Adaptive channel-reduction processing for encoding a multi-channel audio signal

A device comprising:

• a downmix processing module, which applies downmix processing to a multi-channel digital audio signal;
• a coder, which applies a parametric coding to the multi-channel digital audio signal, including coding a mono signal derived from the downmix processing module;
• and
• a quantization module, which codes multi-channel signal spatialization information,
• wherein the downmix processing module comprises:
• an extraction module, which obtains at least one indicator characterizing the channels of the multi-channel digital audio signal, for each spectral unit of the multi-channel signal;
• a selection module, which selects, for each spectral unit of the multi-channel signal, from a set of downmix processing modes, a downmix processing mode as a function of the value of the at least one indicator characterizing the channels of the multi-channel audio signal,
• wherein the downmix processing module is implemented at least in part by a processor and instructions stored in a non-transitory computer-readable medium and executable by the processor.

A method comprising the following acts performed by a processing device:

• processing a decoded multi-channel audio signal comprising a downmix processing to obtain a mono signal to be reproduced, wherein the downmix processing comprises the following acts, implemented for each spectral unit of the multi-channel signal:
• extraction of at least one indicator characterizing the channels of the multi-channel digital audio signal;
• and
• selection, from a set of downmix processing modes, of a downmix processing mode as a function of the value of the at least one indicator characterizing the channels of the multi-channel audio signal.

A device comprising:

• a downmix processing module, which processes a decoded multi-channel audio signal to obtain a mono signal to be reproduced, wherein the downmix processing module comprises:
• an extraction module configured to obtain at least one indicator characterizing the channels of the multi-channel digital audio signal, for each spectral unit of the multi-channel signal;
• and
• a selection module, configured to select, for each spectral unit of the multi-channel signal, from a set of downmix processing modes, a downmix processing mode as a function of the value of the at least one indicator characterizing the channels of the multi-channel audio signal,
• wherein the downmix processing module is implemented at least in part by a processor and instructions stored in a non-transitory computer-readable medium and executable by the processor.

A non-transitory processor-readable medium comprising instructions stored thereon, which when executed by a processor configure the processor to perform acts comprising:

• downmix processing applied to a multi-channel digital audio signal;
• and
• parametric coding of the multi-channel digital audio signal, comprising coding a mono signal derived from the downmix processing applied to the multi-channel signal and coding multi-channel signal spatialization information,
• wherein the downmix processing comprises the following acts, implemented for each spectral unit of the multi-channel signal:
• extraction of at least one indicator characterizing the channels of the multi-channel digital audio signal;
• and
• selection, from a set of downmix processing modes, of a downmix processing mode as a function of the value of the at least one indicator characterizing the channels of the multi-channel audio signal.