You’re publishing a video, and you’ve already written a detailed transcript. Do you really need to add closed captions?
In short, yes. The goal of digital accessibility is to provide the best possible experience for as many users as possible — not to accommodate a single group of people with disabilities.
It’s important to remember that disabilities affect people in profoundly different ways. Some Deaf users may prefer closed captions, but some people with cognitive disabilities might use transcripts to read at their own pace. People with vision disabilities might listen to video captions with a screen reader, then scan through transcripts for important descriptions of visual content.
Your website should provide people with options for accessing content in a way that aligns with their preferences. As such, both transcripts and captions are important for accessibility. Providing both types of text alternatives can enrich your content and expand your audience.
Below, we’ll discuss the Web Content Accessibility Guidelines (WCAG) requirements for both captions and transcripts — and provide a few best practices to help you create more engaging multimedia.
WCAG Requirements for Captions and Transcripts
Published by the World Wide Web Consortium (W3C), WCAG is widely accepted as the international standard for digital accessibility. By following WCAG’s Level AA guidelines, creators can prevent many of the most common accessibility barriers.
Transcripts and captions serve different purposes, and WCAG treats them differently. Captions are synchronized with your multimedia and provide important audio information (such as spoken words and meaningful sound effects). A transcript provides all of that information, but may also include descriptions of the media’s visual presentation.
Here’s a look at WCAG’s Level AA requirements for captions and transcripts:
Video with Audio Content
For both live and pre-recorded content, captions are required to meet WCAG Success Criterion (SC) 1.2.2, “Captions (Prerecorded),” provided that the video conveys important information through audio. For example, if a video has a speaker, it needs captions.
Transcripts are not required at WCAG Level AA, but they’re strongly encouraged for accessibility. Adding a quick transcript has an important practical benefit: Transcripts are enormously beneficial for search engine optimization (SEO).
Video-Only and Audio-Only Content
If a video contains no audio — or if the audio isn’t important for understanding the content — it doesn’t need captions. For example, if your website includes slideshows with simple sound effects, you don’t need to add captions describing the sounds.
However, you will need to provide a detailed transcript to meet WCAG SC 1.2.1, “Audio-only and video-only (Prerecorded).” Providing a transcript improves the experience for people with visual disabilities, non-native speakers, and others who might prefer a text-only presentation.
Under WCAG SC 1.2.1, transcripts are also required for podcasts and all other pre-recorded, audio-only content. Captions for audio-only content are encouraged, but not required for WCAG Level AA conformance.
Writing Closed Captions and Transcripts for Accessibility
While captions and transcripts are fairly straightforward tools, you’ll need to think about them when creating your content — not after publication.
Planning for accessibility can reduce the time you spend on production. When drafting your scripts, include descriptions of important audio cues. Prior to publication, you can use your script to easily create caption files and HTML transcripts.
Some common mistakes to avoid:
- Don’t rely on auto-generated captions. The best automatic caption tools are only about 70% accurate. While that’s technically impressive, automated captions simply aren’t good enough for accessibility.
- Don’t write long descriptions of simple sound effects. Keep descriptions simple and concise.
- Avoid pre-rendered captions. Pre-rendered (or “burned-in") captions can improve accessibility for some people, but they’re not accessible for people who use screen readers and other assistive technologies.
- Don’t hide your transcripts. Put links to transcripts on the same page as your media.
- Don’t forget to check your work. Make sure that your captions are properly synchronized with your media. All captions and transcripts should be reviewed for accuracy — a simple misspelling could dramatically change the meaning of your content.