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Accessible video and audio

The Web Content Accessibility Guidelines (WCAG) 2.2 standards ensure that people who cannot perceive video or audio will not be disadvantaged or prevented from accessing information. This means providing information in an alternative format for most audio, video and synchronised media.

The alternative format will differ depending on the project, but to meet accessibility requirements:

  • audio-only content will need a transcript
  • video-only content will need a descriptive transcript, or audio description
  • synchronised media (audio and video) will need an audio description (if any information is only available visually) and captions
  • live synchronised content requires captions
  • the visual presentation of text and images of text must have a contrast ratio of at least 4.5:1
  • video content must not include anything that flashes more than three times a second
  • background sound must be at least 20 decibels lower than the foreground speech content, apart from occasional sounds that only last for one or two seconds

Plan for accessibility

It is much easier and more cost-effective to plan for accessibility from the start of a project. Planning ahead can also have a big impact on how accessible the end result is. 

  • Descriptive scripts (where the speaker describes what is happening visually) can avoid the need for audio description and adding description into captions post-production.
  • Choose a quiet room without background noise, or echo.
  • Try to ensure that people being filmed are close up, in good light, and speaking slowly and clearly. Some people with a hearing impairment need to see mouth movement to understand spoken language.
  • Avoid logos or text overlapping with captions.

The Web Accessibility Initiative (WAI) has information on planning, scripting, storyboarding and producing accessible audio and video content.

Video and audio accessibility tools

Accessibility tools will depend on the platform where the media is hosted. All media on our own websites must be accessible. We use YouTube for video and audio, and can add captions and transcripts. 

When adding media to social media platforms we are limited by their accessibility tools. But we can still ensure that other aspects of accessibility - contrast, background noise etc, are as good as possible.

Captions provide a text transcription of dialogue and important sounds in a video with audio.

Captions help people with hearing loss who can't hear the audio. They also help people with autism, or a learning disability, to understand and focus on content. They are also helpful for people who are watching videos in a noisy environment, or with the sound off.

Silktide reports on missing captions as an accessibility fail and this affects our overall score.

Closed captions can be turned on and off, and open captions are permanently embedded into a video.

Captions need to have enough contrast to be seen against the images on the screen. For example by using white text on a black box.

Avoid placing logos, banners or text on the screen where captions might overlap.

YouTube can creates captions automatically but it is important to check for accuracy and remove any unnecessary words or utterances which might confuse viewers. 

More information on captions from WAI

Captions are written to be viewed alongside the video, whereas transcripts should include visual information for people who are not viewing the video. If you already have captions, you can use them to create the transcript by adding visual information. 

It is recommended that transcripts are added to the website as text, underneath the video. Although they can also be added to YouTube. (We might need to add the transcript to YouTube for people viewing from social media?) See example of transcript added to webpage: Video Captions | Web Accessibility Initiative (WAI) | W3C

Descriptive transcripts, like captions, include all informative audio, speech, and sounds that help people to understand the video. But descriptive captions also include visual information that is not in the audio. (Basic transcripts are just a text version of the audio, so they do not help people with a visual impairment. For this reason we should use descriptive transcripts.)

Descriptive transcripts cannot be used instead of audio description, but they can be used together.

More information about transcripts from WAI

Audio description is additional audio commentary that describes visual information in a video for people who can't see it. Pre-recorded videos with visual information which is not included in the commentary must have an audio description. This includes demonstrations of how to do something, graphs and text, which are shown on screen but not explained verbally.

If all visual information is also mentioned in the audio, a separate audio description may not be necessary. Planning ahead and including visual information in the script can avoid the need for a separate audio description.

Pre-recorded videos where the visual content does not add information to the content may not need an audio description. An interview with one person where the background does not change would not need an audio description. However a film where several people were interviewed, and they were identified by text on the screen, would need an audio description.

YouTube does not currently support separate audio descriptions, so the options are:

  • integrated audio description where visual information is included in the script
  • create a second version of the video which includes an audio description

More information on audio description - WAI

Video - how to create accessible videos with audio

This video explains what captions, transcripts and audio description are, why they are important, and how to create them.

Please watch in YouTube for more accessibility options. - opens in a new tab

Further guidance

Making audio and video media accessible - Web Accessibility Initiative

How to make video and audio accessible - Norfolk County Council