Getting an audio file in another format from an M4P on OS X

VLC was supposed to be able to open M4P files by reading the authorisation key from an iPod, and could then output the audio directly to a file, but it doesn't work any more, and neither does FairKeys.

This indirect method doesn't preserve the tags, but it's useful for converting DRM-protected M4P files to other formats:

1. Install Soundflower, and in Sound Preferences set the default audio output to Soundflower (2 ch).
2. Run Audacity and set the recording device to Soundflower (2 ch), stereo.
3. Start Audacity recording.
4. Play the M4P file in iTunes, QuickTime Player or qp.
5. Stop Audacity recording. Trim silence with Analyze > Silence Finder. Save as Ogg Vorbis, WAV or MP3.