| Video conference system is a virtual conference achieved by the network communication technology, and is an application system, which can collecte the separated users who communicate information in various ways such as graphics and sound, and make people in real-time long-distance exchange and share information and conduct collaborative work applications. Video conference greatly promoted the real and intuitionistic communication among members. Also it plays an important role in remote teaching and conference. H.323 is a protocol developed by ITU about IP video conference standard protocol. Due to the good manageability and maturity, H.323 protocol becomes the first selection of a carrier-class video conference and video communication system. At present, most domestic and foreign operators of the construction business video conference systems are based on the H.323 protocol.This article first introduced the development of video conference and the basic characteristics of the H.323 protocol, and then introduced the basic content and characteristics of H.323 protocol. It also described the basic components of H.323 protocol, as well as a brief introduction of some protocols privided by H.323 protocol stack. Also, this article indroduced the current audio and video codec technology, and have a reaserch on the relationship between H.323 signaling system and the codec format, and analyze the H.264 format video-conferencing applications.In this article, the key technologies of video conference systems are analysed, including the MCU and the terminal structure, multi-screen splicing and audio mixing technology. Based on the traditional audio and video buffer zone, this article provided a new project based on RTP buffer zone. First set up a two-layer buffer; then do a change on RTP header. Thus, at this stage the packet needed to be discarsed will be thrown away, not in the decode stage. This greatly improved the efficiency of the decoding. At the same time, there is no need a deep copy between the two layers buffer, without any performance loss. This artical also put forward a new type of format of communication between MC and MP. The header format is fixed, so it is simple to change the paragraph message. That is, different messages can be assembled together, when reading the message, the information field needed could be acquired quickly using header format and paragraph message. This provided good efficiency and convenience. The means of this type communication can also be used for other communications platforms.In Visual Studio 2008 development environment, this article develop a practical video conference systems, which can be used to achieve a variety of basic functions, and make the MCU and terminals can run on at PC machine. In the development process, this article fully taking into account the efficiency problem, and do a certain amount of optimization in audio and video codecs, signaling transmission, multi-screen splicing and audio mixing modules, improve the overall performance of video conference. Finally this article tests the system capability, and confirms the system meets the requirements of small-scale video conference. Under the cascade model of the MCU network topology program, a new algorithm is presented, and an appropriate network program could be generated quickly and efficiently. |
PDF Full Text Request