Service Availability for P2P On-Demand Streaming with Dynamic Buffering

In general, on-demand video services enable clients to watch videos from beginning to end. As long as clients are able to buffer the initial part of the video they are watching, on-demand service can provide access to the video to the next clients who request to watch it. In our previous research work, we proposed a novel caching scheme for peer-to-peer on-demand streaming, called Dynamic Buffering. The dynamic buffering relies on the feature of Multiple Description Coding to gradually reduce the number of cached descriptions held in a peer´s buffers once the buffer is full. In this paper, we proposed three description dropping policies for dynamic buffering, called sequence dropping, m-dropping, and binary dropping. Mathematical formulas of the reduced number of buffer adjustments of descriptions and the reduction of the average number of selectable descriptions for m-dropping and binary dropping by factors of n and m were established in the paper. Experimental results showed that the m-dropping, m=[n/2] generally outperformed m-dropping, m=2 and binary dropping in terms of service availability. Even though the accumulated reduction of buffer adjustments for m-dropping polices was less than that for binary dropping, the average number of selectable descriptions for m-dropping was much greater than that for binary dropping.