Let's continue our series of deep dives into WCAG 2.1 Success Criteria. Today, we focus on Success Criterion 1.2.8: Media Alternative (Prerecorded). This is a Level AAA requirement, meaning it represents the highest level of accessibility.
As stated in the official W3C documentation for WCAG 2.1 (section 1.2.8):
"Success Criterion 1.2.8 Media Alternative (Prerecorded) (Level AAA)
An alternative for time-based media is provided for all prerecorded synchronized media and for all prerecorded video-only media."
What does Criterion 1.2.8 mean in practice?
This criterion requires providing a complete and sequenced textual alternative for a wide range of prerecorded multimedia content. Specifically:
- Alternative for Time-Based Media: This is not simply an audio transcript or a separate video description. It refers to a textual document that includes all information communicated visually and audibly in the original media. It must be comprehensive and presented in a logical order, like a detailed script or a narrative text describing the entire multimedia content. According to WCAG, it also includes "time-dependent interactive inputs and equivalent equations" if present.
- Scope of Application: The criterion applies to two types of multimedia content, provided they are prerecorded:
1. Synchronized Media: Content that combines video and audio, where information is presented simultaneously in both formats (e.g., a documentary, a recorded lecture).
2. Video-only Media: Content that contains only visual information without a significant audio track (e.g., a silent video, a slide presentation with animations but no narration).
Level AAA represents the highest level of WCAG conformance, indicating the provision of the best possible accessible experience. This criterion is classified as AAA for the following reasons:
1. Maximum Completeness: It requires an alternative that encompasses every single piece of information presented, both visual and auditory, in a textual format. This goes beyond captions or audio descriptions and demands a holistic integration of all informational elements.
2. Production Effort: Creating such a comprehensive and accurate alternative requires significant time and resource investment, as it involves not only transcribing dialogue but also meticulously describing every relevant visual element, such as actions, expressions, on-screen text, and significant sounds, all within a sequential and readable format.
3. Broad Spectrum of Benefits: While challenging, this type of alternative provides fundamental access to a wide range of users, including:
- Deaf-blind individuals: They can access the content via assistive technologies like braille displays.
- Individuals with cognitive disabilities or learning disorders: They can process information at their own pace and in a format that may be easier to comprehend than time-based media.
- Users with connectivity limitations: They can access the content without the need to stream video or audio.
How is Criterion 1.2.8 implemented?
Effective implementation of this criterion involves:
1. Full Transcription: Accurately transcribe all dialogue and narration present in the media.
2. Detailed Visual Description: Add accurate and complete descriptions of all important visual information, such as character actions, significant facial expressions, crucial objects, on-screen text, and scene changes.
3. Description of Significant Sounds: Include descriptions of non-verbal sounds that are essential for understanding the media's meaning (e.g., "sound of a siren," "background laughter," "doorbell ringing").
4. Sequential and Clear Formatting: Present the alternative in a well-structured, sequential, easily readable, and navigable format (e.g., an HTML page with headings, paragraphs, lists) that mirrors the order of events in the media.
5. Accessibility of the Alternative Itself: Ensure the textual alternative itself is accessible (e.g., semantic HTML, properly tagged PDF), and that it is easily discoverable and linked from the multimedia content.
Criterion 1.2.8 represents a commitment to deeper inclusion, ensuring that no one is excluded from a complete understanding of prerecorded multimedia content, regardless of their sensory abilities or learning preferences.
We invite the community to share their experiences:
- Have you ever created or implemented comprehensive media alternatives to achieve Level AAA? What were the biggest difficulties encountered in the process?
- What tools or methodologies have you found useful for gathering and merging visual and auditory information into a single structured text effectively and clearly?
- Can you provide examples of websites or applications that offer excellent comprehensive media alternatives compliant with 1.2.8?
Warm regards,
Michele (wcgadmfrm)
WCAG Plus Forum Team