Optimization of H.323 terminal under Windows 95/NT

This paper presents a comprehensive way to realize a multimedia communication system based on the PC platform of Microsoft Windows OS and PBN. The ITU-T recommendation H.323 describes terminals and equipment that provide multimedia communications services over PBN (packet based networks) which may not provide a guaranteed quality of service. The H.323 terminals and equipment may carry real-time audio, video and/or data. The H.323 terminals may be used in point-to-point, multi-point, or broadcast configurations. H.323 is composed of video codecs (H.261, H.263 or H.263 plus), audio codecs (G.711, G.722, G.728, G.729, or G.723.1) and system control interface (H.245 for control and H.225.0 for packet and synchronization). We have implemented a multimedia "communication system under Microsoft Windows OS on LAN with developer studio C++ language. Some of advanced features of PC and Windows OS are applied to the system such as multi-task, DirectDraw, AVIcap, waveform audio, multi-thread and so on. Those make the system have outstanding performance and excellent quality. In order to get a real-time H.323 terminal; we take some ways such as simplification of the audio algorithm and utilization of MMX in video algorithm. TCP/IP network protocols serve as a friendly interface with LAN. The system can perform point-to-point real-time audio and video communication.