Hi,

Here is a simple tip to all of you out there experiencing issues when using MS Teams over NDI with vMix:

Last Friday I tested everything in my setup for an upcoming live event (which I have just now ended with good result). During these tests, I verified that MS Teams over NDI worked as it should after the latest updates of Windows, MS Teams, NDI, and vMix. I encountered however severe problems to achieve good quality of the outgoing video feed from MS Teams to guests - a lot worse than usual. And it never kicked in even after several restarts or reboot.

I verified the NDI feed from vMix with NDI Monitor, and that was perfectly fine. I also verified that streaming to Youtube worked as it should, and it did. But the quality in Teams was terrible. My production setting was 1080-25p but I got frame rates below 15FPS in Teams, and resolutions of 960x540 at best. Often much lower that that.

Then i noticed that Teams were using the H264 SW codec - not the H264 HW codec. I tried to figure out how to change the codec and if that would have any effect, but couldn't find a way to do that. After searching in some forums, I found out that clearing the cache memory in Teams could solve a lot of issues. So how to clear that cache...?

MS have not (yet) implemented any easy way of doing that like a reset-button in the UI, but after a while I found out that to clear the cache in Teams, you have to delete a complete folder. So I did just that - and that solved everything! After restart of Teams I got 1920x1080 25p out from Teams to the guests right away, and was now using the H264 HW codec as well. It also actually solved some other strange issues!

So, that's the tip - CLEAR THE CACHE!

To do that, quit Teams and all related processes using Task Manager. Then delete all files and folders in this directory:

• The new Teams app: C:\Users\%username%\AppData\Local\Packages\MSTeams_8wekyb3d8bbwe
  
• (The classic Teams app: %appdata%\Microsoft\Teams)
  

Then restart Teams.

Hope this tip could be useful for someone else. Can't guarantee that it solves your issues, but give it a try. It certainly worked for me. Wish you a great day!
/Peter