Sustainability of Digital Formats
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ISO Base Media File Format

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Format Description Properties Explanation of format description terms

Identification and description Explanation of format description terms

Full name ISO/IEC 14496-12. Information technology -- Coding of audio-visual objects -- Part 12: ISO Base Media File Format (formal name). ISO/IEC 15444-12. Information technology -- JPEG 2000 image coding system -- Part 12: ISO base media file format (formal name). ISO base media file format (common name)
Description

Base format for media file formats, designed to contain time-based audio-visual information 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 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. The file format is designed to be independent of any particular network protocol while enabling efficient support for them in general. (Paraphrased from the specification, p. vi)

Production phase Generally used for middle- and final-state archiving or end-user delivery.
Relationship to other formats
    Has subtype MJP2_FF, Motion JPEG 2000 File Format
    Has subtype MP4_FF_2, MPEG-4 File Format, version 2
    Has subtype MP4_FF_AVCE, MPEG-4 File Format for AVC (Extensions; Part 15)
    Has subtype JP2_FF, JPEG 2000 Part 1 (Core) jp2 File Format
    Has subtype JPX_FF, JPEG 2000 Part 2 (Extensions) jpf File Format
    Has subtype JPM_FF, JPEG 2000 Part 1 (Compound) jpm File Format

Local use Explanation of format description terms

LC experience or existing holdings For JPEG 2000 still image implementations, see JP2_FF. For moving image implementations, see MP4_FF_2.
LC preference For JPEG 2000 still image implementations, see JP2_FF. For moving image implementations, no relevant preferences established.

Sustainability factors Explanation of format description terms

Disclosure Fully disclosed. Developed jointly by the Motion Pictures Expert Group (MPEG) and the Joint Photographic Experts Group (JPEG), two working groups within the ISO/IEC committee structure formally known as ISO/IEC JTC 1/SC 29.
    Documentation

Published as part of both MPEG-4 and JPEG 2000 as technically identical ISO standards:

  • ISO/IEC 14496-12. Information technology -- Coding of audio-visual objects -- Part 12: ISO Base Media File Format. (by MPEG working group)
  • JPEG 2000 ISO/IEC 15444-12. Information technology -- JPEG 2000 image coding system -- Part 12: ISO base media file format. (by JPEG working group)
Adoption JPEG 2000 still image implementations using JP2_FF are being widely adopted. The breadth of adoption of implementations of JPX_FF and JPM_FF is unknown to the compiler of this document. For moving image implementations, there is some adoption of MP4_FF_2; the breadth of adoption of other moving image implementations is unknown to the compiler of this document. At this writing (December, 2011), Motion JPEG 2000 encoding, which would use MJP2_FF, does not appear to be widely adopted. Professional broadcasters appear to favor standards from SMPTE, e.g., MXF.
    Licensing and patents The specification identifies Apple and Matsushita Electric Industrial Co. as holders of relevant patents, adding that "the holders of these patent rights have assured the ISO and IEC that they are willing to negotiate licenses under reasonable and non-discriminatory terms." The specification also cautions that "some of the elements . . . may be the subject of patent rights other than those identified."
Transparency ISO_BMFF itself is transparent as a wrapper. Transparency of subtypes is determined by the encoding of the wrapped content.
Self-documentation The structure includes boxes and headers that contain the technical metadata needed to manage the media streams. Other boxes may contain descriptive ("bibliographic") metadata; for example, see MJP2_FF. Comments welcome.
External dependencies None.
Technical protection considerations None. Files may employ an optional IPR (Intellectual Property Rights) box that indicates whether an item is protected and provides an identifier; see JP2_FF.

Quality and functionality factors Explanation of format description terms

Other
Normal rendering. Many relevant aspects depend on subtype. The format supports timescales that manage the playout of time-based media streams and hint tracks employed in streaming applications.

File type signifiers Explanation of format description terms

Tag Value Note
Filename extension See note.  Depends upon subtype.
Internet Media Type See note.  Depends upon subtype.
Magic numbers See note.  Depends upon subtype.
File type brand (ISO Base Media File Format) isom
ISO_BMFF includes a file type box that contains major and minor brands (identifiers). Regarding isom, the specification states that this would typically be used as the minor or secondary brand. For examples of major brands in ISO_BMFF files, see subtypes listed above; a file type brand has also been established for the related MP4_FF_1 format.

Notes Explanation of format description terms

General

Annex A of the ISO_BMFF specification (both versions) provides a narrative overiew of the format and its structure. Meanwhile, the specification for MJP2_FF states that there is "a family of specifications with common formatting. The other family members include the JPEG2000 single image format, JP2; the MPEG-4 file format, MP4; and the QuickTime file format, on which MP4 and this specification are based. These specifications [for MJP2_FF] share a common definition for the structure of a file (a sequence of objects, called boxes here and atoms in MP4 and QuickTime), and a common definition of the general structure of an object (the size and type)."

History As indicated in the preceding note, ISO_BMCC is derived from Apple's QuickTime. The Apple connection was celebrated in an item in MacWeek, February 16, 1998: "QuickTime received a ringing endorsement last week when a consortium of high-tech companies announced that the International Organization for Standardization, better known as ISO, had adopted QuickTime's file format as a centerpiece of MPEG-4, the forthcoming multimedia standard." (http://www.findarticles.com/p/articles/mi_m0MWK/is_n7_v12/ai_20331478)

Format specifications Explanation of format description terms


Useful references

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Last Updated: 08/31/2013