M4A, M4B, M4P Audio Formats

By Dan Hope

These file extensions are all related to the MPEG-4 format (or MP4), and are basically audio versions of the MP4 codec. The reason that these file extensions are so common is that they have been adopted by Apple for use in the iTunes Music Store. M4A files are very similar to MP4 files, and the M4B format is only different from M4A because it can be “bookmarked,” allowing an MP3 player to return exactly to the last listening point. M4B is popular for audiobooks and podcasts for this very reason.

M4P is Apple’s version of the M4A format that includes DRM protection, called FairPlay. This is the format used for protected music purchased from the iTunes Music Store.

These three extensions of the MP4 format can be embedded with information from AAC , MP2 and MP3 formats, making it versatile. Most media players that support the MP4 format will be able to play M4A and M4B. Playback of M4P will depend on whether the media player can support the DRM protected versions of songs.

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