Weird Audio Synch problem

[EliCat]

For the last couple of months I've been browsing these forums and learned enough to let me edit, cut and join mpeg's and avi without too many probs, but on occassion I do seem to run into a problem that I've not been able to find a solution to yet.

I'll have an avi file that seems to play perfectly, no audio out of synch or anything, but then if I try to either fast forward or jump forward through the movie the sound goes completely out of synch (runs several seconds quicker than the video).

That means that I can never watch part of a movie, shut down my player and watch the rest some other time without it being completely screwed up.


I did some testing today on a recent avi I have that works that way, and it doesn't seem to make a difference if I use DivX Player, WMP, PowerDVD or even VirtualDub to watch the movie.
The movie plays fine ... UNTIL I want to skp to some other portion of it.




Does anyone know what can be causing this and how I can fix it?

[Tommyknocker]

Could you check a few things? First, check to see if both video and files are the same length (use VDub and Gold Wave). Then check to see if the video goes more and more out of synch the further into the movie you go.

[EliCat]

Virtual Dub says:

Video: 0:57:45.768 hrs & 83096 frames
Audio: 83086 frames


Goldwave gives 0:57:11.712 hrs for the audio



That would indicate them being out of synch, but like I mentioned, when played from start to finish there is no noticable out-of-synch behaviour (at least not for the casual observer).

It's just that when I skip to a portion somewhere further in the file that it goes out of synch and there's no good way of telling if it goes out of synch even more as the movie goes on since it's already off by more than a few seconds.


I can give you some extra info on the movie though.
It conists of 2 avi files, both when opened in VirtualDub give one of those "Improper VBR audio encoding" errors.
So I split the video & audio, then stuck them back together again later.

Weird thing is the 1st file now plays back beautifully, even no out of synch stuff when skipping through the file, while the 2nd one keeps messing up.

I know both files have a few bad video frames, but since both have them that can't explain why one file works perfect and the other crap.

[Tommyknocker]

Why will you not remove the bad frames to be sure?

[EliCat]

Because I don't know which frames are bad.

VirtualDub can't find any undecodable frames and the "bad" frames I'm referring to are ones that have some of those blurry/scrambled spots as if your tv cable connection is lousy.

I know these type of frames can sometimes cause out-of-synch sound, but these don't seem to do so in normal playback mode, so why ditch em .. it would only ruin the movie.


And like I said in my first post, I've come across this same problem several times before, not just with this movie file, so I'd like to find a general way to fix this problem, not one specifically tailored to this file ..... if I can figure out what might be causing this weird behaviour then I might be able to come up with a method that fixes it.



I've already tried to the Virtual Dub option to match the length of the video to that of the audio, but that doesn't help either.