The Research And Implementation Of Video Surveillance System Based On Darwin And HTML5

With the rapid development of computer technology, as well as the improvement of security awareness, video surveillance system is gradually booming in industrial applications and personal applications. Meanwhile, with the promotion of the projects such as "Safe City", "Safe Community", "Safe Campus", video surveillance has become a hot research topic in the field of security.Video surveillance system is mainly composed of cameras, streaming media servers and the clients. With the increase of the number of users, the original streaming media server of the project Live 555 emerged poor stability and bottlenecks on the amount of concurrency, needing a server with stable performance to replace it. The client softwares of surveillance system, on the other hand, show inconvenience to ues and poor user experience issues. The PC client-softwares are needed to download, install and configuration, which is inconvenient. While the browser compatibility of web clients which are required to install plugins, needs to be improved. If a kind of new client could be developed which is browser-based plug-free and cross-platform, it is benefit to both companies and customers. For the fommer, the cost of development and deployment of client software could be decreased. And for the latter, the usage of technical barriers could be lowered and the user experience could be enhanced.To solve the problems and to meet the demand above, the major work of this paper is as follows:1. Analyze key technology-related of video surveillance systems, including streaming media transmission protocol RTSP/RTP, video codec technology H.264, Darwin Streaming Server, HTML5 video decoding and rendering technology, WebSocket protocol and Node.JS etc;2. Analyze the kernel principle and related source code of Darwin Streaming Server. Design and implement a new forward module, which aims to solve the high usage of the network bandwidth and server resources caused by the original module;3. Design and implement a proxy server for solving the problems of the communication between the streaming server and HTML5 client. The proxy server is able to resolve the client’s request signaling and converted to RTSP requests to the streaming media server, on the other hand, it could receives video data and transfers data to clients;4. Design and implement a HTML5 client based on WebSocket protocol, it idetifies video data packets and reshapes the video frame, then utilizes H.264 codec implemented by Javascript to decode the frame, and eventually renders image on the canvas to display the surveillance screen.Lastly, the functional test and performance test of the surveillance system are carried out. In functional test, the relevant test points are passed. In performance testing which is in the experimental environment, the average network delay is less than 600 ms, and the system supports 900 users simultaneously accessing the system and Darwin Server. The client could work in 20 fps, rendering 640 * 360 resolution screen, the contrast experiment shows that the performance of Darwin is better than Live555. Test results show that the system has the basic function of video surveillance, and achieves the anticipated goal of the design.