基于H.245的可视通信控制协议研究

Research on the Control Protocol for Visual Communication Based on H.245

该文研究了H.245多媒体通信控制协议,提出了可视通信系统中基于H.245协议的通信控制总体流程,介绍了PSTN可视电话的主从确定、能力交换、终端工作模式的转换等主要通信过程的控制设计,并通过扩展H.245协议,完成了音频编解码算法扩展、声像自动均衡模式识别、产品识别等扩展功能,提高了PSTN可视电话的兼容性和适应性。

This paper studies the control protocol for multimedia communication-H.245.It analyzes the principle of recommendation H.245and the relationship between recommendation H.245and recommendation H.223.It constructs collectivity flow based on recommendation H.245communication control in visual communication system.It designs and realizes the state transferring chart&the primitive exchange sequence between H.245's entities and H.245's users,for example,capability exchange,master slave determination,mode request,etc.And by expanding recommendation H.245messages&signals,it realizes unique functions,for example,additional audio CODEC algorithms changing,video-audio auto -balancing,product version identifying,and so on.The visual communication control mechanism according to recommendation H.245in this paper can promote the compatibility,transmission performance and adaptability of a PSTN videophone.