WCAG 1.2.8: Media Alternative (Prerecorded)
Understanding WCAG 1.2.8: Media Alternative (Prerecorded)
WCAG 1.2.8, titled “Media Alternative (Prerecorded)”, is a Level AAA success criterion that ensures all users, especially those with disabilities, can access the full content conveyed through prerecorded media. This criterion mandates the provision of a complete text alternative for both prerecorded synchronized media (like videos with audio) and prerecorded video-only media.
What is WCAG 1.2.8?
At its core, WCAG 1.2.8 requires that a text document be made available that provides all the information conveyed by the media. This goes beyond just captions or audio descriptions. For synchronized media (video with audio), the alternative must include a full transcript of all spoken dialogue and significant sounds, combined with a detailed description of all significant visual information. For video-only media, it requires a comprehensive textual description of all visual content.
Why is this criterion important?
Providing a full text alternative for prerecorded media offers significant benefits for a diverse range of users:
- Users who are deaf-blind: These individuals cannot access audio or visual content directly. A full text alternative, especially when presented in a structured and semantic way, can be processed by screen readers and converted to braille or tactile displays, providing complete access to the media’s information.
- Users with cognitive or learning disabilities: Some individuals process information more effectively when it’s presented in text form, allowing them to read at their own pace, re-read sections, or use assistive technologies that aid comprehension (e.g., text-to-speech, translation tools).
- Users who cannot access audio or video: This includes individuals who cannot hear the audio, see the video, or those in environments where playing media is not possible (e.g., noisy public spaces, quiet libraries). A text alternative ensures they don’t miss out on vital information.
- Users who prefer text: Many users prefer to scan text for specific information, use it for note-taking, or easily search for keywords, making the content more usable and accessible.
- SEO and discoverability: Full text alternatives make media content indexable by search engines, improving the discoverability and reach of the information.
Understanding the Requirements
Success Criterion 1.2.8 (AAA) Explained
The success criterion states: “A full text alternative for all prerecorded synchronized media and for all prerecorded video-only media is provided.” Let’s break down the key terms:
- Prerecorded: This refers to media that is not live. Live media has different requirements (WCAG 1.2.9 Audio-only (Live), WCAG 1.2.9 Video-only (Live), WCAG 1.2.9 Synchronized Media (Live)).
- Synchronized media: This refers to media that presents both audio and video, where the audio is synchronized with another format for presenting information and/or with time-based interactive components. Examples include movies, webinars, and educational videos.
- Video-only media: This refers to a time-based presentation that contains only video and no audio. Examples include silent animations, visual instructions without voiceover, or video backgrounds.
- Full text alternative: This is the most crucial part. It means a text document that contains *all* the information conveyed by the media. This includes:
- For synchronized media: A verbatim transcript of all spoken dialogue, identification of speakers, descriptions of significant sound effects, and a detailed narrative of all significant visual information (e.g., actions, on-screen text, changes in scene, relevant expressions or gestures). This is essentially a comprehensive script of the entire media.
- For video-only media: A detailed, step-by-step description of all significant visual information and actions presented in the video.
It’s vital to understand that a “full text alternative” is distinct from, and more comprehensive than, captions (which primarily cover audio) or audio descriptions (which primarily cover visuals for blind users). It’s a single, cohesive document that merges both into a textual representation.
Practical Guidelines for Compliance
To meet WCAG 1.2.8, you must provide a link to a separate web page or document containing the full text alternative. This link should be clearly identifiable and placed in close proximity to the media player.
How to Provide a Full Text Alternative
For Prerecorded Synchronized Media (Video with Audio)
- Create a complete transcript: Transcribe all spoken words accurately, including speaker identification (e.g., “[Narrator]”, “[Alice]”, “[Bob]”).
- Describe significant sound effects: Include descriptions of non-speech audio that conveys meaning (e.g., “[Loud crash]”, “[Soft music playing]”, “[Audience applauds]”).
- Describe all significant visual information: This is where it goes beyond typical captions. Describe actions, scene changes, on-screen text, objects, graphs, charts, and any other visual elements that convey meaning. Integrate these descriptions chronologically within the text alternative alongside the dialogue and sound effects. For example:
- “[00:01:15] (The presenter, Sarah, walks to the whiteboard and picks up a marker.)”
- “[00:01:20] Sarah: ‘As you can see from this diagram…’ (She draws a Venn diagram on the board illustrating two overlapping sets.)”
- Structure the document: Use headings, paragraphs, and lists to make the text alternative easy to read and navigate. Consider adding timestamps for easier correlation with the video content.
- Link clearly: Provide a prominent link to this combined text alternative near the media player.
For Prerecorded Video-Only Media
- Create a detailed visual description: Write a narrative that describes everything visually significant that happens in the video. This includes actions, objects, on-screen text, and any changes in the scene.
- Maintain chronological order: The description should flow in the same order as the events in the video.
- Be specific and objective: Describe what is seen, avoiding interpretation where possible, but ensuring all information conveyed visually is present in text.
- Link clearly: Provide a prominent link to this detailed text description near the media player.
Best Practices
- Accessible link text: Use clear and descriptive link text such as “View complete transcript and visual description” or “Full text alternative.”
- Accessible document format: Provide the text alternative in an accessible format (e.g., an HTML page with proper semantic markup, or an accessible PDF).
- Timestamps: While not strictly required, adding timestamps to the text alternative can help users locate specific parts of the video or audio.
- Searchable content: Ensure the text alternative is searchable, allowing users to quickly find information.
- Maintain consistency: If the media content is updated, ensure the text alternative is also updated to reflect the changes.
Examples
Correct Implementations
Example 1: Prerecorded Synchronized Media (Video with Audio)
A video lecture on web accessibility, offering a comprehensive text alternative.
<h3>Lecture: Introduction to WCAG Principles</h3>
<video controls poster="lecture-thumbnail.jpg" aria-describedby="lecture-desc">
<source src="lecture.mp4" type="video/mp4">
<track kind="captions" srclang="en" src="lecture-captions.vtt" label="English Captions">
<p>Your browser does not support the video tag.</p>
</video>
<p id="lecture-desc">A lecture covering the core principles of WCAG 2.1, presented by Dr. Jane Doe.</p>
<p><strong><a href="lecture-full-alternative.html">View complete transcript and visual description for this lecture (WCAG 1.2.8)</a></strong></p>The lecture-full-alternative.html file would contain the full text alternative, including all dialogue, speaker identification, significant sound effects, and detailed descriptions of all on-screen visuals (e.g., presentation slides, presenter’s actions, diagrams drawn).
Example 2: Prerecorded Video-Only Media (Silent Animation)
A silent animation demonstrating a complex process, with a full visual description.
<h3>Animation: How a Payment Gateway Works</h3>
<video controls loop autoplay muted aria-describedby="payment-gateway-desc">
<source src="payment-gateway.mp4" type="video/mp4">
<p>Your browser does not support the video tag.</p>
</video>
<p id="payment-gateway-desc">A short animation illustrating the step-by-step process of an online payment transaction.</p>
<p><strong><a href="payment-gateway-visual-description.html">View detailed visual description for this animation (WCAG 1.2.8)</a></strong></p>The payment-gateway-visual-description.html file would contain a detailed textual narrative describing each visual event and transition in the animation.
Incorrect Implementations
Here are common mistakes that do not meet WCAG 1.2.8:
Incorrect 1: Missing any form of full text alternative
<h3>Product Demonstration Video</h3>
<video controls src="product-demo.mp4">
<p>Your browser does not support the video tag.</p>
</video>
<!-- No link to a full text alternative. -->This fails because no full text alternative is provided, making the content inaccessible to users who rely on text.
Incorrect 2: Providing only captions for synchronized media
<h3>Conference Keynote</h3>
<video controls src="keynote.mp4">
<track kind="captions" srclang="en" src="keynote-captions.vtt" label="English Captions">
<p>Your browser does not support the video tag.</p>
</video>
<p>Captions are available for this video.</p>
<!-- Captions only cover spoken dialogue and some sound effects; they do not include visual descriptions. -->While captions are essential for WCAG 1.2.2, they alone do not constitute a “full text alternative” for synchronized media as required by 1.2.8, because they typically lack detailed descriptions of significant visual information.
Incorrect 3: Providing only audio description for synchronized media
<h3>Tutorial Video</h3>
<video controls src="tutorial.mp4">
<track kind="descriptions" srclang="en" src="tutorial-audio-description.vtt" label="Audio Description">
<p>Your browser does not support the video tag.</p>
</video>
<p>Audio descriptions are available for this video.</p>
<!-- Audio descriptions supplement the audio for blind users, describing visuals. They don't provide a comprehensive text alternative for deaf-blind users or those who prefer text entirely. -->Audio descriptions, while crucial for WCAG 1.2.5, are designed to convey visual information *audibly* for users who are blind or have low vision. They are not a full text alternative for those who need all information in text, especially for deaf-blind users who use braille displays.
Common Pitfalls
- Confusing captions/audio descriptions with full text alternatives: As illustrated above, these are separate requirements. A full text alternative is a standalone document that synthesizes all information.
- Incomplete visual descriptions: Ensure that *all* visual information that conveys meaning is described, not just major actions. This includes on-screen text, graphs, subtle gestures, and facial expressions if they are relevant to the content.
- Lack of speaker identification: For synchronized media, identifying who is speaking is crucial for context.
- Poorly formatted text alternatives: A lengthy block of unformatted text can be just as inaccessible as no alternative. Use proper headings, paragraphs, and lists.
- Difficult to find or access: The link to the text alternative must be prominent and clearly labeled, and the document itself must be easily accessible (e.g., not requiring extra software to open).
Related WCAG Guidelines
WCAG 1.2.8 complements other time-based media guidelines:
- WCAG 1.2.1 Audio-only and Video-only (Prerecorded): Requires an alternative for time-based media or an audio track for video-only.
- WCAG 1.2.2 Captions (Prerecorded): Requires captions for all prerecorded audio content in synchronized media.
- WCAG 1.2.3 Audio Description or Media Alternative (Prerecorded): Requires an audio description or a full text alternative for prerecorded video content in synchronized media.
- WCAG 1.2.4 Captions (Live): Requires captions for all live audio content in synchronized media.
- WCAG 1.2.5 Audio Description (Prerecorded): Requires audio description for all prerecorded video content in synchronized media.
Conclusion
WCAG 1.2.8 is a Level AAA criterion that pushes for the highest level of accessibility for prerecorded media. By providing a comprehensive full text alternative, you ensure that everyone, including those with deaf-blindness, cognitive disabilities, or specific preferences, can fully understand and engage with your content. It demands a thorough approach, integrating both audio and visual information into a single, well-structured, and easily accessible text document. Adhering to this criterion significantly enhances the inclusivity and usability of your web content.