Audio out of sync in middle of video only...

[clm3s]

I'm attempting to repair an old video in which the video and audio are exactly the same length, but only the beginning and end of the video are synced. The video slowly goes out of sync and then near the middle slowly starts to go back into sync, so a simple audio delay/stretch will not work.

I have never encountered this type of sync issue before and I would think I'd need some sort of 'multi-point' audio stretching software with the ability to also show a video track. Does such a tool exist? Anyone encountered this issue before and what kind of solutions did you use to correct it?

I can convert the audio/video to any format needed. I am familiar with most AV software including Virtual Dub/Vegas/etc.

Anyone have any advice?

[JVRaines]

It would be pretty easy to fix in Vegas. Split the audio event at the point where the drift reverses direction. Then stretch or shrink each half accordingly.

[clm3s]

It would be pretty easy to fix in Vegas. Split the audio event at the point where the drift reverses direction. Then stretch or shrink each half accordingly.

Tried that out and it sorta works. The middle, beginning and end are all sync'd, but everything in between each of those points isn't.

Thank you for the tip, but it looks like the audio speed change is more variable than that.

[JVRaines]

Then split the audio into as many parts as you need to pound it into shape. Go scene-by-scene if you have to. I have done this sort of work syncing Super 8 projector sound to frame-scanned video, and while tedious, it does work.

[clm3s]

Then split the audio into as many parts as you need to pound it into shape. Go scene-by-scene if you have to. I have done this sort of work syncing Super 8 projector sound to frame-scanned video, and while tedious, it does work.

Thanks for this tip! I am trying that now. I have already noticed that this is not exactly quick work, nor is it very accurate. It is a shame that Vegas or something like it doesn't have a variable audio stretch function.

[JVRaines]

Adobe Audition (at least the old 3.01 version I'm using) has a "Gliding Stretch" effect that changes linearly from one ratio to another. But that may be even more work unless you have a perfectly linear variation.

[johns0]

Might wanna check for video frames that are corrupted near the sync issue,that will put the audio out of sync for a while and then it will resync due to another frame issue.

[clm3s]

Might wanna check for video frames that are corrupted near the sync issue,that will put the audio out of sync for a while and then it will resync due to another frame issue.

On closer inspection it looks as I have multiple video frame corruption points. The sync issue is more random then I thought.