[MEncoder-users] 5.1 sound

[scostas]

Hi all:

I'm creating video DVDs with mencoder and I want to ensure that they 
have 5.1 sound.

If the original video already has 5.1 sound, but is NOT coded with 
AC3, is enough to add "-channels 6" to ensure that the final MPEG 
video has 5.1 sound? (of course, using "-oac lavc" and setting ac3 as 
output audio codec, with the right bitrate).

If the original video has 5.1 sound, is coded with AC3, and I use 
"-oac copy", must I add the "-channels 6", or can I avoid setting it?

Finally, if I have a video with multiple audio languages, and they are 
NOT coded in AC3, how can I recompress all the languages in AC3 in the 
final MPEG-2 video file? (with and without 5.1 sound). And when the 
original video has them already coded in AC3?

Thanks.