The first step of this process involves decoding the data on the DVD. DVDs use a type of encryption that jumbles the information if you simply try to copy it to your computer hard drive. This is done as an anti-copyright-infringement measure. Several programs are available that do this, such as MacTheRipper for Macintosh and iSkySoft DVD Ripper for Windows. Use this program to decode the information on the DVD to a folder on your hard drive.
DVD-ripping software will create a folder inside your rip folder entitled "VIDEO_TS." "VIDEO_TS" stands for video transport-stream. This folder is where the majority of the audio and video is decoded from the DVD. In this filter you will find a number of VOB files. VOB stands for video object and is the standardized format for DVD audio-video container files. It includes both audio and video streams that need to be separated.
To convert the decoded VOB files into audio files, you will need a secondary program like HandBrake or ffmpegX to re-encode the VOB into individual audio and video streams.
Import the VOB file into HandBrake or ffmpegX. In the output settings, you will need to specify what file format you want the audio exported as (e.g., MP3, AAC). Deselect the video output setting. This will create only audio files from the VOB file. Run the encoding process to rip the audio track from the VOB.
Now that you have individual audio streams, you will need a third-party audio editing program, such as Audacity, to locate the music from the DVD and crop it from the large MP3 or AAC files that were created by Handbrake or ffmpegX. Once you have completed this step, you will have the music from your DVD ready to play as an MP3 or AAC file.