On this page:

SM6: Providing audio description in SMIL 1.0

Applicability

Applies whenever SMIL 1.0 player is available

This technique relates to:

Success Criterion 1.2.3 (Audio Description or Media Alternative (Prerecorded))
- How to Meet 1.2.3 (Audio Description or Media Alternative (Prerecorded))
- Understanding Success Criterion 1.2.3 (Audio Description or Media Alternative (Prerecorded))
Success Criterion 1.2.5 (Audio Description (Prerecorded))
- How to Meet 1.2.5 (Audio Description (Prerecorded))
- Understanding Success Criterion 1.2.5 (Audio Description (Prerecorded))

Description

The objective of this technique is to provide a way for people who are blind or otherwise have trouble seeing the video in audio-visual material to be able to access the material. With this technique a description of the video is provided via audio description that will fit into the gaps in the dialogue in the audio-visual material.

Examples

Example 1: SMIL 1.0 audio description sample for QuickTime player

Example Code:

   
<?xml version="1.0" encoding="UTF-8"?>
<smil xmlns:qt="http://www.apple.com/quicktime/resources/smilextensions" 
  xmlns="http://www.w3.org/TR/REC-smil" qt:time-slider="true">
  <head>
    <layout>
      <root-layout background-color="black" height="266" width="320"/>
      <region id="videoregion" background-color="black" top="26" left="0" 
      height="144" width="320"/>
    </layout>
  </head>
  <body>
    <par>
      <video dur="0:01:20.00" region="videoregion" src="salesdemo.mov" 
      alt="Sales Demo"/>
      <audio dur="0:01:20.00" src="salesdemo_ad.mp3" 
      alt="Sales Demo Audio Description"/>
    </par>
  </body>
</smil>

Example 2: SMIL 1.0 audio description sample for RealTime player

Example Code:

 
<?xml version="1.0" encoding="UTF-8"?>
<smil xmlns="http://www.w3.org/TR/REC-smil">
  <head>
    <layout>
      <root-layout background-color="black" height="266" width="320"/>
      <region id="videoregion" background-color="black" top="26" left="0" 
      height="144" width="320"/>
    </layout>
  </head>
  <body>
    <par>
      <video src="salesdemo.mov" region="videoregion" title="Sales Demo" 
      alt="Sales Demo"/>
      <audio src="salesdemo_ad.mp3" title="audio description" 
      alt="Sales Demo Audio Description"/>
    </par>
  </body>
</smil>

Resources

Resources are for information purposes only, no endorsement implied.

Tests

Procedure

Find method for turning on audio description from content/player (unless it is always played by default)
Play file with audio description
Check whether audio description is played

Expected Results

#3 is true

If this is a sufficient technique for a success criterion, failing this test procedure does not necessarily mean that the success criterion has not been satisfied in some other way, only that this technique has not been successfully implemented and can not be used to claim conformance.

Techniques are Informative

Techniques are informative—that means they are not required. The basis for determining conformance to WCAG 2.0 is the success criteria from the WCAG 2.0 standard—not the techniques. For important information about techniques, please see the Understanding Techniques for WCAG Success Criteria section of Understanding WCAG 2.0.

This Web page is part of Techniques and Failures for Web Content Accessibility Guidelines 2.0. The entire document is also available as a single HTML file. See the The WCAG 2.0 Documents for an explanation of how this document fits in with other Web Content Accessibility Guidelines (WCAG) 2.0 documents. To send public comments, please follow the Instructions for Commenting on WCAG 2.0 Documents.