Last update: 2011/08/21
The technologies that are used to interact with digital media
The user interface is a very important component of Digital Media devices and services. The sleek user interface offered by Apple products is quoted as a key element for their success.
Recently user interfaces have evolved in two main directions: inclusion of more media types such as audio, video, 2D/3D graphics and rich media functionalities, and aggregating small dedicated applications called Widgets to create effective and user friendly interfaces. The "atomic" nature of widgets promises to provide users with homogeneous and unified experiences when they interact with their heterogeneous devices such as desktop computers, mobile devices, home appliances, TVs, STBs, tablets etc.
ISO/IEC 23007, also known as MPEG-U, defines a specification for the exchange, the control and the communication of widgets with other entities. The standard is an extensions of the W3C specification for widgets packaging and configuration to support the following functionalities:
Compatibility of the widget packaging format and configuration documents with the MPEG media types
Transportability of widgets on any existing transport mechanisms (particularly MPEG file format and MPEG-2 TS)
Applicability to domains other than Web (e.g. broadcast, mobile or home networking)
Ability of a widget to communicate with other entities (including widgets) that are either remote or running in the same environment
Ability to dynamically update the widget presentation or to display a widget in a dynamic and interactive simplified representation
Mobility across devices while maintaining the state of the widget.
A definition of MPEG-U widget is “a self-contained computer code within a Rich Media User Interface endowed with extensive communication capabilities”.
Widgets can be processed by entities running on different devices, called Widget Managers, in charge of managing the life cycle of the widgets supporting communications with other entities locally or remotely deployed and enabling widget mobility across devices.
MPEG-U specifies normative interfaces between Widgets and Widget Managers, to allow Widgets from different service providers to run, communicate and be transferred within a unique framework.
The main elements of a Widget environment are:
| Element | Definition |
| Manager | the Widget “decoder” in charge of executing the Widget, communicating with Widgets or other entities |
| Manifest | a XML description containing all the information necessary for the Manager to process the Widget |
| Scene Description | description of a multimedia presentation in terms of spatiotemporal layout, and interactions for use by the Widget |
| Presentation Engine | entity processing the Scene Description to provide an animated and interactive behaviour for the Widget |
| Resource | A component of a Widget Manager or Presentation Engine required as a file or a stream to process and present the Widget |
| Package | Assembly of Manifest and associated Resources formatted for a particular transport (network or storage) |
| Context | set of data needed to reproduce a state and preferences of a widget, e.g. after it is deactivated/reactivated, possibly by a different Manager |
| Representation | Full or Simplified description of the widget appearance and behaviour, expressed in a Scene Description language |
The following walkthrough can be used to highlight the role of the elements defined above:
A graphical description of the MPEG-U components is provided by Fig. 1
Fig. 1 – A graphical description of the MPEG-U components
