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Multi-task Downloading for P2P-VoD: An Empirical Perspective

For current P2P-VoD systems, three fundamental problems exit in user experience: exceedingly large startup delay, long jump latency, and poor playback continuity. These problems primarily stem from lack of media data. In this paper, we propose Multi-Task Downloading with Bandwidth Control (MTD(BC)), an efficient and practical mechanism to prefetch media data. In MTD, a user can download multiple videos in parallel with its current viewing, which significantly decreases video switching delays. However, MTD brings a serious problem: downloading "other" tasks could impede the playback performance of the current viewing, especially in low-bandwidth network. This problem is solved through our design of bandwidth control. To our knowledge, we are the first to propose MTD with bandwidth control for P2P-VoD and conduct empirical evaluations in the real-world system. The running results show that MTD(BC) achieves better streaming quality than the traditional method. In particular, our mechanism reduces 75% of startup delay and 36% of jump latency in low-bandwidth network with high system scalability.