Using Closed Captions with Chromecast Integration

You can use closed captions for VOD (all streams) and Live (HLS and eHLS) content with the Chromecast Integration. Closed captions are enabled by default on the sample sender and receiver applications. By default, the player displays a closed caption button for all assets with closed captions. You must copy over the closed caption (CC) code from our sample sender and receiver applications to have this supported by default on your own sender and receiver applications. For an introduction, see Closed Captions in Player V4.

Note: The Chromecast Integration currently does not support user styling (FCC styling), but we are working on implementing this in the future.

Supported Closed Caption Formats

  • TTML (formerly DFXP)
  • Embedded CES-608/708 (Live)
Note: For closed caption support on iOS and Android, you must ingest files in TTML (formerly DFXP) format.
For additional information, see Supported Closed Captions.


The following steps outline the workflow for closed captions for VOD assets:
  1. The sender issues a command to set the language.
  2. The receiver accepts and instantiates a <track> element to show CC.
  3. The receiver uses Chromecast's browser default support.


No enablement is needed. Closed captions are enabled by default on the sender and receiver applications.

Upload Closed Caption Files

Simply upload your closed caption file for your asset via the Backlot UI or via the Backlot API.

Sender Application

The iOS and Android sender applications do the following for closed captions:
  • Display a CC button for assets containing CC file (Live, VoD).
  • Send a CC message to the Receiver to turn captions on or off.
  • Display the current status of CC (on or off) on the sender device via icon highlighting.
The end user can do the following with the sender application:
  • Turn captions on or off at any time.
  • Select or change a caption language at any time.

Receiver Application

The receiver application listens to the sender application to display the closed caption language selection set by the end user. If the end user changes the closed caption language on the sender application, the receiver displays the new language closed captions.