Chromecast/Cast device discovery not working on GrapheneOS (sandboxed Google Play) - OpenSongApp v6.8.6 (464)

[Josep Molins]

Hi all,

I'm running OpenSongApp v6.8.6 (464) on GrapheneOS with sandboxed Google Play Services installed in a secondary user profile. OpenSongApp cannot detect any Cast devices on the network when trying to use the casting feature, even though the phone is on the same Wi-Fi network as the target device.

What I've already verified in that profile:
- Google Play Services has Network permission granted
- Google Play Services has Nearby Devices permission granted
- Location permission is enabled
- No VPN is active
- No Private DNS is configured
- OpenSongApp's own permissions look correct
- Already on the latest available version

Key comparison data that narrows this down to OpenSongApp specifically:

1. YouTube, installed in the same GrapheneOS profile, detects and casts to the same Cast-enabled display without any issue. This confirms the underlying network, mDNS discovery, and Google Play Services Cast framework are working correctly on this device/profile.

2. I use OpenSongApp together with an ESShare-compatible display. On a regular (non-GrapheneOS) Android phone, after connecting to the display via ESShare, OpenSongApp connects to it without any problem. On GrapheneOS, I can connect to the same display via ESShare just fine, but OpenSongApp then fails to detect any device - same "no devices found" symptom as above. Same app version, same display, only the phone's OS differs.

So it seems isolated to how OpenSongApp specifically discovers Cast devices when running under GrapheneOS's sandboxed Google Play compatibility layer - other apps using the same Cast framework (YouTube) work fine, and OpenSongApp works fine on stock Android with the same display.

(Separately, neither phone could connect to my home Smart TV via OpenSongApp - that seems to be an unrelated issue, possibly specific to the TV, so I'm not including it as part of this report.)

Is there anything specific to how OpenSongApp initializes the Cast framework (e.g. CastContext, or maybe an older Cast SDK version) that could behave differently under a sandboxed/non-privileged Google Play Services setup? Happy to provide logs or any other debugging info that would help.

Thanks for your work on this app!

[Gareth Evans]

Hi Joseph, 

OpenSongApp does use the standard Cast context to connect, but because the app doesn't use a hosted web address to stream to the cast device (as YouTube, etc uses), it does work differently.  It actually works as a second screen in the background rather than a standard Cast method. If you have the option to mirror your screen to a smart TV or cast device before starting OpenSongApp, the app should detect this on start up and use the second screen. 

I'm away just now for a few days, but I'll have a look at the code when I get back. 

Gareth

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