Thanks to UV4L it is possible to create or join an existing room and broadcast live video and audio to all the participants or viewers in the room from a camera and a microphone connected to the Raspberry Pi. It's also possible to automatically hear and see other participants if you have speakers and display (HDMI, touchscreen, etc…) connected to the Raspberry Pi. Of course, other participants can be other Raspberry Pi's. The great news is that you do not need any browser installed on the Raspberry Pi to do this.
It's necessary to install the required packages before proceeding: uv4l, uv4l-server, uv4l-webrtc, uv4l-xmpp-bridge and one video driver (e.g. uv4l-raspicam, uv4l-uvc, etc…). Please refer to these installation instructions for more details.
To start and stop streaming to a particular Jitsi Meet server (called videobridge), it's enough to invoke the corresponding commands by means of the UV4L Streaming Server installed on the Raspberry Pi. This can be done in two ways.
The first convenient way is through a browser by using the Jitsi Meet control page available at the URL the Streaming Server itself is listening to (e.g. http://myraspberrypi:8080), from which it's possible to specify all the mandatory informations (i.e. XMPP and/or BOSH signalling server, chat room, your username and password) required to establish a connection and to click on start/stop buttons in order to join or leave the specified room respectively.
where raspberrypi will have to be replaced with the real hostname of your Raspberry Pi in your network (it can be localhost if you are executing the command from within your Raspberry Pi) and port will have to be replaced with the real port number the Streaming Server is listening to (8080 is the default). The above command will make the Raspberry Pi create or join a conference at http://meet.jit.si/testroom.
If the UV4L Streaming Server is providing HTTPS instead of HTTP, be careful to specify 'https://[…]' in the URL. You may also desire to add the –insecure option to curl to turn off the verification of the server's certificate (see the curl manual for more details).
All the above settings can be optionally specified once for all in the UV4L configuration file (except action) (see the uv4l-server manual for more details).