SIA-R34<video> element visual-only 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, without audio, are descriptive.

Applicability

This rule applies to every prerecorded <video> element that is visible where the video does not contain audio and contains a <track> element with a kind attribute whose value is descriptions.

Expectations

  1. The visual information of each test target is described with a description <track> element that has the same language as the video or the same language as the page.

    While multiple description <track> elements may be useful for different languages, at least one must match the language of the video or the language of the page.

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. 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.

Examples

Acknowledgments

This document includes material copied from or derived from https://act-rules.github.io/rules/ac7dc6/. Copyright © 2021 W3C® (MIT, ERCIM, Keio, Beihang).