VIDEO_TS with audio out of sync

[Levina]

The audio on this DVD is slightly but annoyingly out of sync and I could use a bit of guidance as how to correct it. I have searched the forum and found tomlee59's directions:

First, rip the disc as a single VOB, then demux into elementary streams.

If the sync error is a fixed offset, then a simple remux operation will take care of the problem. VLC is very useful in determining the correct offset value (in the preferences menu you can specify a time offset in milliseconds). Verify the offset value at several points in the movie to confirm that it is truly a fixed value. Then, in ffmpegx, remux with an offset that is the algebraic inverse of the number you discovered with VLC. So, if you had to dial in a +500ms offset in VLC, you would type a value of -500 in ffmpegx's muxing tool. Mux, reauthor, and burn.

I have ripped my file as a single VOB and demuxed that into elementary streams. But now I'm stuck because I don't understand this 'offset value' stuff (I googled, but that only got me more confused).

For starters - and this should give you a pretty good idea of my utter stupidity here - how do I load my demuxed files into VLC? I can load either the m2v file or the ac3 file but obviously not both. But doesn't one need both the audio and video to set certain points of reference?

Also, where can I find/determine/set this offset value in VLC's Preferences exactly? And how exactly do I verify it?

In short, I'm lost and could do with a bit of help. Tomlee maybe?
Thanks in advance.

L.

[Herve]

But now I'm stuck because I don't understand this 'offset value' stuff

the 'offset value' means when begins audio compared to the begining of the video.
2 out-of synch:
audio begins too early (add a positive value)
audio begins too late (add a negative value)

and now the biggest question: "Which value?"
nobody know, make your own tries.
First, with a watch, try to find the value when playing the mpeg in VLC.
Report the value you collected. Begin the process (elementaries streams to mpeg) and check the result with VLC (no need to wait for the end of the process).
If the synch is not so good, stop the process and change the value
...and again and again...
and your mpeg won't be out-of-synch

bye

[Levina]

Right. I understand and will try it out (and report back in due time). For now, thank you very much, Herve.

[Levina]

Oh my, I thought I would need tons of time to get this right, but I only needed a few attempts. So the procedure worked beautifully and I now have a new mpeg file with perfectly synchronized audio that I will convert back to a DVD later today. Thanks again Herve (and of course Tomlee!).

[ffooky]

You can get a more accurate idea of the offset required during playback with VLC. Hit G (until synched) while the unfixed MPEG is playing to speed up the audio or F to slow it down. VLC will show the offset but, as Tomlee said, you need to enter a - value in ffmpegX for a + value in VLC....but he said it much more cleverly than I can.

[Levina]

It's not for fine tuning, as each hit shifts the audio with 50 ms (I needed a shift of exactly +220 and not 200 or 250), but it sure gets you in the right range just about immediately, so it's really very handy. Thanks ffooky.

[tomlee59]

And thank you guys for all the thanks, but you did all the work!

I'm happy that the sync error was a fixed time offset. The ones that drift are annoying, and the ones that have a combination of offset, jumps and drift can drive you mad.

[Levina]

Hi Tomlee! See, even when you're not here, you're greatly appreciated! And I'm happy as can be that your solution worked really very well and even happier that, like you say, the sync error was a fixed one. I have already authored a new DVD that now has perfectly synced audio. So I can't thank you - and Herve - enough really.

[tomlee59]

You are much too kind, Levina. I'm glad that everything is working well -- may it always be so!

Tot ziens!