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Ergonomic, split keyboard chair combination. Television is one of the most amazing technological inventions of our time. Its popularity has only grown, and we are now able to view thousands of programs and movies in the comfort of our own living rooms. As a media format, television satisfies our natural quest for information, entertainment and communication. It's no surprise that we would so quickly desire to bring audio and video features to the Web.
For people with sensory disabilities, however, the content in television programs is often inaccessible. People who are blind can likely hear the audio, but they may miss certain visual elements that put the audio into context. On the other hand, Deaf people can watch the movies, but they will not hear any conversations or other audio cues.
The traditional television community has embraced making its media accessible to people with disabilities. Many programs and movie releases offer closed captioning, which is used to display captioned text that is synchronized with the audio track of the presentation. Open captioning is sometimes provided as an alternative. It is similar to closed captioning, but the captioned text is part of the video itself, for example, subtitling.
Some television programs and movies offer Descriptive Video Service (DVS), a standard developed by the Media Access Group at WGBH in Boston, Massachusetts. Designed for people who are blind or who have low vision, DVS presents a separate audio track that can be activated by the viewer which verbally describes the activity, events, and other pertinent features on the screen.
The Web community, unfortunately, has been slow to embrace these concepts. Streaming media, and downloadable media files, are everywhere on the Internet. However, very few mirror the accessibility features that traditional television offers.
According to WebAIM.org, television closed captioning is used by 28 million Americans who are Deaf or hard of hearing, and millions more use it in the office, classroom, or in noisy environments like restaurants and airports. As our nation's population ages, more people will develop hearing or visual disabilities, and there will be a growing need for accessible media.
Including audio and video components on a Web site can be useful to supplement text-based information, for example, to provide training videos or demonstrations along with documentation, or for coverage of speeches, meetings, events, etc., along with transcripts or textual descriptions. When made accessible through the use of captioning techniques, audio and video components can greatly enhance the content on a Web site.
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, Part 1194.22, Paragraph (m)]
Equivalent alternatives for any multimedia presentation shall be synchronized with the presentation. [Section 508, Part 1194.22, Paragraph (b)]
Pages shall be designed to avoid causing the screen to flicker with a frequency greater than 2 Hz and lower than 55 Hz. [Section 508, Part 1194.22, Paragraph (j)]
Until user agents allow users to control flickering, avoid causing the screen to flicker. [W3C WCAG 1.0, Checkpoint 7.1 Priority 1]
Provide a text equivalent for every non-text element (e.g., via "alt", "longdesc", or in element content). This includes: images, graphical representations of text (including symbols), image map regions, animations (e.g., animated GIFs), applets and programmatic objects, ASCII art, frames, scripts, images used as list bullets, spacers, graphical buttons, sounds (played with or without user interaction), stand-alone audio files, audio tracks of video, and video. [W3C WCAG 1.0, Checkpoint 1.1 Priority 1]
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. [W3C WCAG 1.0, Checkpoint 1.3 Priority 1]
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. [W3C WCAG 1.0, Checkpoint 1.4 Priority 1]
On the Web, synchronized, equivalent captions should be provided any time audio content is present. If the multimedia file is produced by a television studio, open or closed captioning can be done during the editing of the video. As an alternative, a caption track can be created that is activated by multimedia players like Quicktime, RealPlayer, and Windows Media Player.
The only drawback is that Web video currently does not have a standard file format, and there are two different methods for providing the caption track.
One method involves a World Wide Web (W3C) language called SMIL (pronounced "smile") that Quicktime, RealPlayer, and some other media players use. SMIL, or Synchronized Multimedia Integration Language, is a markup technique used to author multimedia presentations that integrate streaming audio and video with images, text and other content. Using SMIL, different media components are divided into separate files and streams, which are then displayed together on a user's computer as if they were a single multimedia stream.
The second method is available from Microsoft which has its own version of the language for Windows Media Player, called Synchronized Accessible Media Interchange, or SAMI. This is similar to SMIL, but it is proprietary and is only supported by Microsoft products such as Windows Media Player.
With either language, the general concept is that you have a video file, and an associated text file that contains the captioning. Then, using the application language, you code in the time segments to synchronize the caption track with the video.
Instead of trying to code the captioning track yourself, use MAGpie 2.01. This free tool creates closed captions and audio descriptions. Authors can add captions and audio descriptions to QuickTime, Real, or Windows Media Player. The application, and complete instructions, can be downloaded from the Web site for the National Center for Accessible Media.
Transcripts are always helpful in addition to any captioning you offer. Transcripts provide an easy way for people to skim and reference the information in an audio or video file, without having to listen to or watch the entire clip. Always include a transcript with any audio or video media on your page.
For high-bandwidth content, offer a low-bandwidth option. Additionally, include more than one media format, and preferably, a non-proprietary format as well. For example, include your video in a proprietary format like Windows Media Player, along with a standard MPEG. If preservation of the content is important, then include multiple proprietary formats; for example, offer your video in both Windows Media Player and Quicktime. The more options you provide, the easier it is for visitors to your site to view the content using whatever default viewer is installed on their computer or device.
If you include an audio or video file in a proprietary format such as Quicktime, RealPlayer or Windows Media Player, include a link on the same page to the appropriate player. For example:
Some features on this page require the free
RealPlayer plug-in for viewing.
Some features on this page require the free
Windows Media Player plug-in for viewing.
Some features on this page require the free
Apple Quicktime Media Player plug-in for viewing.
A generic audio or video icon can be used for non-proprietary file formats such as .WAV, .MP3, or .MPG. For non-streaming media, always indicate the file size and format. For example:
Audio clip (2,607K WAV)
Video clip (5,848K MPEG-1)
If you offer video files that are closed captioned (rather than open captioned), include a way to indicate this to the user. The standard "CC" symbol from WGBH is appropriate to display on the page:
Media on this page is closed-captioned.
