I'm a bit confused on this and hopefully someone can clarify because I would like to do something similar.
I have the Incubus: Alive at Red Rocks dvd and I love listening to it. I'd like to get it played only as audio, so I could listen to it as i'm driving. Is this something possible with iMovie? and if so, how so?
From
http://www.ripdifferent.com forums:
With MTR (MacTheRipper) 2.6.6:
Change MTR to Title Only (if you want the entire title to be a single audio file) or Title - Chapter (if you want one chapter per audio file), select the "D" button, then hit the "Streams" button. In the stream selection drawer, select only the AC3 track you want (or PCM if that's all there is). Then, extract the title or chapters you want. In the current version of MTR, you'll need to extract one chapter at a time if you want them to be separate, but in version 3.0, there is a MUCH better interface for chapter selection.
With MTR 3.0:
Rip the DVD with MTR 3.0 in Title - Chapter mode, with 'demux streams' enabled, only audio tracks enabled (ac3, dts, and pcm, not m2v or subtitles), and 'merge chapters' disabled. This will output the audio from the selected chapters of the DVD, typically as AC3 files.
Once you have the AC3 or PCM files extracted, you'll need to convert them to a usable format. For AC3, get the freeware app mAC3Dec to convert them to MP3 or AAC. For PCM, get PCM2AIFF, or AIFF from PCM and convert them to AIFF format, which you can import into iTunes and convert to MP3.
http://www.ripdifferent.com/phpbb2/viewtopic.php?t=3966
This method worked for me when I wanted just the audio from the Blueman Complex Rock tour DVD.
