Remote/RTSP is broken: Failed to bind RTCP server

[rrygl]

Describe Your Environment

• Version of ZoneMinder [release version, development version, or commit] Debian 1.36.33+dfsg1-1
• How you installed ZoneMinder [e.g. PPA, RPMFusion, from-source, etc] Debian 12
• Full name and version of OS: Debian 12
• Browser name and version (if this is an issue with the web interface): Irrelevant

Describe the bug
Remote/RTSP is broken with error log: "Failed to bind RTCP server"
I think the bug was introduced in 71edb9d. Before this commit RtpCtrlThread needs to call .start() but this commit changed it to start without it.
Then in zm_rtsp.cpp there is a ctrl thread that doesn't want to start:

      // These never actually run
      RtpDataThread rtpDataThread( *this, *source );
      RtpCtrlThread rtpCtrlThread( *this, *source );

Now it starts and fails.

To Reproduce
Simply use Remote/RTSP.

Expected behavior
It should work

Debug Logs

08/26/23 01:44:53.536731 zmc_m11[9752].DB2-zm_rtsp.cpp/574 [RTSP Seq is 44366]
08/26/23 01:44:53.536737 zmc_m11[9752].DB2-zm_rtsp.cpp/575 [RTSP Rtptime is 2099095912]
08/26/23 01:44:53.536760 zmc_m11[9752].DB3-zm_rtp_source.cpp/59 [RTP CName = zm-11@server]
08/26/23 01:44:53.536767 zmc_m11[9752].DB3-zm_rtp_source.cpp/92 [Initialising sequence]
08/26/23 01:44:53.536969 zmc_m11[9753].DB2-zm_rtp_data.cpp/65 [Starting data thread 2131313403 on port 0]
08/26/23 01:44:53.536990 zmc_m11[9754].DB2-zm_rtp_ctrl.cpp/252 [Starting control thread 7f0942fb on port 1]
08/26/23 01:44:53.537061 zmc_m11[9754].DB1-zm_comms.cpp/543 [bind(): Trying '0.0.0.0', family '2', proto '17']
08/26/23 01:44:53.537072 zmc_m11[9753].DB1-zm_comms.cpp/543 [bind(): Trying '0.0.0.0', family '2', proto '17']
08/26/23 01:44:53.537096 zmc_m11[9753].DB3-zm_rtp_data.cpp/79 [Bound to :0]
08/26/23 01:44:53.537114 zmc_m11[9754].ERR-zm_comms.cpp/559 [bind(), Could not bind]
08/26/23 01:44:53.537124 zmc_m11[9754].FAT-zm_rtp_ctrl.cpp/264 [Failed to bind RTCP server]

[welcome]

Thanks for opening your first issue here! Just a reminder, this forum is for Bug Reports only. Be sure to follow the issue template!

[connortechnology]

I'm not so sure... it looks to me like the port isn't configured and it isn't getting a hostname for localhost... What do you have in Options->Network->MIN_RTP_PORT ? Default is 40200. You might try changing this...

[rrygl]

MIN_RTP_PORT is still default 40200.

The error log shows that it tried to bind port 0 and 1 (comes from 0+1). Binding 0 was fine because it picked a random one instead. Binding 1 failed.
This simply means that the port number variables were only initial default values.

These two threads are not supposed to run at all (the comment says so). But yet they run and try to bind port 0 and 1. That's the problem.

[romale]

I've this issue too

[glorang]

I have the same issue on Debian 11, zoneminder-1.36.33-bullseye1 from the zoneminder APT repo.

This is what I got from the debug output:

02/14/24 22:07:32.611078 zmc_m3[132786].DB2-zm_rtsp.cpp/474 [Got RTSP session BBD57073, timeout 60 secs]
02/14/24 22:07:32.611090 zmc_m3[132786].DB2-zm_rtsp.cpp/479 [Got RTSP transport RTP/AVP/TCP;unicast;interleaved=0-1;ssrc=001FF16F;mode="PLAY"]
02/14/24 22:07:32.611107 zmc_m3[132786].DB2-zm_rtsp.cpp/517 [RTSP Method is RTP/RTSP]
02/14/24 22:07:32.611116 zmc_m3[132786].DB2-zm_rtsp.cpp/518 [RTSP Distribution is unicast]
02/14/24 22:07:32.611124 zmc_m3[132786].DB2-zm_rtsp.cpp/519 [RTSP SSRC is 1ff16f]
02/14/24 22:07:32.611133 zmc_m3[132786].DB2-zm_rtsp.cpp/520 [RTSP Local Host is ]
02/14/24 22:07:32.611142 zmc_m3[132786].DB2-zm_rtsp.cpp/521 [RTSP Local Ports are 0/0]
02/14/24 22:07:32.611150 zmc_m3[132786].DB2-zm_rtsp.cpp/522 [RTSP Remote Ports are 0/0]
02/14/24 22:07:32.611159 zmc_m3[132786].DB2-zm_rtsp.cpp/523 [RTSP Remote Channels are 0/1]
02/14/24 22:07:32.611175 zmc_m3[132786].DB2-zm_rtsp.cpp/43 [Sending RTSP message: PLAY rtsp://cam3.domain.com:80/axis-media/media.amp?videocodec=h264&resolution=1280x960 RTSP/1.0^M

I dug a bit in the source (I'm not an expert!) but it seems that a new RtpSource object is created here in zm_rtsp.cpp:

  switch( mMethod ) {
    case RTP_RTSP :
    case RTP_RTSP_HTTP :
    {
      RtpSource *source = new RtpSource( mId, "", remoteChannels[0], mHost, remoteChannels[0], ssrc, seq, rtpClock, rtpTime, codecId );
    }
  }

Where remoteChannels[0] (3rd parameter) is passed further down to fill the values of localPortBase / mLocalPortChans which are used by getLocalCtrlPort()

But looking at the source (again in zm_rtsp.cpp):

  } else if (StartsWith(parts[i], "interleaved=") ) {
      method = "RTP/RTSP";
      StringVector subparts = Split(parts[i], "=");
      StringVector channels = Split(subparts[1], "-");
      remoteChannels[0] = strtol( channels[0].c_str(), nullptr, 10 );
      remoteChannels[1] = strtol( channels[1].c_str(), nullptr, 10 );

it seems to just parse the value from interleaved=0-1 in the RTSP transport response and pass that as port number to the bind calls later on.

MIN_RTP_PORT is only used in requestPorts() but that is only called for type RTP_UNICAST it seems.

Hope this makes any sense and helps you track down the issue.