MKV to AVI, sound out of sync?

[IAmATeaf]

Been playing around with converting an MKV to AVI just for the hell of it but the sound always seems to be out of sync.

What I do is extract the audio and video from the MKV. Use AVC2AVI to produce an output that can be loaded into VirtualDubMod, then convert to XVid and then finally mux the audio back with the converted XVid. When using AVC2AVi and VirtualDubMod I always make sure that the fps is as per the orginal but no matter what I do the XVid ouput is always slightly a different length then the original source.

Anybody have any clues as to what I am doing wrong?

 

[AbsenceJam]

VBR track? Does the MKV have delay added?
Could be all sorts of things really.

 

[IAmATeaf]

I've checked all the above, there's no delay according to Media Info and the videos not VFR, i think it might be related to the frame rate, Media Info reports 23.976 but looking at mkvinfo I get 23.976xxxxx so I'm wondering if me just putting the frame rate at 23.976 is enough to throw things out.

Problem with doing testing is takes around 3 hours before you know if things have improved.