Provide text alternatives for video-only content
A video with no soundtrack puts all of its information into moving pixels. G159 asks for a document that presents the same information in text, covering the actions, the setting, the on-screen text and graphics, and anything a viewer is meant to notice. It serves as the long description for the video and it goes in the same language as the page. This is a sufficient technique for 1.2.1 Audio-only and Video-only (Prerecorded) at Level A, and W3C lists it again for the Level AAA media alternative rule, so one good description answers both. Description is the operative word. 'A video showing how to reset the router' names the video. It does not tell anyone how to reset the router.
How we find it in an audit
Our reviewers watch each silent video and ask what somebody who could not see it would have missed. Then we read the text alternative and check whether it carries that. The gap is widest on screen recordings, product demos and process animations. Those steps only ever existed on screen.
How affected users experience it
A blind reader meeting a silent screen recording gets an announcement that a video is present and nothing else. There is no audio to fall back on, so unlike most media there is no partial access at all. Written steps beside the video also help sighted readers who cannot play it, and they are searchable, which the video is not.
Passes vs. fails
Passes
Beside the video sit numbered text steps describing what is shown, which button to hold, for how long, and what the lights do at each stage.
Fails
A silent screen recording shows how to reset a router, and every step exists only as moving pixels.
How this gets tested
The W3C publishes test rules that define what a checker looks for here.
- Audio element content has text alternativeA tool finds candidates, you decide
- Video element visual-only content has accessible alternativeA tool finds candidates, you decide
- Audio and visuals of video element have transcriptA tool finds candidates, you decide
Other ways to satisfy this rule
6 guides on this site are filed under 1.2.1 Audio-only and Video-only (Prerecorded). W3C lists this one as sufficient for that rule on its own. Implement it correctly, in a way your readers' software actually supports, and the rule is met.
This guide is our interpretation of W3C technique G159: Providing an alternative for time-based media for video-only content. W3C publishes its techniques as guidance rather than as the standard, and says so on every one of them. The success criterion is what conformance is measured against, and a technique is one documented way to meet it.