Avoid These 4 Mistakes When Writing Video Captions for Accessibility

Accurate captions benefit everyone — and for businesses, neglecting multimedia accessibility can be costly. 

Research shows that videos with captions perform better than videos without captions, improving brand recall and ad memory quality. In one study from Verizon Media and Publicis Media, 80% of respondents said that they are more likely to watch an entire video when captions are available.

For many people with disabilities, captions are an essential feature. By writing scripts while drafting your content, you can create more effective multimedia for those people — and for users of all abilities. Here are a few key mistakes to avoid when writing text for your videos.

1. Don’t use automatic captions without reviewing them

Many video hosting services offer free tools for writing captions with artificial intelligence. YouTube introduced automatic captions in 2009, and Facebook began rolling out a similar feature in 2017. These tools dramatically increased the number of accessible videos overnight, and they’re especially useful for transcribing live content. 

But while automatic captions are convenient, they’re far from perfect. According to the University of Minnesota at Duluth’s Media Hub, YouTube automatic captions typically provide about 60-70% accuracy. To comply with the Web Content Accessibility Guidelines (WCAG), captions must not omit dialogue or important sound effects. In other words, 70% accuracy isn’t sufficient. 

The safest way to write captions is to draft them manually. If you choose to use automatic captions, make sure to review the output. Fix any inaccuracies before posting your media — not afterwards. 

Related: Do YouTube's Automatic Captions Improve Accessibility?

2. Don’t use pre-rendered captions

Pre-rendered (or “burned-in") captions may be necessary for certain social media platforms that don’t support caption files. However, pre-rendered captions may not be accessible for screen readers and other assistive technologies. Users will have no control over the font or font size, and in some cases, video compression artifacts can affect the readability of the text. 

If you can’t add caption files, pre-rendered captions are acceptable. However, make sure that they’re legible: Choose an accessible font and follow WCAG’s requirements for color contrast.

Related: How Do "Burned In" Captions Affect Accessibility?

3. Don’t neglect important sound cues and contextual information

Your captions should include descriptions of all important sound effects and music cues. In many cases, these sounds can change the meaning of a video; you’ll want to provide all viewers with the information they need to understand your content. 

Tips to keep in mind: 

• Use brackets to identify non-speech audio. For example: [man coughing]
• If a speaker is offscreen, use round brackets to identify them. For example: (Thomas)
• When writing descriptions of music and other non-verbal sounds, use objective terms. For example, writing “violins playing fast-paced music" is more appropriate than “violins playing beautiful music.”
• Identify pauses in dialog by using ellipses (...).
• If necessary, omit descriptions of non-essential sounds to keep the captions synchronized with the video.

Related: What Website Developers Need to Know About Closed Captions

4. Don’t assume that captions alone will make your videos accessible

Adding captions to your videos is an excellent way to improve multimedia accessibility. However, even with appropriate captions, your videos might create barriers for some users. Some quick tips to keep in mind:

• Check that your captions are synchronized with the video playback. 
• Make sure all sentences remain on screen for at least 2 seconds.
• Make sure viewers can control the video player using a keyboard alone.
• Avoid using autoplay. Autoplay is bad for accessibility and can frustrate users, regardless of their abilities.
• If possible, choose a video player that gives users control over the caption font and font size.
• Consider providing transcripts. Transcripts provide people with more ways to enjoy your content, and they’re helpful for search engine optimization (SEO).

While adding captions takes time, it’s well worth the effort. Providing text alternatives to non-text content expands your audience considerably, and if you plan for captions when drafting your scripts, you’ll be able to add them easily during editing. 

For more tips for creating accessible videos, download the Bureau of Internet Accessibility’s free Video Accessibility Checklist.