Originally posted by attar:

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Is the audio out of sync a constant value after the thirty minute mark?
If so you could select the good part (must be on a key frame) then 'Edit > Crop to selection' and save it as part 1 using 'Video > Direct stream copy'.
Undo the Crop and select from the same key frame to the end.
Go to 'Audio > Interleaving' and insert a 'Skew' value.
If you estimate the audio is leading the video by half a second, insert a negative value of 500 and play the video.
When satisfied, save part 2 and exit VirtualDub.
Restart VirtualDub and load part 1 then 'Append' part 2.
Select 'Video > Direct stream copy' and save.


Edited for clarity.

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