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).[1][2][3][4][5][6]

MPEG-21 is based on two essential concepts:

  • definition of a Digital Item (a fundamental unit of distribution and transaction)
  • users interacting with Digital Items

Digital Items can be considered the kernel of the Multimedia Framework and the users can be considered as who interacts with them inside the Multimedia Framework. At its most basic level, MPEG-21 provides a framework in which one user interacts with another one, and the object of that interaction is a Digital Item. Due to that, we could say that the main objective of the MPEG-21 is to define the technology needed to support users to exchange, access, consume, trade or manipulate Digital Items in an efficient and transparent way.

MPEG-21 Part 9: File Format defined the storage of an MPEG-21 Digital Item in a file format based on the ISO base media file format, with some or all of Digital Item's ancillary data (such as movies, images or other non-XML data) within the same file.[7] It uses filename extensions .m21 or .mp21 and MIME type application/mp21.[8]

Digital Rights Management

MPEG-21 defines also a "Rights Expression Language" standard as means of managing restrictions for digital content usage. As an XML-based standard, MPEG-21 is designed to communicate machine-readable license information and do so in a "ubiquitous, unambiguous and secure" manner.

Among the aspirations for this standard, that the industry hope will put an end to file sharing, is that it will constitute: "A normative open framework for multimedia delivery and consumption for use by all the players in the delivery and consumption chain. This open framework will provide content creators, producers, distributors and service providers with equal opportunities in the MPEG-21 enabled open market."

See also


  1. ^ ISO. "ISO/IEC TR 21000-1:2004 - Information technology -- Multimedia framework (MPEG-21) -- Part 1: Vision, Technologies and Strategy". Retrieved 2017-08-30.
  2. ^ ISO. "ISO/IEC 21000-2:2005 - Information technology -- Multimedia framework (MPEG-21) -- Part 2: Digital Item Declaration". Retrieved 2017-08-30.
  3. ^ ISO. "ISO/IEC 21000-3:2003 - Information technology -- Multimedia framework (MPEG-21) -- Part 3: Digital Item Identification". Retrieved 2017-08-30.
  4. ^ MPEG. "About MPEG - Achievements". Archived from the original on July 8, 2008. Retrieved 2009-10-31.
  5. ^ MPEG. "Terms of Reference". Archived from the original on February 21, 2010. Retrieved 2009-10-31.
  6. ^ MPEG. "MPEG standards". Archived from the original on April 20, 2010. Retrieved 2009-10-31.
  7. ^ ISO (2006). "MPEG-21 File Format white paper - Proposal". Retrieved 2010-08-20.
  8. ^ ISO/IEC 21000-9 First edition, 2005-07-01, AMENDMENT 1 2008-10-01, Information technology — Multimedia framework (MPEG-21) — Part 9: File Format AMENDMENT 1: MIME type registration (PDF), retrieved 2010-08-20

Further reading

External links

Acoustic fingerprint

An acoustic fingerprint is a condensed digital summary, a fingerprint, deterministically generated from an audio signal, that can be used to identify an audio sample or quickly locate similar items in an audio database.Practical uses of acoustic fingerprinting include identifying songs, melodies, tunes, or advertisements; sound effect library management; and video file identification. Media identification using acoustic fingerprints can be used to monitor the use of specific musical works and performances on radio broadcast, records, CDs, streaming media and peer-to-peer networks. This identification has been used in copyright compliance, licensing, and other monetization schemes.


AXMEDIS is a set of European Union digital content standards, initially created as a research project running from 2004 to 2008 partially supported by the European Commission under the Information Society Technologies (IST DG-INFSO) programme of the Sixth Framework Programme (FP6). It stands for "Automating Production of Cross Media Content for Multi-channel Distribution". Now it is distributed as a framework, and is still being maintained and improved. A large part of the framework is under open source licensing. The AXMEDIS framework includes a set of tools, models, test cases, documents, etc. supporting the production and distribution of cross media content.


For the architectural modelling technique see Building information modelingBiM (Binary MPEG format for XML) is an international standard defining a generic binary format for encoding XML documents.

The technical specifications for BiM are found in: MPEG systems technologies - Part 1: Binary MPEG format for XML (ISO/IEC 23001-1) It is also known as MPEG-B Part 1.

Comparison of audio player software

The following comparison of audio players compares general and technical information for a number of software media player programs. For the purpose of this comparison, "audio players" are defined as any media player explicitly designed to play audio files, with limited or no support for video playback. Multi-media players designed for video playback, which can also play music, are included under comparison of video player software.

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.

A Digital Item may be a combination of resources like videos, audio tracks or images; metadata, such as descriptors and identifiers; and structure for describing the relationships between the resources.

It is becoming difficult for users of content to identify and interpret the different intellectual property rights that are associated with the elements of multimedia content. For this reason, new solutions are required for the access, delivery, management and protection of this content.

Douglas Armati

Douglas "Doug" Armati (born 1950) is an Australian writer, researcher, consultant, business development executive and technical diplomat.

Doug Armati undertook research work on digital copyright issues at Murdoch University in Western Australia in 1990–91 before taking a role in international efforts to standardize the identification of digital objects.

After a speech on the importance and potential economic benefits of uniform approach to identification of digitized copyright content to the International Association of Scientific, Technical, and Medical Publishers at the Frankfurt Book Fair in October 1994 he wrote two pivotal reports in 1995 – the first for the STM group on Information Identification and the second for the Association of American Publishers on Uniform File Identifiers. Armati's work for these global publishing bodies was an important catalyst for the birth of the Digital Object Identifier Foundation.

His 1996 speech at the joint ICSU/UNESCO Electronic Publishing in Science conference in Paris on "Tools and standards for protection, control and archiving" and his book later that year on "Intellectual Property in Electronic Environments" both helped frame the legal, scientific and technical debate in the emerging field of Digital Rights Management. Armati was also part of the digital copyright experts group that worked closely with the World Intellectual Property Organization in the period leading up to the ratification of the WIPO Copyright Treaty in December 1996.

In 1996 Armati joined InterTrust Technologies, the leading company in the then nascent field of Digital Rights Management, where he was a member of the leadership group through the company's 1999 IPO until its sale to Sony and Philips in early 2003.

During his time with InterTrust, Armati was also active in international standards groups, having been a vice-chairman of the Recording Industry Association of America's international Secure Digital Music Initiative, a board member of the Open eBook Forum (now the International Digital Publishing Forum) and a significant contributor to the Moving Picture Experts Group (MPEG), particularly in the development of a standard for the management and protection of intellectual property in MPEG-4, MPEG-7 and MPEG-21.


G.723 is an ITU-T standard speech codec using extensions of G.721 providing voice quality covering 300 Hz to 3400 Hz using Adaptive Differential Pulse Code Modulation (ADPCM) to 24 and 40 kbit/s for digital circuit multiplication equipment (DCME) applications. The standard G.723 is obsolete and has been superseded by G.726.

Note that this is a completely different codec from G.723.1.

ISO base media file format

ISO base media file format (ISO/IEC 14496-12 – MPEG-4 Part 12) defines a general structure for time-based multimedia files such as video and audio.

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. It is used as the basis for other media file formats (e.g. container formats MP4 and 3GP).

List of XML markup languages

This is a list of notable XML markup languages.


MPEG-4 is a method of defining compression of audio and visual (AV) 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 (MPEG) (ISO/IEC JTC1/SC29/WG11) under the formal standard ISO/IEC 14496 – Coding of audio-visual objects. Uses of MPEG-4 include compression of AV data for web (streaming media) and CD distribution, voice (telephone, videophone) and broadcast television applications.


MPEG-7 is a multimedia content description standard. It was standardized in ISO/IEC 15938 (Multimedia content description interface). This description will be associated with the content itself, to allow fast and efficient searching for material that is of interest to the user. MPEG-7 is formally called Multimedia Content Description Interface. Thus, it is not a standard which deals with the actual encoding of moving pictures and audio, like MPEG-1, MPEG-2 and MPEG-4. It uses XML to store metadata, and can be attached to timecode in order to tag particular events, or synchronise lyrics to a song, for example.

It was designed to standardize:

a set of Description Schemes ("DS") and Descriptors ("D")

a language to specify these schemes, called the Description Definition Language ("DDL")

a scheme for coding the descriptionThe combination of MPEG-4 and MPEG-7 has been sometimes referred to as MPEG-47.

MPEG Industry Forum

The MPEG Industry Forum (MPEGIF) is a non-profit consortium dedicated to "further the adoption of MPEG Standards, by establishing them as well accepted and widely used standards among creators of content, developers, manufacturers, providers of services, and end users."

The group is involved in many tasks, including promotion of MPEG standards (particularly MPEG-4, MPEG-4 AVC / H.264, MPEG-7 and MPEG-21); developing MPEG certification for products; organising educational events; and collaborating on development of new de facto MPEG standards.

MPEGIF, founded in 2000, has played a significant role in facilitating the widespread adoption and deployment of MPEG-4 AVC/H.264 as the industry’s standard video compression technology powering next generation television and most mainstream content delivery and consumption applications including packaged media. MPEGIF serves as a single point of information on technology, products and services for these standards, offers interoperability testing, a conformance program, marketing activities and is supporting over 50 international trade shows and conferences per year.

The key activities of the forum are structured via three main Committees:

Technology & Engineering

Interoperability & Compliance

Marketing & Communication

Moving Picture Experts Group

The Moving Picture Experts Group (MPEG) is a working group of authorities that was formed by ISO and IEC to set standards for audio and video compression and transmission. It was established in 1988 by the initiative of Hiroshi Yasuda (Nippon Telegraph and Telephone) and Leonardo Chiariglione, group Chair since its inception. The first MPEG meeting was in May 1988 in Ottawa, Canada. As of late 2005, MPEG has grown to include approximately 350 members per meeting from various industries, universities, and research institutions. MPEG's official designation is ISO/IEC JTC 1/SC 29/WG 11 – Coding of moving pictures and audio (ISO/IEC Joint Technical Committee 1, Subcommittee 29, Working Group 11).


mp3PRO is an unmaintained proprietary audio compression codec that combines the MP3 audio format with the spectral band replication (SBR) compression method. At the time it was developed it could reduce the size of a stereo MP3 by as much as 50% while maintaining the same relative quality. This works, fundamentally, by discarding the higher half of the frequency range and algorithmically replicating that information while decoding.

The technology behind SBR was developed by the former Swedish company Coding Technologies AB (acquired by Dolby Laboratories in 2007) in the late 1990s. It was included in their MPEG-2 AAC derived codec aacPlus, which would later be standardized as MPEG-4 HE-AAC. Thomson Multimedia (now Technicolor SA) licensed the technology and used it to extend the MP3 format, for which they held patents, hoping to also extend its profitable lifetime. This was released as mp3PRO in 2001.It was originally claimed that mp3PRO files were compatible with existing MP3 decoders, and that the SBR data could simply be ignored. The reality was that MP3 players lacking specific mp3PRO decoding capability experienced a significant reduction in audio quality when playing mp3PRO files as only the lower half of the original frequency range is available.mp3PRO development has been abandoned. The format was never standardized and there is no publicly available reference source code or documentation in existence. A very old software encoder/player exists, but is not maintained. Nero's Soundtrax application, bundled in the Nero Multimedia Suite, is capable of encoding and decoding this format into several others. Some versions of the outdated MusicMatch Jukebox player were able to decode and encode this format, too. In the early 2000s, mp3PRO was usable in several portable music players and in popular music software, but its market share has deteriorated rapidly. The codec itself is largely surpassed in quality and efficiency, as well as device and application support, by modern codecs like AAC and its HE-AAC variants which employ the same SBR method.


The Open Digital Rights Language (ODRL) is a policy expression language that provides a flexible and interoperable information model, vocabulary, and encoding mechanisms for representing statements about the usage of content and services.

An example of ODRL policy follows, which can be intepreted as "John can play mysong.mp3".

Registration authority

Registration authorities exist for many standards organizations, such as ANNA (Association of National Numbering Agencies for ISIN), the Object Management Group, W3C, IEEE and others. In general, registration authorities all perform a similar function, in promoting the use of a particular standard through facilitating its use. This may be by applying the standard, where appropriate, or by verifying that a particular application satisfies the standard's tenants. Maintenance agencies, in contrast, may change an element in a standard based on set rules – such as the creation or change of a currency code when a currency is created or revalued (i.e. TRL to TRY for Turkish lira). The Object Management Group has an additional concept of certified provider, which is deemed an entity permitted to perform some functions on behalf of the registration authority, under specific processes and procedures documented within the standard for such a role.

An ISO registration authority (RAs) is not authorized to update standards but provides a registration function to facilitate implementation of an International Standard (e.g. ISBN number for books). Frequently, facilitating the implementation of an ISO standard’s requirements is best suited, by its nature, to one entity, an RA. This, de facto, creates a monopoly situation and this is why care needs to be taken with respect to the functions carried out and the fees charged to avoid an abuse of such a situation. In most cases, there is a formal legal contract in place between the standards body, such as the ISO General Secretariat, and the selected registration authority.

ISO registration authorities differ from a maintenance agency. Maintenance agencies are authorized to update particular elements in an International Standard and as a matter of policy, the secretariats of MAs are assigned to bodies forming part of the ISO system (member bodies or organizations to which a member body delegates certain tasks in its country). The membership of MAs and their operating procedures are subject to approval by the Technical Management Board.

While registration authorities for a particular standard typically do not change, the position is not formally guaranteed and is subject to review and reassignment to a different firm or organization. In some cases, the concept of a registration authority may not exist for a standard at all.

By further example, the equivalent registration authority organization for Internet standards is the Internet Assigned Numbers Authority.

Rights Expression Language

A Rights Expression Language or REL is a machine-processable language used to express intellectual property rights (such as copyright) and other terms and conditions for use over content. RELs can be used as standalone expressions (i.e. metadata usable for search, compatibility tracking) or within a DRM system.

RELs are expressible in a machine-language (such as XML, RDF , RDF Schema, and JSON). Although RELs may be processed directly, they can also be encountered when embedded as metadata within other documents, such as eBooks, image, audio or video files.


XrML is the eXtensible Rights Markup Language which has also been standardized as the Rights Expression Language (REL) for MPEG-21. XrML is owned by ContentGuard.

XrML is based on XML and describes rights, fees and conditions together with message integrity and entity authentication information.

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