The first principle of the Web Content Accessibility Guidelines (WCAG) states that "information and user interface components must be presentable to users in ways they can perceive".
Since not all web users can see video content or hear audio, this means that you need to provide users with:
- Text alternatives for any non-text content
- Alternatives for time-based media
- Content that can be presented in different ways
- Distinguishable, easy to see and hear content
This article covers the specific guidelines for time-based media. Time-based media represents audio-only, video-only or audio-video content.
Unless the audio or video is a media alternative and is clearly labeled as such, it must follow the guidelines below. These are applicable to both new and existing time-based media:
Prerecorded audio-only
- An alt text provides a descriptive identification
- A text version presents equivalent information
Prerecorded video-only
- An alt text provides a descriptive identification
- A text version presents equivalent information or an audio track is provided
Prerecorded audio-video
- An alt text provides a descriptive identification
- A text description or an audio description is provided
- Captions or sign language interpretation is provided
Recommended format for audio-video
- Video file with a separate caption WebVTT file
- Video should not include embedded captions
- Translations should be provided as a caption file
- Upload your video on YouTube or Microsoft Stream
References
- Captioning YouTube Videos
- Captioning on Microsoft Stream
- WCAG 2.0 Guidelines
- Standard sur l'accessibilité des sites Web (SGQRI 008 2.0)
- WebVTT format captions
- Audio description example
Version 1.0
Last updated: April 2, 2020