Hosting large meeting on Jitsi

I am evaluating Jitsi for hosting an event with about 400-450 participants (meeting with camera) and event youtube stream to about 3000 people.
My concern is, has Jitsi ever been used to host a meeting of this size. If so, what are the experiences, precaution and system design should be used. Should I use load balancer or should I use specific AWS instance etc.

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Jitsi have been used up to 30-40 people with camera enabled.

Jitsi have been used up to 120 users in the same room, when only a handfull have camera enabled.

Jitsi have been used with 3000+ users on youtube.

Thanks @xranby for the answer. I want to know if Jitsi can handle such event? If I have to setup a test call, what should be the config (no of meet server/no of videobridge) etc.

Out of the box you will not be able to host a meeting event with 400+ participants with camera enabled. The bottleneck is not on the server side, the bottleneck is on the client web-browser side that each client can not handle the network band-with nor the processing of 400 incoming video streams.

A typical client webbrowser can handle up to 10 simultaneous video streams. A high end client webbrowser work up to 30. This is why jitsi work well up to around those numbers but not above.

The jitsi server with additional videobridges can handle several hundred simultaneous participants, typically 100 participants per videobridge, but the participants has then to be grouped 10-30 in different rooms.

Why is Jitsi sending back all the participants feed to everyone? WebRTC support SFU and Simulcast, which can be used to selectively forward feeds to a client browser. We can have one main HD stream and rest 20 odd low quality thumbnail streams. The 20 low quality streams can be switched in batches of 20 by the user…

20 low quality thumbnail stream still consume 4Mbit bandwidth and may be too much for some clients internet connections.

Fullscreen mode would be ideal for jitsi as a SFU you can in optimal conditions only need to send the active speakers video. You can also improve jitsi by configure it to use lastN configuration and work to enable off stage layer suppression.

Only by extending jitsi to contain a MCU mixing server would make it possible to host larger meetings easy.

I did some calculation numbers here: