get the recently received CSeq
CURLcode curl_easy_getinfo(CURL *handle, CURLINFO_RTSP_CSEQ_RECV, long *cseq);
Pass a pointer to a long to receive the most recently received CSeq from the
server. If your application encounters a CURLE_RTSP_CSEQ_ERROR then you
may wish to troubleshoot and/or fix the CSeq mismatch by peeking at this
Added in 7.20.0
Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.