Multi-channel audio signal processing

A signal processing device for processing a multi-channel audio signal comprising an input sum signal representing a sum of a first audio signal and a second audio signal and an input difference signal representing a difference between the first and second audio signals, the device comprising:

• a decorrelation module configured to receive the sum signal and provide a decorrelated sum signal;
• a parameter estimation module configured to calculate a first gain from a cross-correlation of the sum and difference signals and a power of the difference signal and a second gain from a cross-correlation of the sum and difference signals and a power of the sum and difference signals;
• a first amplifier configured to receive the sum signal and amplify the sum signal according to the first gain;
• a second amplifier configured to receive the decorrelated sum signal and amplify the decorrelated sum signal according to the second gain;
• a summing module configured to sum output signals from the first and second amplifiers to provide an output difference signal;
• and
• an output stage configured to calculate an output stereo signal from a combination of the sum signal and the output difference signal from the summing module.