Ensure that blind users can still understand the content of a video.
Why it matters
If you’ve ever been in another room listening to a TV show and wondering what the heck is going on because you can’t see the picture, you know what it’s like to try to understand a video by sound alone.
People with Visual Disabilities generally require an audio description to make sense of a video. An audio description track is an audio track that describes important visual elements while the original video is playing. An extended audio description track is one where the original video can be paused so that thorough descriptions can be provided to the listener.
An example of an audio description track
The following video, from the beginning of the movie Lion King, contains an audio description track.
How to implement
Technical implementation is highly dependent on the video player being used. Some video players may allow for the audio description track to play at the same time as the original video — and allow the user to toggle the audio description track on or off. Other players require one version of the video with the audio track and one version without. HTML allows for a WebVTT description file, but it may or may not be compatible with your chosen player.
Planning the original video
When planning a video, consider what a blind user needs to know to understand it.
If your video is of the “talking heads” variety, with little to no visual content, you may be able to include the bulk fo the description during the initial recording, so that little to no content is needed in a separate audio track.
3Play’s best practices for creating accessible video for blind and low-vision viewers recommends describing what is happening in the video as if you are recording a podcast or are on the radio. Assume that all of your viewers are listeners and don’t see the visual portion of the video.
Make sure that your video’s scrip contains pauses so that there is room for additional description where it’s necessary.
Identify who’s speaking as part of the original. Describe any participation from other people in the video.
Review Text Transcripts for tips on writing an audio track’s content.
Producing the audio description track
These recommendations are taken from the Audio Description Project’s Organizing Principles.
- Never override the dialogue unless it is absolutely necessary; e.g., if someone in the video draws a gun.
- If you must talk over the actors, do so over the least consequential dialogue.
- Match your style, tone and pace to the video you are describing. The voice of the audio description presenter is that of a restrained but appreciative spectator.
- Make your voice confident, interested, warm and authoritative. Be sensitive to the mood of the scene. Do not be patronising or chummy.
- Do not fill every pause. Allow the atmosphere and background noise to come through.
- Employ good microphone technique.
- Describe at the same time as the action unfolds, or anticipate slightly. Respect the timing of the scene, particularly for comic or horrific situations. You want your listeners to experience the same emotions as the sighted audience at the same time.