Matrix supports both video and audio chat over WebRTC. IIUC this provides strong e2e encryption and very good performance (it is the best looking video call I have used as they don't seem to really have any limit on the resources used because it is p2p). However it is limited to 1:1 right now.

Element (and some other clients, but I don't think it is part of the standard) also supports multi-user voice and video using Jitsi which works very well but you loose e2e encryption (although IIUC Jitsi has some experiments for this) and need to run it separately.

Even if it's P2P, you still need TURN servers because participants might be behind NAT that are hard to pierce through. This basically means you're proxying the full video traffic between both participants.

Have you had success with encrypting TURN servers? In trying to host my own Matrix server and have E2E encryption for texts, video, and voice, I found that video/voice had to be disabled as Let's Encrypt and SSL weren't compatible.

You definitely can make it work with Let's Encrypt, that shouldn't disturb anything.

Setting up STUN and TURN is a real pain, though, if you run into any issues.

Interesting! Were you able to set up a fully encrypted TURN server to use with Matrix? Any tips? I wasn't able to succesfully.

Tip: read the "Be precise and informative about your problem" section [0] of the infamous "How To Ask Questions The Smart Way".

Actually, I'd suggest reading the entire document when you have time. For now, though, at least have a read of that section (it's short and sweet).

[0]: http://www.catb.org/~esr/faqs/smart-questions.html#beprecise

That was a good tip, thanks! :) Will read the document so I can be a better contributor in the future.

If you pop in to #voip-tester:librepush.net I may be able to lend an ear at least.

You won't be the first (nor the last, though if I can have the chance to improve that at some point I would love to) person to have struggled with it.

Thanks for pointing me in this direction!