Definition

Indicates that synchronized closed captions are available for audio and video content.

Examples

Example 1 — EPUB 3
<meta property="schema:accessibilityFeature">
   closedCaptions
</meta>
Example 2 — EPUB 2
<meta name="schema:accessibilityFeature"
      content="closedCaptions"/>
Example 3 — Audiobooks
"accessibilityFeature": ["closedCaptions"]

Explanation

The closedCaptions value is used to indicate that a publication includes closed captions for auditory content.

Closed captions are defined separately from the video stream, allowing users to turn them on or off and control their appearance. Open captions, by contrast, are burned directly into the video stream and are always visible in an unchangeable form.

Captions provided for an HTML video using a track element.

<video>
   <source src="speech.mp4" type="video/mp4"/>
   <track src="captions.vtt" kind="captions" srclang="en"
          label="English for the hard of hearing"/>
</video>

Note

The HTML audio element cannot be used to render captions, as it does not provide a display area for them.

Closed captions provide a transcription of the dialogue that is being spoken as well as describe any relevant sounds that are occurring (e.g., music playing, a phone ringing, etc.). They are intended to help when the audio is muted or cannot be fully heard.

Closed captions are not the same as subtitles, which are strictly a transcription of the dialogue (and typically available in additional languages than that being spoken). They differ from audio descriptions in that they do not describe actions.

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