/* Add in RTSP headers */
    out_buf = buf;
    rt->seq++;
    snprintf(buf, sizeof(buf), "%s %s RTSP/1.0\r\n", method, url);
    if (headers)
        av_strlcat(buf, headers, sizeof(buf));
    av_strlcatf(buf, sizeof(buf), "CSeq: %d\r\n", rt->seq);
    if (headers)
    av_strlcat(buf, headers, sizeof(buf));
    av_strlcatf(buf, sizeof(buf), "User-Agent: %s\r\n",  rt->user_agent);
    if (rt->session_id[0] != '\0' && (!headers ||
        !strstr(headers, "\nIf-Match:"))) {
        av_strlcatf(buf, sizeof(buf), "Session: %s\r\n", rt->session_id);
    }
    if (rt->auth[0]) {
        char *str = ff_http_auth_create_response(&rt->auth_state,
                                                 rt->auth, url, method);
        if (str)
            av_strlcat(buf, str, sizeof(buf));
        av_free(str);
    }
    if (send_content_length > 0 && send_content)
        av_strlcatf(buf, sizeof(buf), "Content-Length: %d\r\n", send_content_length);
    av_strlcat(buf, "\r\n", sizeof(buf));