SIA-R36<video> element visual content has description track

Accessibility requirements

This rule is not required for conformance to any accessibility requirements.

Description

This rule checks that description tracks that come with prerecorded <video> elements are descriptive.

Applicability

This rule applies to every prerecorded <video> element that is visible where the video contains audio and a <track> element with a kind attribute whose value is descriptions.

Expectations

  1. The visual information of each test target not available through its audio is described with a description <track> element.

    Multiple description <track> elements may be useful for different languages, but at least one must match the language of the video.

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

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/f196ce/. Copyright © 2021 W3C® (MIT, ERCIM, Keio, Beihang).