between the channels of the multi-channel audio signal; and

provide a residual signal; and

a residual signal processor configured to vary an amount of residual signal included into the encoded representation in dependence on the multi-channel audio signal, the residual signal processor configured to:

time-variantly determine the amount of residual signal included into the encoded representation in dependence on a currently available bitrate; and

decide for which frequency bands and for how many frequency bands the residual signal is included in the encoded representation based on the multi-channel audio signal.

14. A method for providing an encoded representation of a multi-channel audio signal, comprising:

acquiring a downmix signal on the basis of the multi-channel audio signal,

providing parameters describing dependencies between the channels of the multi-channel audio signal; and

providing a residual signal;

varying an amount of residual signal included into the encoded representation in dependence on the multi-channel audio signal;

detecting a cancellation of signal components of the multi-channel audio signal in the downmix signal; and

selectively including the residual signal into the encoded representation for time portions and/or for frequency bands in which a formation of the downmix signal results in the cancellation of signal components of the multi-channel audio signal.

15. A non-transitory computer-readable storage medium storing instructions that, when executed by a processor, cause the processor to perform the method according to claim 14 .

16. A method for providing an encoded representation of a multi-channel audio signal, comprising:

acquiring a downmix signal on the basis of the multi-channel audio signal,

providing parameters describing dependencies between the channels of the multi-channel audio signal; and

providing a residual signal;

wherein an amount of residual signal included into the encoded representation is varied in dependence on the multi-channel audio signal;

wherein the method comprises time-variantly determining the amount of residual signal included into the encoded representation in dependence on a currently available bitrate; and

wherein it is decided for which frequency bands and/or for how many frequency bands the residual signal is included in the encoded representation.

17. A non-transitory computer-readable storage medium storing instructions that, when executed by a processor, cause the processor to perform the method according to claim 16 .