Put Multi- in Your Media!
Video, audio, and animation are important resources for many Web developers, especially those working on news, entertainment, and online learning. The ability to enrich a Web site with multimedia elements enables developers to provide the "equivalent alternatives" that we have emphasized throughout this book. These same elements, however, can pose formidable obstacles for people who are blind or visually impaired, people who are deaf or hard of hearing, or people with other challenges (such as cognitive impairments and learning disabilities) if they are not integrated into the site through accessible means.
If you are worried that making your Web sites more accessible for people with disabilities means giving up multimedia, you can relax. It's simply not true; in fact, the opposite may be closer to the truth. In some cases, the best way to enhance accessibility may be to use more media! Think about it for a minute using more ways to deliver information means there are more ways for users to get to the information on your site. The key is to use these options as the alternatives they are and not to rely on a single sensory capability to receive important information. Used in the right way, multimedia is a critical resource for accessibility!
In this chapter, we talk about strategies and techniques for making multimedia accessible. We address the requirements for transcribing audio files and captioning the soundtrack in video presentations; we also explain how to add synchronized audio descriptions to video clips. We talk briefly about simple animations such as those created with animated GIF images, then move on to the thornier accessibility barriers posed by Flash movies created with Flash 5.0 and earlier versions, and we show you some workarounds. Let's dive in.
HTML Elements and Attributes Addressed in This Chapter 
 This chapter also contains references to elements and attributes of other markup languages, including Synchronized Multimedia Integration Language (SMIL), Extensible Markup Language (XML), and Synchronized Accessible Media Interchange (SAMI).
<object>, <embed>, <noembed>
param, name, value
Accessibility Checkpoints and Standards Addressed in This Chapter
Web Content Accessibility Guidelines 1.0 Checkpoints
1.1. Provide a text equivalent for every non-text element. [Priority 1]
1.3. Until user agents can automatically read aloud the text equivalent of a visual track, provide an auditory description of the important information of the visual track of a multimedia presentation. [Priority 1]
1.4. For any time-based multimedia presentation (e.g., a movie or animation), synchronize equivalent alternatives (e.g., captions or auditory descriptions of the visual track) with the presentation. [Priority 1]
7.1. Until user agents allow users to control flickering, avoid causing the screen to flicker. [Priority 1]
8.1. Make programmatic elements such as scripts and applets directly accessible or compatible with assistive technologies. [Priority 1 if functionality is important and not presented elsewhere, otherwise Priority 2]
9.3. For scripts, specify logical event handlers rather than device-dependent event handlers. [Priority 2]
14.2. Supplement text with graphic or auditory presentations where they will facilitate comprehension of the page. [Priority 3]
Section 508 Standards, §1194.22
(b) Equivalent alternatives for any multimedia presentation shall be synchronized with the presentation.
(j) Pages shall be designed to avoid causing the screen to flicker with a frequency greater than 2 Hz and lower than 55 Hz.
(m) When a Web page requires that an applet, plug-in or other application be present on the client system to interpret page content, the page must provide a link to a plug-in or applet that complies with 1194.21(a) through (l) [Section 508 Software Accessibility Standards].