Vegas Question - Audio progressively out of sync in rendered movie

[Matt]

Hi all!

I know this is off topic (i.e. not a NT product) but I'm having no luck elsewhere! And you guys know more about this stuff than me!

A client of ours had a DVD of a project we worked on made, quite professionally done, we want to recompress it for the web.

I extracted the 18min movie as a VOB file using Xilisoft DVD Ripper Platinum 4 (does a good job too) renamed it to .mpg so I could bring it into Vegas, which works fine.

If I play it back in the timeline within Vegas everything is fine. I've recompressed it as a .MOV (Sorenson3 codec) half size of the original with lower audio (mono, 22Khz) the left FPS as the original (29.97).

When I play it back in Quicktime the audio slips out of sync about a third of the way, and gets progressively worse.

Any idea what might be causing this? It is because it's a muxed mpg? Is it because I'm re-encoding the audio at a lower rate?

Could really do with some help here, it's not urgent, it was just a nice to have really, but now it's bugging me!

Cheers
Matt

[Bobt]

Frame rate mismatch maybe?
It would about every 10 seconds you would loose a frame if
you are at 30 fps and its really 29.97
Just guessing.
Does it have this issue when playing back from the timeline?

[Matt]

Nope, it's fine in the timeline, just when rendered out, so it must be something I'm doing.

Thing is, when I import the mpg it's properties are 29.97fps, and I haven't changing that.