help with dvd decriptor delay values

[troy]

I am trying to get some avi clips from commercial dvds. What I do is rip only one chapter of the dvd for the clip I want into a .vob. I put the vob into virtualdub-mpg and create an avi. This avi is perfectly in sync with the video even though I put audio delay correction of 0 in virtualdub-mpb. When I read the stream information I get a delay of -168ms. Why is this. Does dvd decriptor fix the delay. Also I noticed that dvd decriptor will report a delay of one value for one chapter and a delay of another value for another chapter. This seems very odd to me since I would think that the whole movie would have the same delay. Any help or suggestions.

[Asmodian]

I am not sure but it might be that you just can't tell that the sound is off by 0.168 seconds (it is pretty hard to notice that small of an error - it is possible but it is not a very obvious desync - to me at least).
I think the different delay values might be caused by DVD decrypter starting on some structure in the audio/vob structure that doesn't exactly start at the chapter points. i.e. the first usable audio chunk starts just before or just after the chapter and the amount of the "just" before or after changes from chapter to chapter (but the video is cut on the exact frame for each chapter).

Of course I would like to be corrected by those who know if this is incorrect. :)