What Exactly is an MP4?

Is it audio, video, or both?

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This digital format FAQ briefly explains the basics of the MP4 format.


Even though the MP4 format is often thought of as a video encoding algorithm, it is actually a container format that can host any type of data. As well as being able to host any number of video or audio streams, an MP4 file can store other media types such as images and even subtitles. The confusion that the MP4 format is video-only often stems from video-capable portable devices being referred to as MP4 players.


Based on Apple's QuickTime format (.mov), the MP4 container format first came into being in 2001 as the ISO/IEC 14496-1:2001 standard. Now at version 2 (MPEG-4 Part 14), the ISO/IEC 14496-14:2003 standard was released in 2003.

Popular File Extensions

As mentioned previously, an MP4 container can host various types of data streams and can be represented by the following file extensions:

  • Video: .M4v, .3gp, .3g2
  • Audio: M4a, .M4p, .M4b, .M4R, .AAC