UV4L WebRTC demo seemingly not working, how to fix?

Question

There is a demo which comes with UV4L demo OS for Raspberry PI, https://raspberry:8080/stream/webrtc. When i run it on a macOS computer (Firefox browser), and select that a screen is to be shared, it always says 'no suitable video device found!' and apparently doesn't connect anywhere. Same happens when i go there on a Chromium browser on a Raspberry PI itself. There doesn't seem to be any error messages anywhere - some deprecation warnings but no more than that:

onopen()  webrtc:197:25
navigator.mozGetUserMedia has been replaced by navigator.mediaDevices.getUserMedia  webrtc:251:32
WebRTC interfaces with the “moz” prefix (mozRTCPeerConnection, mozRTCSessionDescription, mozRTCIceCandidate) have been deprecated.  webrtc:105:25
{"iceServers":[{"urls":["stun:stun.l.google.com:19302","stun:192.168.0.101:3478"]}]}  webrtc:104:21
onaddstream is deprecated! Use peerConnection.ontrack instead.  webrtc:107
peer connection successfully created!  webrtc:110:21
URL.createObjectURL(MediaStream) is deprecated and will be removed soon.  webrtc:255:60
call(), request={"what":"call","options":{"force_hw_vcodec":false,"vformat":"60"}}  webrtc:193:25
message =message  webrtc:281:25

Where shall i look into?

Clarification: i can see my desktop in a 'local' box, so sharing has been successful, same on Raspberry PI. But it never goes to the other side, i can't even use the data channel - it is greyed out - so apparently no connection happens, at all.

Answer 1

I would check if the camera module on the pi itself is attached correctly. Did you try to capture a test image using something likeraspistill -o test.jpg yet? I've seen the 'No Suitable devices found' problem come up when I either didn't enable the camera on raspi-config or I didn't insert the camera's ribbon cable correctly. You can also check if you've connected the GPIO corresponding pins right.

Answer 2

The following command runs an instance of UV4L that allows to mirror your desktop or window to the Raspberry Pi HDMI display. Note that you must pass the SSL certificates .key and .crt (see the UV4L installation instructions to know how to generate them):

uv4l --enable-server --driver dummy --server-option '--use-ssl=yes' --server-option '--ssl-private-key-file=/home/pi/selfsign.key' --server-option '--ssl-certificate-file=/home/pi/selfsign.crt' --verbosity=7 --server-option '--enable-webrtc-video=no' --server-option '--enable-webrtc-audio=no' --server-option '--webrtc-receive-video=yes' --server-option '--webrtc-renderer-fullscreen=yes' --server-option=--webrtc-renderer-window=0 0 1920 1080 --server-option '--webrtc-receive-datachannels=yes' --server-option '--webrtc-receive-audio=yes' --auto-video_nr --server-option '--webrtc-receive-audio=yes --server-option '--port=9000'

You can then access the WebRTC streaming page at:

https://raspberry:9000/stream/webrtc

You must explicitly enable screen sharing in firefox or chrome according to the instructions written in the the same page.