First MPEG-21 application online

The research group Multimedia Lab of the Ghent University (Belgium) succeeded in putting the first MPEG-21 application online. MPEG-21 technology is the most recently developed technology for multimedia applications. After the MPEG-1, -2, -4, and MPEG-7 standards, MPEG-21 is currently considered to be one of the most promising new standard in the field of multimedia systems and applications.

The research activities of Multimedia Lab at Ghent University, Belgium (Department of Electronics and Information Systems, Faculty of Engineering) are situated in the field of multimedia systems and applications. Several types of multimedia applications are studied: synchronously presentation of text, image, audio and video data trough the Internet; mobile multimedia applications (e.g., watching a video via a Personal Digital Assistant, or PDA); enhancing the quality of TV images; etc.

Besides, Multimedia Lab is very active in the development of the newest multimedia standards. The most important worldwide initiative in this domain is MPEG. MPEG stands for Moving Picture Experts Group and unites experts in coding and using multimedia data (e.g., audio, text, still images, video, digital TV). These experts are coming from both the industry (Sony, Intel, IBM, Microsoft, HP, IFPI, and many others) and university research groups. In the past, several very important standards have been developed by MPEG. These standards are currently widely used: MPEG-1 forms the basis for the well known MP-3 format for the storage and delivery of digital music; MPEG-4 becomes very important, e.g., in mobile applications; MPEG-7 standardizes the description of multimedia data (e.g., author, title, publisher and ISBN number of an electronic book).

The most recent standardization effort within MPEG was named MPEG-21 (or “Multimedia Framework”) and was started in June 2000. The name “Multimedia Framework” shows already that the MPEG-21 standard will become a very widely applicable standard. E.g., one of the aims is to realize integration between several already existing standards. Examples of such integration could be:

• Allowing to use different image formats within a single multimedia presentation, without having to transcode one format into another or vice versa.
• Making it possible that a video fragment can be shown on a small display of a mobile phone, and on a professional digital TV; so-called “scalability” of multimedia data is very important in this context.
• Allowing applications to modify themselves, depending on the resources that are available, e.g., by switching to a lower image resolution when the available network bandwidth is decreasing.

From the very beginning of the MPEG-21 activities on, Multimedia Lab has been an important player within these activities. In May 2002, the first official MPEG-21 standard will be presented to the international community. This standard was developed under the guidance of 6 official editors, one of them being Rik Van de Walle from Multimedia Lab. The other editors are coming from Intel (USA), LG Electronics (South Korea) and INESC Porto (Portugal).

First MPEG-21 application put online by Ghent University (Belgium)
(Stay tuned at multimedialab.elis.rug.ac.be/demo.asp)

Multimedia Lab has succeeded in putting the first MPEG-21 application online. This application can be seen freely by using a standard web browser (Internet Explorer 6.0) at multimedialab.elis.rug.ac.be/demo.asp. The purpose of this demo application is to show that MPEG-21 technology can be used for the synchronization of multimedia data. In this application, the specific data streams are: a trailer of the movie Gladiator (video+audio); photographs of the main actors of this movie; their names. These data streams are stored on a so-called data server (see figure). End-users/clients can get access to this data server by surfing to a web server (multimedialab.elis.rug.ac.be/demo.asp) via a standard web browser (IE 6.0). This can be done through a dedicated network (e.g., a cable network in the case of interactive digital TV), or via the ubiquitous Internet. Once the web server has “noticed” the client, it sends a command to the data server to deliver the different data streams to the client, again through the network that connects the clients with the servers.

If one would present these data streams to the end-user without further processing, they would not be synchronized. E.g., a certain photograph of a main actor could be shown too early (or too late) with respect to the video that is shown at the same time. In other words, the synchronization between the data streams would not be guaranteed.

At this point of the demo MPEG-21 is coming into play, in combination with some other modern web and multimedia technologies. Before showing the data streams to the end-user they are processed in the background by the web browser of the end-user, where “in the background” implies that the end-user does not notice anything of this processing step. This processing is based on the use of MPEG-21 and XML technology (eXtensible Markup Language), a so-called markup language that is often considered to be the successor of HTML (HyperText Markup Language) but which is used in much more applications than just web applications. The processing step allows the browser to know perfectly which data stream (or fragments of data streams, e.g., a video fragment) has to be shown to the end-user at each time. It should be noted that it is important that this processing is performed at the client side and not at the server side: by doing so the negative influence of the “dynamic character of the network” (the Internet is often performing very well, but this is not guaranteed since the Internet is a “best-effort network”) on the presentation quality can be minimized.

After the synchronization of the data streams, the most difficult part of the application has been dealt with. The only thing that remains to be done is to actually present (“play”) the multimedia data to the end-user. This is done by using so-called data players that run within the web browser environment; these are able to present still images, video, text, video, etc. to the end-user.

This first MPEG-21 application of Multimedia Lab has already been discussed within the MPEG committee. Other research groups of universities or companies are currently also working on the first of what has to become a long list of MPEG-21 applications. It is indeed expected that MPEG-21 will be a very important standard within a few years. This statement is endorsed by the fact that a lot of major companies that are active in the field of multimedia systems and applications are currently heavily involved in the MPEG-21 activities.