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
A multi-channel audio decoder for providing at least two output audio signals on the basis of an encoded representation is configured to perform a weighted combination of a downmix signal, a decorrelated signal and a residual signal, to obtain one of the output audio signals. The multi-channel audio decoder is configured to determine a weight describing a contribution of the decorrelated signal in the weighted combination in dependence on the residual signal. A multi-channel audio encoder for providing an encoded representation of a multi-channel audio signal is configured to obtain a downmix signal on the basis of the multi-channel audio signal, to provide parameters describing dependencies between the channels of the multi-channel audio signal, and to provide a residual signal. The multi-channel audio encoder is configured to vary an amount of residual signal included into the encoded representation in dependence on the multi-channel audio signal.
1. A multi-channel audio decoder for providing at least two output audio signals on the basis of an encoded representation, comprising:
a weighting combiner configured to perform a weighted combination of a downmix signal, a decorrelated signal and a residual signal, to acquire two output audio signals ch1 and ch2 of the at least two output audio signals, and
a weight determinator configured to determine a weight describing a contribution of the decorrelated signal in the weighted combination in dependence on the residual signal;
wherein the weighting combiner is configured to compute the two output audio signals ch1, ch2 of the at least two output audio signals according to
(
ch
1
ch
2
)
=
[
u
dmx
,
1
r
·
u
dec
,
1
max
{
u
dmx
,
1
·
0.5
}
u
dmx
,
2
r
·
u
dec
,
2
-
max
{
u
dmx
,
2
·
0.5
}
]
·
(
x
dmx
x
dec
x
res
)
wherein output audio signal ch1 represents one or more time domain samples or transform domain samples of a first output audio signal of the at least two output audio signals,
wherein output audio signal ch2 represents one or more time domain samples or transform domain samples of a second output audio signal of the at least two output audio signals,
wherein x dmx represents one or more time domain samples or transform domain samples of the downmix signal;
wherein x dec represents one or more time domain samples or transform domain samples of the decorrelated signal;
wherein x res represents one or more time domain samples or transform domain samples of the residual signal;
wherein u dmx,1 represents a downmix signal upmix parameter for the first output audio signal;
wherein u dmx,2 represents a downmix signal upmix parameter for the second output audio signal;
wherein u dec,1 represents a decorrelated signal upmix parameter for the first output audio signal;
wherein u dec,2 represents a decorrelated signal upmix parameter for the second output audio signal;
wherein max represents a maximum operator; and
wherein r represents a factor describing a weighting of the decorrelated signal in dependence on the residual signal.
2. A method for providing at least two output audio signals on the basis of an encoded representation, the method comprising:
performing a weighted combination of a downmix signal, a decorrelated signal and a residual signal, to acquire two output audio signal ch1 and ch2 of the at least two output audio signals,
wherein a weight describing a contribution of the decorrelated signal in the weighted combination is determined in dependence on the residual signal;
wherein the method comprises computing the two output audio signals ch1, ch2 of the at least two output audio signals according to
(
ch
1
ch
2
)
=
[
u
dmx
,
1
r
·
u
dec
,
1
max
{
u
dmx
,
1
·
0.5
}
u
dmx
,
2
r
·
u
dec
,
2
-
max
{
u
dmx
,
2
·
0.5
}
]
·
(
x
dmx
x
dec
x
res
)
wherein output audio signal ch1 represents one or more time domain samples or transform domain samples of a first output audio signal of the at least two output audio signals,
wherein output audio signal ch2 represents one or more time domain samples or transform domain samples of a second output audio signal of the at least two output audio signals,
wherein x dmx represents one or more time domain samples or transform domain samples of the downmix signal;
wherein x dec represents one or more time domain samples or transform domain samples of the decorrelated signal;
wherein x res represents one or more time domain samples or transform domain samples of the residual signal;
wherein u dmx,1 represents a downmix signal upmix parameter for the first output audio signal;
wherein u dmx,2 represents a downmix signal upmix parameter for the second output audio signal;
wherein u dec,1 represents a decorrelated signal upmix parameter for the first output audio signal;
wherein u dec,2 represents a decorrelated signal upmix parameter for the second output audio signal;
wherein max represents a maximum operator; and
wherein r represents a factor describing a weighting of the decorrelated signal in dependence on the residual signal.
3. 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 2 .