Execute harmony activity when chromecast audio streams music?

I have seen some threads on how to set up chromecast as a DLNA device using a node.js server or some type of “middleman” service. I’m hoping there is a more straightforward solution for my need.

Basically, I would like my harmony hub to run an activity (turn on my soundbar and change the input) when music is cast to the chromecast audio.

Thanks in advance

I’d be interested in that too, not sure if it’s possible to use casting as a trigger but subscribing to this thread just in case…