Like many, I am still stuck with a sea of .m4p files. These are the old FairPlay-encrypted AAC files that were supposed to be superseded by iTunes Plus. iTunes Plus did away with DRM music, and for a small fee, you were able to “upgrade” all your old music; getting higher quality versions sans-DRM.
At least, that was what was supposed to happen. See, most iTunes Plus early adopters got stuck with only partial conversions, leaving them with many songs stuck in the jailed FairPlay format. And unlike iOS, the only jailbreak was to downsample and burn to a CD-R audio disc, finally reconverting it back to an AAC.
Thankfully, that is now over with via iCloud & iTunes In The Cloud. Here’s a quick step-by-step to remedy the issue.
Step 1) Find your iTunes Library folder in Mac OS X Finder or Windows Explorer.
Step 2) Do a file search for files within the folder ending in .m4p
Step 3) Make a list of all the audio files listed. Then, drag those results to the Trash / Recycle Bin.
Step 4) Go to iTunes Store > Purchased and enter each song name in.
Step 5) Re-download those songs.
Step 6) Empty the Trash / Recycle Bin.
The result will be your songs have been replaced with iTunes Plus, DRM-free versions of the content. Keep in mind that this may leave some references to the deleted un-Plus versions of the song, but it’s also much faster to upgrade the way I described.
Note: Some songs are still indeed stuck in .m4p. Some record labels never signed onto iTunes Plus, and are still downloaded in FairPlay-encrypted .m4p format.