Charles Krasic

Assistant Professor
Email: krasic [at] cs [dot] ubc [dot] ca
Office: ICCS 327
Phone: 604-822-5628

Curriculum Vitae

B.Math, University of Waterloo(1992); M.Math, University of Waterloo(1996); Ph.D., OGI/OHSU (2003).


Operating Systems


Advances in computer hardware and consumer electronics are resulting in an abundance of cheap and powerful devices. It is increasingly common for these devices to support continuous media types such as digital audio and video. Moreover, a rising number of these devices are network enabled, and as a result the Internet is becoming rich with candidate sources and destinations for continuous media types. With all these devices, we would seem to be poised to experience a growing degree of access to audio and video over the Internet which would echo what the arrival of the web did for access to text and images. The field of multimedia networking is concerned with systems software issues related to realizing this potential.

My research concerns sytems and application support for quality adaptive, time sensitive computing, which is about the design of systems that simultaneously support the normally conflicting goals of real-time performance and a best-effort service model. Traditional approaches to the design of real-time systems involve techniques whereby resources are provisioned sufficiently to meet the worst case demands of the application. These techniques are generally infeasible in the current Internet due to its fundamentally best-effort architecture, and this situation is unlikely to change. Quality-adaptive approaches reconcile this dilemma by restructuring real-time systems so that they can adjust the quality of results that they deliver to match available resources, thereby ensuring that they can deliver their results within the fundamental timing constraints of the application.

For example, a main focus of my research has been the development of a system called QStream which does adaptive video streaming over the Internet. Video streaming exemplifies the type of application that must be both real-time and best-effort. The goal of QStream is to simplify the resource management issues of video streaming to the point of a "encode once, stream anywhere" ideal. The research associated with QStream has spanned several areas such as scalable video compression, network protocols, and operating system support of time sensitive applications.

Selected Publications

Charles Krasic, Jonathan Walpole, and Wu-chi Feng, "Quality-Adaptive Media Streaming by Priority Drop", 13th International Workshop on Network and Operating Systems Support for Digital Audio and Video (NOSSDAV 2003), June 2003.

Ashvin Goel, Luca Abeni, Charles Krasic, Jim Snow, and Jonathan Walpole, "Supporting time-sensitive applications on general-purpose operating systems", Fifth USENIX Symposium on Operating Systems Design and Implementation (OSDI 2002), Dec 2002.

Charles Krasic, Kang Li and Jonathan Walpole, "The Case for Streaming Multimedia with TCP", 8th International Workshop on Interactive Distributed Multimedia Systems (iDMS 2001), Lancaster, UK, September 2001.

Dylan McNamee, Jonathan Walpole, Crispin Cowan, Calton Pu, Charles Krasic, Ashvin Goel, Perry Wagle, Charles Consel, Gilles Muller and Renault Marlet, "Specialization Tools and Techniques for Systematic Optimization of Systems Software", ACM Transactions on Computer Systems, May 2001.

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