Audio description for videos

Audio description (AD) is a narration of meaningful visual information in a video to provide context, clarify speakers, and articulate visual elements. (Think of it like alternative text for videos.)

Audio description logo.Often, people can understand much of a video’s content merely by listening to its audio. However, if a video includes content that is only presented visually, such as on-screen text, graphics, or 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. 

Who benefits from audio description?

Audio description is essential for people who are blind or have low vision, but it also benefits those with certain cognitive disabilities who have difficulty understanding visually what is happening. 

Harvard’s Digital Accessibility Policy cites the Web Content Accessibility Guidelines (WCAG) 2.1 AA as a standard, which recommends that audio description be provided for video content.

 

Learn more about AD: 

  • Watch: Audio description in a couple minutes
  • Experience it yourself: Most streaming platforms provide audio description (AD) as a toggle in audio language settings and allow you to search by titles that include AD.

How do I implement audio description?

Audio description is only necessary when there are visual-only elements in a video that are not mentioned or described in the main audio track. With some foresight and planning, you can significantly minimize the need for third-party post-production audio description. 

Plan ahead (recommended approach)

Illustration of person watching a video and wearing headphones.Not all video content needs audio description to be added. By planning ahead, a video producer can script and create content that includes descriptions of meaningful visual elements and actions so that additional audio description isn’t needed. 

  • Have your subjects identify themselves and their surroundings within the script itself (instead of, or in addition to, showing text on screen). This allows the audience to clearly understand who is speaking.
  • If there are title cards or text visible on screen, include those words in the script or audio. 
  • If there is dense content in the video, such as data tables or visualizations, consider making accessible versions of that content available separately.

Do it yourself

If it's not possible to describe visual information within the script or audio, then you'll need to add narration of the visual-only elements, actions, or on-screen text. Some tips for adding AD: 

  • Explain the visual information only to the extent necessary for viewers to understand. Focus on describing what is seen, and not what is unseen, such as motivations or intentions. The job of the describer is to describe what is physically observable, not to provide the listener with personal assumptions or conclusions.
  • You don’t need to describe content which is meant to be decorative. 
  • Close your eyes and listen to your video. What information is missing? 

Third-Party Audio Description

Post-production AD services can be purchased from vendors. 3Play Media, a Harvard vendor often used for captioning, offers AD service using automated audio. With their standard $7/minute service, descriptions are fit into natural pauses in the video’s audio track. 3Play’s extended service, priced at $11/minute, inserts pauses in the video to make room for descriptions, as needed. 

Getting started with 3Play Media

Video Players that support audio description

One of the challenges with implementing audio description is player support. Most browsers and video players do not support the playing of description in the same way that they support captions. However, there are a few video players that do support audio description, including:

  • Able Player: a fully accessible cross-browser HTML5 media player that supports both audio and video. Able Player offers support for audio description as a separate video, or in a Web Video Timed Text (WebVTT) file read aloud by modern browsers.
  • Panopto: supports WebVTT files.
  • Kaltura: supports single MP4 files with multiple audio tracks, which can include AD.
  • Brightcovesupports multiple audio tracks as well.

The 3Play Plugin is a free tool that allows you to easily generate a simple embed code or hosted link for a video with audio description. The 3Play Plugin is customizable and compatible with most video players and publishing platforms, including learning management (LMS) systems.