- Online Courses
Video and audio content can help make web pages and course curricula more engaging. However, they can also erect barriers unless delivered with accessibility in mind. When delivering audio or video content, you must consider the following accessibility issues:
Captions are a text version of the spoken audio, plus a description of important sounds, synchronized with the video. Typically users can toggle captions on or off using a CC button on their media player. Captions must be available in order to ensure audio content is accessible to people from the Deaf and Hard of Hearing community. They also help people for whom English is a second language, people who process information better if presented in multiple modes (sound and text), people who are unfamiliar with the vocabulary used in the video, people who have the sound turned off on their devices, and people in noisy environments who are unable to hear the sound from their devices. Also, in supporting media players, captions make it possible for users to search the video, and can be repurposed as an interactive transcript so users can jump directly to particular points in the video from the transcript text.
Subtitles are similar to captions, but are used for translating spoken content into another language. If subtitles are available for a video, they’re typically provided in a list of languages, accessed via the CC button on the media player. Some media players erroneously use the term subtitles when referring to captions.
Audio description is a separate narration track that provides access to any important information that’s otherwise presented only visually. This benefits people who are unable to see the video due to blindness or low vision. It also benefits users who are visually distracted, watching a video in the background while multitasking.
Transcripts are text versions of the video content, provided as an alternative to watching the video. This benefits people who are deaf-blind, accessing the web using a Braille device; as well as people with slow Internet connections or other technical issues that prevent media from playing. Also, transcripts can easily be searched or scanned quickly, so they provide a more efficient means for busy people to access the video’s content. Since a transcript is an alternative to the video, it should include both audio content and descriptions of important visual information.
Accessible media players
Accessible media players are those that support accessibility features such as captions and audio descriptions, and are designed to be accessible as explained throughout this IT Accessibility Checklist. For example, an accessible player can be operated with the keyboard alone, has sufficient contrast, and has controls that are properly labelled for assistive technology users.
WCAG 2.1 success criteria
The issues described on this page, and associated Techniques pages, map to the following success criteria in the W3C’s Web Content Accessibility Guidelines (WCAG) 2.1:
- 1.2.1 Audio-only and Video-only (Prerecorded) (Level A)
- 1.2.2 Captions (Prerecorded) (Level A)
- 1.2.3 Audio Description or Media Alternative (Prerecorded) (Level A)
- 1.2.4 Captions (Live) (Level AA)
- 1.2.5 Audio Description (Prerecorded) (Level AA)
- 1.4.2 Audio Control (Level A)