After DVDs CSS encryption has broken back in 1999 the music idustry tried to create a muh more secure mechanism for DVD-Audio (CPPM) .. this has been circumvented
http://www.cdfreaks.com/news/12061
Several tools to work with DVD-Audio (read: ripping)
They require WinDVD 5, 6 or 7 installed, as they don't do the decryption themselves, and instead patch WinDVD to output the decrypted stream to disk instead of the sound card.
The tools are:
- DVD-A ripper: Intended to decrypt CPPM protected AOB and VOB files on DVD-Audio discs.
- PPCM ripper: Intended to capture Packed PCM (MLP) stream (stereo or multichannel) to .WAV files.
- DVD-A Explorer: Intended to peep&grab on DVD-Audio tracks (PCM and Packed PCM).
This tool is available at Rarewares here.
http://www.cdfreaks.com/news/12061