audio/video out of sync

[geohei]

I have a DivX here which is 1:48:21 long. However when using TMPGEnc to split it into 3 SVCDs, the audio/video gets out of sync.

I used VirtualDub to extract the audio part. It's only 1:48:08 long (13 seconds shorter).

How can I make audio/video sync again?

TIA

[bugster]

You dont actually say in what way the audio is out of sync, is it before or after the video, is the amount out of sync constant or variable, if variable is it a gradual loss of sync or apparently random? This information is needed before anyone can give you a sensible answer. In the meantime why dont you read some of the guides and howtos or search the forum for information (the search button is at the top of the page). Many people have sync problems and there is a VERY good chance your problem has already been solved by one of the many hardworking and helpful people here at vcdhelp.

[geohei]

1. The audio/video are sync at the beginning. They gradually move away from each other. I believe the split is linear (proportional to time).

2. Believe me (search the newsgroups for my name) ... I checked groups.google, the TMPGEnc BBS, this BBS (VirtualDub), some Knowledge bases and also Howtos. This problem doen't seem to occur on a regular basis, hence not very many people do have answers to this. To make it short ... I looked this issue up for hours without any result before posting this article.

Ciao.

[fantomlord]

1. The audio/video are sync at the beginning. They gradually move away from each other. I believe the split is linear (proportional to time).

2. Believe me (search the newsgroups for my name) ... I checked groups.google, the TMPGEnc BBS, this BBS (VirtualDub), some Knowledge bases and also Howtos. This problem doen't seem to occur on a regular basis, hence not very many people do have answers to this. To make it short ... I looked this issue up for hours without any result before posting this article.

Ciao.

did you search the forum here? gradual sync issues have been covered
search-->gradual sync

[bugster]

Yes, fantomlord is right, this issue has been covered many times and you should be able to find the answer on the forums. Just a hint though, have a look at the fps of the source compared to the fps of the target TmpGenc SVCD template you are using. Good chance they are different.

[geohei]

bugster: the sopurce fps is 25.006, the target (SVCD PAL) was 25.000 this makes exactly 1 second for the entire duration of the mivie. This cannot be an indication where the problem comes from since the sync mismatches already by 2 seconds after 10 minutes.

fantomload: the problems discussed here rarely deal with DivX avi files which have problems.

Anyway ... I selected direct stream for auto and video in VirtualDub, changed the frame rate in the video menu to match the audio (25.007), and the result was the same. OUT-OF-SYNC ... ;(

BTW ... what does the "Preload Skew" in VirtualDub's "File Information" audio part mean?

Thanks.

[bugster]

Ok, so the frame rate doesnt explain the problem.

Hmm, a bit stuck here. Is there a chance that the audio is encoded with a variable bit rate, this has been know to cause problems for both virtualdub and TmpGenc. Try extratcting the audio with BeSweet instead (I think thats the right tool) and encode with that - other than that not really sure.

I think preload skew is an offset between the audio and video in terms of the interleaving of them in the file and the actual timing required to get sync, not 100% sure tho so maybe someone else can answer this one.

[fantomlord]

bugster: the sopurce fps is 25.006, the target (SVCD PAL) was 25.000 this makes exactly 1 second for the entire duration of the mivie. This cannot be an indication where the problem comes from since the sync mismatches already by 2 seconds after 10 minutes.

fantomload: the problems discussed here rarely deal with DivX avi files which have problems.

Anyway ... I selected direct stream for auto and video in VirtualDub, changed the frame rate in the video menu to match the audio (25.007), and the result was the same. OUT-OF-SYNC ... ;(

BTW ... what does the "Preload Skew" in VirtualDub's "File Information" audio part mean?

Thanks.

just so you know, if you do a search for "divx audio sync" you will come up with over 100 posts. if you had done a search and gone through the results, I would just about bet a kidney that you would have found something that would either solve your problem, or started you on your way to solving the problem.

[geohei]

I realized that, calling this problem "out-of-sync" might by false.

I checked the source DivX avi file now in detail. There are problems with this avi file! To my big surprise, I realized that this is by far not the only file which is somewhat corrupt. I downloaded 2 versions of a certain movie, and both were corrupt! I'm quite

Movie version 1 (that's the one I have been talking about since the beginning of this thread):

Issue 1 - I get sometimes "jumps" in the movie. I believe frames are missing here. Can I do something about that? The VirtualDub "scan video stream or errors" reports NO errors.

Issue 2 - Further down the movie, I get a "replay". The movie jumps back a few frames (# 0.5 second). After that, the movie continues double speed for # 2 seconds. Did this happen during encoding? Can I do something about it.
Movie version 2:

Issue 1 - The first few seconds of the movie have stuck frames, replays, audio out of sync, ... well, virtually everything what can possibly go wrong. But after # 2 minutes, everyting is perfect till the end.

I wonder how all this is possible. Is it due to the DivX 5.0.1 codec I use? Was the movie encoded using a different codec? Does this generate this kind of problems? Do I have to trash these two files (not possible to recover them)?

I searched through this forum, but the point is that I don't really know how to formulate this query. This issues require a big deal of experience.
Many thanks!