Should also work when person only has microphone and no cam

[jancborchardt]

In many cases people don’t have a webcam but only microphone (or headset), especially on desktop computers. Instead of not working at all, we should handle this gracefully:

• Still ask for permission to use the microphone
• Show the avatar placeholder for yourself and for the others (currently a black video view is shown)
• Maybe give some feedback about the missing webcam in case it’s not working or you forgot you have one

cc @fancycode @Ivansss @LukasReschke can we make that work?

[fancycode]

See here for an example on how we handle something similar with spreed-webrtc (we do a transparent graceful fallback to the avaliable device):
strukturag/spreed-webrtc#395

[jancborchardt]

Killer work here @Ivansss 🎉 :)