audio/video out of sync

[igs_77]

i have a few avi files which seems to have sync problems with the audio and video. this happens when viewed from mediaplayer, with the latest gordionknot codecs installed. some files play ok when i use powerdvd, for some reason, but most of them still have the prob no matter which player i use (incl zoomplayer and others).

Is there any way i can fix this up... like separating the audio and video and merging it myself?

thx...

[echooff]

Have you explored virtualdub or virtualdubmod? Is the audio uniformly out of sync throughout the avi file? :confused: If it is the interleave function can fix that. If the sync problem is not uniform, It requires more drastic action. Please give as much info as you can when requesting help. This will usually result in a better response taylored more to your needs.:D :D :D

[igs_77]

thanks echooff i will look into those programs, im sure they installed as part of Gordionknot Rippack. The audio is uniformly out of sync in all the ones i tested, so your suggestion hopefully works. Ive never played around with those settings, is there anything specific that i should bear in mind or watch out for when doing so?:D

[echooff]

It is mostly trial and error to find the right sync. I usually start at 500 and go from there. Good luck. Nothing special to watch out for. Since it is uniformly out of sync this will work.

[igs_77]

Ok it seems that I was wrong. Almost always, at the start of the video file, the sync is fine. About 5-7 minutes into the video the sync problem appears, slight difference at first, but it gets progressively worse, up to 2 seconds difference between the audio and video towards the end. :confused: :confused:

[Wilbert]

Could you demux the video and audio to see if they have equal length?

[echooff]

Try cool edit or some other audio app. Its a little more effort, but you have to adjust the ending time.

[igs_77]

i know a bit more about my problem now. the avi files im working with wasnt originally 1 continuous stream, but is the combination of a few individual avi files merged together to form the final product. obviously that explains why the syncing problems happen at irregular intervals. what helps me is that i can then identify at what time the changeover from 1 to the next is, and thats where the audio goes out of sync.

Now, im still a bit in the dark as to how to do what i'm gonna propose... split the video and audio back into two separate files, i mean 1 audio, 1 video (i have no idea of how to do this). use an avi splitting tool such as virtualdub to split the video and the audio back into the original portions that now make up the combined file.

Add the video and audio portions back together again (how to do this?), after ive edited the audio files to insert an empty space as required to sync with the video (i presume cooledit etc will do for this).

Please comment on whether this seems like a feasible solution, and can you please help with the areas where ive indicated that i dont know how to execute the action.

Your help is much appreciated. Thanks.

[Atamido]

If you are really dedicated, seperate the file back into seperate files that contain both A/V. Seperate where the file was originally joined so that you can work on each segment individually. Import each segment individually into MKV, adjusting the audio offset so that each segment is in synch. Then append the files back together. MKV is fine with having gaps in the audio or video, so the file will remain in synch.

[igs_77]

Sorry, what is MKV?:confused: :confused:

[Wilbert]

Matroska:

http://forum.doom9.org/showthread.php?s=&threadid=54306

[igs_77]

OK im using nandub (im unfamiliar with matroska; dont have the program) now to split the avi files at the points where the sync problem occurs. after the whole exercise i now sit with +- 17 avi's instead of the original file. I then use nandub's audio interleave function on each to delay the audio start by the appropriate time required to sync the a/v.

Problem is now that when i cut the bigger avi into smaller chunks with nandub (using HOME and END to mark the beginning and end of the portion i want to split), i end up with the starting point of each new file containing the last 4 seconds of a/v from the previous portion. I keep the marker at the position where I pressed END to end the last chunk, and immediately after saving it, press HOME to mark the start of the new one, still it includes 4 seconds worth of the previous one.:confused: :confused:

Other than that i think ive found a solution for my original problem, albeit a very frustrating one as the whole splitting and interleaving takes a lot of trial n error to sort out.