标准的rtsp server不要keep live
对于Windows Media Server和realnetwork streaming server
需要每隔一段时间发个垃圾消息给服务器，然服务器觉得你的client还活着
具体参见如下代码
/* send dummy request to keep TCP connection alive */
if ((rt->server_type == RTSP_SERVER_WMS ||
rt->server_type == RTSP_SERVER_REAL) &&
(av_gettime() - rt->last_cmd_time) / 1000000 >= rt->timeout / 2) {
if (rt->server_type == RTSP_SERVER_WMS) {
snprintf(cmd, sizeof(cmd) - 1,
"GET_PARAMETER %s RTSP/1.0\r\n",
s->filename);
rtsp_send_cmd_async(s, cmd, reply, NULL);
} else {
rtsp_send_cmd_async(s, "OPTIONS * RTSP/1.0\r\n",
reply, NULL);
}
}
