Screen Sharing with Camera¶

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¶

code

const onStopped = function(session) {
    if (cameraStats) {
        cameraStats.stop();
    }
    if (screenStats) {
        screenStats.stop();
    }
    ...
}