ISO base media file format
Encyclopedia
ISO base media file format defines a general structure for time-based multimedia
files such as video and audio. It is used as the basis for other media file format
s (e.g. container formats MP4 and 3GP
). ISO base media file format was specified as ISO
/IEC
14496-12 (MPEG-4 Part 12).
The identical text is published as ISO/IEC 15444-12 (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.
’s QuickTime container format
and was generalized from MP4 file format. It was developed by MPEG (ISO/IEC JTC1
/SC29/WG11). 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 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, Motion JPEG 2000).
The MP4 file format (ISO/IEC 14496-14) defined some extensions over 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. Some of these extensions are used by other formats based on ISO base media file format (e.g. 3GP). The 3GPP file format (.3gp) specification also defined extensions, to support H.263
video, AMR-NB, AMR-WB
, AMR-WB+
audio and 3GPP Timed Text in files based on the ISO base media file format. The 3GPP2 file format (.3g2) defined extensions for usage of EVRC
, SMV
or 13K (QCELP
) voice compression formats. The JPEG 2000
specification (ISO/IEC 15444-3) defined usage of Motion JPEG 2000 video compression and uncompressed audio (PCM
) in ISO base media file format (.mj2). The "DVB File Format" (.dvb) defined by DVB Project allowed storage of DVB services in the ISO base media file format. It allows the storage of audio, video and other content in any of three main ways: encapsulated in a MPEG transport stream, stored as a reception hint track; encapsulated in an RTP
stream, stored as a reception hint track or stored directly as media tracks. The MPEG-21
File Format (.m21, .mp21) defined the storage of an MPEG-21 Digital Item
in ISO base media file format, with some or all of its ancillary data (such as movies, images or other non-XML data) within the same file. The OMA DRM
Content Format (.dcf) specification from Open Mobile Alliance
defined the content format for DRM
protected encrypted media objects and associated metadata. There are also other extensions, such as ISMA
ISMACryp
specification for encrypted/protected audio and video, G.719
audio compression specification, AC3 and E-AC-3 audio compression, DTS audio compression, Dirac
video compression, VC-1
video compression specification and others, which are named on the MP4 Registration authority's website.
There are some extensions over ISO base media file format, which were not registered by the MP4 Registration authority. Adobe Systems introduced in 2007 new F4V file format for Flash Video and declared that it is based on the ISO base media file format. The F4V file format was not registered by the MP4 registration authority, but the F4V technical specification is publicly available. This format can contain H.264 video compression and MP3 or AAC audio compression. In addition, F4V file format can contain data corresponding to the ActionScript Message Format
and still frame of video data using image formats GIF
, JPEG and PNG.
Microsoft Corporation announced in 2009 a file format based on the ISO base media file format — ISMV (Smooth Streaming format), also known as Protected Interoperable File Format (PIFF). As announced, this format can for example contain VC-1, WMA
, H.264 and AAC compression formats. Microsoft published a Protected Interoperable File Format (PIFF) specification in 2010. It defined another usage of multiple encryption and DRM systems in a single file container. PIFF brand was registered by the MP4 registration authority in 2010. Some extensions used by this format (e.g. for WMA support) were not registered. Usage of WMA compression format in ISO base media file format was not publicly documented so it’s possible that they may be unsupported by some platforms.
Files conforming to the ISO base media file format are formed as a series of objects, called "boxes". All data is contained in boxes and there is no other data within the file. This includes any initial signature required by the specific file format. The "box" is object-oriented building block defined by a unique type identifier and length. It was called "atom" in some specifications (e.g. the first definition of MP4 file format).
A presentation (motion sequence) may be contained in several files. All timing and framing (position and size) information must be in the ISO base media file and the ancillary files may essentially use any format. They must be only capable of description by the metadata defined in ISO base media file format.
code, used for a similar purpose for media embedded in AVI
container format. A brand might indicate the type of encoding used, how the data of each encoding is stored, constraints and extensions that are applied to the file, the compatibility, or the intended usage of the file. Brands are a printable four-character codes. A File Type Box contains two kinds of brands. One is "major_brand" which identifies the specification of the best use for the file. It is followed by "minor_version", an informative 4 bytes integer for the minor version of the major brand. The second kind of brand is "compatible_brands", which identifies multiple specifications to which the file complies. All files shall contain a File Type Box, but for compatibility reasons with an earlier version of the specification, files may be conformant to ISO base media file format and not contain a File Type Box. In that case they should be read as if they contained an ftyp with major and compatible brand "mp41" (MP4 v1 - ISO 14496-1, Chapter 13). Many in-use brands (ftyps) are not registered and can be found on some webpages.
A multimedia file structured upon ISO base media file format may be compatible with more than one concrete specification, and it is therefore not always possible to speak of a single "type" or "brand" for the file. In this regard, the utility of the Multipurpose Internet Mail Extension type and file name extension is somewhat reduced. In spite of that, when a derived specification is written, a new file extension will be used, a new MIME type and a new Macintosh file type.
of media data over a network as well as local playback. A file that supports streaming includes information about the data units to stream (how to serve the elementary stream
data in the file over streaming protocols). This information is placed in additional tracks of the file called "hint" tracks. Separate "hint" tracks for different protocols may be included within the same file. The media will play over all such protocols without making any additional copies or versions of the media data. Existing media can be easily made streamable for other specific protocols by the addition of an appropriate hint tracks. The media data itself need not be reformatted in any way. The streams sent by the servers under the direction of the hint tracks, need contain no trace of file-specific information. When the presentation is played back locally (not streamed), the hint tracks may be ignored. Hint tracks may be created by an authoring tool, or may be added to an existing file (presentation) by a hinting tool. In media authored for progressive download the moov atom, which contains the index of frames should precede the movie data mdat atom.
Multimedia
Multimedia is media and content that uses a combination of different content forms. The term can be used as a noun or as an adjective describing a medium as having multiple content forms. The term is used in contrast to media which use only rudimentary computer display such as text-only, or...
files such as video and audio. It is used as the basis for other media file format
File format
A file format is a particular way that information is encoded for storage in a computer file.Since a disk drive, or indeed any computer storage, can store only bits, the computer must have some way of converting information to 0s and 1s and vice-versa. There are different kinds of formats for...
s (e.g. container formats MP4 and 3GP
3GP
3GP is a multimedia container format defined by the Third Generation Partnership Project for 3G UMTS multimedia services. It is used on 3G mobile phones but can also be played on some 2G and 4G phones....
). ISO base media file format was specified as ISO
International Organization for Standardization
The International Organization for Standardization , widely known as ISO, is an international standard-setting body composed of representatives from various national standards organizations. Founded on February 23, 1947, the organization promulgates worldwide proprietary, industrial and commercial...
/IEC
International Electrotechnical Commission
The International Electrotechnical Commission is a non-profit, non-governmental international standards organization that prepares and publishes International Standards for all electrical, electronic and related technologies – collectively known as "electrotechnology"...
14496-12 (MPEG-4 Part 12).
The identical text is published as ISO/IEC 15444-12 (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.
History
ISO base media file format is directly based on AppleApple Computer
Apple Inc. is an American multinational corporation that designs and markets consumer electronics, computer software, and personal computers. The company's best-known hardware products include the Macintosh line of computers, the iPod, the iPhone and the iPad...
’s QuickTime container format
QuickTime File Format
QuickTime File Format is a computer file format used natively by the QuickTime framework.- Design :The format specifies a multimedia container file that contains one or more tracks, each of which stores a particular type of data: audio, video, effects, or text...
and was generalized from MP4 file format. It was developed by MPEG (ISO/IEC JTC1
ISO/IEC JTC1
ISO/IEC JTC 1 is Joint Technical Committee 1 of the International Organization for Standardization and the International Electrotechnical Commission . It deals with all matters of information technology....
/SC29/WG11). 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 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, Motion JPEG 2000).
| Edition | Release date | Latest amendment | Standard | Description |
|---|---|---|---|---|
| First edition | 2004 | ISO/IEC 14496-12:2004, ISO/IEC 15444-12:2004 | ||
| Second edition | 2005 | 2008 | ISO/IEC 14496-12:2005, ISO/IEC 15444-12:2005 | |
| Third edition | 2008 | 2009 (next expected in 2011) | ISO/IEC 14496-12:2008, ISO/IEC 15444-12:2008 |
Extensions
The ISO base media file format is designed as extensible file format. List of all registered extensions for 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 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.The MP4 file format (ISO/IEC 14496-14) defined some extensions over ISO base media file format to support MPEG-4
MPEG-4
MPEG-4 is a method of defining compression of audio and visual digital data. It was introduced in late 1998 and designated a standard for a group of audio and video coding formats and related technology agreed upon by the ISO/IEC Moving Picture Experts Group under the formal standard ISO/IEC...
visual/audio codecs and various MPEG-4 Systems features such as object descriptors and scene descriptions. The MPEG-4 Part 3
MPEG-4 Part 3
MPEG-4 Part 3 or MPEG-4 Audio is the third part of the ISO/IEC MPEG-4 international standard developed by Moving Picture Experts Group. It specifies audio coding methods...
(MPEG-4 Audio) standard also defined storage of some audio compression formats. Storage of MPEG-1/2 Audio (MP3
MP3
MPEG-1 or MPEG-2 Audio Layer III, more commonly referred to as MP3, is a patented digital audio encoding format using a form of lossy data compression...
, 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
H.264/MPEG-4 AVC
H.264/MPEG-4 Part 10 or AVC is a standard for video compression, and is currently one of the most commonly used formats for the recording, compression, and distribution of high definition video...
video compression. Some of these extensions are used by other formats based on ISO base media file format (e.g. 3GP). The 3GPP file format (.3gp) specification also defined extensions, to support H.263
H.263
H.263 is a video compression standard originally designed as a low-bitrate compressed format for videoconferencing. It was developed by the ITU-T Video Coding Experts Group in a project ending in 1995/1996 as one member of the H.26x family of video coding standards in the domain of the ITU-T.H.263...
video, AMR-NB, AMR-WB
AMR-WB
Adaptive Multi-Rate Wideband is a patented speech coding standard developed based on Adaptive Multi-Rate encoding, using similar methodology as Algebraic Code Excited Linear Prediction...
, AMR-WB+
AMR-WB+
Extended Adaptive Multi-Rate – Wideband is an audio codec that extends AMR-WB. It adds support for stereo signals and higher sampling rates. Another main improvement is the use of transform coding additionally to ACELP. This greatly improves the generic audio coding...
audio and 3GPP Timed Text in files based on the ISO base media file format. The 3GPP2 file format (.3g2) defined extensions for usage of EVRC
EVRC
Enhanced Variable Rate CODEC is a speech codec used in CDMA networks. It was developed in 1995 to replace the QCELP vocoder which used more bandwidth on the carrier's network, thus EVRC's primary goal was to offer the mobile carriers more capacity on their networks while not increasing the amount...
, SMV
SMV
Selectable Mode Vocoder is variable bitrate speech coding standard used in CDMA2000 networks. SMV provides multiple modes of operation that are selected based on input speech characteristics....
or 13K (QCELP
QCELP
Qualcomm code-excited linear prediction , also known as Qualcomm PureVoice, is a speech codec developed in 1994 by Qualcomm to increase the speech quality of the IS-96A codec earlier used in CDMA networks. It was later replaced with EVRC since it provides better speech quality with fewer bits...
) voice compression formats. The JPEG 2000
JPEG 2000
JPEG 2000 is an image compression standard and coding system. It was created by the Joint Photographic Experts Group committee in 2000 with the intention of superseding their original discrete cosine transform-based JPEG standard with a newly designed, wavelet-based method...
specification (ISO/IEC 15444-3) defined usage of Motion JPEG 2000 video compression and uncompressed audio (PCM
Pulse-code modulation
Pulse-code modulation is a method used to digitally represent sampled analog signals. It is the standard form for digital audio in computers and various Blu-ray, Compact Disc and DVD formats, as well as other uses such as digital telephone systems...
) in ISO base media file format (.mj2). The "DVB File Format" (.dvb) defined by DVB Project allowed storage of DVB services in the ISO base media file format. It allows the storage of audio, video and other content in any of three main ways: encapsulated in a MPEG transport stream, stored as a reception hint track; encapsulated in an RTP
Real-time Transport Protocol
The Real-time Transport Protocol defines a standardized packet format for delivering audio and video over IP networks. RTP is used extensively in communication and entertainment systems that involve streaming media, such as telephony, video teleconference applications, television services and...
stream, stored as a reception hint track or stored directly as media tracks. The MPEG-21
MPEG-21
The MPEG-21 standard, from the Moving Picture Experts Group, aims at defining an open framework for multimedia applications. MPEG-21 is ratified in the standards ISO/IEC 21000 - Multimedia framework .MPEG-21 is based on two essential concepts:...
File Format (.m21, .mp21) defined the storage of an MPEG-21 Digital Item
Digital Item
Digital Item is the basic unit of transaction in the MPEG-21 framework. It is a structured digital object, including a standard representation, identification and metadata....
in ISO base media file format, with some or all of its ancillary data (such as movies, images or other non-XML data) within the same file. The OMA DRM
OMA DRM
OMA DRM is a Digital Rights Management system invented by the Open Mobile Alliance, whose members represent mobile phone manufacturers , mobile system manufacturers , mobile phone network operators OMA DRM is a Digital Rights Management (DRM) system invented by the Open Mobile Alliance, whose...
Content Format (.dcf) specification from Open Mobile Alliance
Open Mobile Alliance
The Open Mobile Alliance is a standards body which develops open standards for the mobile phone industry.- Principles :Mission: To provide interoperable service enablers working across countries, operators and mobile terminals....
defined the content format for DRM
Digital rights management
Digital rights management is a class of access control technologies that are used by hardware manufacturers, publishers, copyright holders and individuals with the intent to limit the use of digital content and devices after sale. DRM is any technology that inhibits uses of digital content that...
protected encrypted media objects and associated metadata. There are also other extensions, such as ISMA
Internet Streaming Media Alliance
The Internet Streaming Media Alliance was Founded in December 2000, by Apple Computer, Cisco Systems, IBM, Kasenna, Philips, and Sun Microsystems. It is a non-profit corporation whose mission is to accelerate the market adoption of open standards for streaming and progressive download of rich...
ISMACryp
ISMACryp
The ISMA Encryption and Authentication, Version 1.1 specification specifies encryption and message authentication services for MPEG-4 over RTP streams...
specification for encrypted/protected audio and video, G.719
G.719
G.719 is an ITU-T standard audio codec providing high quality, moderate bit rate wideband audio coding at low computational load...
audio compression specification, AC3 and E-AC-3 audio compression, DTS audio compression, Dirac
Dirac (codec)
Dirac is an open and royalty-free video compression format, specification and system developed by BBC Research at the BBC. Schrödinger and dirac-research are open and royalty-free software implementations of Dirac...
video compression, VC-1
VC-1
VC-1 is the informal name of the SMPTE 421M video codec standard, which was initially developed as a proprietary video format by Microsoft before it was released as a formal SMPTE standard video format on April 3, 2006...
video compression specification and others, which are named on the MP4 Registration authority's website.
There are some extensions over ISO base media file format, which were not registered by the MP4 Registration authority. Adobe Systems introduced in 2007 new F4V file format for Flash Video and declared that it is based on the ISO base media file format. The F4V file format was not registered by the MP4 registration authority, but the F4V technical specification is publicly available. This format can contain H.264 video compression and MP3 or AAC audio compression. In addition, F4V file format can contain data corresponding to the ActionScript Message Format
Action Message Format
Action Message Format is a binary format used to serialize objects graphs such ActionScript objects and XML, or send messages between an Adobe Flash client and a remote service, usually a Flash Media Server or third party alternatives....
and still frame of video data using image formats GIF
GIF
The Graphics Interchange Format is a bitmap image format that was introduced by CompuServe in 1987 and has since come into widespread usage on the World Wide Web due to its wide support and portability....
, JPEG and PNG.
Microsoft Corporation announced in 2009 a file format based on the ISO base media file format — ISMV (Smooth Streaming format), also known as Protected Interoperable File Format (PIFF). As announced, this format can for example contain VC-1, WMA
WMA
WMA may refer to:- Organizations :*Western Manufactured Housing Communities Association, a nonprofit trade association for owners of manufactured home communities in California*Western Marble Arch, a synagogue in central London...
, H.264 and AAC compression formats. Microsoft published a Protected Interoperable File Format (PIFF) specification in 2010. It defined another usage of multiple encryption and DRM systems in a single file container. PIFF brand was registered by the MP4 registration authority in 2010. Some extensions used by this format (e.g. for WMA support) were not registered. Usage of WMA compression format in ISO base media file format was not publicly documented so it’s possible that they may be unsupported by some platforms.
Technical details
ISO base media file format contains the timing, structure, and media information for timed sequences of media data, such as audio-visual presentations. The file structure is object-oriented. A file can be decomposed into basic objects very simply and the structure of the objects is implied from their type.Files conforming to the ISO base media file format are formed as a series of objects, called "boxes". All data is contained in boxes and there is no other data within the file. This includes any initial signature required by the specific file format. The "box" is object-oriented building block defined by a unique type identifier and length. It was called "atom" in some specifications (e.g. the first definition of MP4 file format).
A presentation (motion sequence) may be contained in several files. All timing and framing (position and size) information must be in the ISO base media file and the ancillary files may essentially use any format. They must be only capable of description by the metadata defined in ISO base media file format.
File Type Box
In order to identify the specifications to which a file based on ISO base media file format complies, brands are used as identifiers in the file format. They are set in a box named File Type Box ('ftyp'), which must be placed in the beginning of the file. It is somewhat analogous to the so-called fourccFourCC
A FourCC is a sequence of four bytes used to uniquely identify data formats.The concept originated in the OSType scheme used in the Macintosh system software and was adopted for the Amiga/Electronic Arts Interchange File Format and derivatives...
code, used for a similar purpose for media embedded in AVI
Audio Video Interleave
Audio Video Interleave , known by its acronym AVI, is a multimedia container format introduced by Microsoft in November 1992 as part of its Video for Windows technology. AVI files can contain both audio and video data in a file container that allows synchronous audio-with-video playback...
container format. A brand might indicate the type of encoding used, how the data of each encoding is stored, constraints and extensions that are applied to the file, the compatibility, or the intended usage of the file. Brands are a printable four-character codes. A File Type Box contains two kinds of brands. One is "major_brand" which identifies the specification of the best use for the file. It is followed by "minor_version", an informative 4 bytes integer for the minor version of the major brand. The second kind of brand is "compatible_brands", which identifies multiple specifications to which the file complies. All files shall contain a File Type Box, but for compatibility reasons with an earlier version of the specification, files may be conformant to ISO base media file format and not contain a File Type Box. In that case they should be read as if they contained an ftyp with major and compatible brand "mp41" (MP4 v1 - ISO 14496-1, Chapter 13). Many in-use brands (ftyps) are not registered and can be found on some webpages.
A multimedia file structured upon ISO base media file format may be compatible with more than one concrete specification, and it is therefore not always possible to speak of a single "type" or "brand" for the file. In this regard, the utility of the Multipurpose Internet Mail Extension type and file name extension is somewhat reduced. In spite of that, when a derived specification is written, a new file extension will be used, a new MIME type and a new Macintosh file type.
Streaming
The ISO base media file format supports streamingStreaming media
Streaming media is multimedia that is constantly received by and presented to an end-user while being delivered by a streaming provider.The term "presented" is used in this article in a general sense that includes audio or video playback. The name refers to the delivery method of the medium rather...
of media data over a network as well as local playback. A file that supports streaming includes information about the data units to stream (how to serve the elementary stream
Elementary stream
An elementary stream as defined by MPEG communication protocol is usually the output of an audio or video encoder. ES contains only one kind of data, e.g. audio, video or closed caption. An elementary stream is often referred to as "elementary", "data", "audio", or "video" bitstreams or streams...
data in the file over streaming protocols). This information is placed in additional tracks of the file called "hint" tracks. Separate "hint" tracks for different protocols may be included within the same file. The media will play over all such protocols without making any additional copies or versions of the media data. Existing media can be easily made streamable for other specific protocols by the addition of an appropriate hint tracks. The media data itself need not be reformatted in any way. The streams sent by the servers under the direction of the hint tracks, need contain no trace of file-specific information. When the presentation is played back locally (not streamed), the hint tracks may be ignored. Hint tracks may be created by an authoring tool, or may be added to an existing file (presentation) by a hinting tool. In media authored for progressive download the moov atom, which contains the index of frames should precede the movie data mdat atom.
External links
- RFC 4281 - The Codecs Parameter for "Bucket" Media Types