Overview
The example shows a presentation case: webcamera and screen sharing streams publishing from a single page with optional streams mixing at server side.
Screen sharing parameters:
- FPS - framerate per second
- Width - picture width
- Height - picture height
Server stream mixing parameters:
- Add to mixer - add streams automatically to mixer
- Mixer - mixer name
Connection parameters:
- Websocket URL of WCS sever
The code of the example
The code of the example is on WCS server by the following path:
/usr/local/FlashphonerWebCallServer/client2/examples/demo/streaming/screen-camera-mixer
screen-camera-mixer.css - styles file
screen-camera-mixer.html - example HTML page
screen-camera-mixer.js - main example script
The example may be tested by the following address:
https://host:8888/client2/examples/demo/streaming/screen-camera-mixer/screen-camera-mixer.html
where host is WCS server address.
Analyzing the code
To analyze the code let's take a screen-camera-mixer.js version with hash 42b55d1, which is available here and may be downloaded in build 2.0.247.
1. API initialization.
Flashphoner.init() code
Flashphoner.init();
2. Connecting to the server
Flashphoner.createSession() code
const connect = function() {
...
let url = field("url");
...
console.log("Create new session with url " + url);
Flashphoner.createSession({urlServer: url}).on(SESSION_STATUS.ESTABLISHED, function(session){
...
}).on(SESSION_STATUS.DISCONNECTED, function(){
...
}).on(SESSION_STATUS.FAILED, function(){
...
});
}
3. Receiving the event confirming successful connection
STREAM_STATUS.ESTABLISHED code
const connect = function() {
...
let url = field("url");
...
console.log("Create new session with url " + url);
Flashphoner.createSession({urlServer: url}).on(SESSION_STATUS.ESTABLISHED, function(session){
//session connected, start streaming
setStatus("screen", SESSION_STATUS.ESTABLISHED);
setStatus("camera", SESSION_STATUS.ESTABLISHED);
onConnected(session);
}).on(SESSION_STATUS.DISCONNECTED, function(){
...
}).on(SESSION_STATUS.FAILED, function(){
...
});
}
4. Screen sharing stream publishing
Session.createStream(), Stream.publish() code
The following parameters are passed to createStream() method:
- streamName - stream name
- constraints.video.width - picture width
- constraints.video.height - picture height
- constraints.video.frameRate - publishing framerate
- constraints.video.type: "screen" - stream type: screen sharing
- constraints.video.withoutExtension: true - screen sharing from browser without a special extension
- constraints.video.mediaSource: "screen" - for screen sharing from Firefox browser only
- localVideoScreen - div tag to display a local video
- disableConstraintsNormalization = true - disable constraints normalization (for MacOS Safari only)
const startStreamingScreen = function(session) {
let streamName = getStreamName("screen", field("url"));
let constraints = {
video: {
width: parseInt($('#width').val()),
height: parseInt($('#height').val()),
frameRate: parseInt($('#fps').val()),
type: "screen",
withoutExtension: true
}
};
if (Browser.isFirefox()) {
constraints.video.mediaSource = "screen";
}
let options = {
name: streamName,
display: localVideoScreen,
constraints: constraints
}
if (isSafariMacOS()) {
options.disableConstraintsNormalization = true;
}
session.createStream(options).on(STREAM_STATUS.PUBLISHING, function(screenStream) {
...
}).on(STREAM_STATUS.UNPUBLISHED, function() {
...
}).on(STREAM_STATUS.FAILED, function(stream) {
...
}).publish();
}
5. Receiving the event confirming successful screen publishing
STREAM_STATUS.PUBLISHING code
Screen sharing stream WebRTC statistics collection and web camera stream publishing start on this event
const startStreamingScreen = function(session) {
...
session.createStream(options).on(STREAM_STATUS.PUBLISHING, function(screenStream) {
/*
* User can stop sharing screen capture using Chrome "stop" button.
* Catch onended video track event and stop publishing.
*/
document.getElementById(screenStream.id()).srcObject.getVideoTracks()[0].onended = function (e) {
screenStream.stop();
};
document.getElementById(screenStream.id()).addEventListener('resize', function(event){
resizeVideo(event.target);
});
setStatus("screen", STREAM_STATUS.PUBLISHING, screenStream);
screenStats = StreamStats("screen", screenStream, STAT_INTERVAL);
startStreamingCamera(session, screenStream);
}).on(STREAM_STATUS.UNPUBLISHED, function() {
...
}).on(STREAM_STATUS.FAILED, function(stream) {
...
}).publish();
}
6. Web camera stream publishing
Session.createStream(), Stream.publish() code
The following parameters are passed to createStream() method:
- streamName - stream name
- localVideoCamera - div tag to display a local video
const startStreamingCamera = function(session, screenStream) {
let streamName = getStreamName("camera", field("url"));
let options = {
name: streamName,
display: localVideoCamera
}
session.createStream(options).on(STREAM_STATUS.PUBLISHING, function(cameraStream) {
...
}).on(STREAM_STATUS.UNPUBLISHED, function() {
...
}).on(STREAM_STATUS.FAILED, function(stream) {
...
}).publish();
}
7. Receiving the event confirming successful camera publishing
STREAM_STATUS.PUBLISHING code
Web camera stream WebRTC statistics collection starts on this event
const startStreamingCamera = function(session, screenStream) {
...
session.createStream(options).on(STREAM_STATUS.PUBLISHING, function(cameraStream) {
document.getElementById(cameraStream.id()).addEventListener('resize', function(event){
resizeVideo(event.target);
});
setStatus("camera", STREAM_STATUS.PUBLISHING, cameraStream);
cameraStats = StreamStats("camera", cameraStream, STAT_INTERVAL);
onStarted(cameraStream);
}).on(STREAM_STATUS.UNPUBLISHED, function() {
...
}).on(STREAM_STATUS.FAILED, function(stream) {
...
}).publish();
}
8. WebRTC statistics collection and displaying
Stream.getStats(), stats.outboundStream.video.bytesSent, stats.otherStats.availableOutgoingBitrate code
The following parameters are displayed:
- current publishing bitrate
- maximum available bitrate for the stream estimated by browser
const StreamStats = function(type, stream, interval) {
const streamStats = {
type: type,
timer: null,
stream: stream,
bytesSent: 0,
start: function(interval) {
if (!streamStats.timer) {
streamStats.timer = setInterval(streamStats.displayStats, interval);
}
},
stop: function() {
if (streamStats.timer) {
clearInterval(streamStats.timer);
streamStats.timer = null;
}
setBitrate(streamStats.type, "");
setAvailableBitrate(streamStats.type, "");
},
displayStats: function() {
if (streamStats.stream) {
streamStats.stream.getStats((stats) => {
if (stats) {
if (stats.outboundStream && stats.outboundStream.video) {
let vBitrate = (stats.outboundStream.video.bytesSent - streamStats.bytesSent) * 8;
setBitrate(streamStats.type, vBitrate);
streamStats.bytesSent = stats.outboundStream.video.bytesSent;
}
if (stats.otherStats && stats.otherStats.availableOutgoingBitrate !== undefined) {
setAvailableBitrate(streamStats.type, stats.otherStats.availableOutgoingBitrate);
}
}
});
}
}
};
streamStats.start(interval);
return streamStats;
}
9. Stop camera publishing
Stream.stop() code
const setPublishButton = function(action, session, cameraStream) {
$("#publishBtn").text(action).off('click').click(function(){
if (action == "Start") {
...
} else if (action === "Stop") {
$(this).prop('disabled', true);
cameraStream.stop();
}
}).prop('disabled', false);
}
10. Stop screen publishing
Stream.stop() code
const startStreamingCamera = function(session, screenStream) {
...
session.createStream(options).on(STREAM_STATUS.PUBLISHING, function(cameraStream) {
...
}).on(STREAM_STATUS.UNPUBLISHED, function() {
setStatus("camera", STREAM_STATUS.UNPUBLISHED);
screenStream.stop();
}).on(STREAM_STATUS.FAILED, function(stream) {
...
}).publish();
}
11. Stop WebRTC statistics collection
const onStopped = function(session) {
if (cameraStats) {
cameraStats.stop();
}
if (screenStats) {
screenStats.stop();
}
...
}