Captions are text versions of the audio content, synchronized with the video. They are essential for ensuring your video is accessible to students, employees, and members of the public who are deaf or hard of hearing. They also help non-native English speakers to understand the video, make it possible to search for content within the video, help all students learn the spelling of technical terms spoken in the video, and make it possible to generate an interactive transcript where users can click anywhere in the transcript to watch the video where that text is spoken.

You can caption your own videos using one of several free online tools, including:

Subtitle Horse

The end product generated by both options is a caption file. Most caption files are plain text files with time codes indicating the start and stop times. However, there are various types of caption files with slight variations in their syntax. Once you have a caption file, the final step is to add this file to your video. How you do this, and the types of caption file supported, depends on where your video is hosted. For specific instructions, select one of the following options:

Audio Description

Audio description is a separate narrative audio track that describes important visual content, making it accessible to people who are unable to see the video. Individuals who are blind can understand much of a video’s content by listening to its audio. However, if a video includes content that is only presented visually (e.g., on-screen text or key actions that are not obvious from the audio) this visual information must be described in order to be accessible to people who are unable to see it.

Like captions, there are two general approaches to producing audio description for video:

  • Outsource.
  • Do it yourself.

Outsourcing Audio Description

The American Council of the Blind has compiled a comprehensive list of commercial services for producing audio description. 

The typical deliverables provided by professional audio description services are either an audio file with soundtrack and description mixed together, or an audio described version of the video, with the described audio replacing the original program audio. In either case, these can be made available to users by announcing that the video is “Also available with audio description”, where “audio description” is a link to the described version.

Live Captioning and Description

If live events are simulcast over the Web, live captioning is needed in order to provide access to the audio content for audience members who are deaf or hard of hearing. Similarly, live description may be needed if key visual content will otherwise not be verbalized, such as in a dramatic production. At the University of Colorado Denver and the Anschutz Medical Campus, these services needed by students with accommodations are coordinated through the Disability Resources for Students.


A transcript is a text version of the media content. A transcript should capture all the spoken audio, plus on-screen text and descriptions of key visual information that wouldn’t otherwise be accessible without seeing the video. Transcripts make video content accessible to everyone, including people who are unable to view the video due to accessibility problems or technical limitations. They are also helpful for people who want to quickly scan or search a video’s content but do not have the time to watch the entire video.

If you have captioned your video, a transcript is available as one of the optional output formats produced by the closed captioning process. This is true of both the free online tools and the commercial service providers. To make the transcript available simply link to it from your web page, wherever you link to or display the associated video.

Able Player, the accessible open-source media player developed at the University of Washington, generates an interactive transcript automatically using the caption and/or description tracks. For additional information see the following section.

Choosing an Accessible Media Player

When choosing how to deliver your video, it is important to consider options that are fully accessible. Whether you are selecting a media player plugin or module for your website or selecting a service to host your videos, the following questions should be answered about the available options:

  1. Does the media player support closed captions?
  2. Does the media player support audio description in a way that enables users to toggle the narration on and off?
  3. Can the media player’s buttons and controls be operated without a mouse?
  4. Are the media player’s buttons and controls properly labeled so they can be operated by a blind person using a screen reader?
  5. Is the media player fully functional, including all of its accessibility features, across platforms and in all major browsers?

One player that satisfies all of these criteria is Able Player, a free, open-source media player that was developed at the University of Washington with accessibility in mind. For additional information see  Able Player on GitHub.

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