Audio Gateway - Dual Source

I am looking for a solution where I can add Chromecast audio to my Pi3 running Emteria. I tried to find a software solution, but it appears that Google deprecated the ability several years ago to create your own Chromecast receiver by validating their certificate on the device.

I am currently running LANnouncer ( on the Pi3 and it is connected to the auxillary input in my intercom system via the headphone output jack on the Pi3. This works great for doing door notifications from my SmartThings hub. I previously had delay issues and this setup solved them.

I decided that it would also be nice to be able to do whole house audio through the speakers on my intercom as well. I wanted to use a receiver software that is compatible with my Android phones that doesn't require 3rd party casting software. I have found though trial and error that the only solution that comes close to achieving this is a Google Chromecast Audio. These are very cheap and easy to use devices. The issue is that the auxiliary input of the intercom is already in use by the Pi3 running LANnouncer.

I could simply send my door announcements through the Chromecast and eliminate the Pi3, but I have found that this introduces a 3 second delay that there does not appear to be a workaround for. This means that you don't get the audio message of a door opening until 3 seconds after it has happened. Even a 1 second delay is too annoying. The Chromecast does have another advantage in SmartThings that it is seen as a different type of speaker that allows for additional audio messages to be sent to it that cannot be sent to LANnouncer.

This brings me to what I believe the solution to be. I want to input the analog audio (headphone plug) from the Chromecast into my Pi3 running Emteria and have the Pi3 simply replay that line in audio via the built in headphone output that I am already using for the LANnouncer software running on the Pi3. I can easily do this with a PC running Windows. Is there a way to do this with a Pi3 and Emteria. I am thinking that I could use a USB soundcard dongle that that has a line input on it. But, even if I could get Emteria to see it and take in the audio, will it replay that audio to the headphone output and do it without knocking out the audio coming from LANnouncer in the process?


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