| PPStream is the first IPTV software with live and video-on-demand by which we can watch movie, sports, news and so on. It is completely free of charge, fluently playing and absolutely necessarily of Internet users. As far as we know, there is much more research on PPLive than on PPStream. We can not know the system model because PPStream's protocol is proprietay and no source code is provided. Therefore, this paper captures data of start-up and play process, taking passive measurement.Start-up process means a new client taking part in. Including peerlist return, BM and Offset return, the first request chunk, the first advertising BM information. This paper analyzes the rules of video request and sending at the channel startup process.At the play process, we begin to reveal the peers' application behavior. Including the period peerlist request and return, the same Offset of different clients for the same channel, the connection peer number; download and upload traffic distributing, the download and upload rate, sharing ratio, redundancy ratio.Measurement, analysis and research on start-up and play process, the paper reveals that 20 percent peers are download-provider while 80 percent are free-riders. The fetching strategy is sequence mixed disorder strategy. PPSream takes sequence strategy at the start-up process. This paper contributes that PPStream's system is a 'big' buffer system with jump small sharing window. The characteristics of this system are unstable on reciprocal relationship and download surroundings. We analyze the difference of jump and glide window on peer connection and download surroundings from phase space. This paper finds some angle of view for the large-scale measurement and provides academic knowledge for the perfect of PPStream in the future. |
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