Commit 9c8fa20d authored by Martin Storsjö's avatar Martin Storsjö Committed by Ronald S. Bultje
Browse files

When using RTP-over-UDP, send dummy packets during stream setup, similar to

what e.g. RealPlayer does. This allows proper port forwarding setup in NAT-
based environments.

Patch by Martin Storsjö <$firstname at $firstname dot st>.

Originally committed as revision 21856 to svn://svn.ffmpeg.org/ffmpeg/trunk
parent fe74099a
......@@ -273,6 +273,45 @@ int rtp_check_and_send_back_rr(RTPDemuxContext *s, int count)
return 0;
}
void rtp_send_punch_packets(URLContext* rtp_handle)
{
ByteIOContext *pb;
uint8_t *buf;
int len;
/* Send a small RTP packet */
if (url_open_dyn_buf(&pb) < 0)
return;
put_byte(pb, (RTP_VERSION << 6));
put_byte(pb, 0); /* Payload type */
put_be16(pb, 0); /* Seq */
put_be32(pb, 0); /* Timestamp */
put_be32(pb, 0); /* SSRC */
put_flush_packet(pb);
len = url_close_dyn_buf(pb, &buf);
if ((len > 0) && buf)
url_write(rtp_handle, buf, len);
av_free(buf);
/* Send a minimal RTCP RR */
if (url_open_dyn_buf(&pb) < 0)
return;
put_byte(pb, (RTP_VERSION << 6));
put_byte(pb, 201); /* receiver report */
put_be16(pb, 1); /* length in words - 1 */
put_be32(pb, 0); /* our own SSRC */
put_flush_packet(pb);
len = url_close_dyn_buf(pb, &buf);
if ((len > 0) && buf)
url_write(rtp_handle, buf, len);
av_free(buf);
}
/**
* open a new RTP parse context for stream 'st'. 'st' can be NULL for
* MPEG2TS streams to indicate that they should be demuxed inside the
......
......@@ -73,6 +73,19 @@ int rtp_set_remote_url(URLContext *h, const char *uri);
void rtp_get_file_handles(URLContext *h, int *prtp_fd, int *prtcp_fd);
#endif
/**
* Send a dummy packet on both port pairs to set up the connection
* state in potential NAT routers, so that we're able to receive
* packets.
*
* Note, this only works if the NAT router doesn't remap ports. This
* isn't a standardized procedure, but it works in many cases in practice.
*
* The same routine is used with RDT too, even if RDT doesn't use normal
* RTP packets otherwise.
*/
void rtp_send_punch_packets(URLContext* rtp_handle);
/**
* some rtp servers assume client is dead if they don't hear from them...
* so we send a Receiver Report to the provided ByteIO context
......
......@@ -1146,6 +1146,12 @@ static int 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 (!(rt->server_type == RTSP_SERVER_WMS && i > 1))
rtp_send_punch_packets(rtsp_st->rtp_handle);
break;
}
case RTSP_LOWER_TRANSPORT_UDP_MULTICAST: {
......
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