Hi, I don't know if a function like that already exists but I wrote a small one which automaticaly adds borders and resizes to matche with dvd resolutions to feed your mpeg2 encoder or dvd rebuilder. I also added an option ('care' Correct Aspect Ratio Estimation) if the input has not the correct aspect ratio, just set it to have only one resizing in the script.
LAST UPDATE (v0.3a) :
http://forum.doom9.org/attachment.ph...1&d=1261000196