The Research Of MCU In Video Conference System

With the development of science and technology, the traditional video conference can not meet people's demands,high-definition video conference systems have become mainstream. Multi-point Control Unit(MCU) is an important control component in video conference, Its performance directly influences the quality of the video conference.For the MCU of video conference system, this paper studies the development status of the video conference system of domestic and international, and to do analysis of the current research focus, and introduce MCU's main features. Author do a detailed study on audio and video codecs used in video conference system, and do a specific test for open source library about the H.261, H.263, H.264,G.711,G.729codec, compare the change of audio signal waves and the video image's size and quality after encoding and decoding. The article also describes the H.323 protocol stack, and give a detailed description about the stack of the various components and signaling. It study the basic structure of MCU based on H.323,and do a comparative analysis software MCU and hardware MCU, and do a software requirements analysis of software MCU systems management capabilities. This paper research and design a simple MCU according to VIS H.323 DLL Library provided API functions, achieve the audio and video forwarding and conference control, and detailed design the online text discussion modules based on the TCP/IP protocol. Finally, propose a new method about the split screen based on VLC's ActiveX controls. Achieve the interface design of MCU with MFC.At the end of the paper, author test the system function of realized MCU, and do a summary and outlook for the development of MCU. The contents of the studied items from the actual Project of video conference, has some practical value.