Web checklist

Captions are provided for pre-recorded multimedia.

The purpose of this checkpoint is to allow deaf people and people with hearing impairments to get access to the audio portion of multimedia. Captions are text on the screen that identify speakers, dialogue, music, and sound effects. There are two types of captions. Open captions are "burned" into the image, similar to subtitles, and cannot be turned off. Closed captions are a separate data stream that is synchronized with the multimedia. The user can turn these captions on or off.

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Compliance with this checkpoint requires at least one of the following techniques to be met.

1. Open captions: Provide open (always visible) captions.
2. Closed captions: Provide closed captions.

Examples for General developers

1. Open captions: Provide open (always visible) captions.

To comply with this technique, all of the following examples must be implemented.

Example 1

Open captions are embedded into the multimedia presentation. The captions are "burned into" the video image, and cannot be turned off by users. The advantage of this type of captioning is that additional software or technology is not needed to view the captions. The open captions can be placed on any video stream, regardless of whether or not the technology supports closed captioning. The disadvantage of open captions is that users do not have the ability to turn them off, so users without visual or hearing impairments will see the dialogue in addition to hearing it from the audio track.

An example of captions embedded into the video stream is shown in the screen shot below. The user does not have the option to turn the captions off. They run automatically when the video is played.

For additional information, refer to WCAG 2.0 examples for providing open (always visible) captions (link resides outside of ibm.com).

2. Closed captions: Provide closed captions.

To comply with this technique, all of the following examples must be implemented.

Example 2

Closed captions are usually created as a stream of data that runs in parallel with the multimedia. A user has the ability to turn on or off these captions. Closed captions must be provided using any readily available media format that has a video player that is free of charge and supports closed captioning.

An example of a multimedia presentation that contains captions is shown in the screen shot below. Notice the "cc" button at the bottom of the screen, which allows the user to turn the captions on or off:

SMIL 1.0 and SMIL 2.0 are used to create closed captions for a variety of different media players. For a detailed list of players that support SMIL 1.0 and SMIL 2.0, refer to the W3C Synchronized Multimedia (link resides outside of ibm.com) page.

For additional information, refer to WCAG 2.0 examples for providing closed captions (link resides outside of ibm.com).

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Examples for Flash developers

For techniques that have no Flash-specific examples, refer to the General examples section for guidance.

1. Open captions: Provide open (always visible) captions.

There are no Flash specific examples for implementing this technique.

2. Closed captions: Provide closed captions.

Example 3

For movie clips and other meaningful Flash objects, make sure that there is a full description of what is happening in the clip. Do not rely on subtitles only, because these do not adequately describe all of the action on the screen. In addition, provide audio playback controls for users to control the speed, volume, and navigation of audio clips. Please review Checkpoint 2.1a Keyboard Functionality to ensure that all provided controls are keyboard accessible.

Developers using Flash CS3 Pro and including captions should use the FLVPlaybackCaptioning component. This component allows developers to easily add captions to video in Flash. The FLVPlaybackCaptioning component enables captioning for the FLVPlayback component. The FLVPlaybackCaptioning component downloads a World Wide Web Consortium (W3C) Timed Text XML file (DFXP) and applies those captions to an FLVPlayback component to which this component is partnered.

More information on utilizing the FLVPlaybackCaptioning component can be found on the Adobe Flash Accessibility Design Guidelines website for Captions (link resides outside of ibm.com).

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The techniques above are required; the following techniques are recommended to enhance accessibility:

1. Ensure your captions adhere to the standard captioning guidelines.

Captions should adhere to the following guidelines:

• Provide information at the beginning of the movie (or with the link to the movie) that describes the type of captioning used (open or closed), and in what language the captions are provided.
• Add captions to the bottom of the movie or object. Ensure that the captions do not block out any important action in the movie. The captions should enhance the movie, not detract from it.
• Ensure that the captions do not take up more than three lines at one time.
• Follow sentence capitalization and proper punctuation standards, and use italics to emphasize words or sentences.
• All spoken text should be included in the captions, and the captions should be synchronized with the video and spoken text.
• Use high contrasting colors and easy to read, sans-serif fonts for the captions.
• Put the speaker name before the caption each time a speaker changes.
• Include information about background sounds, music, and other relevant information in parentheses. However, do not describe someone's physical appearance or race unless those aspects are germane to the understanding of the video material.

2. Provide a note saying "No sound is used in this clip" for video-only clips. Use SMIL 1.0 to provide captions for all languages for which there are audio tracks.

3. Use SMIL 2.0 to provide captions for all languages for which there are audio tracks.

4. Provide audio descriptions in multiple languages in SMIL 1.0.

5. Provide audio descriptions in multiple languages in SMIL 2.0.

6. Provide a pop-up text window for a short audio presentation.

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The following test tools and techniques are required to test this checkpoint.

1. Test tools
2. Required accessibility verification test techniques

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