Mocha : A quality adaptive multimedia proxy cache for Internet streaming

Multimedia proxy caching is a client-oriented solution for large-scale delivery of high quality streams over heterogeneous networks such as the Internet. Existing solutions for multimedia proxy caching are unable to adjust quality of cached streams. Thus these solutions either can not maximize delivered quality or exhibit poor caching efficiency. This paper presents the design and implementation of Mocha, a quality adaptive multimedia proxy cache for layered encoded streams. The main contribution of Mocha is its ability to adjust quality of cached streams based on their popularity and on the available bandwidth between proxy and interested clients. Thus Mocha can significantly improve caching efficiency without compromising delivered quality. To perform quality adaptive caching, Mocha implements fine-grained replacement and fine-grained prefetching mechanisms. We describe our prototype implementation of Mocha on top of Squid and address various design challenges such as managing partially cached streams. Finally, we validate our implementation and present some of our preliminary results.