[MPlayer-users] down-mix to stereo

[Zongyao QU]

I am developing an program 
which serves as a front-end of mplayer, in Mac OSX.

http://code.google.com/p/mplayerx/

I found, mplayer will not down-mix the multi-channels, 
such as AC3, DTS, FLAC, COOK to stereo, AUTOMATICALLY.

So I decide to do it in my app.

I have read some docs and found each of decoders has
different definition of channel map.

My question is that
does mplayer re-map the channels to its own channel
definition? 
such as [FL, FR, SL, SR, CF, LFE]
(this could be found at 
http://www.mplayerhq.hu/DOCS/HTML/en/advaudio-channels.html)

so that I could use one set of parameters for the PAN filter.

is there any docs explaining the details?