The way to Convert DVD to MP3 (M4A) audio is displayed in this guide at great length. I have a bunch of DVD concerts, and often rip music from DVD to mp3 in legal way. So I am able to play mp3 on my iPod, iPad, etc.
ImElfin DVD Ripper helps us rip audio from DVD to mp3 in high sound quality. By the way, there are some personalized settings. For example, set output format as iTunes M4A, popular mp3, AAC, etc. And rip any segment from DVD concerts. It provides fast convert speed and fully supports dual core CPU.
Refer to: Convert Concert DVD to MP3 for iPod