MPEG-21 Vision, Technology, and Strategy

Today, many elements exist to build an infrastructure for the delivery and consumption of multimedia content. There is, however, no 'big picture' to describe how these elements, either in existence or under development, relate to each other. The aim for MPEG-21 is to describe how these various elements fit together. Where gaps exist, MPEG-21 will recommend which new standards are required. ISO/IEC JTC 1/SC 29/WG 11 (MPEG) will then develop new standards as appropriate while other relevant standards may be developed by other bodies. These specifications will be integrated into the multimedia framework through collaboration between MPEG and these bodies.

Thus, the vision for MPEG-21 is to define a multimedia framework to enable transparent and augmented use of multimedia resources across a wide range of networks and devices used by different communities.

Figure shows the timeline of the current MPEG-21 achievements.

Digital Items

A Digital Item is a structured digital object with a standard representation, identification and metadata within the MPEG-21 framework. This entity is the fundamental unit of distribution and transaction within this framework.

In practice, a Digital Item is a combination of resources, metadata, and structure. The resources are the individual assets or (distributed) resources. The metadata comprises informational data about or pertaining to the Digital Item as a whole or to the individual resources included in the Digital Item. Finally, the structure relates to the relationships among the parts of the Digital Item, both resources and metadata.

An example of a Digital Item may be a movie compilation including the movie but also photos, a soundtrack and lyrics thereof, animation graphics, scores, a “making of” including interviews with the actors, news related to the movie, statements by an opinion maker, ratings of an agency, position in the hit list, navigational information driven by user preferences, bargains, etc.

Users

In MPEG-21 a User (with capitalized “U”) is any entity that interacts in the MPEG-21 environment or makes use of Digital Items. Such Users, e.g., include individuals, consumers, communities, organizations, corporations, consortia, and governments or even software agents. Users are identified specifically by their relationship to another User for a certain interaction. From a purely technical perspective, MPEG-21 makes no distinction between a “resource provider” and a “consumer”—both are Users. A single entity may use a resource in many ways (publish, deliver, consume, etc.), and so all parties interacting within MPEG-21 are categorized as Users equally. However, a User may assume specific rights and responsibilities according to their interaction with other Users within MPEG-21.

At its most basic level, MPEG-21 can be seen as providing a framework in which one User interacts with another User and the object of that interaction is a Digital Item (Figure ).

Some such interactions are creating resources, providing resources, modifying resources, archiving resources, rating resources, enhancing and delivering resources, aggregating resources, delivering resources, syndicating resources, retail selling of resources, consuming resources, subscribing to resources, regulating resources, facilitating transactions that occur from any of the above, and regulating transactions that occur from any of the above. Any of these are “uses” of MPEG-21, and the parties involved are Users.

Resources

Within MPEG-21 a resource is defined as an individually identifiable asset such as a video or audio clip, an image, or a textual asset. Hence, terms like multimedia content, media data, image, graphics, video, movie, visual content, audio data, speech content, etc. become unnecessary and should be avoided in the context of MPEG-21 when referring to resources with no specific context.