ISO base media file format

The ISO base media file format (ISOBMFF) is a container file format that defines a general structure for files that contain time-based multimedia data such as video and audio. It is standardized in ISO/IEC 14496-12, a.k.a. MPEG-4 Part 12, and was formerly also published as ISO/IEC 15444-12, a.k.a. JPEG 2000 Part 12.

It is designed as a flexible, extensible format that facilitates interchange, management, editing and presentation of the media. The presentation may be local, or via a network or other stream delivery mechanism. The file format is designed to be independent of any particular network protocol while enabling support for them in general.

The format has become very widely used for media file storage and as the basis for various other media file formats (e.g. the MP4 and 3GP container formats), and its widespread use was recognized by a Technology & Engineering Emmy Award presented on 4 November 2021 by the National Academy of Television Arts and Sciences.

The ISO base media file format is directly based on Apple's QuickTime container format. It was developed by MPEG (in ISO/IEC JTC 1/SC 29, originally Working Group 11 MPEG, currently Working Group 3 MPEG Systems). The first MP4 file format specification was created on the basis of the QuickTime format specification published in 2001. The MP4 file format known as "version 1" was published in 2001 as ISO/IEC 14496-1:2001, as revision of the MPEG-4 Part 1: Systems. 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 known as MPEG-4 file format "version 2".

The MP4 file format was generalized into the ISO base media file format (ISO/IEC 14496-12:2004 or ISO/IEC 15444-12:2004), which defines a general structure for time-based media files. It is used as the basis for other file formats in the family such as MP4, 3GP, and Motion JPEG 2000).

Historically, the text was also published as ISO/IEC 15444-12 (JPEG 2000 Part 12), although the JPEG 2000 version of the standard was withdrawn in January 2017 since it was redundant with the MPEG-4 publication.

The ISO base media file format is designed as an extensible file format. A list of all registered extensions for the ISO base media file format is published on the official registration authority website, www.mp4ra.org. The registration authority for code-points (identifier values) in "MP4 Family" files is Apple Inc., and it is named in Annex D (informative) in MPEG-4 Part 12. Codec designers should register the codes they invent, but the registration is not mandatory and some of the invented and used code-points are not registered. When someone is creating a new specification derived from the ISO base media file format, all the existing specifications should be used both as examples and a source of definitions and technology. If an existing specification already covers how a particular media type is stored in the file format (e.g., MPEG-4 audio or video in MP4), that definition should be used and a new one should not be invented.

MPEG has standardized a number of specifications extending the ISO base media file format: The MP4 file format (ISO/IEC 14496-14) defined some extensions over the ISO base media file format to support MPEG-4 visual/audio codecs and various MPEG-4 Systems features such as object descriptors and scene descriptions. The MPEG-4 Part 3 (MPEG-4 Audio) standard also defined storage of some audio compression formats. Storage of MPEG-1/2 Audio (MP3, MP2, MP1) in the ISO base media file format was defined in ISO/IEC 14496-3:2001/Amd 3:2005. The Advanced Video Coding (AVC) file format (ISO/IEC 14496-15) defined support for H.264/MPEG-4 AVC video compression. The High Efficiency Image File Format (HEIF) is an image container format using the ISO base media file format as the basis. While HEIF can be used with any image compression format, it specifically includes support for HEVC intra-coded images and HEVC-coded image sequences, taking advantage of inter-picture prediction.