The MP4 file format was generalized into the ISO Base Media File format ISO/IEC 14496-12:2004, which defines a general structure for time-based media files.

In 2003, the first version of the MP4 file format was revised and replaced by MPEG-4 Part 14: MP4 file format (ISO/IEC 14496-14:2003), commonly named as MPEG-4 file format version 2. The MPEG-4 file format, version 1 was published in 2001 as ISO/IEC 14496-1:2001, which is a revision of the MPEG-4 Part 1: Systems specification published in 1999 (ISO/IEC 14496-1:1999). MPEG-4 Part 14 revises and completely replaces Clause 13 of ISO/IEC 14496-1 (MPEG-4 Part 1: Systems), in which the file format for MPEG-4 content was previously specified. MPEG-4 Part 14 is essentially identical to the QuickTime File Format, but formally specifies support for Initial Object Descriptors (IOD) and other MPEG features. MPEG-4 Part 14 is an instance of the more general ISO/ IEC 14496-12:2004 (MPEG-4 Part 12: ISO base media file format) which is directly based upon the QuickTime File Format which was published in 2001. Portable media players are sometimes advertised as ' MP4 players', although some are simply MP3 players that also play AMV video or some other video format, and do not necessarily play the MPEG-4 Part 14 format. MPEG-4 Part 14 (formally ISO/ IEC 14496-14:2003) is a standard specified as a part of MPEG-4. The only filename extension for MPEG-4 Part 14 files as defined by the specification is. Like most modern container formats, it allows streaming over the Internet.

MPEG-4 Part 14 or MP4 is a digital multimedia container format most commonly used to store video and audio, but it can also be used to store other data such as subtitles and still images.

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