Video content is a great way to share information. If you host videos on your site, however, you must ensure this information is available to everyone. Many site visitors won’t be able to access or learn from audio-visual content. For example:
- People who are Deaf or hard of hearing may not be able to hear your video’s dialogue.
- People with attention disorders may need text along with speech to remain focused.
- Many users simply retain written information more easily than spoken words.
That’s why the Web Content Accessibility Guidelines (WCAG) — the most-trusted global standards for digital accessibility — tell you to include captions for all “synchronized media presentations.” To conform to WCAG, you’ll need to understand captions. But when you start your research, you’ll encounter two terms that are rarely explained: open captions and closed captions. What’s the difference?
Here’s what every site owner needs to know about the difference between open and closed captions, plus which option supports digital accessibility for the broadest audience.
The Difference Between Open and Closed Captions
Before you learn about open and closed captions, it will help to understand exactly what captions are — and what they’re not. Captions don’t just convey dialog. Text descriptions of dialog alone are called subtitles.
Captions, on the other hand, provide text descriptions of everything users might need to understand the content. That includes dialog, certainly, but also important sound effects, background music, non-verbal vocalizations (laughter, for instance), explanations of who’s speaking, and more.
So what does it mean for captions to be open or closed? Here’s the difference between open and closed captions:
- Open captions can’t be turned off. They’re “burned into” the video file and are always visible when the video plays.
- Closed captions are optional. Users turn them on or off. They’re contained within separate digital files from the video , which means they’re only available when media players support closed caption file formats like SubRip (SRT).
At first glance, open captions may appear to be the more accessible option. After all, activating closed captions could present a barrier to some users. On closer inspection, however, open captions create their own set of accessibility issues.
In fact, it’s usually the better accessibility practice to choose closed captions whenever possible. Here’s why.
Choosing Between Open and Closed Captions
Closed captions allow users to personalize their experience. That’s almost always the best approach to digital accessibility. Every visitor approaches your site with a unique set of skills, abilities, preferences, and needs. No single mode of presentation could possibly offer the best experience to everyone.
Open captions, on the other hand, are fixed. They’re static. You render them in your video file just like any other image, so they can’t be altered by the user. That leads to a few disadvantages if your goal is to make video content accessible for a diverse user base:
- Some users, including hearing neurodiverse viewers, may find captions distracting. To access information conveyed in your video, these people will benefit from being able to turn captions off.
- Closed caption files support text in multiple languages, so they make content accessible to multiple language communities at once.
- Some viewers, including people with low vision, may prefer large text captions. Only closed captions support user-initiated text resizing.
- Screen readers and other assistive technology can rarely access text within images. That includes open captions in video files. But these tools can read closed caption files.
All this argues in favor of closed captions. To improve accessibility with closed captions, however, it’s essential to make on/off buttons highly visible and clearly labeled. Poorly designed closed caption buttons may create barriers to access. But with well-designed controls, closed captions are generally the better choice for accessibility.
That said, open captions are better than no captions at all. Most of today’s internet media players do support closed captions. Some social media sites don’t. If you’re sharing video content through platforms that don’t support closed captioning, open captions are your only choice — and they can provide conformance with key parts of WCAG.
Open Vs. Closed Captions in WCAG
WCAG is organized into success criteria, each of which addresses a single accessibility issue. Two criteria require the use of captions:
- WCAG Success Criterion (SC) 1.2.2, “Captions (Prerecorded)” requires the inclusion of captions on all prerecorded audio-visual content. The only exception is media that’s used as an alternative for existing text, and includes a label to that effect.
- WCAG SC 1.2.4, “Captions (Live)” requires captions in live videos and presentations (or what WCAG calls “synchronized media.”)
Note that WCAG lists SC 1.2.2, “Captions” as the A level of conformance, while SC 1.2.4, “Captions (Live)” is listed as Level AA. Most accessibility experts recommend Level AA conformance with WCAG, which means it’s best to strive to conform to both of these success criteria.
Supporting documents for these Success Criteria offer multiple “sufficient techniques” for conformance. These techniques include both open and closed captions. In other words, WCAG doesn’t recommend one over the other.
However, WCAG’s description of Technique G93: Providing Open (Always Visible) Captions, states that “the objective of this technique is to provide a way for people who are deaf or otherwise have trouble hearing the dialogue in audio visual material to be able to view the material.”
The WCAG guidance on Technique G87: Providing Closed Captions says something similar, but with an important addition: “...without requiring people who are not deaf to watch the captions.”
Your videos should be accessible to as many people as possible, including people with and without specific disabilities. As WCAG’s description of closed captions suggests, this technology provides the most options to each individual user, which expands your content’s reach.
To learn more about multimedia accessibility, download our free Video Accessibility Checklist, a one-page guide for creating accessible videos,