Technical Research On H.323 Stack And Its Realization

In recent years, the rapid development of the computer networks has brought the enormous change for the global development of various fields. Among them, multimedia communications technology which based on IP network offers a convenient and low-priced way to shorten the distance among the people, and gives an end to traditional circuit-switched communication.The H.323 protocol is ITU-T's standard for multimedia conference over packet-based network,It applies TCP/IP agreement, supports the real-time codec and transmitting of video, audio and data in Internet network, therefore, multimedia conference can be hold between or in LANs, even among the remote computers connected by Internet. With the rapid popularization of Internet and extensive use of TCP/IP agreement, H.323 standards have very wide application prospects. This paper first gives an overview of the H.323 standards, including the entity, stack and operation principles of videoconferencing in the Internet. Secondly, Uses UML to build a general and useful model for H.323 stack, and divides the stack into several modules under the principle of OOA, and realizes the stack programming with OOP language on the base of a cross-platform classes-pwlib. Subsequently, fluctuation in video transmission is deeply analyzed and a useful solution is presented. Finally, a simulation terminal software is developed on the base of H.323 stack, then the stack is tested with unit testing and systemic testing. The result shows the stack in which this paper developes, has the merit of stability, dependability and maintainability;Has a characteristic of running on Windows and Unix platform, can communicated with the main H.323 termainal products of some domestic and international videoconferencing producers, which proves that our H.323 stack completely accords with ITU-T's standard of H.323 Recommendation, and reaches our designing requirement.