Chromecast Closed Captions

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 will show a closed caption button for all assets with closed captions. You will need to 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. Supported closed caption formats include:
  • DFXP v2006 format
  • Embedded CES-608 (if the Google Media Player Library is used for the streams)
Note: The Chromecast Integration currently does not support user styling (FCC styling), but are working on implementing this in the future.

Workflow

The following steps outline the workflow for closed captions for VOD assets.
  1. Sender issues a command to set the language.
  2. Receiver will accept and instantiate a <track> element to show CC.
  3. Receiver will use Chromecast's browser default support.

Enablement

There is no enablement necessary. Closed captions are enabled by default on the sender and receiver applications. Simply upload your closed caption file for your asset in 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

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 will display the new language closed captions.

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