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Revision as of 11:17, 20 March 2019 by Oleg (talk | contribs) (Notes)
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  • 10393 series
  • /usr/bin/str


  • In situations when streaming across middleboxes (switches and other devices) make sure the camera link is the slowest one.
  • Example congestion situatation:
camera <-- 1000Mbps --> Gigabit switch <-- 100Mbps (PC NIC limited) --> PC
PC might not get all the packets depending on switch's buffers sizes (e.g. for netgear GS105 has 128kB which gets overflowed at image sizes 200+kB)
  • Setting link speed examples:
ethtool -s eth0 speed 100 duplex half autoneg off
ethtool -s eth0 speed 1000 duplex full autoneg off
  • dump UDP packets log on the camera (tcpdump if installed):
tcpdump -i eth0 -n udp port <someport> -w packets.pcap
  • log network packets on PC:
wireshark works fine
  • live555 is used by vlc and mplayer while gstreamer is standalone
As UDP has no congestion control there might be several workarounds:
1. patch live555 and gstreamer
2. slow down camera link
  • Patching live555 options:
1. Stick close to RFC4585 and RFC6679, also checkout RFC8087 & RFC8311?
2. Make RTCP RR reports sent out by the receiver for every 50 (or any other number) packets received - implement handling this info in the sender (camera)
Implementing 2:
        if (fSource != NULL && fSource->RTPgs() == RTCPgs) {
            // We're receiving RTCP reports that are multiplexed with RTP, so ask the RTP source
            // to give them to us:
        } else {
            // need to register our RTCP instance here it will be passed to MultiFramedRTPSource.c which receive RTP packets
            // just reused the instance for multiplexed packets
        // insert after this line something like:
        int pnum = receptionStatsDB().totNumPacketsReceived();
        if ((pnum%50)==0){
            if (fRTCPInstanceForMultiplexedRTCPPackets!=NULL){
                // here fRTCPInstanceForMultiplexedRTCPPackets is just reused
  • Patching gstreamer:
First, need to find how to make gstreamer send RR reports. Then proceed as with live555.

Other links

  • Loss, Latency, and Speed - some general info
  • RFC4585: Extended RTP Profile for Real-time Transport Control Protocol (RTCP)-Based Feedback (RTP/AVPF)
  • RFC6679: Explicit Congestion Notification (ECN) for RTP over UDP
  • RFC8087: The Benefits of Using Explicit Congestion Notification (ECN)
  • RFC8311: Relaxing Restrictions on Explicit Congestion Notification (ECN) Experimentation