说明：  本文描述RTP（real-time transport protocol），实时传输协议。RTP在多点传送（多播）或单点传送（单播）的网络服务上，提供端对端的网络传输功能，适合应用程序传输实时数据，
(This article describes the RTP (real-time transport protocol), Real-time Transport Protocol. RTP in the multicast (multicast) or unicast (unicast) network services, providing end-to-end network transport functions suitable for applications of real-time data transmission,)