Web Posted on: February 25, 1998
NEW DEVELOPMENTS IN WEB-BASED ACCESSIBLE MULTIMEDIA
David Bolnick, Ph.D.
Accessibility Program Manager Consumer Systems Division
Microsoft Corporation
Redmond, WA 98052-6399
voice: (206) 936-8342
e-mail: davebo@microsoft.com
Geoff Freed
Project Manager
Web Access Project
CPB/WGBH National Center for Accessible Media
125 Western Ave.
Foundation
Boston, MA 02134
voice/tty: 617 492-9258
fax: 617 782-2155
e-mail: geoff freed@wgbh.org
For millions of Americans, the World Wide Web is an exciting new tool for learning and communicating. For millions of graphics, audio, and video capabilities are out of reach. At least two organizations, the CPB/WGBH National Center for the problem of inaccessible Web-based multimedia.g to resolve National Center for Accessible Media (NCAM; CPB/WGBH http://www.wgbh.org/ncam), joined the global effort to helplower or remove accessibility barriers from the Web. NCAM is a research and development facility dedicated to the issues homes, workplaces, schools and communities. NCAM is the latest media access initiative of WGBH, Boston's public Descriptive Video Service in 1990. With a background in making the content of media accessible, NCAM's contributionhas focused largely, but not exclusively, on this aspect of Web access.Microsoft Corporation is committed to making its products and the World Wide Web accessible to all. Its Accessibility & developers and testers solely dedicated to this goal. The members of this team have four primary responsibilities: 1) drive good accessibility practices within Microsoft's product teams; 2) encourage good accessibility practices by thirdimprove accessibility; and 4) educate users on the ies to accessibility features in our products. A full review of thecurrent accessibility efforts at Microsoft can be found at: http://microsoft.com/enable/.multimedia more accessible to users who are deaf, hard of ed hearing, blind or visually impaired: NCAM's use of Apple'sAccessible Media Interchange (SAMI) format. nchronized
Movie and audio clips are becoming more and more prevalent on the World Wide Web. The inherent problem with this media is hard-of-hearing computer users. In order to make multimedia more accessible, NCAM has developed methods which applyand audio descriptions-- to the Web. gies-- closed captions NCAM has been experimenting with works best using QuickTime software from Apple. QuickTime 3.0 (due for release in early captions and descriptions to be created and added to a movie using either a Macintosh or PC. Previous versions of Macintosh platform. Whatever version of QuickTime is used, the end result may be played back on either aA QuickTime movie is made up of separate video and audio tracks. At least one multimedia player (MoviePlayer version2.1 or higher) allows the user to toggle the tracks on and off. Because they are discrete, a movie may have multipleby the user. A user can select the appropriate language ed track at the time of playback.In addition to video and audio tracks, multiple text tracks may be included with the clip. A text track becomes, for provide foreign-language subtitles or even as a search engine indexed by keywords. If the user views the movie clip caption track is open-- that is, it can't be turned off.
However, if the clip is downloaded and played locally usingoff, thus simulating closed captions. (Note: QuickTime 3.0 allows this toggling on either the Macintosh or PC; previous If the clip is downloaded and played using any other ntosh.) multimedia player, the captions remain open.A captioned movie clip, therefore, contains the normal video and audio tracks plus the additional text track. Unlike picture, captioned movie clips display the text track in a small window below the video (although QuickTime 3.0 allows experiments, NCAM was able to fit approximately 19 rows of text below a movie clip before running out of space on theof text at once may prove impractical as the viewer may have difficulty reading the captions and keeping up with the Sample captioned movie clips and step-by-step details of the captioning process may be found at edmovies.html.ston.com/wgbh/pages/ncam/currentprojects/caption
Not only is it possible to add text tracks to a QuickTime movie clip, it is also possible to add extra audio tracks-specifically, an audio description track, which increases a movie clip's accessibility for people who are blind orAudio descriptions of QuickTime clips are similar to those found on certain television programs or home videos. Briefthe pauses of the dialog. This narration makes it easier for blind or visually impaired users to follow the action of a using QuickTime's MoviePlayer 2.1 or greater, pasted into the movie. (QuickTime 3.0's MoviePlayer will add sound using will add sound using a Macintosh only.) Like captioned r QuickTime movies, the user may toggle the audio descriptionbeing used. To view several different examples of described movie clips, visit s.html.ton.com/wgbh/pages/ncam/currentprojects/captionedmovie
Instructions on creating described movie clips can be foundhere, as well.
While QuickTime captioning and description methods require authors to encode accessibility features into the multimedia Microsoft has developed a new accessibility authoring format and associated tools called the Synchronized Accessible Media media with externally stored and referenced caption or audio description content. Because SAMI is based on HTML, it can authoring. This also allows developers to easily add or point to captioning content for Web-based or offlinemultimedia, such as CD-ROM. SAMI files are text files, so they can be read by any operating system. Caption or description files can be stored and transmitted from the same location as the primary media or can be played in sync with codes and references are properly matched.long as the time information which corresponds to elapsed time in a multimedia source file, such as audio, video or animation. The source which synchronizes it with a SAMI file to render the captions or descriptions at the appropriate time. The user can toggle supports multiple languages as well as multiple user styles such as "Normal" or "Big Print" and "High Contrast." SAMI is will be available to the public in June of 1998. For more information about SAMI, visit the Microsoft Accessibility http://www.microsoft.com/enable/products/multimedia.htm.
Deaf and hard-of-hearing Web users are the immediate and obvious beneficiaries of captioned movie clips. However, the benefits extend beyond this audience. Those using computers which lack sound capability, for example, can view captioned Also, as many educators have already discovered, captions ly. used in conjunction with both audio and video can be aadults.e tool for improving reading skills of children and reference tool: some movie players (such as QuickTime and SAMI) have a "search" feature which allows the user to scaneasy to locate a specific spot in the movie clip. Depending on the software, this search function works even when a text Another useful feature of a captioned movie clip is the transcript which is generated as part of the captioningprocess. Displaying a link to the movie's transcript allows the user to read the text before deciding if it is worth the transcripts may be used by those who do not have any video-playback capability, as a partial substitute for the clip itself. For maximum accessibility, transcripts should always be used in conjunction with audio-only clips.beyond the primary audience of blind or visually impaired users. Preliminary research has shown that, in a broadcast environment, described movies or television programs can help reinforce concepts or vocabulary in classroom situations. The importantly, a Web-based movie clip is not limited to being played only in real-time. That is, the clip may be stopped, and/or video tracks may be paused while other tracks continue to play. For example, during a clip that deals with a audio-description track delivers an in-depth explanation of the equation displayed on the screen. When applied toscience or math multimedia, this technique allows for greater understanding of concepts that might otherwise go by the Adding captions or descriptions to Web-based multimedia has one further potential benefit-- preservation of bandwidth. providers utilize byte-intensive multimedia, access for all users will become slower and slower. As accessibilityrequest and download specific media components. That is, a blind user will be able to ignore the video portion of aonly, thus avoiding the transfer of large amounts of unneeded data. Likewise, a deaf user may only want to download the This paper has only briefly described some of the work being conducted by NCAM and Microsoft. Both will continue to multimedia. For more information on access technology, visit http://microsoft.com/enable/. NCAM on the Web at http://www.wgbh.org/ncam, or Micros