converting a vob, video is double speed and sound is distorted

I've tried several videos - Aliens, Fiddler On The Roof, Gladiator. This is specifically on Ubuntu 10.04 with only packages from the official repos and libdvdcss from medibuntu, but I've had the exact same issue on older versions of Ubuntu.

I extract the vob from the dvd using 'vobcopy -l'. I can play the vob and it looks great in vlc. I then try converting the vob with 'ffmpeg2theora --audiostream 1 file.vob'. The resulting file, the video plays through at double speed and the audio plays at normal speed but is very distorted. If I add the --sync option, the video plays normal and audio plays normal speed but the audio is distorted even worse.

I don't understand why it won't produce a good copy for me, I hear lots of people convert vobs with ffmpeg2theora just fine. Also, Thoggen does works fine, and produces a good ogv file, but I would prefer a commandline program.