# Adding extended audio description in SMIL 2.0

ID: SM2

Technology: smil

Type: Technique

## When to Use

Applies whenever SMIL 2.0 player is available

## Description

The purpose of this technique is to allow there to be more audio description than will fit into the gaps in the dialogue of the audio-visual material.

With SMIL 2.0 it is possible to specify that particular audio files be played at particular times, and that the program be frozen (paused) while the audio file is being played.

The effect is that the video appears to play through from end to end but freezes in places while a longer audio description is provided. It then continues automatically when the audio description is complete.

To turn the extended audio description on and off one could use script to switch back and forth between two SMIL scripts, one with and one without the extended audio description lines. Or script could be used to add or remove the extended audio description lines from the SMIL file so that the film clips would just play uninterrupted.

If scripting is not available then two versions of the SMIL file could be provided, one with and one without extended audio description.

## Examples

### Video with extended audio description

    <smil xmlns="https://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>
      <excl>
        <priorityClass peers="pause">
          <video src="movie.rm" region="video" title="video" alt="video" />
          <audio src="desc1.rm" begin="12.85s" alt="Description 1" />
          <audio src="desc2.rm" begin="33.71s" alt="Description 2" />
          <audio src="desc3.rm" begin="42.65s" alt="Description 3" />
          <audio src="desc4.rm" begin="59.80s" alt="Description 4" />
        </priorityClass>
      </excl>
    </body>
    </smil>

## Tests

### Procedure

1. Play file with extended audio description
2. Check whether video freezes in places and plays extended audio description

### Expected Results

- #2 is true

## Related Techniques

- G81
- SM7
- SM11

## Resources

- Synchronized Multimedia Integration Language (SMIL 2.0)
- Synchronized Multimedia Integration Language (SMIL 3.0)
- Accessibility Features of SMIL