SIA-R37<video> element visual content has strict accessible alternative

Accessibility requirements

This rule tests conformance of the following accessibility requirements:

Description

This rule checks that <video> elements with audio have audio description.

Applicability

This rule applies to every prerecorded <video> element that is visible, where the video contains audio.

Expectations

  1. For each test target, the outcome of at least one of the following rules is passed:

Assumptions

  • This rule assumes that a mechanism is available to start the video and that the video element is not simply used to display the poster.
  • This rule assumes that the language of each test target can be correctly determined (either programmatically or by analyzing the content), and sufficiently understood.

Accessibility support

There are only a few implementations of video players (without third party technologies) that support audio description tracks at the time of writing.

Currently the description track is not supported by most assistive technology. Accessibility support for the description track attribute is relatively low to non-existent. Video players may be able to work around the lack of support for the description track by using aria-live but few do this today.

This means that the rule can only provide a pass for these success criteria if assistive technology support the description track or if the video player that is used has implemented such a work around.

Examples

Acknowledgments

This document includes material copied from or derived from https://act-rules.github.io/rules/1ec09b/. Copyright © 2021 W3C® (MIT, ERCIM, Keio, Beihang).