HTML <track> Tag

The HTML <track> tag is used to specify external timed text tracks for media elements.

HTML5 defines two elements as "media elements": the <video> element and the <audio> element).

There are 5 kinds of text tracks: subtitles, captions, descriptions, chapters, and metadata.

Syntax

The <track> tag is written as <track src=""> (no end tag). The src attribute is a required attribute that provides the URL of the text track.

You can use the (optional) type attribute to specify the kind of text track. The srclang attribute must be present if the kind attribute is in the subtitles state. Note that, if you omit the type attribute, it defaults to subtitles, so you will need to provide a srclang attribute in this case.

You can also include the (optional) label attribute to provide a user-visible label.

The <track> tag must be nested inside a media element (i.e. either <video> or <audio>).

Like this:

Example

In this example, the <track> element is used to provide subtitles in English.

The above example uses a file called countdown_en.vtt to present subtitles.

Here are the contents of the countdown_en.vtt file:

The file simply specifies which text to display at which parts of the video. To add more subtitles, simply add more text and specify the appropriate points in the video that they should be displayed.

Multiple <track> Tags

You can include multiple <track> tags if required. For example, if you have subtitles in many languages, you could provide a different <track> tag for each language.

Like this:

Attributes

Attributes can be added to an HTML element to provide more information about how the element should appear or behave.

There are 3 kinds of attributes that you can add to your HTML tags: Element-specific, global, and event handler content attributes.

The <track> element accepts the following attributes.

Element-Specific Attributes

This table shows the attributes that are specific to the <track> tag/element.

AttributeDescription
kindSpecifies the kind of text track. This attribute is an enumerated attribute.

The possible values for the "kind" attribute are:

ValueDescription
subtitlesTranscription or translation of the dialogue. This can be useful for when the sound is in a different language to what the user can understand. Any subtitles are overlaid on the video. This is the default value.
captionsTranscription or translation of the dialogue, sound effects, relevant musical cues, and other relevant audio information. This can be useful 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). Any captions are overlaid on the video; labeled as appropriate for the hard-of-hearing.
descriptionsTextual descriptions of the video component of the media resource, intended for audio synthesis 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). Any descriptions are synthesized as audio.
chaptersChapter titles, intended to be used for navigating the media resource. Any chapters are displayed as an interactive list in the user agent/browser's interface.
metadataTracks intended for use from script. Not displayed by the user agent.
srcSpecifies the URL of the text track data. Required attribute.
srclangSpecifies the language of the text track. The value must be a valid BCP 47 language tag. This attribute is required if the element's kind attribute is "subtitles".
labelProvides a user-readable title for the track.
defaultSpecifies that the track is to be enabled if the user's preferences do not indicate that another track would be more appropriate. There must not be more than one track element with the same parent node with the default attribute specified.

Global Attributes

The following attributes are standard across all HTML5 elements. Therefore, you can use these attributes with the <track> tag , as well as with all other HTML tags.

For a full explanation of these attributes, see HTML 5 global attributes.

Event Handler Content Attributes

Event handler content attributes enable you to invoke a script from within your HTML. The script is invoked when a certain "event" occurs. Each event handler content attribute deals with a different event.

Below are the standard HTML5 event handler content attributes.

Again, you can use any of these with the <track> element, as well as any other HTML5 element.

For a full explanation of these attributes, see HTML 5 event handler content attributes.

Differences Between HTML 4 & HTML 5

The <track> element is new in HTML5.

For more information on this element, see HTML5 <track> Tag. Also check out the links to the official specifications below.

Template

Here's a template for the <track> tag with all available attributes for the tag (based on HTML5). These are grouped into attribute types, each type separated by a space. In many cases, you will probably only need one or two (if any) attributes. Simply remove the attributes you don't need.

For more information on attributes for this tag, see HTML5 <track> Tag.

Tag Details

For more details about the <track> tag, see HTML5 <track> Tag.

Specifications

Here are the official specifications for the <track> element.

What's the Difference?

W3C creates "snapshot" specifications that don't change once defined. So the HTML5 specification won't change once it becomes an official recommendation. WHATWG on the other hand, develops a "living standard" that is updated on a regular basis. In general, you will probably find that the HTML living standard will be more closely aligned to the current W3C draft than to the HTML5 specification.

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