Software Design For PC Client Of Multi-Channel Digital Video Server Based On H.264

The network video server is one kind of digital and network applications which has several advantages. It is easy to arrange surveillance system as network and it has long distance coverage. Moreover, it has strong anti-noise ability, has good picture quality and is easy to query. So it can be extensively applied in telecommunication, power, transportation, bank, irrigation works, intelligence mansion etc. The video server system can real-timely, visually, truly reflect the things that is supervised and controlled, and also can obtain the information of it, which increasing the efficiency of management and the level of official automatization.The Multi-Channel digital video server system is a new technique product that electronics technique, calculator technique, correspondence technique joining together with automatization technique and developing quickly.As video sequence has huge data capacity, while transmission network only has limited bandwidth, vide coding plays a key role in network video server system. H.264 is the latest ITU_T standard of video coding, and now is being used widely because of its strong adaptability, high compression efficiency, excellent video quality. So we choose it as the video compression protocol of the video server system.In realization of the client of digital video server system, based on COM (Component Object Model) and DirectShow Filter, we built client of the digital video system distance-computer Filter Graph, which achieved video receiving from network, decoding, displaying, recording and playback. We modified Intel DirectShow RTP framework, which we used to achieve the transmission mode of H.263 over RTP". Based on DirectShow architecture, we can expend the function of the client of digital video server system by adding or deleting DirectShow Filter, without change the system framework macroscopically. So, the system, we had developed, had very good compatibility and extensibility. The H.264 standard and RTP protocol, which had been introduced in the client of digital video system, guaranteed high-performance of the video transmission on low-bit rate network.In the aspect of the pan-and-tilt drives and lens control, we based on XML and SIP, realized direct communication between ahead-computer and pan-and-tilt decoder. Using winsock, windows network application-programming interface, we achieved network communication of control instruction between ahead- embedded device and client-computer.Motion detection is a valuable technique in video surveillance system. By analyzing digital video sequences, the system can find out whether there is something moving inside the monitor scene. According to the results, it can take some actions, for example, tracing the object, alarming, starting the recording or transmitting process.The scheme adopted C/S network modes and adapted well to high real time requirement for network video streaming transmission. This thesis mostly analyses and studies these techniques of client of Multi-Channel digital video server system, and it also realizes practically a "Software Design for PC Client of Multi-Channel Digital Video Server Based on H.264 ".The process of the design and realization of the software for client of digital video server can be divided into following steps.(1) The next generation video compression standard H.264 is designed to compress the source images and videos with lower distortion, less bit rates and higher compression ratio, and in the hope that it can be applied in many occasions. H.264 adopts many advanced algorithms. With these algorithms, it makes a perfect balance between the computation complexity and the coding performance. Compared with the other techniques, H.264 has high compression performance, and its system can be well applied in the mobile and the IP network. For the purpose of universality and expansibility of the software of client of digital video server system, the architecture development is based on DirectX standard. This system implements the functions of video decoding with H.264, playing back, displaying and network communicating and transmitting under the framework of DirectShow. Microsoft' s DirectShow, which is built for the streaming media which runs on the Windows operations, and makes the play of multimedia flexible, and provides service for almost all kinds of media format, especially for capture and replay of video streams.(2) Client/Server Model is one of the normal communication model which based on TCP/IP. There are programs run respectively in Client terminals (remote) and Server terminal (local), the Client terminal send request to Server terminal, then the Server terminal reply it accordingly. It studies the control principle and functions of the PAN/TILT and LENS control, alarming system. The signaling in PAN/TILT and LENS control, alarming and parameter control in the Client terminal are transmitted to the Server terminal are all completed with the same mode. They make SIP as the application protocol and encapsulate the signal with XML, and send the signal as Content in SIP to the Server terminal. In the realization of communication, we adopt Winsock to complete the oriented-connection (TCP) C/S model.(3) A SIP/SDP protocol stack for session initializing and media format describing and a RTP/RTCP protocol stack for realtime multimedia streams' transmitting are also realized.(4) MFC (Microsoft Foundation Class) and its SDK is applied in the interface of the Client terminal. The program was completed in VC environment and with C++ as programming language. The custom can kick ActiveX button and connect to the Server terminal, change the video format, switch between one channel and four channels. The client software also support the local storage, snap, zoom in, zoom out and so on. The interface of the client is appropriate and easily to use, and achieve many targets as anticipation.Function testing is carried out in both IPv6/IPv4 LAN and IPv4 with public internet network environment. Result indicates that the terminal can receive, decode and playback video and audio streams persistently. Video streaming is played smoothly and the audio streaming is synchronized favourably. The PAN/TILT and L ENS control and alarming are realized by the software. The Software can be expanded because the COM is used as criterion, so the software can be used as the second development codec.