Rainer Koster


January 1997

Document Type


Degree Name



Dept. of Computer Science and Engineering


Oregon Graduate Institute of Science & Technology


Multimedia applications are becoming more and more common. Possible features such as real-time access to remote data, combining information, and customizing presentations create a large potential for novel uses. On today's computers and networks, however, resources are still scarce for real-time processing of audio and video. Hence, good quality of service (QoS) management is necessary. The preferred quality as well as the appearance of a presentation may be user or task specific. Moreover, resources are shared among several users in unpredictable ways, requiring adaptation to varying resource availability. This thesis describes the architecture of a real-time video and audio player integrating approaches to these requirements. It is based on a QoS model of independent content, view, and quality definitions [31, 33]. Authors can edit the content of presentations. Video and audio clips from different servers can be combined. View and quality is controlled in the two dimensions of temporal and spatial resolution. The user can customize the appearance by adjusting the view parameters of play speed and image size. Independently, frame rate and image resolution control the quality. A feedback mechanism provides automatic adaptation of the frame rate to resource availability. This prototype demonstrates that advanced quality of service control and support for complex presentation can be provided and shows the implementation complexity involved.





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