Push Popular Segments in P2P VoD System: Possibility and Design

Video-on-demand (VoD) services have attracted a lot of attentions in recent years. Measurement studies show that VCR (video cassette recorder) operations, such as pause, rewind, and fast forward/backward, influence the pattern of the access to video segments and viewer(session) sojourn time. Moreover, some VCR features (e.g., bookmarking) newly proposed can further magnify such effects. This work analyzes the possibility to discern popular segments (highlights) from normal non-popular segments (normal-content) and how to reduce playback jitter in P2P streaming by leveraging this difference in segment popularity. Our contributions are two folds. First, a user playback model is presented, based on which we come to an affirmative conclusion on the possibility aforementioned. Besides, we also examine a real workload trace to validate the model and conclusions. Second, we propose a hybrid system, namely PITAPAT, which pro-actively pushes out hlghlights and pulls in normal-content on demand. In order to reduce the playback jitter, the overlay topology is designed to provide a pull demand as many desired sessions as possible. The performance of PITAPAT is evaluated by using a queuing model and simulations, whose results show that PITAPAT outperforms the traditional mesh-pull based P2P system in terms of playback continuity.