Multi-Channel Decorrelator, Multi-Channel Audio Decoder, Multi-Channel Audio Encoder, Methods and Computer Program using a Premix of Decorrelator Input Signals

A multi-channel decorrelator for providing a plurality of decorrelated signals on the basis of a plurality of decorrelator input signals,

• wherein the multi-channel decorrelator is configured to premix a first set of N decorrelator input signals into a second set of K decorrelator input signals, wherein K<N;
• wherein 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;
• and
• wherein the multi-channel decorrelator is configured to upmix the first set of K′ decorrelator output signals into a second set of N′ decorrelator output signals, wherein N′>K′;
• wherein the multi-channel decorrelator is configured to premix the first set {circumflex over (Z)} of N decorrelator input signals into the second set {circumflex over (Z)}mix of K decorrelator input signals using a premixing matrix Mpre according to
• {circumflex over (Z)}mix=Mpre{circumflex over (Z)}
• wherein the multi-channel decorrelator is configured to acquire the first set {circumflex over (Z)}mixdec of K′ decorrelator output signals on the basis of the second set {circumflex over (Z)}mix of K decorrelator input signals, and
• wherein the multi-channel decorrelator is configured to upmix the first set {circumflex over (Z)}mixdec of K′ decorrelator output signals into the second set W of N′ decorrelator output signals using a postmixing matrix Mpost according to
• W=Mpost{circumflex over (Z)}mixdec;
• wherein the multi-channel decorrelator is configured to select the premixing matrix Mpre in dependence on correlation characteristics or covariance characteristics of the channel signals of the first set {circumflex over (Z)} of N decorrelator input signals.