Guideline 2
Provide access to multimedia presentations for users with sensory disabilities.

Audio description provides access to multimedia for people who are blind or visually impaired by adding narration which describes the visuals, including action, scene changes, graphics, and on-screen text. Closed captions added to multimedia presentations ensure that the audio components of the presentation are accessible to individuals who are deaf or hard-of-hearing. Both audio description and closed captions are useful learning tools for a wide array of users in addition to their originally intended audiences. Closed captions can provide a powerful search tool, allowing users to search the caption text to locate a specific video, or an exact point in a video. . They are also useful for people learning to read or learning English as a second language. Audio description can assist students with learning disabilities by reinforcing through audio what the user is watching on the screen.

There are several formats that support the inclusion of audio description and closed captions in digital multimedia presentations - Synchronized Multimedia Integration Language (SMIL), Synchronized Accessible Media Interchange (SAMI), and QuickTime. In all three formats, users can choose to view closed captions when needed, once the developer has provided them. QuickTime users can also turn audio description on and off. SMIL 1.0 does not allow users to turn audio description on and off, but this feature is expected to be included in SMIL 2.0, due to be released in December 2000. SMIL was developed by the World Wide Web Consortium (W3C), an international industry consortium that publishes protocols for the Web. SMIL multimedia presentations are made up of elements - sound, pictures, text - which are stored separately and then synchronized as the clip is played. SMIL formatted multimedia can be delivered via the internet and locally via a CD or DVD-ROM. One common tool for playing SMIL presentations is the RealPlayer (G2 or later versions) from RealNetworks. Visit the W3C's Synchronized Multimedia page at www.w3.org/AudioVideo for a complete list of tools.

SAMI is a Microsoft-authored public specification that allows closed captions to be played in the Windows Media Player. At the time of this writing, SAMI does not support audio description. When the Windows Media Player is used in a separate window, users can turn closed captions on and off using a menu selection. However, when the Media Player is embedded in another application, such as in Encarta, the developer must provide this feature in the application's interface.

In QuickTime, captions are added as a text track, and descriptions are recorded onto a separate audio track which can be played in addition to the program audio and video tracks. For the user to toggle the description and caption tracks on and off, the Pro version of the QuickTime Player must be installed.

A free tool, Media Access Generator (MAGpie), is available to assist software developers in adding accessibility to digital multimedia. MAGpie can be used to create and add captions in the three formats described above, and to add audio description tracks to SMIL presentations. MAGpie is available from:

The CPB/WGBH National Center for Accessible Media (NCAM)
http://ncam.wgbh.org/webaccess/magpie

Samples of accessible multimedia delivered in the three formats mentioned above, including accessible clips and source code, are available from www.ncam.org/webaccess by following the link to "Captioning and Description on the Web."

Checkpoint 2.1
Add audio description to multimedia presentations.
Priority 1
Visual images are often used to convey educational content. Without audio description, students who are blind are at a distinct disadvantage as they have to depend on teachers or classmates to obtain the visual information. Depending on the subject matter, some students may be reluctant to ask others to describe the visuals to them. The techniques below show how to add audio description to three popular multimedia formats.

Creating meaningful audio description requires specialized training in how best to convey visual images verbally. The narration should be carefully crafted to fit precisely into the natural pauses in the program dialog. It may be best to contact one of the resources listed in Appendix 3, Closed Captioning and Audio Description Resources, since these organizations have expertise in providing audio description for an array of media (broadcast television, movies on video, and multimedia). Check with service providers to be sure they can deliver the final product in the preferred file or video tape format.

Technique 2.1.1
Add audio description to QuickTime movies.
In a QuickTime movie, sound and video are contained in separate tracks. Sound tracks to accommodate different languages or audio descriptions can be added easily. Keep in mind that the audio descriptions will be inserted only into the pauses in the movie's dialog. NCAM's method of adding and manipulating sound tracks is based on instructions in "QuickTime and Movie Player Pro 3" by Judith L. Stern and Robert A. Lettieri. (Peachpit Press, 1998) The method applies to QuickTime Player for both Macintosh and Windows, with slight variations in keyboard commands.

1. Open the QuickTime Player and the clip you want to describe. Choose Get Info from the Movie menu, or press Command-I on Macintosh, or Control-I on Windows.

2. Using the sound-recording software of your choice, record or import and edit the first description you want to incorporate into the movie clip. Select, or highlight, the entire sound clip (or the portion you want to insert into the movie clip). Copy the sound clip onto the clipboard.

3. In the QuickTime Player, move the slider to the end of the pause where the description will go. Hold down the Shift key and move the slider backwards until you reach the beginning of this pause. This selects the segment of the movie clip which will receive the audio description.

4. On Macintosh, hold down the Option key, open the Edit menu, and choose Add. On Windows, hold down Control and Alt, open the Edit menu, and choose Add. The description will be added to the movie as a new sound track. In the Get Info window, click on the left drop-down menu. You will see that "Sound Track 2" is now one of the menu choices.

5. Play the clip to hear the narration you've just inserted.

6. Repeat steps 2-5 to insert subsequent audio descriptions. Always remember to select the segment which will contain the audio description by first going to the end of that segment and then moving the slider backwards to the beginning. If you do not, the QuickTime Player will add the description to the end of the segment, rather than the beginning.

Technique 2.1.2
Add audio description to SMIL formatted multimedia.
The easiest solution for adding audio description to SMIL presentations is to use the Media Access Generator (MAGpie). MAGpie is available from http://ncam.wgbh.org/webaccess/magpie and includes a comprehensive set of instructions on how to add audio description to SMIL presentations.

Checkpoint 2.2
Add closed captions to multimedia presentations.
Priority 1
The inclusion of closed captions in educational multimedia presentations dictates whether the student who is deaf or hard-of-hearing is an active learner or passive learner when the media is used in class. While a good percentage of the presentation may be visual, any audio that compliments the visual information must be captioned.

Providing closed captions is significantly different from providing a text transcript of the audio portion of the presentation. For example, special techniques are used to identify speakers and sound effects. For this reason, it may be best to contact one of the resources listed in Appendix 3, Captioning and Audio Description Resources.

Technique 2.2.1
Add closed captions to digital multimedia
The Media Access Generator (MAGpie) allows developers to add closed captions to digital multimedia delivered in QuickTime, SMIL and SAMI. MAGpie is available from http://ncam.wgbh.org/webaccess/magpie and includes comprehensive instructions for adding closed captions in all three multimedia formats.