How to extract sound from a DVD movie to mp3

I have some workout DVD's which I would like to listen to while on the park (I don't have a big living room).

What can I use to extract the sound from the movies, on a Ubuntu machine, and convert it to mp3, or any other format?

I needed to do this a couple of years ago and followed this guide.

Basically, go to terminal (I still don't think it is in the add/remove programs) and type:

sudo apt-get install transcode

Next type

transcode -i /dev/dvd -x dvd -T 1,-1 -a 0 -y raw -m audiotrack.mp3

This should convert the whole disk to .mp3, if you read that guide, it goes in to a lot more detail and how to customise the command to do a whole lot more, such as single chapters.