We’re still working with video and audio in 1.2.2. I’ve mentioned captions in the previous A11y 101 posts. Success Criterion 1.2.2 lays out the specifics for captions.
Simply put, if there is video with speaking you need captions. Did you provide an audio description? Those get added to the captions.
Caption Styles
There are two basic ways to provide captions, open and closed. In either case, you need to have someone transcribe the audio. They need to include the time when the display of the text starts.
Open Captions
Open captions are the minimum support you should provide. Open captions are “printed” into the video. They are baked in and designed to fit the design aesthetic of the video.
Why do I call this minimal? Well the user lacks control to customize it. Additionally, this only supports deaf and hard-of-hearing folks. Our next version offers more features.
Closed Captions
Since open captions are part of the video, they can actually create problems. The most problematic is that they may move around the screen depending on what the video needs. This makes it hard for users, especially low-vision users, to keep track and find them.
Closed captions provide and answer to this. Closed captions are a separate file called in the <video> element. Usually it is a .VTT file. It’s pretty simple to build. I have an article on a11yproject.com that I published in 2013 that explains how to do it.
The next thing that closed captions bring – screen reader and Braille display support. Closed captions are considered real text on the page for screen readers. Now the Blind-Deaf can get the story too. The low-vision user can lean back on the screen reader to help. It also helps with SEO.