Control subtitles via player API?

Is it possible to control whether subtitles (captions / CC) are switched on or off, or a specific language selected, via the Stream player API?

I only see methods for play() and pause() which looks negative … although, I can set properties such as the current time - ideally I would set a property for the currently selected CC - is this possible? If so which property?

I need to do this because we have a custom / branded UI for the Cloudflayer video player.