Here are the commands I’m using for importing DVDs into the iPod. Shown is the script for the Muppets DVD. It requires the libdvdcss libraries to be added, as well as the MP4Box app. MP4Box takes the mencoder-encoded file and stamps it with the appropriate iPod bits to make it show.
GUEST="Vincent_Price"; time mencoder dvd://8 -dvd-device /dev/scd0 -sws 9 -of lavf -lavfopts format=mp4 -vf scale=320:240 -ovc x264 -x264encopts bitrate=1381:vbv_maxrate=1500:vbv_bufsize=2000:nocabac:me=umh:trellis=1:level_idc=30:global_header:threads=2:pass=1:turbo -oac faac -faacopts mpeg=4:object=2:br=160:raw -channels 2 -srate 48000 -o Muppets-$GUEST.mp4 && MP4Box -add Muppets-$GUEST.mp4 output/Muppets-$GUEST.mp4 && [ -f output/Muppets-$GUEST.mp4 ] && rm Muppets-$GUEST.mp4 && echo "done."
Also see this helpful Ubuntu forum post for other cool tools.
you should be using Handbrake!