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 [1]) 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 hIghlighTs 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.