OGM A/V Sync Problems Late in Movie

[juicemansam]

OK, I've tried searching for the solution on the forums, but have found nothing to ease my pain. I have an audioless AVI (112 minutes long), and the proper AC3 audio file. I have converted the AC3, in Linux, with a52dec piped to ogg123. Every thing is fine at this point. I then used ogmtools's OGMMERGE to merge the XVID video and the Vorbis audio. The problem is that about the 1/3 - 1/2 of the movie, the audio has lost sync with the video. The following is the extra information that may help in a proper diagnosis:

1. OGMMERGE cmd-line: ogmmerge -o movie.ogm -A movie.avi -s 19 movie.ogg
2. AC3 file, demuxed via DVD2AVI, has a 19ms sync num.
3. Video is FILM according to DVD2AVI, and is set to 23.976fps, but encoded via MENCODER, no problem with video after forcing video fps.
4. Audio is 48kbps, 48kHz, stereo.
5. The source video is 6 VOBs re-encoded into 6 AVIs, concatenated via AVICAT.

I suspect that the sync loss is due to the nature of split VOBs and having a single audio file, in which the ending/starting frames/samples are misaligned because frame sets aren't closing as they normally would in a single file. Any words of advise, or comments about better ways to achieve the desired result of XVID video and Vorbis audio?

Thanks in advance.

[Koepi]

I experienced that once when I didn't use "force film" in dvd2avi but did IVTC. It seems film is real 24fps vs 23.976 telecined...

Regards
Koepi

[juicemansam]

I have had no luck with setting the frame rate to either 23.976 or 24. The audio is said to be 19ms delayed by DVD2AVI, but vStrip shows the audio stream in question starting at 00:00:00.217. What makes it slightly harder is that the audio is not the original language but the one of the DUBBED choices, so visually syncing is more challanging.

OK, to sum it all up, the audio is still out of sync after each try with different frame rates. Do you think that it might be due to the nature of Ogg/Vorbis audio not having constant point sizes? Or it has to do with the me encoding the VOBs seperate, then concatenating them, and the audio being encoded from a single file.

Another thing, I have encoded, let say vts_04_4.vob, into vts_04_4.avi and it's audio into vts_04_4.ogg. Just muxing them still results in out of sync audio, even muxing it with a 19ms delay. Any thoughts on that?

Thanks.

[Hiro2k]

What I try to do when I'm manualy syncing a file, is that I try to look for a part of the movie where you can noticbly time the audio to the video. Something like glass breaking, water splashing, even lip syncing works to some extent, but not in your case since it's a dub. If you can find the correct delay for one part, then hopefully you can use that same delay on each other part.

Why are you encoding each vob into and avi and ogg seperately? Seems like a waste of time, unless it's an episode or something like that.

[Human_USB]

Audio syncing is the most painful thing to do in a encoded item when things go bad.