Video Accessibility

The accessibility requirements for video are based on the following distinctions:

  • Is the video live or prerecorded?
  • Is it presented with or without audio?

We will start with a brief description and list of accessibility requirements for each type of video. The Details for Individual Requirements section provides more information about each of the accessibility requirements.

WCAG success criteria (SC) and conformance criteria (CC) may be referenced by their SC or CC number. The referenced criteria are linked in the WCAG Reference section at the end of the page.

  • Prerecorded means any video that is not live.
  • Live video is captured from a real-world event and transmitted to the user's device with no more than a broadcast delay.
  • A broadcast delay may allow time to censor the feed, but is not sufficient to allow significant editing.
  • If the video is completely computer generated, it is not live.
  • Video without audio is referred to as video-only in the Web Content Accessibility Guidelines (WCAG), so the same term is used here.

Live Video

A live video is transmitted to the user with minimal delay. The requirements for live video only apply to the original broadcast/stream of the video. Any rebroadcast or attempt to provide the video at a later date/time must meet the requirements for prerecorded video.

Live Video-only (No Audio)

Examples of live video without audio might include nature webcams, cameras used for wildfire monitoring, construction cameras, etc. These videos require:

Live Video with Audio

Examples of live video with audio might include commencement video streams, zoom meetings/calls, or live TV broadcasts. These videos require:

*The limitations of live captioning (either through the use of a captioning service or AI captioning) are expected and understood by this requirement. Captions are only expected to be provided in the same language as the audio.

Prerecorded Video

Prerecorded video is any video that is not live.

Prerecorded Video-only (No Audio)

Prerecorded video-only content could be either video which does not include an audio track or video which is presented in such a way as to prevent the audio from being available. In the latter case, if there is a method available for the user to access the audio, then the additional requirements for video with audio must be met.

Common examples of prerecorded video-only content might include video playing in the background of a section of a webpage or a recording of content previously provided as live video-only content.

Video without audio requires:

Prerecorded Video with Audio

Any prerecorded video with audio must meet the following requirements:

Details for Individual Requirements

For all video content, the user must be able to stop/pause and resume playback of the video [SC 2.2.2]. Audio, if present, must remain synchronized with the video.

  • For prerecorded video, the user should be able to resume playback from the point at which they paused the video.
  • For live video, the user may be returned to the current live feed rather than resuming playback from when the user stopped. (Resuming from the point at which playback was paused is permitted, but not expected for live video.)

If the user has expressed a preference for reduced motion, video must not start playing automatically [CC 5.2.5]. People may choose to use these preferences due to a vestibular motion disorder or to help manage developmental or cognitive disabilities.

For our purposes, this preference can be tested with a CSS media query (prefers-reduced-motion) which can also be tested in JavaScript via the matchMedia() method. This media query allows the user to express this preference in their browser, operating system, or device preferences. Site- or application-specific preferences can be used as well, but should take their initial value from the media query, if provided, or give the user a chance to express their preference before playing videos or using animation.

A description of the visual content of the video must be provided. The purpose of the description is to inform the user of the video's contents, so users can decide whether they should seek the content in another format, if needed [SC 1.1.1].

  • For a live video without audio, a brief description identifying the content in a general sense may be all that is required.
  • In all other cases, a text alternative, audio description, or both may also be required.

Text Alternative

For videos presented on the web, this should be a descriptive transcript which may be provided either on the same page as the video or in a page/file linked in a manner which clearly identifies it as a text alternative for the video.

  • Prerecorded video requires a text alternative, regardless of the presence of audio [SC 1.1.1, SC 1.2.1, SC 1.2.3].
  • Due to the nature of live video, a text alternative is not required, though it should be provided, if possible. (For example, if slides or a script have been prepared for a live event, those materials could be made available to users alongside the live video.)

Audio Description

An audio description of visual information is either an audio track or a separate version of the video which provides an audio description of visual information in the video. If the video included audio, the audio description has to be presented in such a way that it doesn't interfere with the original audio's synchronization with the video. If the audio description is created as a separate audio track, ensure that the player to be used for the video provides support for playing the alternative audio track alongside the video.

  • Prerecorded video with audio requires an audio description [SC 1.2.5].
  • An audio description may be provided for prerecorded video without audio, but is not required when a text alternative is present [SC 1.2.3].

Nothing in the video flashes more than three times in any one second period [SC 2.3.1]. Flashing content can cause migraines, dizziness, nausea, and seizures.

If there is any chance that a flashing effect is visible in the video (even in only a small part of the screen), please take the time to review and understand the WCAG general flash and red flash thresholds. An additional resource is Understanding WCAG 2.1 SC 2.3.1.

When prerecorded video includes audio, captions must be provided. The Web Accessibility Initiative (WAI) has more information about providing captions.

WCAG Reference

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