Baseline Widely available
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 in WebVTT format (.vtt
files) â Web Video Text Tracks.
<video controls src="/shared-assets/videos/friday.mp4">
<track
default
kind="captions"
srclang="en"
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 the global 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 one track
element per media element.
kind
How the text track is meant to be used. If omitted the default kind is subtitles
. If the attribute contains an invalid value, it will use metadata
. The following keywords are allowed:
subtitles
captions
chapters
metadata
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 â unless the <audio>
or <video>
parent element of the track
element has a crossorigin
attribute.
srclang
Language of the track text data. It must be a valid BCP 47 language tag. If the kind
attribute is set to subtitles
, then srclang
must be defined.
The type of data that track
adds to the media is set in the kind
attribute, which can take values of subtitles
, captions
, chapters
or metadata
. 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 one track
with the same kind
, srclang
, and label
.
The underlying TextTrack
, indicated by the track
property, receives a cuechange
event every time the currently-presented cue is changed. This happens even if the track isn't associated with a media element.
If the track is associated with a media element, using the <track>
element as a child of the <audio>
or <video>
element, the cuechange
event is also sent to the HTMLTrackElement
.
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 is HTMLTrackElement
. The text track associated with an element can be obtained from the HTMLTrackElement.track
property, and is of type TextTrack
.
TextTrack
objects also can be added to a HTMLVideoElement
or HTMLAudioElement
elements using the HTMLMediaElement.addTextTrack()
method. The TextTrack
objects associated with a media element stored in a TextTrackList
, which can be retrieved using the HTMLMediaElement.textTracks
property.
<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 -->
â¦
</video>
Technical summary Specifications Browser compatibility See also
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