Videos that contain any audio narration need to have captions to be accessible for users. Accessible video is video with captions that are accurate, readable, and complete.
Accurate: Captions have, on average, no more than 1 word in error for every 100 words.
Readable: Captions are displayed with enough time to be read completely, are synchronized with the audio, are not blocking the visual content, and are legible.
Complete: Captions represent all spoken audio, speaker identification, meaningful sound effects, and meaningful music.
This means that auto-generated captions must be corrected.
Captions can be created and edited in most video players such as YouTube and MiVideo, but there are other tools like SubtitleHorse that are free and available for anyone to use.
We recommend creating closed captions so that the captions are not burned onto the video, but rather displayed via the video player, such a YouTube, MiVideo, or VLC. This provides the viewer with the ability to adjust the size, color, shape of the captions to best meet their needs. For more info: http://videohelp.cit.cornell.edu/captioning-videos
You will likely have some videos that contain audio narration and therefore must be captioned. Keep in mind that closed captions typically display in the lower 1/4 th part of the screen when a video is being played, so it’s good to keep important information out of this area so that users can view the video with captions and without missing anything.
If you are creating a screencast with audio, ensure that any important information you shown is also said. For example, you might display a text callout with additional info about a particular topic. However, users with visual impairments may not be able to view this text info, therefore making it inaccessible to them. By also saying out loud what you have shown, it ensures that all audiences can gather all of the same info.
If you don’t have audio in your video, then make sure any important information is provided in the video description, available for download, or is available is a different format.
Video descriptions translate visual information into text for users who cannot access the original visual (e.g. blind users, low vision users). The best and simplest practice is to produce educational video content that does not require video description because the visuals and the audio are already redundant. Examples:
The video is a screen capture or screen share of a process, and the audio is a narrative voiceover describing the process as it happens.
The video is a close shot of a person talking and doesn’t require description.
The video is a lecture and the lecturer describes the diagrams and images they show.
The video is an animation that enhances a voice narration.
It is good instructional design to offer multiple formats of info to learners to address the needs and learning styles of diverse users. This is the same for accessibility needs. When possible, it is recommended to provide alternate methods to presenting information.
When creating your video, keep in mind of color and color contrast and whether your color choices are accessible for those with low vision or varying levels colorblindness. Make sure callouts, text, arrows, etc. are all highly visible against their backgrounds.
Please be aware of users who may be sensitive to gratuitous animation or movements in a video. We recommend using zooming and panning in your screencast, but ensure that movements are at a speed that will not make viewers sick or uncomfortable.