Originally Posted by VirusKiller
This assumes that there are enough available MIPS to demux prior to upsampling (which is the first DSP operation for incoming 1x sampled PCM).
Demuxing doesn't take any CPU power. It is just reading data from another spot.

Originally Posted by VirusKiller
It's a nice idea, but I can't really see it happening as it would require changes to both HD621 and G6x code. M would also need to find a means of flagging that the rear channels were muxed (though I think that would probably be the easiest bit). If it does happen, great.
Technically it is very, very, very simple to do, it is more a question of wanting to do this. Flagging can be easily done using the sidechannel of the SPDIF.