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While developing a WebRTC video chat application I have encountered receiving remote the video stream. The video stream blob is received, but the video is just black.

I have gone through these answers and tried almost everything I could to get it to work Remote VideoStream not working with WebRTC

......
Globalvars.socket.on('call', function (signal) {
    if(!Globalvars.pc){
        Methods.startCall(false, signal);
    }

    if(signal.sdp){
        temp = new RTCSessionDescription({"sdp" : decodeURIComponent(signal.sdp), "type" : signal.type});
        Globalvars.pc.setRemoteDescription(temp);
        for(i = 0; i < Globalvars.iceCandidateArray.length; i++){
            Globalvars.pc.addIceCandidate(new RTCIceCandidate({
                sdpMLineIndex: decodeURIComponent(signal.sdpMLineIndex),
                candidate: decodeURIComponent(signal.candidate)
            }));
        }

        Globalvars.iceCandidateArray = [];
    }
    else{
        if(Globalvars.pc.remoteDescription){
            Globalvars.pc.addIceCandidate(new RTCIceCandidate({
                sdpMLineIndex: decodeURIComponent(signal.sdpMLineIndex),
                candidate: decodeURIComponent(signal.candidate)
            }));
            console.log("remot");
        }
        else{
            Globalvars.iceCandidateArray.push(new RTCIceCandidate({
                sdpMLineIndex: decodeURIComponent(signal.sdpMLineIndex),
                candidate: decodeURIComponent(signal.candidate)
            }));
            console.log("ice candidate to temp array");
        }
    }
});


$("#roster-wrap").on("click", ".roster-list-item", function(e){
    //Globalvars.socket.emit('call', {"receiver_id" : $(this).attr("data-id"), "caller_id" : Globalvars.me.id});
    params = {"receiver_id" : $(this).attr("data-id"), "caller_id" : Globalvars.me.id};
    Methods.startCall(true, params);
    e.preventDefault();
});
.....


.....
// run start(true) to initiate a call
"startCall" : function (isCaller, params) {
    var configuration = {"iceServers": [{"url": "stun:stun.l.google:19302"}]};
    Globalvars.pc = new RTCPeerConnection(configuration);

    // send any ice candidates to the other peer
    Globalvars.pc.onicecandidate = function (evt) {
        //alert("ice candidate");
        if (!Globalvars.pc || !evt || !evt.candidate) return;
        var candidate = evt.candidate;
        Globalvars.socket.emit("call",{ "candidate": encodeURIComponent(candidate.candidate), "sdpMLineIndex" : encodeURIComponent(candidate.sdpMLineIndex), "receiver_id" :  params.receiver_id, "caller_id" : params.caller_id});
    };

    // once remote stream arrives, show it in the remote video element
    Globalvars.pc.onaddstream = function (evt) {
        console.log("add stream");
        if (!event) return;
        $("#remote-video").attr("src",URL.createObjectURL(evt.stream));
        Methods.waitUntilRemoteStreamStartsFlowing();
    };

    // get the local stream, show it in the local video element and send it
    navigator.getUserMedia({ "audio": false, "video": true }, function (stream) {
        $("#my-video").attr("src", URL.createObjectURL(stream));
        Globalvars.pc.addStream(stream);

        if (isCaller){
            Globalvars.pc.createOffer(getDescription, null, { 'mandatory': { 'OfferToReceiveAudio': true, 'OfferToReceiveVideo': true } });
        }
        else{
            console.log("Got Remote Description");
            console.log(Globalvars.pc.remoteDescription);               
            //Globalvars.pc.createAnswer(Globalvars.pc.remoteDescription, getDescription);
            Globalvars.pc.createAnswer(getDescription, null, { 'mandatory': { 'OfferToReceiveAudio': true, 'OfferToReceiveVideo': true } });
        }

        function getDescription(desc) {
            Globalvars.pc.setLocalDescription(desc);
            console.log("my desc");
            console.log(desc);
            Globalvars.socket.emit("call", {"sdp": encodeURIComponent(desc.sdp), "type": desc.type, "receiver_id" :  params.receiver_id, "caller_id" : params.caller_id});
            //signalingChannel.send(JSON.stringify({ "sdp": desc }));
        }
    });
},
......

The complete code is available at and

While developing a WebRTC video chat application I have encountered receiving remote the video stream. The video stream blob is received, but the video is just black.

I have gone through these answers and tried almost everything I could to get it to work https://stackoverflow.com/a/17424224/923109 Remote VideoStream not working with WebRTC

......
Globalvars.socket.on('call', function (signal) {
    if(!Globalvars.pc){
        Methods.startCall(false, signal);
    }

    if(signal.sdp){
        temp = new RTCSessionDescription({"sdp" : decodeURIComponent(signal.sdp), "type" : signal.type});
        Globalvars.pc.setRemoteDescription(temp);
        for(i = 0; i < Globalvars.iceCandidateArray.length; i++){
            Globalvars.pc.addIceCandidate(new RTCIceCandidate({
                sdpMLineIndex: decodeURIComponent(signal.sdpMLineIndex),
                candidate: decodeURIComponent(signal.candidate)
            }));
        }

        Globalvars.iceCandidateArray = [];
    }
    else{
        if(Globalvars.pc.remoteDescription){
            Globalvars.pc.addIceCandidate(new RTCIceCandidate({
                sdpMLineIndex: decodeURIComponent(signal.sdpMLineIndex),
                candidate: decodeURIComponent(signal.candidate)
            }));
            console.log("remot");
        }
        else{
            Globalvars.iceCandidateArray.push(new RTCIceCandidate({
                sdpMLineIndex: decodeURIComponent(signal.sdpMLineIndex),
                candidate: decodeURIComponent(signal.candidate)
            }));
            console.log("ice candidate to temp array");
        }
    }
});


$("#roster-wrap").on("click", ".roster-list-item", function(e){
    //Globalvars.socket.emit('call', {"receiver_id" : $(this).attr("data-id"), "caller_id" : Globalvars.me.id});
    params = {"receiver_id" : $(this).attr("data-id"), "caller_id" : Globalvars.me.id};
    Methods.startCall(true, params);
    e.preventDefault();
});
.....


.....
// run start(true) to initiate a call
"startCall" : function (isCaller, params) {
    var configuration = {"iceServers": [{"url": "stun:stun.l.google.com:19302"}]};
    Globalvars.pc = new RTCPeerConnection(configuration);

    // send any ice candidates to the other peer
    Globalvars.pc.onicecandidate = function (evt) {
        //alert("ice candidate");
        if (!Globalvars.pc || !evt || !evt.candidate) return;
        var candidate = evt.candidate;
        Globalvars.socket.emit("call",{ "candidate": encodeURIComponent(candidate.candidate), "sdpMLineIndex" : encodeURIComponent(candidate.sdpMLineIndex), "receiver_id" :  params.receiver_id, "caller_id" : params.caller_id});
    };

    // once remote stream arrives, show it in the remote video element
    Globalvars.pc.onaddstream = function (evt) {
        console.log("add stream");
        if (!event) return;
        $("#remote-video").attr("src",URL.createObjectURL(evt.stream));
        Methods.waitUntilRemoteStreamStartsFlowing();
    };

    // get the local stream, show it in the local video element and send it
    navigator.getUserMedia({ "audio": false, "video": true }, function (stream) {
        $("#my-video").attr("src", URL.createObjectURL(stream));
        Globalvars.pc.addStream(stream);

        if (isCaller){
            Globalvars.pc.createOffer(getDescription, null, { 'mandatory': { 'OfferToReceiveAudio': true, 'OfferToReceiveVideo': true } });
        }
        else{
            console.log("Got Remote Description");
            console.log(Globalvars.pc.remoteDescription);               
            //Globalvars.pc.createAnswer(Globalvars.pc.remoteDescription, getDescription);
            Globalvars.pc.createAnswer(getDescription, null, { 'mandatory': { 'OfferToReceiveAudio': true, 'OfferToReceiveVideo': true } });
        }

        function getDescription(desc) {
            Globalvars.pc.setLocalDescription(desc);
            console.log("my desc");
            console.log(desc);
            Globalvars.socket.emit("call", {"sdp": encodeURIComponent(desc.sdp), "type": desc.type, "receiver_id" :  params.receiver_id, "caller_id" : params.caller_id});
            //signalingChannel.send(JSON.stringify({ "sdp": desc }));
        }
    });
},
......

The complete code is available at https://bitbucket.org/ajaybc/meetchat-client and https://bitbucket.org/ajaybc/meetchat-server

• javascript
• html
• webrtc

Share Improve this question Follow edited May 23, 2017 at 12:08 CommunityBot 111 silver badge asked Sep 20, 2013 at 9:19 ajaybcajaybc 4,05988 gold badges4545 silver badges5858 bronze badges 7

• Have you tried getting more debugging information from chrome? Just go to "chrome://webrtc-internals/" in your Chrome browser, and see if all of the webrtc steps complete successfully. You can also post the info here, and I can take a peek to see if anything stands out... – Aki Commented Oct 7, 2013 at 20:42
• 1 @Awalias Yes I got it working. It actually due to a bug in the signalling mechanism I was using – ajaybc Commented Mar 31, 2014 at 3:53
• 14 You may want to answer your own question with exactly what you did for posterity. – Benjamin Trent Commented Jul 22, 2014 at 17:54
• 1 @RTB he may be use this link for sollution for signalling mechanism Signaling: session control, network and media information – Jignesh Vagh Commented Sep 11, 2014 at 6:25
• 3 @RTB A black remote screen usually means the remote SDP was not set. Maybe that helps you. – Kevin Commented Oct 21, 2014 at 7:55

 |  Show 2 more comments

4 Answers 4

Sorted by: Reset to default 1

You may need to add

<uses-permission android:name="android.permission.RECORD_AUDIO" />
<uses-permission android:name="android.permission.CAMERA" />

into your AndroidManifest.xml

I verified WebRTC works with https://download.01.org/crosswalk/releases/crosswalk/android/beta/7.36.154.12/ and https://apprtc.appspot.com/ on my Nexus 5.

Hope it works for you.

I had the same issues as you, but only for some clients, and I explored the same avenues that you did. The last thing (and probably the ultimate cause of my issues) was related to the NAT situation behind at least one of the clients. There will always be the possibility of a situation where one of the clients cannot get a hole punched in their NAT, and therefore a STUN server will not work. In these cases, you need a TURN server to relay the video to that client.

What configuration do you have for your iceServers in your peerConnection? Does it contain any TURN servers that you know to work?

You can create a free account on this site http://xirsys.com/simplewebrtc/, and follow the simple instructions on getting credentials for a TURN server on their hosting, which you can then use to test if this is the issue.

First create Peer connection and then add MediaStream to it. Only after adding mediastream to peerconnection exchange of offer,answer,candidates should be done.

Instead of using "decodeURIComponent" why don't you try "JSON.stringify"? That will ensure a smooth transformation to a string and you can then use JSON.parse to get out the object you sent. From my experience with black screen WebRTC, I sense a dirty SDP payload.

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