Multimedia Presentations

General comments

Web developers are frequently using multimedia technologies, in addition to images and programmed non-text elements (see Rule a, Rule l and Rule m). Video requires captioning for the audio portion and an audio description of visual information. Captioning must be synchronized with the audio.

If the Web site offers an audio file, a text equivalent, such as a transcript, must be provided. Similarly, a (silent) Web slide show does not require an audio description, but does require a text alternative for graphic elements.

Helpful Hints

Generally, multimedia presentations require users to rely on more than one sense, such as combining a reliance on hearing and vision, to understand the content.  To ensure that multimedia is accessible to users with visual impairments, Web designers should include audio descriptions of video information in all cases, except where the video portion of a presentation is unimportant to understanding it.  For example, if a multimedia presentation includes video of a cook stirring ingredients, along with text instructions that say "Next, stir the ingredients," it is not necessary to include a redundant audio description of the stirring.  Audio descriptions are usually selectable, so that a non-disabled user can choose not to turn them on.

To ensure that multimedia presentations are accessible to users with hearing impairments, text captioning should be provided to convey in text any important audio information.  Such captioning can be included as part of the video track of the presentation, and can also be selectable.

Finally, Web designers should be aware that because multimedia content cannot be rendered using HTML, plug-ins or other applications will be necessary in order to view multimedia content.  Because plug-ins are really separate computer software applications created by third-party manufacturers, the accessibility requirements extend beyond those aimed purely at web pages.  See 36 C.F.R. §1194.21.

Department of Commerce Web Advisory Council (WAC)
U.S. Department of Commerce

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Page last updated October 12, 2010