Sung-Ju Lee

Caching strategies in transcoding-enabled proxy systems for streaming media distribution networks

With the wide availability of high-speed network access, we are experiencing high quality streaming media delivery over the Internet. The emergence of ubiquitous computing enables mobile users to access the Internet with their laptops, PDAs, or even cell phones. When nomadic users connect to the network via wireless links or phone lines, high quality video transfer can be problematic due to long delay or size mismatch between the application display and the screen. Our proposed solution to this problem is to enable network proxies with the transcoding capability, and hence provide different, appropriate video quality to different network environment. The proxies in our transcoding-enabled caching (TeC) system perform transcoding as well as caching for efficient rich media delivery to heterogeneous network users. This design choice allows us to perform content adaptation at the network edges. We propose three different TeC caching strategies. We describe each algorithm and discuss its merits and shortcomings. We also study how the user access pattern affects the performance of TeC caching algorithms and compare them with other approaches. We evaluate TeC performance by conducting two types of simulation. Our first experiment uses synthesized traces while the other uses real traces derived from an enterprise media server logs. The results indicate that compared with the traditional network caches, with marginal transcoding load, TeC improves the cache effectiveness, decreases the user-perceived latency, and reduces the traffic between the proxy and the content origin server.

Performance Evaluation of Transcoding-Enabled Streaming Media Caching System

We evaluate the performance of transcoding-enabled streaming media caching proxy system (TeC). TeC is designed for efficient delivery of rich media web contents to heterogeneous network environments and client capabilities. Depending on the connection speed and processing capability of an end user, the proxy transcodes the requested (and possibly cached) video into an appropriate format and delivers it to the user. We study the TeC performance by simulation using real traces derived from enterprise media server logs.