Track Problem

[mkemalgokce]

Hello, i want to send video from browser (with javascript) on C++ libdatachannel.

My connection completed like below.
2022-08-21 01:31:42.170 INFO [50857] [rtc::impl::DtlsTransport::runRecvLoop@576] DTLS handshake finished 2022-08-21 01:31:42.170 INFO [50857] [rtc::impl::DtlsSrtpTransport::postHandshake@266] Deriving SRTP keying material (OpenSSL) 2022-08-21 01:31:42.170 VERB [50843] [rtc::impl::IceTransport::LogCallback@354] juice: Entering poll on 1 sockets for 10000 ms 2022-08-21 01:31:42.170 INFO [50857] [rtc::impl::PeerConnection::changeState@1132] Changed state to connected

But track not working, i cant get any data with track. But some logs(like below), they said i am receiving some datas. When connection is completed, i took these datas like every second. How can i get these datas with tracker or something ?

2022-08-21 02:04:11.913 VERB [55558] [rtc::impl::IceTransport::LogCallback@354] juice: Received application datagram 2022-08-21 02:04:11.913 VERB [55639] [rtc::impl::DtlsSrtpTransport::recvMedia@174] Incoming SRTP packet, size=46 2022-08-21 02:04:11.913 VERB [55558] [rtc::impl::IceTransport::RecvCallback@327] Incoming size=1058 2022-08-21 02:04:11.913 VERB [55639] [rtc::impl::DtlsSrtpTransport::recvMedia@188] Unprotected SRTP packet, size=36 2022-08-21 02:04:11.913 VERB [55558] [rtc::impl::DtlsTransport::incoming@513] Incoming size=1058 2022-08-21 02:04:11.913 VERB [55558] [rtc::impl::IceTransport::LogCallback@354] juice: Receiving datagram 2022-08-21 02:04:11.913 VERB [55639] [rtc::impl::DtlsSrtpTransport::demuxMessage@212] Demultiplexing DTLS and SRTP/SRTCP with first byte, value=144 2022-08-21 02:04:11.913 VERB [55639] [rtc::impl::DtlsSrtpTransport::recvMedia@150] Demultiplexing SRTCP and SRTP with RTP payload type, value=97 2022-08-21 02:04:11.913 VERB [55558] [rtc::impl::IceTransport::LogCallback@354] juice: No more datagrams to receive 2022-08-21 02:04:11.913 VERB [55558] [rtc::impl::IceTransport::LogCallback@354] juice: Bookkeeping... 2022-08-21 02:04:11.913 VERB [55639] [rtc::IsRtcp@49] Demultiplexing RTCP and RTP with payload type, value=97 192.168.0.18:52340

And also this is my tracker:

`

    rtc::Description::Video media("video", rtc::Description::Direction::RecvOnly);
    media.addH264Codec(96);
    media.setBitrate(
        2500);
    auto track = pc->addTrack(media);

    auto session = std::make_shared<rtc::RtcpReceivingSession>();
    track->onOpen([]{
                      std::cout << "Track Open!\n";
                  });
    track->setMediaHandler(session);
    track->onError([](std::string err) {
        std::cout << "\n Err on" << err << std::endl;
    });

    track->onMessage([session, sock, addr](rtc::binary message) {

        //decode_data(message, message.size(),number);
        for(auto val : message) printf("%hhx", val);
        sendto(sock, reinterpret_cast<const char *>(message.data()), int(message.size()), 0,
               reinterpret_cast<const struct sockaddr *>(&addr), sizeof(addr));


    },nullptr);

`

[paullouisageneau]

It looks like the browser sends media for different track. How do you handle the media on browser side?

[mkemalgokce]

const media = await navigator.mediaDevices.getUserMedia({ video: { width: 400, height: 320 } , audio : false }); media.getTracks().forEach(track => pc.addTrack(track, media));

I am using like this on js. I looked your examples, it looks like same.

[mkemalgokce]

I am sending offer from browser. This is my answer. Am I update or something with track on this block ??
`

    if (message["type"] == "offer") {
    qInfo("Offer comed ! \n");
    rtc::Description offer(message["sdp"].get<std::string>(), message["type"].get<std::string>());
    std::cout << message.dump() << std::endl;
    pc->setRemoteDescription(offer);
    pc->setLocalDescription();
    
    std::string ss_id = message["ss_id"];
    json message = {{"ss_id", ss_id},
                    {"sdp", pc->localDescription()->generateSdp()},
                    {"type", pc->localDescription()->typeString()}};
    ws->send(message.dump());
    std::cout << "CANDIDATES:" << candidates.size() << std::endl;
    for(int i=0; i < candidates.size(); ++i) {
        std::cout << "Sent!" << i << std::endl;
        ws->send(candidates[i]);
    }

`

And also thanks for your answer

[paullouisageneau]

This way of performing signaling is incorrect for multiple reasons:

• You need to wait for candidates to be gathered in order to send them as the process is asynchronous, either by waiting for GatheringState::Complete to send the description or, better, by sending the candidates in the onLocalCandidatecallback.
• You should also send the description in the onLocalDescription callback rather than synchronously.
• Adding a track with addTrack() requires an offer to advertise the new track to the remote side (with a call to setLocalDescription()), so I think what you actually want to do here is offering from the libdatachannel client after you add the track and answering from the browser.

[mkemalgokce]

Ok thanks for your answers. Have a nice day