# Providing captions through synchronized text streams in SMIL 2.0

ID: SM12

Technology: smil

Type: Technique

## When to Use

Applies to SMIL 2.0

## Description

The objective of this technique is to provide a way for people who are deaf or otherwise have trouble hearing the dialogue in audio visual material to be able to view the material. With this technique all of the dialogue and important sounds are available in a text stream that is displayed in a caption area.

With SMIL 2.0, separate regions can be defined for the video and the captions. The captions and video playback are synchronized, with the caption text displayed in one region of the screen, and the corresponding video displayed in another region.

## Examples

### SMIL 2.0 caption sample with internal text streams for RealMedia player

    <?xml version="1.0" encoding="UTF-8"?>
    <smil xmlns="https://www.w3.org/2001/SMIL20/Language">
    <head>
      <layout>
        <root-layout backgroundColor="black" height="310" width="330"/>
        <region id="video" backgroundColor="black" top="5" left="5"
         height="240" width="320"/>
        <region id="captions" backgroundColor="black" top="250"
         height="60" left="5" width="320"/>
      </layout>
    </head>
    <body>
      <par>
        <video src="salesdemo.mpg" region="video" title="Sales Demo"
         alt="Sales Demo"/>
        <text src="data:,This%20is%20inline%20text." region="captions"
         begin="0s" dur="3">
          <param name="charset" value="iso-8859-1"/>
          <param name="fontFace" value="System"/>
          <param name="fontColor" value="yellow"/>
          <param name="backgroundColor" value="blue"/>
        </text>
        <text src="data:,This%20is%20a%20second%20text."
         region="captions" begin="3s" dur="3">
          <param name="charset" value="iso-8859-1"/>
          <param name="fontFace" value="System"/>
          <param name="fontColor" value="yellow"/>
          <param name="backgroundColor" value="blue"/>
        </text>
      </par>
    </body>
    </smil>

This example shows a `text` element that includes synchronized text streams within the SMIL file.

## Tests

### Procedure

1. Enabled caption preference in player, if present
2. Play file with captions
3. Check whether captions are displayed

### Expected Results

- #3 is true

## Related Techniques

- SM11

## Resources

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