rtsp: punch holes again after pause

When a client behind a NAT issues a pause command, and stay paused for a
long time, the router may stop the RTP/RTCP port redirection. Resend the
hole punching packets before each PLAY command to cause the router to
restart the port redirection in that case.

Move the existing code for sending the packets from the SETUP phase
to the PLAY phase.
Signed-off-by: Martin Storsjö <martin@martin.st>

libavformat/rtsp.c

@@ -1537,13 +1537,6 @@ int ff_rtsp_make_setup_request(AVFormatContext *s, const char *host, int port,
                 err = AVERROR_INVALIDDATA;
                 goto fail;
             }
-            /* Try to initialize the connection state in a
-             * potential NAT router by sending dummy packets.
-             * RTP/RTCP dummy packets are used for RDT, too.
-             */
-            if (CONFIG_RTPDEC &&
-                !(rt->server_type == RTSP_SERVER_WMS && i > 1) && s->iformat)
-                ff_rtp_send_punch_packets(rtsp_st->rtp_handle);
             break;
         }
         case RTSP_LOWER_TRANSPORT_UDP_MULTICAST: {

libavformat/rtspdec.c

@@ -504,6 +504,18 @@ static int rtsp_read_play(AVFormatContext *s)
     av_log(s, AV_LOG_DEBUG, "hello state=%d\n", rt->state);
     rt->nb_byes = 0;
 
+    if (rt->lower_transport == RTSP_LOWER_TRANSPORT_UDP) {
+        for (i = 0; i < rt->nb_rtsp_streams; i++) {
+            RTSPStream *rtsp_st = rt->rtsp_streams[i];
+            /* Try to initialize the connection state in a
+             * potential NAT router by sending dummy packets.
+             * RTP/RTCP dummy packets are used for RDT, too.
+             */
+            if (rtsp_st->rtp_handle &&
+                !(rt->server_type == RTSP_SERVER_WMS && i > 1))
+                ff_rtp_send_punch_packets(rtsp_st->rtp_handle);
+        }
+    }
     if (!(rt->server_type == RTSP_SERVER_REAL && rt->need_subscription)) {
         if (rt->transport == RTSP_TRANSPORT_RTP) {
             for (i = 0; i < rt->nb_rtsp_streams; i++) {