Note: This document is deprecated, please use dvd2mp3 v2.0

How to rip DVD audio tracks to MP3

You will need a couple of tools do the job, all of which you can obtain here.
Start by putting the DVD in the drive and running vobdec info this will tell you if the DVD is readable, and how many audio tracks there are availalble.
VobDec+ 0.311 - VOB Decryption Utility          ('Q' to Quit)

found DVD on drive f:

DVD 'DUNE' is region 1
found only audio stream 0x80
0x80 is language English
This tells us that there is only one audio track available which makes things easy. We would now run vobdec 1 99 -0 +ac3 XX where XX is the audio track that you want to rip (in the above example it's 80). Audio tracks are numbered starting at 80 and going up. All the titles can be listed by looking on the dvd in the \video directory for vts_YY_Z.vob files. YY denotes the title, and Z is the sub-section of that title (titles have to be split at the 1 gigabyte mark). -0 tells vobdec to skip the multiangle search, and +ac3 tells it to only get the audio.
decrypting file f:\video_ts\vts_01_1.vob ---> vts_01_1.vob
decrypting, 100% done    4:54

It should rip the appropriate audio tracks to the file audio_XX.ac3. Once you have the ac3 files it's just a simple matter of converting them to a listenable format (MP3). ac3dec audio_XX.ac3 -wav outfile.mp3 will launch ac3dec and a little window allowing you to select an output codec. Simply select MPEG Layer-3 and the appropriate bit rate and let it begin to compress. A while later you should have a file outfile.mp3 that you can load into WinAmp or onto your MP3 device.

I find this a very effective way to get director's commentary tracks, or movie scores in a more easy to access format.