Make RTSP-MS-over-UDP negotiation work. See "[PATCH] RTSP-MS 8/15: fix

RTSP-MS UDP" thread on mailinglist.

Basically, UDP setup needs to be done in a particular order (first rtx
on two UDP ports (one for RTP, one for RTCP), then the other streams over
one, single port for all of them together). Not doing this correctly results
in a "461" error (invalid transport) during setup.

Originally committed as revision 17777 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/rtsp.c

@@ -888,7 +888,7 @@ make_setup_request (AVFormatContext *s, const char *host, int port,
                     int lower_transport, const char *real_challenge)
 {
     RTSPState *rt = s->priv_data;
-    int j, i, err, interleave = 0;
+    int rtx, j, i, err, interleave = 0;
     RTSPStream *rtsp_st;
     RTSPMessageHeader reply1, *reply = &reply1;
     char cmd[2048];
@@ -906,12 +906,38 @@ make_setup_request (AVFormatContext *s, const char *host, int port,
     for(j = RTSP_RTP_PORT_MIN, i = 0; i < rt->nb_rtsp_streams; ++i) {
         char transport[2048];
 
+        /**
+         * WMS serves all UDP data over a single connection, the RTX, which
+         * isn't necessarily the first in the SDP but has to be the first
+         * to be set up, else the second/third SETUP will fail with a 461.
+         */
+        if (lower_transport == RTSP_LOWER_TRANSPORT_UDP &&
+             rt->server_type == RTSP_SERVER_WMS) {
+            if (i == 0) {
+                /* rtx first */
+                for (rtx = 0; rtx < rt->nb_rtsp_streams; rtx++) {
+                    int len = strlen(rt->rtsp_streams[rtx]->control_url);
+                    if (len >= 4 &&
+                        !strcmp(rt->rtsp_streams[rtx]->control_url + len - 4, "/rtx"))
+                        break;
+                }
+                if (rtx == rt->nb_rtsp_streams)
+                    return -1; /* no RTX found */
+                rtsp_st = rt->rtsp_streams[rtx];
+            } else
+                rtsp_st = rt->rtsp_streams[i > rtx ? i : i - 1];
+        } else
         rtsp_st = rt->rtsp_streams[i];
 
         /* RTP/UDP */
         if (lower_transport == RTSP_LOWER_TRANSPORT_UDP) {
             char buf[256];
 
+            if (rt->server_type == RTSP_SERVER_WMS && i > 1) {
+                port = reply->transports[0].client_port_min;
+                goto have_port;
+            }
+
             /* first try in specified port range */
             if (RTSP_RTP_PORT_MIN != 0) {
                 while(j <= RTSP_RTP_PORT_MAX) {
@@ -932,13 +958,15 @@ make_setup_request (AVFormatContext *s, const char *host, int port,
 
         rtp_opened:
             port = rtp_get_local_port(rtsp_st->rtp_handle);
+        have_port:
             snprintf(transport, sizeof(transport) - 1,
                      "%s/UDP;", trans_pref);
             if (rt->server_type != RTSP_SERVER_REAL)
                 av_strlcat(transport, "unicast;", sizeof(transport));
             av_strlcatf(transport, sizeof(transport),
                      "client_port=%d", port);
-            if (rt->transport == RTSP_TRANSPORT_RTP)
+            if (rt->transport == RTSP_TRANSPORT_RTP &&
+                !(rt->server_type == RTSP_SERVER_WMS && i > 0))
                 av_strlcatf(transport, sizeof(transport), "-%d", port + 1);
         }
 
@@ -1022,7 +1050,8 @@ make_setup_request (AVFormatContext *s, const char *host, int port,
                 /* XXX: also use address if specified */
                 snprintf(url, sizeof(url), "rtp://%s:%d",
                          host, reply->transports[0].server_port_min);
-                if (rtp_set_remote_url(rtsp_st->rtp_handle, url) < 0) {
+                if (!(rt->server_type == RTSP_SERVER_WMS && i > 1) &&
+                    rtp_set_remote_url(rtsp_st->rtp_handle, url) < 0) {
                     err = AVERROR_INVALIDDATA;
                     goto fail;
                 }
@@ -1286,18 +1315,21 @@ static int udp_read_packet(AVFormatContext *s, RTSPStream **prtsp_st,
         fd_max = -1;
         for(i = 0; i < rt->nb_rtsp_streams; i++) {
             rtsp_st = rt->rtsp_streams[i];
+            if (rtsp_st->rtp_handle) {
             /* currently, we cannot probe RTCP handle because of blocking restrictions */
             rtp_get_file_handles(rtsp_st->rtp_handle, &fd1, &fd2);
             if (fd1 > fd_max)
                 fd_max = fd1;
             FD_SET(fd1, &rfds);
             }
+        }
         tv.tv_sec = 0;
         tv.tv_usec = 100 * 1000;
         n = select(fd_max + 1, &rfds, NULL, NULL, &tv);
         if (n > 0) {
             for(i = 0; i < rt->nb_rtsp_streams; i++) {
                 rtsp_st = rt->rtsp_streams[i];
+                if (rtsp_st->rtp_handle) {
                 rtp_get_file_handles(rtsp_st->rtp_handle, &fd1, &fd2);
                 if (FD_ISSET(fd1, &rfds)) {
                     ret = url_read(rtsp_st->rtp_handle, buf, buf_size);
@@ -1309,6 +1341,7 @@ static int udp_read_packet(AVFormatContext *s, RTSPStream **prtsp_st,
                 }
             }
         }
+    }
 }
 
 static int rtsp_read_packet(AVFormatContext *s,