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Perceivable WCAG 1.2.8

1.2.8 Media Alternative (Prerecorded)

A full text alternative must be provided for all prerecorded synchronized media and all prerecorded video-only media, presenting all visual and auditory information in text form.

Level AAA Moderate WCAG 2.0 (new) WCAG 2.1 WCAG 2.2

What this rule means

WCAG 1.2.8 requires a complete text-based alternative for prerecorded synchronized media. This alternative must describe everything that happens in the video — all dialogue, all meaningful sounds, and all significant visual information — in a document that can be read sequentially. This is sometimes called an "enhanced transcript" or "media alternative."

Unlike a simple transcript that only captures dialogue, a media alternative must include descriptions of visual actions, scene changes, on-screen text, and non-verbal communication such as facial expressions and gestures, presented in the correct temporal order.

Why it matters

A full media alternative serves users who are deafblind and access content through refreshable braille displays. It also helps users who cannot play media due to bandwidth constraints, technology limitations, or environmental factors. Additionally, it provides a comprehensive text resource for search engines and supports users with cognitive disabilities who may prefer to read content at their own pace.

This Level AAA criterion recognizes that neither captions nor audio descriptions alone provide a complete text-based experience of the media content.

Related axe-core rules

No axe-core rules test for media alternatives. Verifying the completeness and accuracy of a media alternative document requires human evaluation comparing the text against the full audiovisual content.

How to test

  1. Identify all prerecorded synchronized media and video-only media on the page.
  2. Locate the media alternative — it should be linked directly from or adjacent to the media player.
  3. Play the video while reading the media alternative simultaneously.
  4. Verify that all spoken dialogue is accurately transcribed with speaker identification.
  5. Confirm that visual-only information (actions, scene changes, on-screen text, graphics) is described.
  6. Check that non-speech audio (music, sound effects, silence) is noted.
  7. Ensure the temporal order of events is preserved in the text.

How to fix

Create a structured media alternative document and link it from the video player:

<video controls>
  <source src="/product-overview.mp4" type="video/mp4" />
  <track kind="captions" src="/product-overview.vtt" srclang="en" default />
</video>
<a href="/product-overview-transcript.html">
  Complete media alternative (full transcript with visual descriptions)
</a>

The media alternative document should follow this structure:

<article class="media-alternative">
  <h1>Media Alternative: Product Overview Video</h1>
  <p><strong>Duration:</strong> 4 minutes 32 seconds</p>

  <section>
    <h2>Scene 1: Introduction (0:00 – 0:45)</h2>
    <p><em>[Upbeat background music plays]</em></p>
    <p><em>[Wide shot of a modern office. The company logo appears
    centered on screen in white text on a blue background.]</em></p>
    <p><strong>Narrator:</strong> Welcome to the product overview.
    Today we will explore the three core features of our platform.</p>
    <p><em>[The screen transitions to a dashboard interface showing
    a sidebar navigation and a main content area with charts.]</em></p>
  </section>

  <section>
    <h2>Scene 2: Feature Demo (0:45 – 2:30)</h2>
    <p><em>[Close-up of the dashboard. The cursor clicks on
    "Analytics" in the sidebar.]</em></p>
    <p><strong>Narrator:</strong> The analytics dashboard gives you
    real-time insights into your team's performance.</p>
    <p><em>[A bar chart animates in, showing monthly data.
    The Y-axis is labeled "Tasks Completed" and ranges from 0 to 500.
    March shows the highest bar at approximately 450.]</em></p>
  </section>
</article>

Common mistakes

  • Providing only a dialogue transcript without descriptions of visual content.
  • Omitting speaker identification, making it unclear who is saying what.
  • Not describing on-screen text, charts, or infographics that convey essential information.
  • Placing the media alternative at a URL that is not clearly linked from the media player.
  • Failing to note meaningful silences, music changes, or ambient sounds that set context.
  • Writing the alternative in a disorganized way that does not follow the temporal order of the video.

Resources