Audio out of sync

[Squid_uk]

Hey guys, i have been trying to convert an avi to dvd and see to be having audio/video sync problems.

The avi is approx 2hrs 28mins long the method i am using is as follows,

Open the avi file using virtual dub, click the audio tab, select full processing mode, then file save wav, once this has completed i then use TMPGEnc Xpress and open the file again but this time i change the audio to the WAV file just created, select the output as DVD PAL.

Now when plyaing the outputted MPEG file the audio/video sync is fine (out but by milli seconds) how just after approx 1hr 2mins the picture jumps a little and the audio becomes out of sync for the rest of the file, however in the original avi file it is in sync the whole time but it still has the small jump at the same point.

Can anybody help me with this or tell me why this could be happening?

[guns1inger]

Playback and encoding are two different things. Players are often coded to get a round small glitches, but encoders look at every bit.

To fix this you need to cut the audio where the issue occurs, adjust the second part of the audio till it is back in sync, then save the audio track. You can then replace the audio track with the problem with this new version.

This adjustment is probably best done in a non-linear video editor with reasonable audio capabilities (i.e. not virtualdub)

[Squid_uk]

Ok im not 100% sure how this can be done, would i be able to do this task with goldwave?

Is there anywhere i could get a guide to help a little?

[guns1inger]

If you can see the video in goldwave then yes. If you can't then it becomes hit and miss.

I use Vegas to edit, so I would load the video and audio into Vegas, line up the first half so it was in sync, find the glitch and split the audio at that point. I would then move the second part of the audio around until it was in sync, and save the new audio track to disk. The same principal holds in goldwave, but you need to be able to see the video to sync it up.

[Squid_uk]

Thanks guns1inger i will give a go and repost if i have any troubles

[Squid_uk]

Ok i managed to get hold of Vega, i loaded the MPEG and now i haven't got a clue where to start!

[Barnabas]

Squid_uk,

Audio sync problems are nearly impossible to fix, the exception being when the audio is simply out of the sync the same amount from start to finish. Drifting sync is just not something really fixable. You probably downloaded a file somewhere, so know nothing about how it was captured and converted. Save yourself lots of time and don't try to repair it.

[guns1inger]

Open the mpeg on your timeline. Highlight the audio track. Now scroll along the timeline until you find the point where the glitch occurs. Play through this point several times until you are comfortable that you know exactly where you need to cut. Place the cursor at this point and hit the 's' key. The audio track will now be split at that point. If you click and hold on the second part of the audio clip (not the end of it, click on one of the frames) you can drag it along the timeline. Do this and play back and listen. Keep adjusting the position of the audio track until the second half is back in sync.

Once you have the whole audio back in sync - with a possible dead few frames at the cut point - you can click on File ->Render As and set a type to save you audio as. Save you new audio track, and replace the broken with with it.

Yes, some audio sync issues can be difficult. This one should be dead easy. A single glitch should mean a single cut and a little shuffling.

[Squid_uk]

Ok i managed to split where the glitch is but when i click on drag the audio the video moves with it so nothing happens to the sync i just loose part some of the frames