Take one channel of stereo, make mono, mux again

[Randi]

Hi,
is it possible to take lots of video files (batch mode) in different containers (such as avi, wmv and m2p), take the stereo audio track (which is mp3, divxaudio or wma), extract one channel, and mux it again into for example matroska (or avi), without reencoding the audio track? I know there exists a playback solution (TFM Filter) to do this, but i really prefer "clean" files, for when playing them I dont have change anything in the player all the time. Reason for this is, that left side is one language, right side another, and I obviously dont want to listen to both at the same time :-)
Tried the search, but didnt find anything.

Thanks a lot in advance!
Randi

[pacohaas]

seems to be a pretty tough thing to do, with mp3's at least. I have a mp3 from an online artist's webpage demo section that is just silent in the right side and I've tried tons of stuff to just extract the left audio (without reencoding) as a mono mp3. I think the problem exists because of the joint stereo nature of most mp3's, but maybe someone here knows a solution. I believe there is a thread here somewhere about extracting channels of mp2 files, but that's not much help here.

[Randi]

Thanks for your answer!
Actually come to think about this, I could reencode to something lossless to avoid further quality loss (btw i have never seen a movie file with flac, and google only revealed problems concerning muxing flac. Is it possible now?). I didnt know that 2 completely different audio tracks on either side could be joint stereo, would it be easier if it was not "joint"? (And how do I check it? :-))

cheers
Randi

[pacohaas]

yes, i'm sure if it was dual mono it would be the easiest to split. encspot and other programs can show you what channel mode is used.