What is an M4P file?
The M4P file format, identified by its .m4p extension, is a protected audio standard pioneered by Apple for its iTunes Store. In essence, an M4P file is built upon the high-quality AAC audio codec but is secured with a robust Digital Rights Management (DRM) layer, specifically Apple’s FairPlay system. This integral copy protection restricts playback exclusively to authorized devices, creating a controlled ecosystem. Consequently, M4P files are designed for seamless performance within the Apple universe, meaning they are fully compatible with authorized MacBooks, iTunes on Windows, and iOS devices like the iPhone and iPad, but are inherently incompatible with unauthorized software or hardware.
M4P File Format
The M4P stands for MPEG 4 Protected (audio), and it encodes the audio with advanced audio codec (AAC) and protects the file from un-authorized use of the file. This file format is usually considered as an iTunes Music Store’s audio file format. Apple uses its FairPlay Digital Rights Management (DRM) system to protect M4P files. FairPlay DRM is based on technology developed by Veridisc. Its protection mechanism works by encrypting the AAC audio stream using the AES encryption. The user receives a master key which is assigned to his account for decryption. This file format was introduced as a replacement of the MP3 file format, because the MP3 was not originally intended as an audio file, but as layer III in a MPEG 1 or 2 video file.
Key Characteristics of M4P Files
| Characteristic | Description |
|---|---|
| File Extension | .m4p |
| Format Type | Protected Audio Container Format |
| Primary Codec | Advanced Audio Coding (AAC) |
| Key Feature | FairPlay DRM (Digital Rights Management) |
| Primary Use Case | Purchased music from the legacy iTunes Store |
| Replacement Format | M4A (DRM-free, used by Apple Music today) |
| Platform | Native on Apple devices and iTunes; limited elsewhere |
M4P File Format Specifications
Similar to M4A, the M4P files also consist of consecutive chunks. Each chunk has 8 byte header and sub-divided as:
- 4-byte chunk size (big-endian, high byte first)
- 4-byte chunk type - one of pre-defined signatures: “mdat”, “moov”, “pnot”, “moof”, “udta”, “uuid”, “free”, “skip”, “ftyp”, “jP2 “, “wide”, “load”, “imap”, “matt”, “chap”, “kmat”, “clip”, “crgn”, “sync”, “tmcd”, “PICT”, “scpt”, “ctab”, “ssrc”.
Similar to M4A the First chunk in M4P will be of type “ftype” and has a sub-type at offset 8. The M4P defined by sub-type which must be “M4P_”.
Iterating chunks, until chunk of unknown type is detected, It will compose M4P (MPEG-4 Audio) file.
FAQ
Q1: Can I convert an M4P file to MP3?
A: Yes, but you must first authorize the conversion by burning the songs to a CD using iTunes and then ripping the CD to MP3, or by using a dedicated DRM removal tool.
Q2: Do M4P files still exist?
A: While no longer used for new music purchases, many legacy iTunes purchases are still in M4P format, and the principle of DRM-protected downloads continues with Apple Music.
Q3: How can I play an M4P file on a non-Apple device?
A: You cannot play a standard M4P file on Android or Windows directly; you must first convert it to a DRM-free format like MP3 or M4A.
Q4: What is the main difference between M4A and M4P?
A: The core difference is DRM; M4A files are unprotected and freely playable, while M4P files are protected and restricted to authorized devices.
Q5: Will M4P files play on my current iPhone?
A: Yes, as long as the device is authorized with the Apple ID that purchased the music, your iPhone will play M4P files without any issue.
