It [[http://www.togaware.com/linux/survivor/DVD_Sound.html][could be done]] with [[http://zebra.fh-weingarten.de/~transcode/][transcode]], but it didn't work for me.

I found the following recipe:

<example>
for c in `seq 1 24 | xargs printf "%02.0f\n"`
do
  mplayer dvd://1 -chapter $c-$c -vo null -ao pcm -aofile $c.wav
  oggenc -o track-$c.ogg $c.wav
  rm $c.wav
done
</example>