Peer To Peer Video Streaming Technology And Implementation On Embedded System

In order to distribute video to different devices efficiently, many technologies have been proposed to support real time sreaming media over the past twenty years. However, implementing a low-cost, large-scale video broadcast system still faces considerable challenges. Traditional streaming media technology is based on Client/Server architecture. Limited by server's bandwidth, computer power or other resources, the scalability of the entire system is poor. To solve the problem, IP multicast has been proposed in the 1980s. Through one-to-many video transmission has been achieved, IP multicast has not been widely applied due to many various technical or management reasons. Based on content delivery network (CDN), new streaming media technology appears. CDN needs to place a large number of server nodes in the network, which construct a layer on top of the existing Internet network. According to real-time traffic, the connections of each server node, the load conditions, the user response times and other comprehensive informations, the users'request will be redirected to appropriate server. Because of requiring huge investment on hardware devices and equipment maintenance, large scale deployment of CDN is limited.Recently P2P-based streaming media system, such as commercial streaming media systems PPLive, PPStream, UUSee, CCTVbox and so on, have been widely deployed because it is low-cost, easy to deploy and scalable. According to the topology, there are two types of P2P streaming media systems:tree-based and mesh-based.In this paper, open source softwares, PeerCast and iGM, are taken as examples to analysis the principle and operating mechanism of the tree-based P2P streaming media system and the mesh-based P2P streaming media system. Network simulation tool NS-3 is used to analyze the topology performance of the tree-based P2P streaming media system. We describe a mathematical model to analyze the effect of neighbor number size based on two performance metrics:video quality and distribution delay. Some simulation is done to prove the theory model. The theoretical analysis and the simulation both show that increasing the neighbor number size does little to the system video quality when the buffer size is large enough, but can reduce the distribution delay of chunk effectively. Scalable Video Coding (SVC) is also discussed for bandwith-constrained environment in this paper.In this paper we design an embedded P2P streaming media system. A video source, which captures TS streaming from cable TV system in real time and sends the TS streaming to the P2P streaming media system, is designed based on STi7109 platform. There is no TCP/IP stack in the OS21 operating system which works on STi7109, so a light-weight, open-source TCP/IP stack LwIP is ported to OS21. We design a P2P client based on Davinci platform. Davinci processor uses dual-core architecture, ARM and DSP. The main application is running on ARM and ARM is responsible for the control of the hardware resources. DSP works as a coprocessor, which deals with audio and video encoding and decoding. P2P client, who gets video data form P2P networks and then sends the data to the media player, mainly works on ARM side. The media player calls DSP-side program through DMAI interface to decode audio and video data, and then control the corresponding hardware to play the decoded video or audio data. P2P client's media player is based on the open source multimedia framework Gstreamer. In order to take full advantage of DSP decoding capabilities, the media player uses TI's DMAI-based plugin for Gstreamer.