Creating Audio Description of Visual Information

Terminology

Audio description is called “described video” in some areas, such as Canada.

This page uses “described video” in some places as a shortened form of “a video that includes audio description of the visual information”.

Scope

This page addresses common types of videos designed for the web such as instructional videos, training videos, recordings of presentations, and such.

It does not address all the issues around full-feature movies, television shows, and such.

What Description to Provide for My Video?

Content and Timing Considerations

First, figure out these issues about your video content and timing:

Instead of the speaker saying: The speaker can say:
As you can see on this chart, sales increased significantly from the first quarter to the second quarter. This chart shows that sales increased significantly, from 1 million in the first quarter to 1.3 million in the second quarter.
Whip the mixture until it looks like this. Whip the mixture until the oil, vinegar, and spices are well combined.
Attach this to the green end. Attach the small ring to the green end, which is the larger end.

Use the information from above to answer the following questions in order to determine how to provide audio description for your video.

For New Videos:

  • Can the speakers describe the visual information in the main audio?
    • If yes, provide integrated description. No separate audio description is needed.
    • If no, can you smoothly provide enough space in the main audio for the description? And will you use a media player that supports a separate audio track for the description?
      • If yes, provide description in a separate audio file, or provide a separate described video.
      • If no, provide a separate described video.

For Existing Videos:

  • Is there enough space in the main audio for the description? And will you use a media player that supports a separate audio track for the description?
    • If yes, provide description in a separate audio file, or provide a separate described video.
    • If no, provide a separate described video.

Planning New Videos

Integrated Description

For many videos, the best way to handle audio description is not to need it at all — that is, all the visual information that users need to understand the content is integrated in the main audio. When planned in advance, this is fairly simple for many types of videos on the web, such as presentations and instructional videos. (Example above under Content and Timing Considerations.)

If you develop your video with integrated description, you don’t need to bother with any of the other timing or developing options on this page! You’re done.

Timing for Description

For some types of videos, the description of the visual information cannot be smoothly handled by the speakers and narrator in the main video, because it would make the default video too much longer or more cumbersome. In that case, you will have the description separate. You can make the described version smoother by planning for the description.

Where the description is fairly short, plan space in the audio for the description.

Where the description is longer that you want to leave space in the main audio, you can record extra time in the scene to accommodate the description without having to pause the scene. That is, the same scene is shown with a little longer at the beginning or the end of it. For example:

Narration Main Video Scene Duration Described Video Scene Duration Description
Captions are also handy for people who want to watch video in loud environments. 3 seconds 7 seconds A man is watching the captioned video with a group of people chatting away next to him.
Or where you need to be very, very quiet. 2 seconds 5 seconds Turns out that they are in a library. The group is shushed by the librarian.

An example of this is the Web Accessibility Perspectives: Video Captions video. The main video is 48 seconds long. The described version is 1 minute and 18 seconds long, yet there are no pauses in the visual aspect of the video.

Developing Integrated Description

The process to develop a video with integrated description is basically:

  1. When writing the script, make sure all relevant visual information is included. See Tips for Describing – Writing below.

Before finalizing the video, check to confirm that all relevant visual information is covered in the audio.

That’s it! You don’t need to bother with any of the developing options below.

Developing Description in a Separate Audio File Only

This requires skills and software for audio recording and audio editing.

(Per above, this approach only works when there enough space in the main audio for the description, and the media player supports a separate audio track for the description.)

The process to develop description in a separate audio file is basically:

  1. Write out the descriptions. See Tips for Describing – Writing below.
  2. Record the descriptions. See Tips for Describing - Recording below.
  3. Provide synching data for the audio file … @@…
  4. Provide a caption file of the description. Example VTT file of audio description
  5. Ensure the files are integrated with the player on the web page.

Developing a Separate Described Video

If Descriptions Fit in Spaces

If the descriptions fit in the spaces (as described in @@ above), you need to develop a separate audio file. This requires skills and software for audio recording and video editing. Depending on the player that you are using, you might need video software to regenerate the video.

The process to develop a separate audio file is basically:

  1. Write out the descriptions. See Tips for Describing - Writing below.
  2. Record the descriptions. See Tips for Describing - Recording below.
  3. Create a new audio file by combining the original audio and the new description audio. See Tips for Describing – Combining Audio Files below.
  4. Provide the file(s):
    • If your player uses separate video and audio tracks,
      you’re done.
    • If your player uses a single video file that includes the audio,
      generate the new described video with the audio file that you just created.

(Make sure on the web page where the video is available, the Audio Described version uses the correct version that you just created.)

If Descriptions Do Not Fit in Spaces

If all the descriptions do not fit in the spaces (as described in @@ above), you’ll need to develop a separate audio file and also edit the visual track. This requires skills and software for audio recording, audio editing, and video editing.

The process to develop a separate audio file and edit the visual track is basically:

  1. Write out the descriptions. See Tips for Describing - Writing below.
  2. Record the descriptions. See Tips for Describing - Recording below.
  3. Create a new audio file by combining the original audio and the new description audio. See Tips for Describing – Combining Audio Files below.
  4. Create a new video:
    • If you have source video with longer scenes (as described in @@ above), recut the scenes longer to fill in the visual space where you need to accommodate the time for the description.
    • If not or you’re adding to an existing video, you will need to leave a static image in the video while the description is playing in the audio. (For example, this video pauses at 00:00 for the audio description.)

(Make sure on the web page where the video is available, the Audio Described version uses the correct version that you just created.)

Other Options

{include or not based on decisions in Open Issues, Coverage of Options.}

… description in text file…

… Another option is to provide functionality for the video to pause for the description. This is not suggested in most cases because it requires extra coding and provides a less-than-optimum user experience.

Tips

Tips For Writing Descriptions

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Tips for Recording Descriptions

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Tips for Combining Audio Files

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