Silvermine VideoJS Chromecast Plugin

What is it?

A plugin for videojs versions 6+ that adds a button to the control bar which will cast videos to a Chromecast.

How do I use it?

The @silvermine/videojs-chromecast plugin includes 3 types of assets: JavaScript, CSS, and images.

You can either build the plugin locally and use the assets that are output from the build process directly, or you can install the plugin as an NPM module, include the JavaScript and SCSS source in your project using a Common-JS module loader and SASS build process, and copy the images from the image source folder to your project.

Note that regardless of whether you are using this plugin via the pre-built JS or as a module, the Chromecast framework will need to be included after the plugin. For example:

<script src="https://unpkg.com/video.js@6.1.0/dist/video.js"></script>
<script src="./dist/silvermine-videojs-chromecast.min.js"></script>
<script type="text/javascript" src="https://www.gstatic.com/cv/js/sender/v1/cast_sender.js?loadCastFramework=1"></script>

Building the plugin locally

1. Either clone this repository or install the @silvermine/videojs-chromecast module using npm install @silvermine/videojs-chromecast.
2. Ensure that @silvermine/videojs-chromecast's devDependencies are installed by running npm install from within the videojs-chromecast folder.
3. Run grunt build to build and copy the JavaScript, CSS and image files to the videojs-chromecast/dist folder.
4. Copy the plugin's files from the dist folder into your project as needed.
5. Ensure that the images in the dist/images folder are accessible at ./images/, relative to where the plugin's CSS is located. If, for example, your CSS is located at https://example.com/plugins/silvermine-videojs-chromecast.css, then the plugin's images should be located at https://example.com/plugins/images/.
6. Follow the steps in the "Configuration" section below.

Note: when adding the plugin's JavaScript to your web page, include the silvermine-videojs-chromecast.min.js JavaScript file in your HTML after loading Video.js. The plugin's built JavaScript file expects there to be a reference to Video.js at window.videojs and will throw an error if it does not exist.

Initialization options

• preloadWebComponents (default: false) - The Chromecast framework relies on the webcomponents.js polyfill when a browser does not have document.registerElement in order to create the <google-cast-button> custom component (which is not used by this plugin). If you are using jQuery, this polyfill must be loaded and initialized before jQuery is initialized. Unfortunately, the Chromecast framework loads the webcomponents.js polyfill via a dynamically created <script> tag. This causes a race condition (see #17). Also, including webcomponents.js anywhere on the page will break jQuery's fix for bubbling some events to document (e.g. onchange events for <select>, see #21). Setting preloadWebComponents to true will "fix" these 2 problems by (1) making this plugin add the webcomponents polyfill synchronously when the polyfill is needed and (2) using the webcomponents-lite.js version as it does not include the shadow DOM polyfills, but still provides the registerElement polyfill that the Chromecast framework needs. If you use the preloadWebComponents: true option, you should make sure that this plugin is loaded before jQuery. Then include the Chromecast framework after this plugin as you normally would.

  Note: There is a caveat to using the preloadWebComponents setting. Because the Chromecast plugin uses the shadow DOM to create the <google-cast-button> custom component, the <google-cast-button> custom component may partly render, but it will not be functional. This tag is not used by this plugin. However if you must use this tag elsewhere, you should not use the preloadWebComponents flag.

  tl;dr: if you use jQuery, you should use the preloadWebComponents: true option in this plugin.

Providing initialization options via require()

If requiring this plugin via NPM, any desired initialization options can be supplied to the constructor function exported by the module. For example:

require('@silvermine/videojs-chromecast')(videojs, { preloadWebComponents: true });

Providing initialization options via <script>

If using the prebuilt JS, the initialization options can be provided via window.SILVERMINE_VIDEOJS_CHROMECAST_CONFIG. Note that these options need to be set before the <script> tag to include the plugin.

<script>
   window.SILVERMINE_VIDEOJS_CHROMECAST_CONFIG = {
      preloadWebComponents: true,
   };
</script>
<script src="path/to/silvermine-videojs-chromecast.js"></script>

Configuration

Once the plugin has been loaded and registered, configure it and add it to your Video.js player using Video.js' plugin configuration option (see the section under the heading "Setting up a Plugin" on Video.js' plugin documentation page.

Important: In addition to defining plugin configuration, you are required to define the player's techOrder option, setting 'chromecast' as the first Tech in the list. Below is an example of the minimum required configuration for the Chromecast plugin to function:

var options;

options = {
   controls: true,
   techOrder: [ 'chromecast', 'html5' ], // You may have more Tech, such as Flash or HLS
   plugins: {
      chromecast: {}
   }
};

videojs(document.getElementById('myVideoElement'), options);

Please note that even if you choose not to use any of the configuration options, you must either provide a chromecast entry in the plugins option for Video.js to initialize the plugin for you:

options = {
   plugins: {
      chromecast: {}
   }
};

or you must initialize the plugin manually:

var player = videojs(document.getElementById('myVideoElement'));

player.chromecast(); // initializes the Chromecast plugin

Configuration options

Plugin configuration

• plugins.chromecast.receiverAppID - the string ID of a custom Chromecast receiver app to use. Defaults to the default Media Receiver ID.
• plugins.chromecast.addButtonToControlBar - a boolean flag that tells the plugin whether or not it should automatically add the Chromecast button to the Video.js player's control bar component. Defaults to true.
• plugins.chromecast.buttonPositionIndex - a zero-based number specifying the index of the Chromecast button among the control bar's child components (if addButtonToControlBar is set to true). By default the Chromecast Button is added as the last child of the control bar. A value less than 0 puts the button at the specified position from the end of the control bar. Note that it's likely not all child components of the control bar are visible.
• plugins.chromecast.addCastLabelToButton (default: false) - by default, the Chromecast button component will display only an icon. Setting addCastLabelToButton to true will display a label titled "Cast" alongside the default icon.

Chromecast Tech configuration

• chromecast.requestTitleFn - a function that this plugin calls when it needs a string that will be the title shown in the UI that is shown when a Chromecast session is active and connected. When the this plugin calls the requestTitleFn, it passes it the current source object and expects a string in return. If nothing is returned or if this option is not defined, no title will be shown.
• chromecast.requestSubtitleFn - a function that this plugin calls when it needs a string that will be the sub-title shown in the UI that is shown when a Chromecast session is active and connected. When the this plugin calls the requestSubtitleFn, it passes it the current source object and expects a string in return. If nothing is returned or if this option is not defined, no sub-title will be shown.
• chromecast.requestCustomDataFn - a function that this plugin calls when it needs an object that contains custom information necessary for a Chromecast receiver app when a session is active and connected. When the this plugin calls the requestCustomDataFn, it passes it the current source object and expects an object in return. If nothing is returned or if this option is not defined, no custom data will be sent. This option is intended to be used with a custom receiver application to extend its default capabilities.
• chromecast.modifyLoadRequestFn - a function that this plugin calls before doing the request to load media. The function gets called with the LoadRequest object as argument and expects it in return.

Here is an example configuration object that makes full use of all required and optional configuration:

var titles, subtitles, customData, options;

titles = {
   'https://example.com/videos/video-1.mp4': 'Example Title',
   'https://example.com/videos/video-2.mp4': 'Example Title2',
};

subtitles = {
   'https://example.com/videos/video-1.mp4': 'Subtitle',
   'https://example.com/videos/video-2.mp4': 'Subtitle2',
};

customData = {
   'https://example.com/videos/video-1.mp4': { 'customColor': '#0099ee' },
   'https://example.com/videos/video-2.mp4': { 'customColor': '#000080' },
};

options = {
   // Must specify the 'chromecast' Tech first
   techOrder: [ 'chromecast', 'html5' ], // Required
   // Configuration for the Chromecast Tech
   chromecast: {
      requestTitleFn: function(source) { // Not required
         return titles[source.url];
      },
      requestSubtitleFn: function(source) { // Not required
         return subtitles[source.url];
      },
      requestCustomDataFn: function(source) { // Not required
         return customData[source.url];
      },
      modifyLoadRequestFn: function (loadRequest) { // HLS support
         loadRequest.media.hlsSegmentFormat = 'fmp4';
         loadRequest.media.hlsVideoSegmentFormat = 'fmp4';
         return loadRequest;
      }
   },
   plugins: {
      chromecast: {
         receiverAppID: '1234' // Not required
         addButtonToControlBar: false, // Defaults to true
      },
   }
};

Localization

The ChromecastButton component has two translated strings: "Open Chromecast menu" and "Cast".

• The "Open Chromecast menu" string appears in both of the standard places for Button component accessibility text: inside the .vjs-control-text span and as the <button> element's title attribute.
• The "Cast" string appears in an optional label within the Button component: inside the .vjs-chromecast-button-label span.

To localize the Chromecast button strings, follow the steps in the Video.js Languages tutorial to add "Open Chromecast menu" and "Cast" keys to the map of translation strings.

Using the NPM module

If you are using a module loader such as Browserify or Webpack, first install @silvermine/videojs-chromecast using npm install. Then, use require('@silvermine/videojs-chromecast') to require @silvermine/videojs-chromecast into your project's source code. require('@silvermine/videojs-chromecast') returns a function that you can use to register the plugin with Video.js by passing in a reference to videojs:

var videojs = require('video.js');

// Initialize the Chromecast plugin
require('@silvermine/videojs-chromecast')(videojs);

Then, follow the steps in the "Configuration" section above.

This plugin's source code uses ES6+ syntax and keywords, such as class and static. If you need to support browsers that do not support newer JavaScript syntax, you will need to use a tool like Babel to transpile and polyfill your code.

Alternatively, you can require('@silvermine/videojs-chromecast/dist/silvermine-videojs-chromecast.js') to use a JavaScript file that has already been polyfilled/transpiled down to ES5 compatibility.

Using the CSS and images

If you are using SCSS in your project, you can simply reference the plugin's main SCSS file in your project's SCSS:

@import "path/to/node_modules/@silvermine/videojs-chromecast/src/scss/videojs-chromecast";

Optionally, you can override the SCSS variables that contain the paths to the icon image files:

• $icon-chromecast--default - the path to the icon image that is displayed when the Chromecast button is in its normal, default state. Defaults to "images/ic_cast_white_24dp.png".
• $icon-chromecast--hover - the path to the icon image that is displayed when the user hovers over the Chromecast button when it is in its normal, default state. Defaults to "images/ic_cast_white_24dp.png".
• $icon-chromecast-casting - the path to the icon image that is displayed when the Chromecast button is in the "casting" state (when a Chromecast session is active and connected). Defaults to "images/ic_cast_connected_white_24dp.png".
• $icon-chromecast-casting--hover - the path to the icon image that is displayed when the user hovers over the Chromecast button when it is in the "casting" state (when a Chromecast session is active and connected). Defaults to "images/ic_cast_connected_white_24dp.png".
• $chromecast-icon-size - the width and height of the icon (the button and icon is a square). Defaults to 12px.
• $chromecast-title-font-size - the font size of the title on the screen that is shown while a Chromecast session is active and connected. Defaults to 22px.
• $chromecast-subtitle-font-size - the font size of the sub-title on the screen that is shown while a Chromecast session is active and connected. Defaults to 18px.
• $chromecast-poster-width - the width of the poster image on the screen that that is shown while a Chromecast session is active and connected. Defaults to 100px.
• $chromecast-poster-max-height - the maximum height of the poster image on the screen that is shown while a Chromecast session is active and connected. Defaults to 180px.

Images

The plugin's images are located at videojs-chromecast/src/images. If you have not overridden the icon image path variables in the SCSS, then copy the images from the src/images folder to a folder that is accessible at ./images/, relative to where the plugin's CSS is located. If, for example, your CSS is located at https://example.com/plugins/silvermine-videojs-chromecast.css, then the plugin's images should be located at https://example.com/plugins/images/.

In addition, the ic_cast_white_24dp.png icon image that is used as the default icon for all four button states ("default", "default + hover", "casting", "casting + hover"), the images folder contains grey, black, and blue versions of the icons.

Events

• chromecastConnected - Triggers when Chromecast connected
• chromecastDisconnected - Triggers when Chromecast disconnected
• chromecastDevicesAvailable - Triggers on state change when Chromecast devices are available
• chromecastDevicesUnavailable - Triggers on state change when Chromecast devices are unavailable
• chromecastRequested: Triggers when the user has requested Chromecast playback using this plugin's Chromecast button

How do I contribute?

We genuinely appreciate external contributions. See our extensive documentation on how to contribute.

License

This software is released under the MIT license. See the license file for more details.