M4P file extension

iTunes Audio Format

AAC is the audio layer from the follow-on format to MP3 (see .M4A extension). The .M4P extension is AAC purchased from Apple's Music Store (iTune) and is protected by a Digital Rights Management scheme

The .M4P extension is most famous for its use in Apple's iTunes store, where the format is used to hold audio. The format is currently protected by a Digital Rights Management scheme (DRMS).