Although you can use K9Copy to extract the audio track from DVD some times is more convenient to use the commanline.

Ripping the sound track of a DVD movie through the terminal can be achieved using transcode and lsdvd commands.

These can be installed via

sudo apt-get install transcodelsdvd

Through the following command

lsdvd

you can browse the DVD toc (table of content) in order to locate the track information, and for instance the longest track which would be the movie’s one.

This command would assume you have the DVD inserted in the physical drive /dev/dvd however if you are willing to rip the audio track from a DVD video ISO image you have to first mount the image in a folder

sudo mount dvdimage.iso /media/dvdimage/ -t iso9660 -o loop

and than tell lsdvd where to look for the DVD

lsdvd /media/dvdimage

The output would look similar to the following one

libdvdread: Using libdvdcss version 1.2.5 for DVD access
Title: 01, Length: 01:24:34.286 Chapters: 17, Cells: 17, Audio streams: 08, Subpictures: 32
Title: 02, Length: 00:01:54.086 Chapters: 01, Cells: 01, Audio streams: 01, Subpictures: 03
Longest track: 1

To capture the whole audio track of a title run (according to the codec you want to have the output in)

transcode -i /dev/dvd -x dvd -T 1,-1 -a 0 -y ogg -m audio.ogg
transcode -i /dev/dvd -x dvd -T 1,-1 -a 0 -y wav -m audio.wav

or in case you are manipulating an ISO image

transcode -i /media/dvdimage -x dvd -T 1,-1 -a 0 -y ogg -m audio.ogg
transcode -i /media/dvdimage -x dvd -T 1,-1 -a 0 -y wav -m audio.wav

If you want to capture only a specific chapter (let’s say the 3rd) you can use this string

transcode -i /dev/dvd -x dvd -T 1,3,1 -a 0 -y ogg -m track3.ogg

Basically the arguments identify
[-i] the input as /dev/dvd
[-x] the type of input as DVD
[-T] the title, chapter, and angle to encode, in this case being title 1, chapter 3, and camera angle 1
[-a] the audio track is track 0
[-y] the output format
[-m] the output filename is