jikjoo
commented
4 years ago http://www.linux-projects.org/webrtc-signalling/
RTCPeerConnection = window.RTCPeerConnection || window.webkitRTCPeerConnection;
RTCSessionDescription = window.RTCSessionDescription;
RTCIceCandidate = window.RTCIceCandidate;
function signal(url, onStream, onError, onClose, onMessage) {
if ("WebSocket" in window) {
console.log("opening web socket: " + url);
var ws = new WebSocket(url);
var pc;
var iceCandidates = [];
var hasRemoteDesc = false;
function addIceCandidates() {
if (hasRemoteDesc) {
iceCandidates.forEach(function (candidate) {
pc.addIceCandidate(candidate,
function () {
console.log("IceCandidate added: " + JSON.stringify(candidate));
},
function (error) {
console.error("addIceCandidate error: " + error);
}
);
});
iceCandidates = [];
}
}
ws.onopen = function () {
/* First we create a peer connection */
var config = {"iceServers": [{"urls": ["stun:stun.l.google.com:19302"]}]};
var options = {optional: []};
pc = new RTCPeerConnection(config, options);
iceCandidates = [];
hasRemoteDesc = false;
pc.onicecandidate = function (event) {
if (event.candidate) {
var candidate = {
sdpMLineIndex: event.candidate.sdpMLineIndex,
sdpMid: event.candidate.sdpMid,
candidate: event.candidate.candidate
};
var request = {
what: "addIceCandidate",
data: JSON.stringify(candidate)
};
ws.send(JSON.stringify(request));
} else {
console.log("end of candidates.");
}
};
if ('ontrack' in pc) {
pc.ontrack = function (event) {
onStream(event.streams[0]);
};
} else { // onaddstream() deprecated
pc.onaddstream = function (event) {
onStream(event.stream);
};
}
pc.onremovestream = function (event) {
console.log("the stream has been removed: do your stuff now");
};
pc.ondatachannel = function (event) {
console.log("a data channel is available: do your stuff with it");
// For an example, see https://www.linux-projects.org/uv4l/tutorials/webrtc-data-channels/
};
/* kindly signal the remote peer that we would like to initiate a call */
var request = {
what: "call",
options: {
// If forced, the hardware codec depends on the arch.
// (e.g. it's H264 on the Raspberry Pi)
// Make sure the browser supports the codec too.
force_hw_vcodec: true,
vformat: 30, /* 30=640x480, 30 fps */
trickle_ice: true
}
};
console.log("send message " + JSON.stringify(request));
ws.send(JSON.stringify(request));
};
ws.onmessage = function (evt) {
var msg = JSON.parse(evt.data);
var what = msg.what;
var data = msg.data;
console.log("received message " + JSON.stringify(msg));
switch (what) {
case "offer":
var mediaConstraints = {
optional: [],
mandatory: {
OfferToReceiveAudio: true,
OfferToReceiveVideo: true
}
};
pc.setRemoteDescription(new RTCSessionDescription(JSON.parse(data)),
function onRemoteSdpSuccess() {
hasRemoteDesc = true;
addIceCandidates();
pc.createAnswer(function (sessionDescription) {
pc.setLocalDescription(sessionDescription);
var request = {
what: "answer",
data: JSON.stringify(sessionDescription)
};
ws.send(JSON.stringify(request));
}, function (error) {
onError("failed to create answer: " + error);
}, mediaConstraints);
},
function onRemoteSdpError(event) {
onError('failed to set the remote description: ' + event);
ws.close();
}
);
break;
case "answer":
break;
case "message":
if (onMessage) {
onMessage(msg.data);
}
break;
case "iceCandidate": // received when trickle ice is used (see the "call" request)
if (!msg.data) {
console.log("Ice Gathering Complete");
break;
}
var elt = JSON.parse(msg.data);
let candidate = new RTCIceCandidate({sdpMLineIndex: elt.sdpMLineIndex, candidate: elt.candidate});
iceCandidates.push(candidate);
addIceCandidates(); // it internally checks if the remote description has been set
break;
case "iceCandidates": // received when trickle ice is NOT used (see the "call" request)
var candidates = JSON.parse(msg.data);
for (var i = 0; candidates && i < candidates.length; i++) {
var elt = candidates[i];
let candidate = new RTCIceCandidate({sdpMLineIndex: elt.sdpMLineIndex, candidate: elt.candidate});
iceCandidates.push(candidate);
}
addIceCandidates();
break;
}
};
ws.onclose = function (event) {
console.log('socket closed with code: ' + event.code);
if (pc) {
pc.close();
pc = null;
ws = null;
}
if (onClose) {
onClose();
}
};
ws.onerror = function (event) {
onError("An error has occurred on the websocket (make sure the address is correct)!");
};
this.hangup = function() {
if (ws) {
var request = {
what: "hangup"
};
console.log("send message " + JSON.stringify(request));
ws.send(JSON.stringify(request));
}
};
} else {
onError("Sorry, this browser does not support Web Sockets. Bye.");
}
}
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