well to do it on the fly with mencoder its commandline or write a batch script or use a quick and easy visual basic app to set the options and have it call mencoder
with linux you can use the "man" pages which are help pages for all commands, windows doesnt have this
try the mplayer site:
http://www.mplayerhq.hu/DOCS/HTML-single/en/MPlayer.html
http://www.mplayerhq.hu/DOCS/man/en/mplayer.1.html
basically for mpeg4 family of codecs which xvid and opendivx are both part of use this:
{mencoder dvd://X -aid=Y -o filename -oac <audio codec> -ovc lavc -lavcopts vcodec=mpeg4:vqmin=2:vbitrate=2150 } all one line no braces around it
X= title number on dvd to rip
Y=128 for english audio track
audio codec use "copy" or "mp3lame" w/o quotes
to deinterlace add "-vf-add pp=fd" to the end
the above will rip it into 720x480 resolution with bitrate @2150 which is near dvd quality, about 1GB to 1.7GB for a long movie---its good enough to go backwards and convert back into DVD mpeg2 no problem, very low loss of quality
goto that website and download a windows copy, put it in a folder on your desktop after unzipping it, open a command prompt then move into that folder and enter the above command
if it doesnt work, then download cygwin plus the mysys development kit and then download the linux version and compile it on your system, the version at the mplayer site isnt compiled to work on all systems, but it does have mp3lame, libdvdcss(for encrypted dvd's), xvid and the lavc open source mpeg4 codec compiled in it
**** near all windows encoding apps for video these days rely on mencoder or one of its variants and it comes from linux, just compiled to work on windows-----you will see mencoder.dll in alot of windows apps, you will see ffmpeg alot too
mplayer/mencoder can do almost anything cept encode back into mpeg, that is still experimental
but you can dump audio,video, do post processing, filtering, rescaling, etc etc etc