I've got a broadcast in 2 and a half weeks time and just did the first technical test yesterday. Luckily it's only a host and single guest but the former had horrendous audio delay that made conversation very hard (not impossible). I had <100ms on my second laptop (vMix Call as "guest") but the host was >400ms and by their own admission <3Mbps down and 300Kbps up (return feed was minimum!). By comparison I have 500Mbps up AND down. To be fair even with video <300Kbps vMix Call was managing 30fps.

That evening I did call with the guest on US East Coast (both host and I are in Scotland), and it went smoothly with <60ms delay for both of us. They noted a fractional delay but it didn't cause any issues. Both the guest and host work in film industry so very understanding whereas I've had academics throw hissy fit if it didn't work perfectly immediately.

Both tests had P2P connection only in hope of resolving similar issues with the aforementioned academics. Only difference was that I temporarily switched off the firewall for second test... could that have made such a big difference and if so what's the permanent fix on a domestic router - DMZ? Or is it the simplest thing and the host just had rubbish internet connection and nothing will resolve that?

I went on-site at work as the host might go there. Using my vMix laptop I could connect a vMix Call also originating on same network and latency was 60ms... then 200ms... 600ms... 3s... 30s!!! I assume this would be my works firewall causing this? I'll send them the vMix guidelines and see what they can do.

Anyone's thoughts / suggestions / prayers would be appreciated.

Long delays really can only be caused by restrictive firewalls and slow internet connections.

Specifically if UDP is blocked by firewalls, then being forced to use TCP can cause big delays to build up
if either sides internet connection is too slow. (Whereas with UDP, big delays are not possible).

Pretty much all issues with vMix Call come down to this. So a careful read of our firewall documentation is important:
https://www.vmix.com/kno...ll-firewall-requirements

Tone13, I've seen some impressive set-ups using Zoom but these had a laptop per user, with secondary screen with pinned video - all running into laptop via HDMI capture, and audio running to physical desk. This is far too complex / expensive for our needs.

I tested NDI-out from Teams and whilst video may have not been as good, I had this on a separate laptop running to the local switch (home network) and whilst audio runs to EVERY input, it just took some planning and also managed to run a return feed to Teams with External 2 and audio on separate bus. Did work, but I'd be worried about issues with Teams...

Going to keep trying to work on vMix Call - will fix work firewall as I'll start being on site more (as I'm moving into a campervan which isn't ideal for broadcasts!) and our host next week may just come in to get better connection.

A few options from my side:
- medialooks VT
- Larix broadcaster via SRT and talkback
- https://appr.tc/

In Larix you can set another SRT (program feed) as talkback. Hopefully I find some time to make a video for this use case.

Cool, will look into it. When you say 'as talkback' is that with return vision? If so, thats great but it just needs to be simple enough for the non tech savvy guest at the other end to use.



Interesting! I've generally had more success with people on mobile devices. Will do more tests.