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1. Wrapper function

initLocalDisplay() code

Define top level closure for local media code

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const initLocalDisplay = function(localDisplayElement){

2. Local variables

code

Define local variables

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const localDisplayDiv = localDisplayElement;
const localDisplays = {};

3. Remove local display

removeLocalDisplay() code

Define function that will remove local display once track is ended

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4. Find video element without audio track

getAudioContainer() code

Define function that will find video element without audio track.

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5. Add track to local display

add() code

Define add function which will add new track to local display

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Check if new track is an audio track. If so try to find video element without audio track attached. In case video element was found attach new audio track to it and return.

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if (stream.getAudioTracks().length > 0) {
    let videoElement = getAudioContainer();
    if (videoElement) {
        let track = stream.getAudioTracks()[0];
        videoElement.video.srcObject.addTrack(track);
        videoElement.audioStateDisplay.innerHTML = "Audio state: " + stream.getAudioTracks()[0].enabled;
        track.addEventListener("ended", function() {
            videoElement.video.srcObject.removeTrack(track);
            videoElement.audioStateDisplay.innerHTML = "Audio state: " + false;
            //check video element has no tracks left
            for (const [key, vTrack] of Object.entries(videoElement.video.srcObject.getTracks())) {
                if (vTrack.readyState !== "ended") {
                    return;
                }
            }
            removeLocalDisplay(videoElement.id);
        });
        return;
    }
}

Create new display container

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const coreDisplay = document.createElement('div');
coreDisplay.setAttribute("style","width:200px; height:auto; border: solid; border-width: 1px");
coreDisplay.id = stream.id;

Create and add name container to display container

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const streamNameDisplay = document.createElement("div");
streamNameDisplay.innerHTML = "Name: " + name;
streamNameDisplay.setAttribute("style","width:auto; height:30px");
coreDisplay.appendChild(streamNameDisplay);

Create and add audio state display. Subscribe to "click" event to handle mute/unmute.

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const audioStateDisplay = document.createElement("button");
audioStateDisplay.setAttribute("style","width:auto; height:30px");
audioStateDisplay.innerHTML = "Audio state: " + (stream.getAudioTracks().length > 0 ? stream.getAudioTracks()[0].enabled : false);
audioStateDisplay.addEventListener('click', function(){
    if (stream.getAudioTracks().length > 0) {
        stream.getAudioTracks()[0].enabled = !(stream.getAudioTracks()[0].enabled);
        audioStateDisplay.innerHTML = "Audio state: " + stream.getAudioTracks()[0].enabled;
    }
});
coreDisplay.appendChild(audioStateDisplay);

Create stream display which will hold video element.

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const streamDisplay = document.createElement('div');
streamDisplay.id = id;
streamDisplay.setAttribute("style","width:auto; height:auto");
coreDisplay.appendChild(streamDisplay);

Create video element and add it to stream display.

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const video = document.createElement("video");
streamDisplay.appendChild(video);
video.srcObject = stream;
video.muted = true;
video.onloadedmetadata = function (e) {
    video.play();
};

Subscribe to track's "ended" event. Once track is ended check if video element has any active tracks. If not - remove display.

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stream.getTracks().forEach(function(track){
    track.addEventListener("ended", function() {
        video.srcObject.removeTrack(track);
        //check video element has no tracks left
        for (const [key, vTrack] of Object.entries(video.srcObject.getTracks())) {
            if (vTrack.readyState !== "ended") {
                return;
            }
        }
        removeLocalDisplay(id);
    });
});

Subscribe to resize event to keep video inside the container.

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video.addEventListener('resize', function (event) {
    streamNameDisplay.innerHTML = "Name: " + name + " " + video.videoWidth + "x" + video.videoHeight;
    resizeVideo(event.target);
});

Save display, reassemble local displays and return newly created one.

code

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localDisplays[id] = coreDisplay;
reassembleLocalLayout();
return coreDisplay; 

6. Refresh local display grid

reassembleLocalLayout() code

Define helper which will recalculate local displays grid and reassemble local displays.

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7. Export add function for main code

code

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return {
    add: add
}

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1. Wrapper function

initRemoteDisplay() code

Define top level closure for remote media code

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const initRemoteDisplay = function(room, mainDiv, peerConnection) {

2. Local variables

code

Define local variables

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const constants = SFU.constants;
const remoteParticipants = {};

3. Subscribe to room events

code

Subscribe to related room events

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Find participant. If not found create a new one.

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let participant = remoteParticipants[e.info.nickName];
if (!participant) {
    participant = {};
    participant.nickName = e.info.nickName;
    participant.tracks = [];
    participant.displays = [];
    remoteParticipants[participant.nickName] = participant;
}

Add new tracks to the participant.

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participant.tracks.push.apply(participant.tracks, e.info.info);

Create display for every video track that is beeing added.

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        for (const pTrack of e.info.info) {
            let createDisplay = true;
            for (let i = 0; i < participant.displays.length; i++) {
                let display = participant.displays[i];
                if (pTrack.type === "VIDEO") {
                    if (display.hasVideo()) {
                        continue;
                    }
                    display.videoMid = pTrack.mid;
                    display.setTrackInfo(pTrack);
                    createDisplay = false;
                    break;
                } else if (pTrack.type === "AUDIO") {
                    if (display.hasAudio()) {
                        continue;
                    }
                    display.audioMid = pTrack.mid;
                    createDisplay = false;
                    break;
                }
            }
            if (!createDisplay) {
                continue;
            }
            let display = createRemoteDisplay(participant.nickName, participant.nickName, mainDiv);
            participant.displays.push(display);
            if (pTrack.type === "VIDEO") {
                display.videoMid = pTrack.mid;
                display.setTrackInfo(pTrack);
            } else if (pTrack.type === "AUDIO") {
                display.audioMid = pTrack.mid;
            }
        }
    }

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Find remote participant. If not found return.

code

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const participant = remoteParticipants[e.info.nickName];
if (!participant) {
    return;
}

Walk through tracks

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for (const rTrack of e.info.info) {

Find and remove participant's track that has the same mid as track that is beeing being removed

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for (let i = 0; i < participant.tracks.length; i++) {
    if (rTrack.mid === participant.tracks[i].mid) {
        participant.tracks.splice(i, 1);
        break;
    }
}

Find display that corresponds to the track and remove track from the display. If display has no active tracks remove display as well.

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for (let i = 0; i < participant.displays.length; i++) {
    let found = false;
    const display = participant.displays[i];
    if (display.mids.audio.includes(rTrack.mid)) {
        //remove from mids array
        display.mids.audio.splice(display.mids.audio.indexOf(rTrack.mid), 1);
        //stop track and remove stream
        display.audioStreams[rTrack.mid].getAudioTracks()[0].stop();
        delete display.audioStreams[rTrack.mid];
        //remove audio element
        display.display.removeChild(display.audioElements[rTrack.mid]);
        delete display.audioElements[rTrack.mid];
        found = true;
    } else if (display.mids.video === rTrack.mid) {
        display.mids.video = undefined;
        display.mediaStream.getVideoTracks()[0].stop();
        found = true;
    }
    if (display.mids.audio.length === 0 && display.mids.video === undefined) {
        const video = display.display.getElementsByTagName("video")[0]
        video.pause();
        video.srcObject = null;
        display.display.remove();
        participant.displays.splice(i, 1);
    }
    if (found) {
        break;
    }
}

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Find and remove participant.

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        let participant = remoteParticipants[e.name];
        if (!participant) {
            return;
        }
        participant.displays.forEach(function(display){
            display.dispose();
        })
        delete remoteParticipants[e.name];

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Find participant. Return if not found.

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console.log("Received track quality state");
const participant = remoteParticipants[e.info.nickName];
if (!participant) {
    return;
}

Walk through tracks

code

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for (const rTrack of e.info.tracks) {

Find corresponding display and update quality state

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            const mid = rTrack.mid;
            for (let i = 0; i < participant.displays.length; i++) {
                const display = participant.displays[i];
                if (display.videoMid === mid) {
                    display.updateQualityInfo(rTrack.quality);
                    break;
                }
            }

4. Create remote display

createRemoteDisplay() code

Helper function which will create display based on stream and track info.

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Remove remote display

dispose() code

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            dispose: function() {
                cell.remove();
            }

Hide remote display

hide() code

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            hide: function(value) {
                if (value) {
                    cell.style.display = "none";
                } else {
                    cell.style.display = "block";
                }
            }

Create remote display audio element

setAudio() code

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            setAudio: function(stream) {
                if (audio) {
                    audio.remove();
                }
                if (!stream) {
                    audio = null;
                    this.audioMid = undefined;
                    return;
                }
                audio = document.createElement("audio");
                audio.controls = "controls";
                cell.appendChild(audio);
                audio.srcObject = stream;
                audio.play();
            }

Create remote display video element

setVideo() code

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            setVideo: function(stream) {
                if (video) {
                    video.remove();
                }

                if (stream == null) {
                    video = null;
                    this.videoMid = undefined;
                    qualityDivs.forEach(function(div) {
                        div.remove();
                    });
                    qualityDivs = [];
                    tidDivs.forEach(function(div) {
                        div.remove();
                    });
                    tidDivs = [];
                    return;
                }
                video = document.createElement("video");
                streamDisplay.appendChild(video);
                video.srcObject = stream;
                video.onloadedmetadata = function (e) {
                    video.play();
                };
                video.addEventListener("resize", function (event) {
                    streamNameDisplay.innerHTML = "Name: " + name + " " + video.videoWidth + "x" + video.videoHeight;
                    resizeVideo(event.target);
                });
            }

Display track quality info

setTrackInfo() code

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            setTrackInfo: function(trackInfo) {
                if (trackInfo && trackInfo.quality) {
                    for (let i = 0; i < trackInfo.quality.length; i++) {
                        const qualityDiv = document.createElement("button");
                        qualityDivs.push(qualityDiv);
                        qualityDiv.innerText = trackInfo.quality[i];
                        qualityDiv.setAttribute("style", "display:inline-block; border: solid; border-width: 1px");
                        qualityDiv.style.color = "red";
                        qualityDiv.addEventListener('click', function(){
                            console.log("Clicked on quality " + trackInfo.quality[i] + " trackId " + trackInfo.id);
                            if (qualityDiv.style.color === "red") {
                                return;
                            }
                            for (let c = 0; c < qualityDivs.length; c++) {
                                if (qualityDivs[c].style.color !== "red") {
                                    qualityDivs[c].style.color = "gray";
                                }
                            }
                            qualityDiv.style.color = "blue";
                            room.changeQuality(trackInfo.id, trackInfo.quality[i]);
                        });
                        qualityDisplay.appendChild(qualityDiv);
                    }
                    for (let i = 0; i < 3; i++) {
                        const tidDiv = document.createElement("button");
                        tidDivs.push(tidDiv);
                        tidDiv.innerText = "TID"+i;
                        tidDiv.setAttribute("style", "display:inline-block; border: solid; border-width: 1px");
                        tidDiv.style.color = "gray";
                        tidDiv.addEventListener('click', function(){
                            console.log("Clicked on TID " + i + " trackId " + trackInfo.id);
                            for (let c = 0; c < tidDivs.length; c++) {
                                tidDivs[c].style.color = "gray";
                            }
                            tidDiv.style.color = "blue";
                            room.changeQuality(trackInfo.id, null, i);
                        });
                        tidDisplay.appendChild(tidDiv);
                    }
                }
            }

Update quality state

updateQualityInfo() code

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            updateQualityInfo: function(videoQuality) {
                for (const qualityInfo of videoQuality) {
                    for (const qualityDiv of qualityDivs) {
                        if (qualityDiv.innerText === qualityInfo.quality){
                            if (qualityInfo.available === true) {
                                qualityDiv.style.color = "gray";
                            } else {
                                qualityDiv.style.color = "red";
                            }
                            break;
                        }
                    }
                }
            }

5. Work with peer connection

code

Subscribe to PeerConnection's "ontrack" event.

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Find participant based on track's mid

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let rParticipant;
console.log("Attach remote track " + transceiver.receiver.track.id + " kind " + transceiver.receiver.track.kind + " mid " + transceiver.mid);
for (const [nickName, participant] of Object.entries(remoteParticipants)) {
    for (const pTrack of participant.tracks) {
        console.log("Participant " + participant.nickName + " track " + pTrack.id + " mid " + pTrack.mid);
        if (pTrack.mid === transceiver.mid) {
            rParticipant = participant;
            break;
        }
    }
    if (rParticipant) {
        break;
    }
}

Find corresponding display among participant's displays and add track.

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            for (const display of rParticipant.displays) {
                if (transceiver.receiver.track.kind === "video") {
                    if (display.videoMid === transceiver.mid) {
                        let stream = new MediaStream();
                        stream.addTrack(transceiver.receiver.track);
                        display.setVideo(stream);
                        break;
                    }
                } else if (transceiver.receiver.track.kind === "audio") {
                    if (display.audioMid === transceiver.mid) {
                        let stream = new MediaStream();
                        stream.addTrack(transceiver.receiver.track);
                        display.setAudio(stream);
                        break;
                    }
                }
            }