Real-Time Operating Systems and Multimedia Support
Our work in real-time operating systems considers
several types of problems: support for soft real-time
scheduling of concurrent applications on commercial operating systems,
the integration of hard real-time scheduling with scheduling audio and
video streams, support of mutlimedia in real-time
databases, and on developing smoothing
algorithms for live video.
Multi-Level Soft Real-Time Scheduling with Guarantees
We have developed multi-level real-time scheduling that supports
various types of real-time guarantees. This permits concurrent
applications to run on a commercial operating system where each
application can achieve a guaranteed performance. We also
developed an integrated platform which is capable of meeting requirements
of both traditional real-time processing and multimedia. This has enormous
potential for accomodating various kinds of new applications.
We have developed a multimedia server executing on a real-time
multiprocessor operating system to provide different classes
of guarantee to support both types of processing.
- J. Stankovic, Information Dominance via Global Virtual Databases,
Workshop on Research Directions for the Next Generation Internet,
- H. Kaneko, J. Stankovic, S. Sen and K. Ramamritham, Integrated Scheduling
of Multimedia and Hard Real-Time Tasks,
Real-Time Systems Symposium, Dec. 1996.
- J. Stankovic, S. Son and J. Liebeherr, BeeHive: Global
Multimedia Database Support for Dependable, Real-Time Applications,
chapter in Real-Time Database and Information
Systems, Kluwer Academic Publishers,
1997, pp. 409-422.
- J. Stankovic, Real-Time Global Virtual Machines,
invited contribution, virtual
roundtable discussion, IEEE Concurrency,
Vol. 5, No. 3, Fall 1997.
- O. Gonzalez, S. Sen, K. Ramamritham, and J. Stankovic,
Incorporation of Multimedia Capabilities in Distributed Real-Time
Applications, Workshop on Databases: Active and
Real-Time, Nov. 1996.
- J. Regehr and J. Stankovic, HLS:
A Framework for Composing Soft
Real-Time Schedulers, Proc. of the 22nd IEEE Real-Time
Systems Symposium,, Dec. 2001.
- J. Regehr and J. Stankovic, Augmented
CPU Reservations: Towards Predictable Execution on
General Purpose Operating Systems, Proc. of the
Seventh IEEE Real-Time Technology and Applications
Symposium,, June 2001.
- J. Regehr, J. Stankovic, and M. Humphrey,
The Case for
Hierarchical Schedulers with Performance Guarantees,,
Technical Report, CS-2000-07, March 2000.
- J. Regehr, M. Jones, and J. Stankovic,
System Support for Multimedia: The Programming Model Matters,
submitted for publication, Nov. 2002.
Bandwidth smoothing techniques are effective at reducing the burstiness of a
compressed, pre-recored video stream by prefetching frames into a client
playback buffer in advance of each burst. In contrast to stored video, live
applications have limited knowledge of frame sizes and often require bounds on
the delay between the source and the client(s). We have developed solutions
for smoothing live video transmissions.
- J. Rexford, S. Sen, J. Dey, W. Feng,
J. Kurose, J. Stankovic, and D. Towsley,
Online Smoothing of Live, Variable Bit Rate Video,
NOSSDAV 97, 1997.
- S. Sen, J. Dey, J. Kurose, J. Stankovic, and D. Towsley,
CBR Transmission of VBR Stored Video,
SPIE Int. Symp. and Education Program on Voice,
Video, and Data Communications, Nov. 1997.