Audio out of sync

[toji53]

I used VirtualDubMod to add a black broader around an AVI file. However, the audio is now a good second behind the video. I’ve tried extracting the audio and adding them separately onto a DVD authoring program, but they are still out of sync. Any suggestions?

[abc-123]

When you added the black border you had to re-encode the video. Check your framerate. If your original file was a weird framerate (30 fps for instance) and you set it to the proper 29.97 fps, this might account for the difference if your audio delay is progressive.

If it's not progressive and stays at a minute delay throughout the movie, just use the offset audio option in your authoring program to override when the audio first comes in.

[toji53]

I think this might have something to do with it... When I try to load the video on VirtualDubMod this pops up...



What should I do?

[toji53]

And I did extract the audio from the original file in WAV format, however, it's still slightly off when I combine the audio and video on DVD authoring software.

[toji53]

And offsetting the audio doesn't appear to work. I can get one point in the middle at the perfect place, but later in the video it's out of sync again. It must be the frame rate, but how do I make sure that the video in being re-encoded at the right rate with VirtualDubMod? Of course I'll be trying to figure this out on my own but if someone wants to jump in it's appreciated...

[abc-123]

Virtualdub doesn't know how to handle this audio. Use avi2wav to strip the wav off the avi file and enter that as your audio source for virtualdub to convert.

[toji53]

Ok, so I used avi2wav to extract the audio in WAV format, then used VirtualDub to combine the two. After that I used VirtualDubMod to create the black frame, however I'm still ending up with out-of-sync audio.

The difference is when I open up that new file I created with avi2wav and VirtualDub in VirtualDubMod, I don't get the error message I posted above. But the result is about the same with or without it...

[abc-123]

Check the framerate of both videos. Does the video you created have the same rate as the video it got created from? Is virtualdubmod changing the video to a standard NTSC or PAL framerate and forgetting to apply that to the audio?

[toji53]

It appears the frame rate is the same? 23 fps

[toji53]

[abc-123]

First, check that your audio has a runtime of 0:19:29 as well.

Second, what use is a 23 fps file if you're in America? The standard is NTSC which is 29.97 fps for your dvd player to play. I've never used virtualdubmod so I can't help you with specifics, but in virtualdub (not mod), there is a setting under the video tab>frame rate which allows you to change rate so the audio and video durations match. Then make a fresh copy of the avi, but this time use divx compression and you'll get a much smaller file (video>compression> in virtualdub).

EDIT: Check the framerate of the file virtualdubmod spits out. The third one.

[Abond]

@toji53
Usualy I am answering "No" at VDubMod warning. Then click Streams-Stream list. Right click on the audio stream and select "Full processing". Then on the right side click "Save wav".
If you have constant desynchron with the new audio, it is probably due to a delay in the originaly multiplexed audio track. To see the delay you load the avi in GSpot. In the I/L field there should be something like "p xxx" or "NG xxx" where p is positive and NG is negative, xxx is a number of miliseconds.
I personaly believe that VDubMod can deal with positive delays, but not with negative.
Ofcourse after saving the wav you need to see that the runing time is the same as video.