I recently purchased a LG Music Flow H3 to test my Google Cast app with an 'audio-only' device. I've enabled audio-only device support within the Google Cast Dashboard and I've registered the device for development. My app works as expected when played to Google Chromecasts, however when attempting to load the receiver app on the LG device I get the following error:
{"reason":"NOT_FOUND","requestId":1,"type":"LAUNCH_ERROR"}
Thinking that perhaps 3rd-party devices can't be registered for development, I went ahead and published my app. Unfortunately this did not address the problem.
Upon further investigation, I'm noticing that other Google Cast apps (i.e. Songza, TuneIn, Pandora, etc. on both Android & iOS) aren't able to play to the LG Music Flow H3 either.
I discovered that the only way to get the H3 to play from Google Cast apps (both my app and others) is to first run the LG Music Flow multi-room audio app. Running the LG Music Flow app appears to effect the device's _googlecast._tcp zeroconf service discoverability. And sometimes the H3 shows up in zeroconf yet you still can't play to the speaker unless the LG Music Flow app is running.
This seams like very strange behavior. I called LG Tech Support, and they recommended I return the device and exchange it for a different one. I did this, and I still get the same result.
Is this how Google Cast on 3rd-Party devices is intended to work? Have I encountered a buggy 3rd-party implementation?
This is not the intended behavior for sure. You are supposed to be able to launch your 3rd party application on the speaker. And it works for me.
The fact you are not able to use any other 3rd party apps (TuneIn, Pandora etc) indicate this is a some general problem and not specifically with your app.
Couple of steps I would try: - Setup you H3 speaker on Wifi (vs Ethernet) and get the latest SW version using the Music Flow app.
Have you Factory reset the device? if you did, you will need to go through setup again. I have noticed Google Cast becomes enabled only after first complete setup.
Please try rebooting, and than try casting apps like TuneIn or Pandora and than see if this works (without using the MusicFlow app). I have noticed in the past that if some app is loaded and is behaving badly (for example uses tons of memory) it will put the speaker into a bad state that don't allow any app to work until reboot. So perhaps when you are casting your app, it gets into a bad state causing other apps to fail afterwards.
Have you made sure not to consume to much memory? avoid graphics or video?