The<track>HTML element is used as a child of the media elements,<audio> and<video>.Each track element lets you specify a timed text track (or time-based data) that can be displayed in parallel with the media element, for example to overlay subtitles or closed captions on top of a video or alongside audio tracks.

Multiple tracks can be specified for a media element, containing different kinds of timed text data, or timed text data that has been translated for different locales.The data that is used will either be the track that has been set to be the default, or a kind and translation based on user preferences.

The tracks are formatted inWebVTT format (.vtt files) — Web Video Text Tracks.

Try it

<video controls src="/shared-assets/videos/friday.mp4">  <track    default    kind="captions"    srclang="en"    label="English"    src="/shared-assets/misc/friday.vtt" />  Download the  <a href="/shared-assets/videos/friday.mp4">MP4</a>  video, and  <a href="/shared-assets/misc/friday.vtt">subtitles</a>.</video>

video {  width: 250px;}video::cue {  font-size: 1rem;}

Attributes

This element includes theglobal attributes.

default

This attribute indicates that the track should be enabled unless the user's preferences indicate that another track is more appropriate. This may only be used on onetrack element per media element.

kind

How the text track is meant to be used. If omitted the default kind issubtitles. If the attribute contains an invalid value, it will usemetadata.The following keywords are allowed:

subtitles

Subtitles provide transcription or translation of the dialog. They are suitable for when the sound is available but not understood, such as speech or text that is not English in an English language film. Subtitles may contain additional content, usually extra background information. For example the text at the beginning of the Star Wars films, or the date, time, and location of a scene. Subtitles' information complements the audio and video. It is often embedded in the video itself, but can also be provided separately, especially for whole-film translations.

captions

Closed captions provide transcription or translation of the dialog, sound effects, relevant musical cues, and other relevant audio information, such as the cue's source (e.g., character, environment). They are suitable for when sound is unavailable or not clearly audible (e.g., because it is muted, drowned-out by ambient noise, or because the user is deaf).

descriptions

Descriptions summarize thevideo component of the media resource. They are intended to be synthesized as audio when the visual component is obscured, unavailable, or not usable (e.g., because the user is interacting with the application without a screen while driving, or because the user is blind).

chapters

Chapter titles are intended to be used when the user is navigating the media resource.

metadata

Tracks used by scripts. Not visible to the user.

label

A user-readable title of the text track which is used by the browser when listing available text tracks.

src

Address of the track (.vtt file). Must be a valid URL. This attribute must be specified and its URL value must have the same origin as the document — unless the<audio> or<video> parent element of thetrack element has acrossorigin attribute.

srclang

Language of the track text data. It must be a validBCP 47 language tag. If thekind attribute is set tosubtitles, thensrclang must be defined.

Usage notes

Track data types

The type of data thattrack adds to the media is set in thekind attribute, which can take values ofsubtitles,captions,chapters ormetadata. The element points to a source file containing timed text that the browser exposes when the user requests additional data.

A media element cannot have more than onetrack with the samekind,srclang, andlabel.

Detecting cue changes

The underlyingTextTrack, indicated by thetrack property, receives acuechange event every time the currently-presented cue is changed. This happens even if the track isn't associated with a media element.

If the trackis associated with a media element, using the<track> element as a child of the<audio> or<video> element, thecuechange event is also sent to theHTMLTrackElement.

let textTrackElem = document.getElementById("text-track");textTrackElem.addEventListener("cuechange", (event) => {  let cues = event.target.track.activeCues;});

Adding text tracks programmatically

The JavaScript interface that represents the<track> element isHTMLTrackElement.The text track associated with an element can be obtained from theHTMLTrackElement.track property, and is of typeTextTrack.

TextTrack objects also can be added to aHTMLVideoElement orHTMLAudioElement elements using theHTMLMediaElement.addTextTrack() method.TheTextTrack objects associated with a media element stored in aTextTrackList, which can be retrieved using theHTMLMediaElement.textTracks property.

Examples

<video controls poster="/images/sample.gif">  <source src="sample.mp4" type="video/mp4" />  <source src="sample.ogv" type="video/ogv" />  <track kind="captions" src="sampleCaptions.vtt" srclang="en" />  <track kind="chapters" src="sampleChapters.vtt" srclang="en" />  <track kind="subtitles" src="sampleSubtitles_de.vtt" srclang="de" />  <track kind="subtitles" src="sampleSubtitles_en.vtt" srclang="en" />  <track kind="subtitles" src="sampleSubtitles_ja.vtt" srclang="ja" />  <track kind="subtitles" src="sampleSubtitles_oz.vtt" srclang="oz" />  <track kind="metadata" src="keyStage1.vtt" srclang="en" label="Key Stage 1" />  <track kind="metadata" src="keyStage2.vtt" srclang="en" label="Key Stage 2" />  <track kind="metadata" src="keyStage3.vtt" srclang="en" label="Key Stage 3" />  <!-- Fallback -->  …</video>

Technical summary

Specifications

Browser compatibility

See also

• WebVTT text track format
• HTMLMediaElement.textTracks