You are tasked with developing an educational Web site that includes podcasts, video, and Flash presentations while complying with Section 508. (http://www.access-board.gov/508.htm). Think “details” because government funding of this Web site is at stake. What follows is a rough checklist of considerations when incorporating multimedia into your site.
The biggest challenges in building such a site come in meeting the needs of all potential users.
Keep in mind: users might include individuals who have special needs in the following broad categories:
- physical/motor limitations
In some cases, multimedia may provide a good solution to some users while closing a door on other users. While a podcast may be highly accessible content for a user with poor vision, a hearing-impaired user loses access. The interactive Flash presentation may contain text equivalents to its audio, but a user with limited motor ability may not be able to use a mouse to click on buttons in the changing display. Alternatives must be incorporated into the multimedia or alongside it so that all users may benefit from the content.
A Rough Checklist of Media and Their Additional Requirements for Accessibility
Audio (podcasts, mp3 files, etc.)
- Include a good description of the content
- Include additional HTML pages with text transcripts or a separate text file link
Video (vodcasts, YouTube embeds, etc.)
- As with audio, provide text transcripts
- Consider all audio elements including text, background sounds/music that might be relevant to the message of the video
- As with other accessibility issues, consider carefully what the user needs from the content, and be sure to provide it in alternative formats that are accessible
- Descriptions of action that is relevant to the message of the video must be provided
- Allow user control of playback; therefore, do not incorporate autoplay
- Provide both audio and text descriptions for the video (Visual information necessary to understand the content may not be natively present in the audio track)
- The same considerations for audio and video apply
- Equivalent alternatives for multimedia must be synchronized with the presentation
- For any video content, use captioning — either open or closed
- Closed captioning: user controls whether it is on or off; it exists as a separate data stream from the time-based content and may be archived an searchable in a way that audio is not
- Open captioning: captions are part of the time-based stream (i.e. video-rendered text) and as such are not text-searchable and are subject to loss of quality (eg. during compression or resampling of resolution)
- Visual information necessary to understand the content must be described in an audio file that is synchronized with the video
- Be aware of flickering that might occur in the video of a frequency between 2Hz and 55Hz, as they trigger some seizure disorders, and can distract users with some cognitive disabilities (this applies to all other Web elements as well); any media that must be posted containing such content must be preceded with a warning and must be controllable (again, no autostart) by the user
- Make the Flash content natively accessible to the screen reader user whenever possible
- Make the Flash content self-voicing with on/off control
Provide non-Flash alternatives to the content whenever possible; this content can utilize any of a variety of techniques that are accessible and may indeed need to make use of a variety of media in order to claim adequacy as an alternative to the Flash content
- Make up for areas of Flash content that fail to meet Section 508 standards; although Flash has the potential to provide highly accessible content, it is rarely designed to meet all accessibility standards at the same time
- When Flash content contains audio or video, apply the same considerations as mentioned in the sections above on audio and video content
Resources and References
- Section 508 Guide
- HowTo .gov: a Resource for Agencies
- WebAIM Flash Techniques
- YouTube Closed Captioning explained/illustrated
- Open vs. Closed Captioning
- User testing – nothing beats the perspective of users who need the different kinds of accessibility your site should provide
- Your head …
Remember that making content accessible to all users requires that you think about content in a holistic way: What is its context? What is the message the content conveys? What parts of the content are accessible or not accessible? … and to whom? Asking these questions early and often will help you meet the needs of the broadest possible audience.
This is pretty basic stuff, but here’s an infographic from the folks at WebAIM. A text-only version of the WebAccessibility for Designers infographic is on the WebAIM site.