M4P and Free MP3 Format

M4P is the Protected AAC File. AAC is the audio layer from the follow-on format to MP3. The .M4P extension is AAC purchased from Apple's Music Store (iTune) and is protected by a Digital Rights Management scheme. MP4 files encrypted by FairPlay DRM as sold through Tunes Store use .m4p extension. M4P is for the DRM protected content in iTunes Store, while m4a is for the DRM-free, unprotected content.

The iTunes store began after Apple signed deals with the five major record labels at the time, EMI, Universal, Warner, Sony Music Entertainment, and BMG (the last two would later merge to form Sony BMG). Music from more than 2,000 independent labels was added later, the first from Moby on July 29, 2003.

An MP3 file is made up of multiple MP3 frames, which consist of the MP3 header and the MP3 data. This sequence of frames is called an Elementary stream. Frames are not independent items ("byte reservoir") and therefore cannot be extracted on arbitrary frame boundaries.

The MP3 data is the actual audio payload. The diagram shows that the MP3 header consists of a sync word, which is used to identify the beginning of a valid frame. Tag editing functionality is often built-in to MP3 players and editors, but there also exist tag editors dedicated to the purpose

Free Trial: Converting M4P to MP3

NoteBurner M4P to MP3 Convertercan preserve MP3 ID3 tag, containing Artist name, Song title, Year and Genre of the current audio file. The latest version of NoteBurner can also preserve album name and album art to the converted audio files.

NoteBurner M4P to MP3 Converter utilizes virtual CD burning mechanism to convert audio files between different format. NoteBurner M4P to MP3 Convertersimulates the CD burning and ripping process, but in a virtual way. Due to its working mechanism, NoteBurner must work with media player to complete the conversion.

iTunes keeps track of songs by creating a virtual library, allowing users to access and edit a song's attributes. These attributes, known as metadata, are stored in two library files. The first is a binary file called iTunes Library and it uses a proprietary file format. It caches information like artist and genre from the audio format's tag capabilities (the ID3 tag, for example) and stores iTunes-specific information like play count and rating. iTunes typically reads library data only from this file.

For MP3 files, iTunes writes tags in Unicode ID3v2.2 by default, but converting them to ID3v2.3 and ID3v2.4 is possible via its "Advanced" > "Convert ID3 Tags" toolbar menu. If both ID3v2.x and ID3v1.x tags are in a file, iTunes ignores the ID3v1.x tags.