Initial plan for install

Using an install of BigBlueButton and GreenLight we can do a video conferencing type presentation with a presenter sharing a screen and their own laptop camera, and a fixed video camera in the room.
We can have a separate audio set-up with a fixed ambient mic for the room and a fix mic for the speaker. We also have a wireless mic that could be used. The audio will come into a small mixer, as will any audio from the speaker's laptop.
The speaker's laptop is connected to a video projector/screen directly and audio out via the aforementioned mixer.
We have a laptop dedicated to being the streaming laptop, streaming the room audio and fixed video.
We can record every session using the BBB setup.
At AbbeyField House we have two rooms and felt that we could have one with this set-up in and the other without. So to be recorded streamed you'll need to be in the room, and being recorded or streamed is not compulsory if in the room.
We felt the set-up would work for both 'presenter' style talks with slides etc, a group discussion, a hybrid of the two, and also for a remote speaker.

Final Install during event

We encountered some problems with our set-up when testing on the Friday "streaming-setup workshop":

The set-up was complex and required two stations: one for handling the video and streaming laptop, and one for the audio.
We got feedback when trying to send audio from the presenter's laptop
We got feedback with remote presenters due to the room mic.
We found the room mic was sufficient to cover the presenter and all people in the room and also pick up any audio being played from the presenter's laptop.

We therefore went for the following simpler set-up:

Presenter laptop
1. Connected to video projector or external screen in room.
2. Connected to channel 1 of audio monitors in room.
Room mic
1. Connected to input of external sound card
Sound card
1. Connected to room mic
2. Output connected to channel 2 of audio monitors in room
3. Connected to streaming laptop
Camera
1. Connected to streaming laptop
Big Blue Button
1. Running on presenter and streaming laptops
2. Running on remote speakers laptop where relevant

Presenter laptop
Roland/Edirol MA-15D audio monitors with two separate line inputs
Projector/external screen
HDMI cable from presenter laptop to projector/screen
Audio cable from presenter laptop to audio monitors
Behringer B-2 Pro omnidirectional microphone
PreSonus Studio 68c four-input external sound card
XLR cable between microphone and sound card
Audio cable connecting output of sound card to audio monitors
Sony a6400 camera
USB-C to USB-A cable between camera and streaming laptop
USB-C to USB-A cable between sound card and streaming laptop
Streaming laptop - ThinkPad running Linux with Ffmpeg and v4l2loopback kernel module to make the camera usable as a webcam device

Streaming an event like HacktionLab is not a great fit, given that HL is a very in-person event.
Time-tabling remote speakers for an event with an unconference style programme is difficult.
Less kit is more.
You need all audio to go through the same streaming laptop in order that the noise cancellation can prevent feedback between microphones and the room monitors that are playing videos and the voices of any remote presenters.
This set-up worked well for the first talk of Saturday (on Karrot) where we had two presenters, with one in the room and one remote.
The room mic was more than sufficient to pick up the audience and main presenter so that someone dialling in remote could here.
Some people don't like to be live streamed. It's important to make people aware that this is happening.
The set-up would work great for an all remote event, like a hacklab where everyone is on laptops.
Big Blue Button worked really well.