Google Cast Audio Integration for Control4

Where this came from: this question was asked on r/Control4 — not here. We answered it there, in public, and this is that answer.

The feature in that list I'd actually pay for is the auto room on/off. The thing that has annoyed me for years about Nest speakers living alongside a Control4 system is that the client casts to the kitchen Nest Mini, the room is playing audio, and Control4 has no idea the room is on. So the Off event never fires, the "all off" at the front door doesn't stop the music, and the room lighting scenes tied to room-on don't behave. Getting the Cast session to register as a source in the room fixes a real, daily irritation rather than adding a feature nobody asked for.

Where I'd set expectations: don't sell this to anyone as a way to get a Nest Audio playing in sync with their Triad zones. Cast devices sync to each other within a Cast group on Google's clock, and a matrix amp zone runs on Control4's. My understanding is those two will never be sample-aligned, so the kitchen Nest and the adjacent great room ceiling speakers will slap if they're audible to each other. Treat the Cast device as its own zone, not as an extension of the distributed system. The binding for analog outputs is mostly useful for the old Chromecast Audio pucks with the 3.5mm out and for Cast-built-in receivers, which is a smaller install base than it sounds.

Network side, and this is where I'd expect the support tickets to come from: if the Nest speakers are on an IoT VLAN and the controller is on the main LAN, casting from a phone and any mDNS-based discovery will not cross the boundary unless mDNS repeating is turned on for both VLANs. On the Ubiquiti gear that's the multicast DNS toggle, on Araknis it's under the same idea with a different name. Also give every Cast device a DHCP reservation. Anything doing direct IP control will lose the device the first time the lease rolls over or the router gets swapped, and the symptom is the same one I see constantly with Lutron processors after a router change: the driver is still pointed at the old address and everything looks dead when nothing is actually broken.

Two things I don't know and would ask Chowmain directly. First, what an announcement does to an in-progress cast session, whether it ducks and resumes, or kills the session and leaves the room silent afterwards. That matters a lot if you're using it for doorbell announcements. Second, what happens when Control4 sends off to one member of a Cast group. If it tears down the whole group, that's a support call every time. I'd want both answered before I put it in a client's house.

One practical note for homeowners reading this. Adding any third party driver takes Composer Pro and a DriverCentral setup, so it isn't something you can do yourself from the app, and you'll need whoever holds your project. It's a fifteen minute job for anyone with Pro access, so don't let it turn into a truck roll and a system review.

I'm a Control4 and Lutron dealer, and I do this remotely for a living. If you want to know whether it'll do what you're picturing in your house, tell me your controller model and OS version and which Nest or Cast devices you have and where they sit on the network, and I'll tell you either way.