[mythtv-users] Audio upmixing in 0.22

[ken]

I have just noticed the ability in 0.22 to upmix stereo to 5.1 ac3 audio.
The question I would like to ask is what method does mythtv use to upmix 
to 5.1 ie: does it use dolby pro logic or similar and are there any 
advantages to letting mythtv upmix the audio rather than feeding stereo 
to a AV amplifier and letting the amplifiers dolby pro logic proccesing 
etc decode to 5.1.

Thanks
Ken