Real Time Multimedia Systems
Technical Issues in
Interactive Distributed
Multimedia
Participants
DTU-RTMM is a research project involving four research
groups at The Technical University of
Denmark, DTU:
The project concentrates on the technical issues involved in systems
for Interactive Distributed Multimedia (IDMM). It is part of the
larger project
DMM,
Distributed Multimedia - Technologies and Applications
that deals with many aspects of the development and use of distributed
multimedia. The project is supported by the Danish Research Councils
and the Danish National Centre for IT Research 1998-2001.
Scope
As an example of a typical IDMM system, we are building up a
Virtual Seminar Room:
The Virtual Seminar Room
In the Virtual Seminar Room, participants in the Virtual Seminar
each sit at a suitable graphical device, on which they can see and
hear the other participants. They also have access to a common
virtual blackboard, on which they can (one at a time) write and
draw using virtual chalk, and to which they can point using a
virtual pointer. The leader of the seminar has special
privileges and can run demonstrations using virtual equipment
and display problems for the participants to solve as exercises.
The technical setup in a system for implementing a Virtual Seminar
Room is indicated in the figure above. A principal technical challenge
is to transmit video and audio in real time to all the participants in
a quality which is acceptable, in the sense of giving them the
impression of having genuine contact with one another, and being able
to talk and gesture in a natural manner, just as though they really
were sitting in the same room. Experience shows that current
technology, such as H.320 videoconferencing, is inadequate for this
purpose.
In more detail, the technical problems to be studied fall into two classes:
-
END SYSTEMS
- Real-time operating systems.
- Admission control for new activities, so that real-time
properties are preserved.
- Real-time scheduling of multiple streams (video, audio,
images...)
- Real-time drivers for new technologies such as IEEE 1394
(Firewire ®).
- Real-time compression and expansion using software, if necessary
with hardware support.
- Algorithms for speech enhancement, compression and recognition in
the presence of ambient noise.
- User interfaces for interactive services.
- NETWORKS
- Network technologies: ISDN, ATM,...
- Synchronised multicast.
- Layered multicast and striping.
- Adaptive Quality of Service: Bandwidth and delay.
- Architecture of high-throughput network drivers
- Configuration and architecture of distributed software
systems.
Collaboration with University of Aarhus, Risø National
Laboratory, and Centre for Language Technology on other multimedia
issues - the paedagogical and psychological aspects of teaching via
interactive multimedia - takes place within the framework of funding
from the Danish Research Councils.
Results
During the project prototypes of IDMM systems are to be constructed
and tested. The systems will include sites at DTU and at the University
of Aarhus. A list
of publications is available, and full text reports may be found
at the home page of each research group.
Some demonstration films which show the system in operation can be
found in various formats
here
Return to DMM,
Distributed Multimedia
Last updated: 5 October 2001. Robin Sharp