In the same week as the Tour de France, Ireland hosted a meeting of one of the world's most important multimedia technology groups, MPEG (Moving Pictures Experts Group).
This comparatively low-key event, in terms of publicity, traffic disruption and variety of colourful outfits, was held in Dublin Castle and hosted by Teltec Ireland and RTE on behalf of the National Standards Authority of Ireland. See panel for the background.
MPEG has established standards which are widely used commercially: in interactive CD's, in digital audio broadcasting and digital television and in many video-on-demand trials.
These existing standards improve the compression of AV (audio-visual) material in order to provide more efficient storage and transmission; they have dealt mainly with content created using the traditional `camera and microphone' approach.
In this approach, the level of interactivity allowed is limited to the temporal: playing forwards and backwards at variable speed. Re-use of the content is usually limited to taking a linear piece of video and its associated audio and inserting that into another application. Integration of natural and synthetic content in the same application is difficult and the MPEG compression algorithms designed for `natural' video and audio perform poorly on synthetic material.
Moving beyond the old MPEG-1 and MPEG-2 standards, which revolutionised the multimedia and digital television industries, MPEG is currently completing work on a new AV standard, MPEG-4. The purpose of the Dublin meeting was to complete the MPEG-4 specification, which will be made an International Standard in early 1999, and to move on and attempt the specification of the future MPEG-7 standard. The alert reader needn't wonder what happened to MPEG-3, MPEG-5 and MPEG-6; they don't exist.
MPEG-4 was developed in response to changes in the way in which AV material is being produced, delivered, and consumed. MPEG-4 moves away from the staid video frame with associated audio and concentrates on unified AV objects and scenes. An AV object is an object created by associating a video object and an audio object: for instance a presenter and her dialogue. AV scenes are composed of natural AV objects and synthetic AV objects (computer-generated). These scenes are described using a text-like language called Binary Format for Scenes (BIFS). Exciting application areas for MPEG-4 include, among many others:
Real-time communication systems: requiring strict audio and video synchronisation over networks of varying quality.
Infotainment: where users can get information about subjects of interest in a multimedia environment.
Augmented Reality - an environment in which one perceives both `real' and synthetic objects in a seamless way.
Initial specification of the future MPEG-7 standard was a second priority of the Dublin meeting. MPEG-7 is intended to help AV locate content, as no generally recognised description of this material exists and search engines are text-based. One can't search the Web for "twenty minutes of video according to my specific preferences".
Solutions are being developed, however. Multimedia databases on the market today allow searching for pictures using characteristics like colour, texture and information about the shape of objects in the picture. One could envisage a similar example for audio, in which one could whistle a melody to find a song.
The new member of the MPEG family, MPEG-7, called "Multimedia Content Description Interface", will extend the limited capabilities of today's proprietary solutions in identifying content.
MPEG-7 will specify a standard set of descriptors that can be used to describe various types of multimedia information. This description will be associated with the content itself, to allow fast and efficient searching for material of interest. AV material, with MPEG-7 data associated with it, can be indexed and located in a search.
The material may include: still pictures, graphics, 3-D models, audio, speech, video, and, crucially, information about how these elements are combined.
MPEG-7 could be used in:
Digital libraries (e.g. image catalogue, musical dictionary).
Multimedia directory services (e.g. yellow pages).
Broadcast media selection (i.e. radio channel, TV channel ...).
Multimedia editing (personalised electronic news service).
The importance of the new standard is clear when you consider the potential applications. Two examples of many are: a journalist searching for information about a politician using his name, his voice or his face and a keen shopper searching for clothes of exactly the right colour and shape.
In summary then, the first true multimedia data representation standard, MPEG-4 allows the integration of different types of data, with a representation that is optimised for each data type, providing the user with a powerful way to interact with the content and control the way information is presented.
MPEG-7 represents a powerful complementary standard by providing a way of describing the separate types of multimedia information in order to allow efficient multimedia searches and retrievals.
Eddie Cooke is at cooke@hhi.de