Send RTSP OPTIONS command to detect server type.

Originally committed as revision 15125 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/rtsp.c

@@ -1045,6 +1045,7 @@ static int rtsp_read_header(AVFormatContext *s,
     RTSPHeader reply1, *reply = &reply1;
     unsigned char *content = NULL;
     int protocol_mask = 0;
+    char real_challenge[64];
 
     /* extract hostname and port */
     url_split(NULL, 0, NULL, 0,
@@ -1083,6 +1084,42 @@ static int rtsp_read_header(AVFormatContext *s,
     rt->rtsp_hd = rtsp_hd;
     rt->seq = 0;
 
+    /* request options supported by the server; this also detects server type */
+    for (rt->server_type = RTSP_SERVER_RTP;;) {
+        snprintf(cmd, sizeof(cmd),
+                 "OPTIONS %s RTSP/1.0\r\n", s->filename);
+        if (rt->server_type == RTSP_SERVER_RDT)
+            av_strlcat(cmd,
+                       /**
+                        * The following entries are required for proper
+                        * streaming from a Realmedia server. They are
+                        * interdependent in some way although we currently
+                        * don't quite understand how. Values were copied
+                        * from mplayer SVN r23589.
+                        * @param CompanyID is a 16-byte ID in base64
+                        * @param ClientChallenge is a 16-byte ID in hex
+                        */
+                       "ClientChallenge: 9e26d33f2984236010ef6253fb1887f7\r\n"
+                       "PlayerStarttime: [28/03/2003:22:50:23 00:00]\r\n"
+                       "CompanyID: KnKV4M4I/B2FjJ1TToLycw==\r\n"
+                       "GUID: 00000000-0000-0000-0000-000000000000\r\n",
+                       sizeof(cmd));
+        rtsp_send_cmd(s, cmd, reply, NULL);
+        if (reply->status_code != RTSP_STATUS_OK) {
+            err = AVERROR_INVALIDDATA;
+            goto fail;
+        }
+
+        /* detect server type if not standard-compliant RTP */
+        if (rt->server_type != RTSP_SERVER_RDT && reply->real_challenge[0]) {
+            rt->server_type = RTSP_SERVER_RDT;
+            continue;
+        } else if (rt->server_type == RTSP_SERVER_RDT) {
+            strcpy(real_challenge, reply->real_challenge);
+        }
+        break;
+    }
+
     /* describe the stream */
     snprintf(cmd, sizeof(cmd),
              "DESCRIBE %s RTSP/1.0\r\n"