ISO/IEC 14496-12:2004 specifies the structure and uses of the ISO base media file format. The identical text is published as ISO/IEC 15444-12:2004. This file format is used to contain time-based media such as video and audio. The storage of particular coding schemes is defined in specifications that derive from and reference ISO/IEC 14496-12:2004 and ISO/IEC 15444-12:2004, such as the MPEG-4 file format specified in ISO/IEC 14496-14, or the Motion JPEG file format specified in ISO/IEC 15444-3:2002/Amd.2.

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

The file structure is object-oriented; a file can be decomposed into constituent objects very simply, and the structure of the objects inferred directly from their type.

This technically identical text is published as ISO/IEC 14496-12:2004 for MPEG-4, and as ISO/IEC 15444-12:2004 for JPEG 2000, and reference to this specification should be made accordingly. The recommendation is to reference one, for example ISO/IEC 14496-12:2004, and append to the reference a parenthetical comment identifying the other, for example "(technically identical to ISO/IEC 15444-12:2004)".