Screen sharing example

Screen sharing is available for Chrome and Firefox. To share screen in Chrome before 73 the extension need to build and install, in the latest Chrome versions (73 and newer), Firefox and Safari screen can be shared without extension. Today, it is not recommended to use extension.

Extension for Google Chrome with publication in Chrome Store

Source code for the extension is available by the following link:

Chrome Screen Sharing Extension

Create a Google account

1. Go to google.com and click ‘Sign in’ button

2. On the ‘Sign in’ page, click ‘Create account’ link

3. ‘Create your Google Account’ page will be opened
Fill the required fields and click ‘Next step’ button to create the account.

Register as Chrome Web Store Developer

1. Sign in to Chrome Developer Dashboard with the created Google account
2. Pay a one-time $5 developer signup fee

Customization for your domain

Follow the procedures described below to use the extensions with your domain.
Edit manifest file manifest.json of the Chrome extension.

Change:

• name
• author
• description
• homepage_url
• under "externally_connectable":"matches" change flashphoner.com to your domain

Save your icons for the extension to chrome-extension directory and edit the file names in "icons" and "web_accessible_resources". (For more information, see Manifest - Icons and Supplying Images.)

Package the extension

Package files from chrome-extension folder into ZIP archive.

Publish the extension

1. Sign in to Chrome Developer Dashboard
2. In the dashboard, click ‘Add new item’ button

3. Accept the developer agreement

4. On the ‘Upload’ page, choose the chrome-extension.zip file and click ‘Upload’ button

5. When the extension is uploaded, the page for editing the extension draft will be opened
Edit the extension as required and click ‘Save draft and return to dashboard’ button at the bottom of the page.

6. The extension will appear in the developer dashboard
Click ‘Publish’ link to publish the extension.

A published extension will have status ‘Published’ as on the image below.

For more information, see Chrome Web Store Publishing Tutorial.

Extension Inline Installation

Extension installation can be initiated by clicking a link on the Screen Sharing client page.
Note that the extension to be installed should be customized, published and approved before inline installation can be used.

Follow the procedures described below to use the client with your extensions.

1. When publishing, select ‘Inline Install’ option

2. Verify and add website with your domain to the extension
- Click ‘Add a New Site’

- Google Search Console page will open in a new tab
Enter URL with your domain.

- A page with the instruction for the site verification will open
Follow the procedure steps and click ‘Verify’ button.

- If the verification is passed, a page confirming successful verification will be opened

- The website will appear in the list in the extension options and the extension can be associated with the site

Configuring the client

Edit  Screen-sharing.html and Screen-sharing.js

• In Screen-sharing.html the chrome-webstore-item parameter should point to your extension in the Chrome Store
• In Screen-sharing.js replace the value of the chromeScreenSharingExtensionId parameter to the ID of your extension

To get the ID of the extension, click ‘More info’ of this extension in Chrome Developer Dashboard.

Media source parameters

To configure screen media source parameters, use parameters of the Configuration object passed to the init() method upon initializing of the Flashphoner API instance.

var f = Flashphoner.getInstance();
var configuration = new Configuration();
....
configuration.screenSharingVideoWidth = 1920;
configuration.screenSharingVideoHeight = 1080;
configuration.screenSharingVideoFps = 10;
f.init(configuration);

Parameter list

These parameters set marginal values of resolution and framerate (FPS). For instance, screenSharingVideoWidth = 1080 means the width of the source video cannot be more than 1080 pixels, but can be less. (i.e. when sending a stream of an app window that has the width of 720 pixels).

System sound capture in Chrome browser

In Chrome browser, there is ability to translate audio stream from system sound source while capturing a screen. The feature is useful in screencasting, for example. To capture system sound, set "Share audio" option in Chrome extension dialog window while choosing streaming source window or browser tab:

Chrome extension code:

        callback({sourceId: sourceId, systemSoundAccess: opts.canRequestAudioTrack});

Capture source (screen or window) management in Firefox browser

In Firefox browser, all the screen or some program window can be chosen as video stream source with constraints.video.mediaSource parameter

code:

    constraints.video.type = "screen";
    if (Browser.isFirefox()){
        constraints.video.mediaSource = $('#mediaSource').val();
    }
    session.createStream({
        name: streamName,
        display: localVideo,
        constraints: constraints
    })

Source selection interface example:

Program window capture

Screen capture

Screen sharing without extension

Firefox browser

Firefox browser does not use extension to share screen

Chromium based browsers

Since Chrome 73 and Flashphoner WebSDK 0.5.28.2753.86 screen sharing is possible without extension. To do this constraints.video.withoutExtension parameter should be passed when stream is created

code

 if ($("#woChromeExtension").prop('checked')) {
     constraints.video.withoutExtension = true;
 }

Safari browser in MacOS

Since Safari 13 and Flashphoner WebSDK 0.5.28.2753.152 screen sharing is possible without extension. To do this constraints.video.withoutExtension parameter should be passed when stream is created

code

 if ($("#woChromeExtension").prop('checked') || Browser.isSafari()) {
     constraints.video.withoutExtension = true;
 }

Known limits

1. In Chrome browser, picture resolution and FPS are set by source dimensions (screen, windows or browser tab) and by real picture updating speed, not by constraints/ This issue is fixed since Flashphoner WebSDK build 0.5.28.2753.152

2. System sound capture only works starting from Crome 74

Code of the example

This example uses Flashphoner extensions for work with domain *.flashphoner.com. For work with your domain, build up and publish your extensions as described above.

As temporary solution, IP address of your WCS server can be added to file C:\Windows\System32\drivers\etc\hosts (on Windows OS) as test.flashphoner.com. That way, you will be able to test your WCS server with domain test.flashphoner.com till the extensions for your domain are built up.

With Chrome, the example works only by https://.

The path to the source code of the example on WCS server is:

/usr/local/FlashphonerWebCallServer/client/examples/demo/streaming/screen-sharing

screen-sharing.css - file with styles
screen-sharing.html - page of the screen sharing streamer
screen-sharing.js - script providing functionality for the streamer

This example can be tested using the following address:

https://host:8888/client/examples/demo/streaming/screen-sharing/screen-sharing.html

Here host is the address of the WCS server.

For Chrome, link to the extension is specified directly in file screen-sharing.html line 17

<link rel="chrome-webstore-item" href="https://chrome.google.com/webstore/detail/nlbaajplpmleofphigmgaifhoikjmbkg">

Analyzing the code

1. Initialization of the API.

Flashphoner.init() code

Chrome extension ID is passed to the init() method.

Flashphoner.init({screenSharingExtensionId: extensionId});

2. Connection to WCS server.

Flashphoner.createSession() code

    Flashphoner.createSession({urlServer: url}).on(SESSION_STATUS.ESTABLISHED, function(session){
        //session connected, start streaming
        startStreaming(session);
    }).on(SESSION_STATUS.DISCONNECTED, function(){
        setStatus(SESSION_STATUS.DISCONNECTED);
        onStopped();
    }).on(SESSION_STATUS.FAILED, function(){
        setStatus(SESSION_STATUS.FAILED);
        onStopped();
    });

3. Receiving the event confirming successful connection

ConnectionStatusEvent ESTABLISHED code

    Flashphoner.createSession({urlServer: url}).on(SESSION_STATUS.ESTABLISHED, function(session){
        //session connected, start streaming
        startStreaming(session);
    }).on(SESSION_STATUS.DISCONNECTED, function(){
        ...
    }).on(SESSION_STATUS.FAILED, function(){
        ...
    });

4. Stream constraints setting

resolution and fps code

    var constraints = {
        video: {
            width: parseInt($('#width').val()),
            height: parseInt($('#height').val()),
            //WCS-2014. fixed window/tab sharing
            frameRate: parseInt($('#fps').val())
        }
    };

michrophone usage code

    if ($("#useMic").prop('checked')) {
        constraints.audio = {
            deviceId: $('#audioInput').val()
        };
    }

video source type and Chrome screen sharing without extension code

    constraints.video.type = "screen";
    if ($("#woChromeExtension").prop('checked')) {
        constraints.video.withoutExtension = true;
    }

Firefox media source code

    if (Browser.isFirefox()){
        constraints.video.mediaSource = $('#mediaSource').val();
    }

5. Video streaming

session.createStream(), publish() code

    session.createStream({
        name: streamName,
        display: localVideo,
        constraints: constraints
        ...
    }).publish();

6. Receiving the event confirming successful streaming

StreamStatusEvent PUBLISHING code

When the screen sharing stream is published, preview video stream is created with method session.createStream(), and function play() is called to start playback of the stream in <div> element 'remoteVideo'.

    session.createStream({
        name: streamName,
        display: localVideo,
        constraints: constraints
    }).on(STREAM_STATUS.PUBLISHING, function(publishStream){
        /*
         * User can stop sharing screen capture using Chrome "stop" button.
         * Catch onended video track event and stop publishing.
         */
        document.getElementById(publishStream.id()).srcObject.getVideoTracks()[0].onended = function (e) {
            publishStream.stop();
        };
        document.getElementById(publishStream.id()).addEventListener('resize', function(event){
            resizeVideo(event.target);
        });
        setStatus(STREAM_STATUS.PUBLISHING);
        //play preview
        session.createStream({
            name: streamName,
            display: remoteVideo
            ...
        }).play();
    }).on(STREAM_STATUS.UNPUBLISHED, function(){
        ...
    }).on(STREAM_STATUS.FAILED, function(){
        ...
    }).publish();

7. Receiving the event confirming successful preview stream playback

StreamStatusEvent PLAYING code

        session.createStream({
            name: streamName,
            display: remoteVideo
        }).on(STREAM_STATUS.PLAYING, function(previewStream){
            document.getElementById(previewStream.id()).addEventListener('resize', function(event){
                resizeVideo(event.target);
            });
            //enable stop button
            onStarted(publishStream, previewStream);
        }).on(STREAM_STATUS.STOPPED, function(){
            ...
        }).on(STREAM_STATUS.FAILED, function(){
            ...
        }).play();

8. Preview stream playback stop

stream.stop() code

function onStarted(publishStream, previewStream) {
    $("#publishBtn").text("Stop").off('click').click(function(){
        $(this).prop('disabled', true);
        previewStream.stop();
    }).prop('disabled', false);
}

9. Receiving the event confirming successful playback stop

StreamStatusEvent STOPPED code

On receiving the event, publishStream.stop() is called to stop screen sharing streaming

        session.createStream({
            name: streamName,
            display: remoteVideo
        }).on(STREAM_STATUS.PLAYING, function(previewStream){
            ...
        }).on(STREAM_STATUS.STOPPED, function(){
            publishStream.stop();
        }).on(STREAM_STATUS.FAILED, function(){
            ...
        }).play();

10. Screen sharing streaming stop by click on Chrome extension button

publishStream.stop(). code

        document.getElementById(publishStream.id()).srcObject.getVideoTracks()[0].onended = function (e) {
            publishStream.stop();
        };

11. Receiving the event confirming successful streaming stop

StreamStatusEvent UNPUBLISHED code

    session.createStream({
        name: streamName,
        display: localVideo,
        constraints: constraints
    }).on(STREAM_STATUS.PUBLISHING, function(publishStream){
        ...
    }).on(STREAM_STATUS.UNPUBLISHED, function(){
        setStatus(STREAM_STATUS.UNPUBLISHED);
        //enable start button
        onStopped();
    }).on(STREAM_STATUS.FAILED, function(){
        ...
    }).publish();