I would love something like this, if it could act as a Chromecast receiver. The protocol has been reverse engineered enough to make an open source client. I wonder if there's some technical reason that makes it difficult to make a server. I'd be surprised if the reason was just that no one has been interested enough to do it.
Devices that implement the Google Cast protocol all need a trusted keypair and certificate. Reimplementations of the client protocol can just ignore that, but the official ones validate the certificate and won't talk to devices that don't have one.
Given the relative abundance of supporting devices, they must be easy to extract from at least some of them I'd assume? Revoking these all the time would sound painful for the end user...
Something similar that I've run in the past using the Pogoplug when it was on discount bin prices. It's just Linux packages, but the Pogoplug was enough to shuttle the data to a USB DAC.
It turns your good old hifi system into smart speakers:
When listening to music on your phone, you can choose to listen via Ottercast. Then the music will come out of the hifi system connected to the ottercast.
It does this via Wifi and the protocols Airplay, Pulseaudio, Spotify Connect and Snapcast.
How would I do the reverse? That is, turn smart speakers into regular speakers. I have a Sonos Move but it can't play audio from my desktop PC with no bluetooth. I could buy a bluetooth dongle, but honestly I find wired connections easier to manage than pairing bluetooth devices, especially when you need to switch paired devices. I was hoping this OtterCast would have both bluetooth and line-in so I could do this (connect the bluetooth to the Sonos and the line-in to a desktop or other device).
Presuming you're using linux you can use one of the ottercast devices as a pulseaudio network sinc. It should just show up in your list of audio devices, although I admit I've never actually used a network pulseaudio sinc. If you wanted fancier multi-room audio you could install snapcast on your computer.
It's a small audio streamer that allows you to use some common audio streaming protocols (Airplay for iOS devices, Spotify Connect for Spotify users etc) with audio line out for speakers & headphones. It looks like an open source version of something like a Wiim Mini which should give you something to search against to see what they do.
Sadly it seems like there's no active development anymore and it isn't possible to purchase it directly. You can have it manufactured, but it still needs some manual assembly with SMT parts.
https://kitspace.org/boards/github.com/ottercast/ottercastau...