@brightspace-ui-labs/media-player

media-player

Note: this is a "labs" component. While functional, these tasks are prerequisites to promotion to BrightspaceUI "official" status:

• Design organization buy-in
• Architectural sign-off
• Continuous integration
• Cross-browser testing
• Unit tests (if applicable)
• Accessibility tests
• Visual diff tests
• Localization with Serge (if applicable)
• Demo page
• README documentation

A Lit element based media player component, designed for similarity across browsers. Capable of playing video and audio content.

Displaying video

Displaying audio

Installation

To install from NPM:

npm install @brightspace-ui-labs/media-player

d2l-labs-media-player

<script type="module"> import '@brightspace-ui-labs/media-player/media-player.js'; </script> <d2l-labs-media-player src="/video.webm"></d2l-labs-media-player>

Attributes:

Attribute	Type	Default	Description
allow-download	Boolean	false	If set, will allow the media to be downloaded.
autoplay	Boolean	false	If set, will play the media as soon as it has been loaded.
crossorigin	String	null	If set, will set the crossorigin attribute on the underlying media element to the set value.
duration-hint	Number	1	Measured in seconds. If set and the duration cannot be determined automatically, this value will be used instead.
hide-captions-selection	Boolean	false	If set, the menu item to configure captions is hidden.
hide-seek-bar	Boolean	false	If set, the seek bar will not be shown.
locale	String	en	If set, will display chapter titles in the given locale when possible.
loop	Boolean	false	If set, once the media has finished playing it will replay from the beginning.
media-type	["video", "audio"]	null	Whether the video or audio player should be rendered. If not set, a loading indicator will be displayed until set.
metadata	JSON	false	Metadata JSON of the video, contains chapters and cuts data.
poster	String	null	URL of the image to display in place of the media before it has loaded.
src	String		URL of the media to play. If multiple sources are desired, use <source> tags instead (see below).
thumbnails	String		If set, will show thumbnails on preview. See below for required format.

<!-- Render a media player with a source file and loop the media when it reaches the end --> <d2l-labs-media-player loop src="./local-video.mp4"></d2l-labs-media-player>

Properties:

Property	Type	Get/Set	Description
currentTime	Number	Get & Set	Current time playback time of the media in seconds.
activeCue	Object	Get	VTTCue instance for the currently-displayed captions cue. If no cue is currently displayed, the value is null.
duration	Number	Get	Total duration of the media in seconds.
ended	Boolean	Get	Whether or not the video has ended.
paused	Boolean	Get	Whether or not the video is currently paused.
sourceType	["audio", "video", "unknown"]	Get	The source type of the media.
textTracks	[TextTrack]	Get	The TextTracks, for handling WebVTT. (See MDN link)

// Programatically determine the current playback time of the media player console.log(`Current playback time of the media player = ${this.document.querySelector('d2l-labs-media-player').currentTime} sec`);

Methods:

Method	Type	Description
exitFullscreen()	void	Requests to exit fullscreen mode from the browser. Ignored if it is not playing video content, or if the video is not in fullscreen mode.
play()	void	Begins playing the media. Ignored if the media is already playing.
pause()	void	Pauses the media. Ignored if the media is already paused.
requestFullscreen()	void	Requests fullscreen mode from the browser. Ignored if it is not playing video content, or the video is already in fullscreen mode.

// Programatically pause the media player this.document.querySelector('d2l-labs-media-player').pause();

Events:

Event	Description
cuechange	Dispatched when the currently-displayed captions cue changes.
durationchange	Dispatched when the video or media displayed has changed its duration
ended	Dispatched when the media has reached the end of its duration.
error	Dispatched when the media failed to load.
loadeddata	Dispatched when the media at the current playback position has finished loading. Often the first frame.
loadedmetadata	Dispatched when the metadata for the media has finished loading.
play	Dispatched when the media begins playing.
pause	Dispatched when the media is paused.
timeupdate	Dispatched when the currentTime of the media player has been updated.
trackloaded	Dispatched when a track element has loaded.
trackloadfailed	Dispatched when a track element could not be loaded from the provided src attribute.
tracksmenuitemchanged	Dispatched when the tracks menu item has changed.

// Listen for the loadeddata event this.document.querySelector('d2l-labs-media-player').addEventListener('loadeddata', () => { console.log('loadeddata event has been dispatched'); });

Multiple qualities using <source>

The media player supports switching to different qualities. If multiple <source> tags are present, a quality selector will be available in the menu. In this case, do not set src on d2l-labs-media-player.

<d2l-labs-media-player> <source src="sample-video-144p.mp4" label="SD"> <source src="sample-video.mp4" label="HD" default> </d2l-labs-media-player

Attributes

Attribute	Type	Default	Description
label	String, required		The label for the track, displayed to the user for selection.
src	String, required		The URL of the source file.
default	Boolean	false	The source to be selected by default. If no source has the default attribute, then the first <source> tag is selected by default. Only one default should be set.

Showing thumbnails preview with thumbnails attribute

Provide a url to the thumbnails sprite image. This sprite is a grid of images taken from the video, at a set interval.

e.g. sample video thumbnails sprite

The thumbnail file name must use the following format: th<height>w<width>i<interval>-<hash>.[png|jpg]

• width and height are the width/height px of each individual thumbnail
• interval indicates how many seconds apart each thumbnail is

For example, a sprite image named th90w160i5-<hash>png has the thumbnails 5 seconds apart, with width 160px and height 90px.

Attribute	Required	Default	Description
hash	optional
height	optional	90px	Height px of each individual thumbnail in the sprite.
interval	required		Interval in seconds between each thumbnail.
width	optional	160px	Width px of each individual thumbnail in the sprite.

Chapters with metadata attribute

Provide metadata JSON e.g. getMetadata endpoint

Example format:

{ "cuts": [ "in": 20, "out": 30 ], "chapters": [ { "time": 0, "title": { "en": "Chapter One", "fr": "Chapitre Un" } }, { "time": 30, "title": { "en": "Chapter Two", "fr": "Chapitre Deux" } }, { "time": 70, "title": { "en": "Chapter Three", "fr": "Chapitre Trois" } } ] }

Captions and Subtitles Using <track>

The media player supports captions and subtitles, provided as .srt or .vtt files. If any valid tracks are present, a captions menu will be presented in the settings menu with an item for each track.

<script type="module"> import '@brightspace-ui-labs/media-player/media-player.js'; </script> <d2l-labs-media-player src="/video.webm"> <track src="/english-captions.srt" srclang="en" label="English" kind="captions"> <track src="/french-captions.vtt" srclang="fr" label="French" kind="captions"> </d2l-labs-media-player>

Attributes

Attribute	Type	Default	Description
kind	["captions", "subtitles"], required		The kind of track.
label	String, required		The label for the track, displayed to the user for selection.
src	String, required		The URL of the source file.
srclang	String, required		The language's code.
default	Boolean	false	The track to be selected by default. If D2L.MediaPlayer.Preferences.Track is defined in local storage, then it will take precedence over this attribute.
default-ignore-preferences	Boolean	false	Same as default, but if D2L.MediaPlayer.Preferences.Track is defined, it will be ignored and this track will be selected instead.

Local Storage

The media player uses local storage to persist the user's playback speed, track selections, and volume.

Items

Key	Description
D2L.MediaPlayer.Preferences.Speed	Playback speed that was last selected.
D2L.MediaPlayer.Preferences.Track	Identifier for the kind and language of the track that was last selected.
D2L.MediaPlayer.Preferences.Volume	Volume that was last selected.

Accessibility

The following features are implemented to improve accessibility:

• all controls can be accessed using the mouse or keyboard
• captions can be provided to the media player
• important events, such as a media source failing to load, are displayed visually and announced by screen readers

Developing, Testing and Contributing

After cloning the repo, run npm install to install dependencies.

Running the demos

To start a @web/dev-server that hosts the demo page and tests:

npm start

Troubleshooting Common Issues

• Captions fail to load due to a "Protocols, domains, and ports must match" error
  • Solution: Set the Media Player's crossorigin property to the appropriate value (either "anonymous" or "use-credentials").
  • Explanation: If your captions sources are on a different origin, CORS needs to be enabled on the <video>/<audio> element. Otherwise, the browser will block requests to that origin due to the security measures outlined in the same-origin policy. The Media Player passes its crossorigin property directly to the <video>/<audio> element's crossorigin attribute, which sets the CORS policy. (If the crossorigin attribute isn't defined, CORS will not be used at all.)

Linting

# eslint and lit-analyzer npm run lint # eslint only npm run lint:eslint # lit-analyzer only npm run lint:lit

Testing

# lint & run headless unit tests npm test # unit tests only npm run test:headless # debug or run a subset of local unit tests npm run test:headless:watch

Visual Diff Testing

This repo uses the @brightspace-ui/visual-diff utility to compare current snapshots against a set of golden snapshots stored in source control.

The golden snapshots in source control must be updated by the visual-diff GitHub Action. If a pull request results in visual differences, a draft pull request with the new goldens will automatically be opened against its branch.

To run the tests locally to help troubleshoot or develop new tests, first install these dependencies:

npm install @brightspace-ui/visual-diff@X mocha@Y puppeteer@Z --no-save

Replace X, Y and Z with the current versions the action is using.

Then run the tests:

# run visual-diff tests npx mocha './test/**/*.visual-diff.js' -t 10000 # subset of visual-diff tests: npx mocha './test/**/*.visual-diff.js' -t 10000 -g some-pattern # update visual-diff goldens npx mocha './test/**/*.visual-diff.js' -t 10000 --golden

Versioning & Releasing

TL;DR: Commits prefixed with fix: and feat: will trigger patch and minor releases when merged to main. Read on for more details...

The semantic-release GitHub Action is called from the release.yml GitHub Action workflow to handle version changes and releasing.

Version Changes

All version changes should obey semantic versioning rules:

1. MAJOR version when you make incompatible API changes,
2. MINOR version when you add functionality in a backwards compatible manner, and
3. PATCH version when you make backwards compatible bug fixes.

The next version number will be determined from the commit messages since the previous release. Our semantic-release configuration uses the Angular convention when analyzing commits:

• Commits which are prefixed with fix: or perf: will trigger a patch release. Example: fix: validate input before using
• Commits which are prefixed with feat: will trigger a minor release. Example: feat: add toggle() method
• To trigger a MAJOR release, include BREAKING CHANGE: with a space or two newlines in the footer of the commit message
• Other suggested prefixes which will NOT trigger a release: build:, ci:, docs:, style:, refactor: and test:. Example: docs: adding README for new component.

To revert a change, add the revert: prefix to the original commit message. This will cause the reverted change to be omitted from the release notes. Example: revert: fix: validate input before using.

Releases

When a release is triggered, it will:

• Update the version in package.json
• Tag the commit
• Create a GitHub release (including release notes)
• Deploy a new package to NPM

Releasing from Maintenance Branches

Occasionally you'll want to backport a feature or bug fix to an older release. semantic-release refers to these as maintenance branches.

Maintenance branch names should be of the form: +([0-9])?(.{+([0-9]),x}).x.

Regular expressions are complicated, but this essentially means branch names should look like:

• 1.15.x for patch releases on top of the 1.15 release (after version 1.16 exists)
• 2.x for feature releases on top of the 2 release (after version 3 exists)