Techniques for WCAG 2.0

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# G87: Providing closed captions

## Applicability

Any audiovideo technology where there are user agents that support closed captions.

This technique relates to:

- Success Criterion 1.2.2 (Captions (Prerecorded))
  - How to Meet 1.2.2 (Captions (Prerecorded))
  - Understanding Success Criterion 1.2.2 (Captions (Prerecorded))

## Description

The objective of this technique is to provide a way for people who have hearing impairments or otherwise have trouble hearing the dialogue in synchronized media material to be able to view the material and see the dialogue and sounds - without requiring people who are not deaf to watch the captions. With this technique all of the dialogue and important sounds are embedded as text in a fashion that causes the text not to be visible unless the user requests it. As a result they are visible only when needed. This requires special support for captioning in the user agent.

NOTE: Captions should not be confused with subtitles. Subtitles provide text of only the dialogue and do not include important sounds.

## Examples

### Example 1

Example 1: In order to ensure that users who are deaf can use their interactive educational materials, the college provides captions and instructions for turning on captions for all of their audio interactive educational programs.

Example 2: The online movies at a media outlet all include captions and are provided in a format that allows embedding of closed captions.

Example 3: Special caption files including synchronization information are provided for an existing movie. Players are available that can play the captions in a separate window on screen, synchronized with the movie window.

Example 4: A video of a local news event has captions provided that can be played over the video or in a separate window depending on the player used.

## Resources

Resources are for information purposes only, no endorsement implied.

Guides to Captioning

- Captioning Key: Guidelines and Preferred Techniques

- Best Practices in Online Captioning

SMIL

- Synchronized Multimedia Integration Language (SMIL) 1.0

- Synchronized Multimedia Integration Language (SMIL 2.0)

- Accessibility Features of SMIL

- NCAM Rich Media Accessibility, Accessible SMIL Templates

Other Captioning

- National Center for Accessible Media

- Quicktime Captioning Tutorial

- RealPlayer Captioning Tutorial

- Windows Media Player Captioning Tutorial

## Related Techniques

- G93: Providing open (always visible) captions
- SM11: Providing captions through synchronized text streams in SMIL 1.0
- SM12: Providing captions through synchronized text streams in SMIL 2.0

## Tests

### Procedure

1. Turn on the closed caption feature of the media player

2. View the synchronized media content

3. Check that captions (of all dialogue and important sounds) are visible

### Expected Results

- #3 is true

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