摘要
介绍了H 32 4可视电话系统中多媒体通信控制协议H 2 4 5的原理及其在PC机Windows 95环境下的软件实现 ,讨论了抽象语法符号ASN 1和打包编码原理 (PER)。H 2 4 5主要包括两部分 :一是信令的组成和结构模式 ,另一是通信规程的具体过程。前一部分利用ASN 1和PER对信令进行描述和编码 ,文中采用一种编译器把信令从ASN 1格式转化为C语言数据结构格式 ,然后进行处理 ,后一部分采用有限状态机的形式描述。还简单介绍了H 2 4 5信令在H 32 4系统中的具体传输方法。最后利用PC机Windows 95的资源 ,如多线程实现、事件驱动、消息通信、定时器、回调函数等 ,实现了H 2 4 5控制协议。
In this paper, H.245 protocol (control protocol for multimedia communication) is introduced, which is a section of H.324 protocol (terminal for low bitrate multimedia communication). H.245 protocol is realized in Windows 95 situation on PC. The ASN.1 (abstract systax notation one, X.680 protocol) and PER (X.691 protocol) are also used to encode the signals of H.245, which is realized by a compiler and encoder/decoder. The transporting method of signals of H.245 in H.324 system is also introduced. The resources of OS Windows 95, for example, multithreading, event drive, message communication, timer, call-back function, are used for implementing the control protocol. \;
出处
《红外与激光工程》
EI
CSCD
2000年第5期60-63,72,共5页
Infrared and Laser Engineering
