Local variables for constants, SFU SDK, local display and controls
const constants = SFU.constants; const sfu = SFU; let localDisplay; let cControls;
Default configuration - this one will be used if there was no config.json file available. With this config client will be preconfigured to connect to localhost over WSS, enter room "ROOM1" with pin "1234" and nickname "Alice". Media section directs client to publish audio and video tracks. Video will have two sub-tracks - high (h) and medium (m).
const defaultConfig = {
room: {
url: "wss://127.0.0.1:8888",
name: "ROOM1",
pin: "1234",
nickName: "Alice"
},
media: {
audio: {
tracks: [
{
source: "mic",
channels: 1
}
]
},
video: {
tracks: [
{
source: "camera",
width: 1280,
height: 720,
codec: "H264",
encodings: [
{ rid: "h", active: true, maxBitrate: 900000 },
{ rid: "m", active: true, maxBitrate: 300000, scaleResolutionDownBy: 2 }
]
}
]
}
}
};
Init function that is called when page is finished loading. The function will load config.json or default config, create local display and open entrance modal.
/**
* load config and show entrance modal
*/
const init = function() {
//read config
$.getJSON("config.json", function(config){
cControls = createControls(config);
}).fail(function(){
//use default config
cControls = createControls(defaultConfig);
});
//create local display to show local streams
localDisplay = initLocalDisplay(document.getElementById("localDisplay"));
//open entrance modal
$('#entranceModal').modal('show');
}
Connect function that is called once user clicks connect in entrance modal.
/**
* connect to server
*/
function connect() {
//hide modal
$('#entranceModal').modal('hide');
//disable controls
cControls.muteInput();
//create peer connection
const pc = new RTCPeerConnection();
//get config object for room creation
const roomConfig = cControls.roomConfig();
roomConfig.pc = pc;
//kick off connect to server and local room creation
const session = sfu.createRoom(roomConfig);
session.on(constants.SFU_EVENT.CONNECTED, function(room) {
//connected to server
const chatDiv = document.getElementById('messages');
const chatInput = document.getElementById('localMessage');
const chatButton = document.getElementById('sendMessage');
//create and bind chat to the new room
createChat(room, chatDiv, chatInput, chatButton);
room.on(constants.SFU_ROOM_EVENT.FAILED, function(e) {
const errField = document.getElementById("errorMsg");
errField.style.color = "red";
errField.innerText = e;
}).on(constants.SFU_ROOM_EVENT.OPERATION_FAILED, function (e) {
const errField = document.getElementById("errorMsg");
errField.style.color = "red";
errField.innerText = e.operation + " failed: " + e.error;
})
//setup remote display for showing remote audio/video tracks
const remoteDisplay = document.getElementById("display");
initRemoteDisplay(room, remoteDisplay, pc);
//get configured local video streams
let streams = cControls.getVideoStreams();
//combine local video streams with audio streams
streams.push.apply(streams, cControls.getAudioStreams());
//add our local streams to the room (to PeerConnection)
streams.forEach(function (s) {
//add local stream to local display
localDisplay.add(s.stream.id, "local", s.stream);
//add each track to PeerConnection
s.stream.getTracks().forEach((track) => {
addTrackToPeerConnection(pc, s.stream, track, s.encodings);
subscribeTrackToEndedEvent(room, track, pc);
});
});
//add callback for the new local stream to the local controls
cControls.onTrack(function (s) {
//add local stream to local display
localDisplay.add(s.stream.id, "local", s.stream);
//add each track to PeerConnection
s.stream.getTracks().forEach((track) => {
addTrackToPeerConnection(pc, s.stream, track, s.encodings);
subscribeTrackToEndedEvent(room, track, pc);
});
//kickoff renegotiation
room.updateState();
});
//join room
room.join();
});
}
Lets dive deeper into connect function and see what it does.
Hide modal as we don't need it anymore and mute controls before connect is established
//hide modal
$('#entranceModal').modal('hide');
//disable controls
cControls.muteInput();
Create PeerConnection and prepare the room config for the creation of session and room
//create peer connection const pc = new RTCPeerConnection(); //get config object for room creation const roomConfig = cControls.roomConfig(); roomConfig.pc = pc;
Create session (which will automatically connect to the server).
const session = sfu.createRoom(roomConfig);
Subscribe to session's "CONNECTED" event
session.on(constants.SFU_EVENT.CONNECTED, function(room) {
Once we are connected initialize room chat
//connected to server
const chatDiv = document.getElementById('messages');
const chatInput = document.getElementById('localMessage');
const chatButton = document.getElementById('sendMessage');
//create and bind chat to the new room
createChat(room, chatDiv, chatInput, chatButton);
Subscribe to room error events
room.on(constants.SFU_ROOM_EVENT.FAILED, function(e) {
const errField = document.getElementById("errorMsg");
errField.style.color = "red";
errField.innerText = e;
}).on(constants.SFU_ROOM_EVENT.OPERATION_FAILED, function (e) {
const errField = document.getElementById("errorMsg");
errField.style.color = "red";
errField.innerText = e.operation + " failed: " + e.error;
})
Initialize remote display
//setup remote display for showing remote audio/video tracks
const remoteDisplay = document.getElementById("display");
initRemoteDisplay(room, remoteDisplay, pc);
Get preconfigured local media from controls
//get configured local video streams let streams = cControls.getVideoStreams(); //combine local video streams with audio streams streams.push.apply(streams, cControls.getAudioStreams());
Add each stream to local display (so we can see it on page) and peer connection
//add our local streams to the room (to PeerConnection)
streams.forEach(function (s) {
//add local stream to local display
localDisplay.add(s.stream.id, "local", s.stream);
//add each track to PeerConnection
s.stream.getTracks().forEach((track) => {
addTrackToPeerConnection(pc, s.stream, track, s.encodings);
subscribeTrackToEndedEvent(room, track, pc);
});
});
Add listener to controls so we know if user adds new local streams. Once we have a new stream we will need to add it to local display, add it to peer connection and kickoff renegotiation.
//add callback for the new local stream to the local controls
cControls.onTrack(function (s) {
//add local stream to local display
localDisplay.add(s.stream.id, "local", s.stream);
//add each track to PeerConnection
s.stream.getTracks().forEach((track) => {
addTrackToPeerConnection(pc, s.stream, track, s.encodings);
subscribeTrackToEndedEvent(room, track, pc);
});
//kickoff renegotiation
room.updateState();
});
Finally join the room
//join room room.join();
subscribeTrackToEndedEvent function
This is a helper function that subscribes new local track to "ended" event. Once event fired we remove track from peer connection and kickoff renegotiation.
const subscribeTrackToEndedEvent = function(room, track, pc) {
track.addEventListener("ended", function() {
//track ended, see if we need to cleanup
let negotiate = false;
for (const sender of pc.getSenders()) {
if (sender.track === track) {
pc.removeTrack(sender);
//track found, set renegotiation flag
negotiate = true;
break;
}
}
if (negotiate) {
//kickoff renegotiation
room.updateState();
}
});
};
addTrackToPeerConnection function
This is a helper function which adds new local track to peer connection.
const addTrackToPeerConnection = function(pc, stream, track, encodings) {
pc.addTransceiver(track, {
direction: "sendonly",
streams: [stream],
sendEncodings: encodings ? encodings : [] //passing encoding types for video simulcast tracks
});
}