ok ive since made some progress (thanx abond) and have now have more information...
this concerns the 25 fps xvid avi im trying to convert to 25fps PAL mpeg-2...
-when i open the avi in virtual dub i have roughly 30000 frames
-when i open tmpg it wants to encode roughly 36000 frames
-if i go to a frame in virtualdub, say frame 18000 and then go to "source range" in tmpg and go to frame 18000 the two frames are different
-in tmpg in the source range popup it displays the correct resolution (544 x 44

but the wrong frame rate (it displays 30 fps)
-the duration of the mpeg-2 is exactly 20% more than that of the avi. this corresponds to 30 fps being exactly 20% more than 25 fps.
so it appears that tmpg is reading the avi wrong but how can i correct or account for this?
thanks!