The Research Of P2P Technology In Video System

Along with the fast development of P2P network, various applications which are constructed on the P2P network appear in our life.Based on a statistics,the colony of people who are interested in P2P video service extends fantastically. The typical applications of P2P video systems include PPLive,PPStream and Q-Live-Streaming. Comparing with other traditional applications,P2P video service contains more information. And now, along with the advancement of technology, P2P video service is appeared in tele-education, tele-medicine,interactive movies and TV programs.It is a basic fact that the research of P2P video service is significant and interesting.This paper will focus on two typical applications of P2P video service which are live streaming system and video-on-demand (VoD) system. Our dominating achievements are as following:(1)From the perspective of reducing bandwidth consumption of live streaming system, we propose a data downloading mathematical model and present a strategy for data scheduling by analyzing the state and action of nodes.By adding a small amount of local information to the data information exchange process based on Gossip protocol,it can help people select optimal providers and avoid unnecessary data downloads and finally reduce downloading cost of the system. The emulation experiments show that the strategy can reduce almost 20% downloading cost and obtain a playing continuity more than 99% only at a cost of bringing 8% of controlling cost to the process.(2)Typically, a VoD system contains a large number of nodes which makes it is difficult to be administrated.In order to minish the difficulty of manage this kind of system, we present a P2P video-on-demand system OXVoD based on a layered structure.Those nodes which are playing the same range of date pieces compose a layer. Nodes in the upper layer provide service for nodes in the lower layer, so it can achieve an ideal load balance.OXVoD combines the DHT's accuracy and efficiency and Gossip protocol's simple and practicability. A mathematical model of queuing for the process of data downloading is given. We also propose a solution for it. The emulation experiments show that OXVoD can ensure more than 99% of nodes joining the system normally and obtain a playing continuity more than 96% on the condition that server load is stable. (3)With the help of historical information saved by node, we can forecast its future action.So it is practicable for us to find the optimal provider from several potential suppliers.We calculate the rarity of providers and deadline of data piece and then establish a mathematical model for P2P VoD system. Finally, we convert the problem of improving the playing continuity of P2P VoD system to the problem of finding the optimal solution for job scheduling with deadline.Using the layered P2P structure mentioned above, we propose a new P2P VoD system named CPVoD.In the end, we verify the efficiency of CPVoD through a lot of emulation experiments.