Hello all. I am currently trying to merge two files (video.m2v and audio.ac3) into one mpg file in dvd format. Whenever I enter this command :

mplex -f 8 -o newvideo%d.mpg video.m2v audio.ac3

The resulting mpg file (newvideo1.mpg) has the audio and video about 10 or 15 seconds off. How do I figure out the exact amount and then correct this?

By looking at the mplex man page, there's a sync offset option -O (capital o). You can specify the offset by placing something like -O 10s for a 10 second offset. I think that the offset means delaying the video by a certain amount with regards to the video. I've never had to use it in mplex, so I'm not sure about that. However, I had bad sync issues with Avidemux (with MPEG-TS files) and correcting them is done pretty much by trial and error. You have to match up lip movement with spoken words or sounds with actions as close as possible. Indeed, its a tedious and sometimes frustrating process, especially when the sync changes for EVERY file you work with.

A much better solution would be to look at the program(s) that generated the separate A/V streams and check if it has an option for better sync, or perhaps look for a better program (in my case).

Which better program did you find? I use transcode personally. I still have problems.

I used Project X, but I only use that to demultiplex an MPEG-TS file (from digital TV) into separate audio and video files. ProjectX irons out the packet stream errors and resynchronises the audio.

I then use mplex to recombine them. The resulting file plays in perfect sync.

In essence, I solved the problem further upstream. Your situation might be different.

You could also try using mencoder and ffmpeg. They weren't very successful for me, but I could've done something wrong.