MP4

MP4 usually refers to the multimedia file format defined in Part 14 (and to a lesser extent Part 1) of the MPEG-4 standard.

"MP4" could also mean the entire MPEG-4 standard, or some other subset of MPEG-4. This article only covers the Part 14 file format.

MPEG-4 Part 14 is an application of Part 12. The recommended extension for it is ".mp4", though ".m4a" is often used for audio-only files. It is standardized by ISO/IEC 14496-14.

Imgur uses an MP4 video format for converting animated GIFs uploaded by users into its own "GIFV" format, which is actually an MPR referenced in a video element of an HTML 5 document, which is served with a .gifv extension from their servers.

Specifications

 * ISO/IEC 14496-14:2003 (MP4 file format) (not free to download)

Sample files

 * http://samples.libav.org/MPEG-4/

Software

 * FFmpeg
 * Konvertor

Links

 * Wikipedia article: MPEG-4 Part 14
 * MultimediaWiki: MP4
 * mp4-layout.txt
 * MP4 Registration Authority
 * Complete List of all known MP4 / QuickTime 'ftyp' designations