Not all videos have audio, but this isn’t obvious for people who use closed captions. These fall into two camps: decorative and instructive.
- Decorative videos are often used in the background of pages. They are short, perhaps three seconds long, and may loop. These don’t require a caption file.
- Instructive videos may include a short demonstration or a time-lapse video of a scene. They have no spoken words or environmental sounds. These should have a caption file, as there’s no indication that a person who uses closed captions is missing information.
With the guidance of Sarah Margolis-Greenbaum, I’ve created a sample caption file you can use with your videos: Generic No Audio Caption (Github). This caption file will display “[No audio]” at the 2 second mark and will appear for 3 seconds.
VTT Caption File Text
WEBVTT 00:00:02.000 --> 00:00:05.000 [No audio]
The W3C has guidance on when captions are required.
This section tells you:
- What is required in the WCAG standard at Level A, AA, and AAA. (WCAG is introduced in the Planning page of this resource.)
- What is needed to meet user needs, beyond WCAG. If there are no “A”s, then it is not required in WCAG.