Fix Audio Sync Problems

[Resurrection]

This is a quick guide for correcting out of sync audio on your movie files. If the audio is out of sync throughout the movie by the same amount from start to finish it can usually be corrected during playback without too much difficulty.

Here is a method with Media Player Classic

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1. Open your movie.

2. Determine if the audio comes before or after the video.

3. MPC allows you to shift the audio stream as the movie plays.Go to the PLAY menu and click on AUDIO, then click on Options.In the Internal Filters you'll see Audio Switcher

4. If your movie plays the audio before the video you need to enter a positive value in the Audio time shift box.If your movie plays the audio after the video you need a to enter a negative value.

6. If your movie is an AVI file you can use VirtualDubMod to apply the audio correction permanently.


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Easy.

However If your audio gradually drifts out of sync during playback then you probably
have a stretched audio sync problem that will require more work to put right.

Here is a link I found that explains how

Nicky Pages' Digital Solutions

When the synch is perfect both the audio and video will match, as seen in the first image above. Video frame1 matches to Audio frame 1 as does frames 2, 3 and so on. In the second picture it shows the audio as displaced, which means that both audio and video are correct length, but either the video or audio will start at different times causing displacement. In the third sinerio we have an audio and video sequence that are different lengths because one of them has become stretched somehow.

To fix these problems you must check out the film very carefully. If the audio is equally out of synch at the start of the movie as it is the end of the film, then you have an Audio Displacement problem (see Fixing Audio Displacement below). If the audio is very close to correct at the beginning of the movie, but is quite badly wrong at the end of the movie (or vise versa) you probably have a Stretched Video problem (see Fixing Stretched Audio below). It is possible to have both problems of course ;-P. So if you are sure you have both I suggest you fix the Audio Displacement at the very start of the film first and then fix the Stretched Video problem once you know somewhere in the film is absolutely correct!

According to the tutorial you will need VirtualDub ,Terabits AVI Info ,Cool Edit (or simular audio editing tool)

[takomania]

to do this in vlc rather than mpc:

tools > track synchronisation

there you can adjust a/v sync and subtitle sync :)