An accessible digital multimedia presentation should always contain the following features:
- Captions, which provide a textual equivalent for all audio
- Audio descriptions, which describe important visual elements of the presentation
- A transcript, so braille users can read the contents of the presentation, and so anyone can scan the contents of a presentation prior to viewing it
There are two digital multimedia formats that support the inclusion of audio descriptions and closed captions in digital multimedia presentations: Synchronized Multimedia Integration Language (SMIL) and Synchronized Accessible Media Interchange (SAMI).
Transcripts, captions, and descriptions make media accessible to all users:
- Provide captions. Captions make audible content accessible to people who can’t hear, and more comprehensible to everyone. Do not rely on the auto-captioning feature provided by platforms such as YouTube. In most cases, the accuracy is not sufficient to be useful.
- Put the content in the words. Consider how to convey concepts in a way that will be understood by people who can’t see. For example, a video of a presentation will be more accessible if the speaker describes the content of the slides.
- Use audio description. When essential visual information is not described in the video, one approach is to provide narrative describing visual information. The audio narrative plays during the natural pauses in the video.
- Provide a media transcript. A text-based alternative includes a running description of all visual information, including descriptions of scene changes and the actions and expressions of actors, as well as a transcript of all non-speech sound and spoken dialogue.
