Techniques for WCAG 2.0

On this page:

-

# SM7: Providing audio description in SMIL 2.0

## Applicability

Applies whenever SMIL 2.0 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))

## 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 2.0 audio description sample for RealMedia player

Example Code:

    <smil xmlns="http://www.w3.org/2001/SMIL20/Language">
      <head>
        <layout>
          <root-layout backgroundColor="black" height="266" width="320"/>
          <region id="video" backgroundColor="black" top="26" left="0"
          height="144" width="320"/>
        </layout>
      </head>
      <body>
        <par>
          <video src="salesdemo.mpg" region="video" title="Sales Demo"
          alt="Sales Demo"/>
          <audio src="salesdemo_ad.mp3" begin="33.71s" title="audio description"
          alt="Sales Demo Audio Description"/>
        </par>
      </body>
    </smil>

The example shows a `<par>` segment containing an `<audio>` and a `<video>` tag. The audio stream is not started immediately.

## Resources

Resources are for information purposes only, no endorsement implied.

- Synchronized Multimedia Integration Language (SMIL 2.0)

- Accessibility Features of SMIL

- NCAM Rich Media Accessibility, Accessible SMIL Templates

## Related Techniques

- SM2: Adding extended audio description in SMIL 2.0
- SM6: Providing audio description in SMIL 1.0

## Tests

### Procedure

1. Find method for turning on audio description from content/player (unless it is always played by default)

2. Play file with audio description

3. Check whether audio description is played

### Expected Results

- #2 is true

- Top
- Contents
- Intro
- Previous: Technique SM6
- Next: Technique SM11