When the user changes the captions font size from the settings inside the room, then the captionsFontSizeChanged event will be emitted.

You can also change the captions font size programmatically through the SDK. Use the configureCaptions method to achieve that.

Sample payload

  "type": "captionsFontSizeChanged",
  "data": {
    "fontSize": "large"

Sample subscription code

sambaFrame.on('captionsFontSizeChanged', (event) => {
  const data =;
  //Possible values for "fontSize" field are "small", "medium" and "large"
  console.log('Captions font size has been changed to', data.fontSize);

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