I've been using NDI webcam with vMix and Zoom for a few years without any issues.

Recently, I helped a local church to get setup using 3 NDI POE PTZ cameras, a live streaming Windows 10 desktop computer with vMix 4K and a Ryzen 5 cpu and nVidia 1660TI GPU and 16GB RAM.

I created a vMix Preset that contains pre-saved camera shots, audio to/from Zoom to/from the church mixer, and a holding slide. In vMix, I've set up 3 Outputs: A Master Output for use when the church soon begins streaming to Facebook and/or YouTube, Output #2 which sends content including mix minus audio to a Zoom meeting where remote attendees participate in the service, and Output #3 which sends selected content (e.g. the Zoom Gallery and associated audio during prayer request portion of service, and pinned Zoom guests when it is their turn to do a reading during the service) onto an 85" TV and into overhead speakers in the sanctuary.

After extensive testing, the church had its inaugural hybrid service this past Sunday (with some attendees sitting in the pews and some participating on Zoom) and it went well with one primary exception:

For some reason, a couple of times during the 30 minutes before the service started, the NDI webcam seemed to suddenly just stop working. And instead of seeing the holding slide that was in the output of vMix, the Zoom audience saw a black screen. At one point I think someone mentioned they saw our holding slide for just a second but then it went to black. So we had to restart NDI and ensure in the NDI submenu in the taskbar on the computer that vMix Output 2 was selected (which it was and that didn't change) and then the problem was solved. But this happened twice during the pre-service and not at all again during the service.

Could it be that we were just using the holding slide in the Output of vMix for too long? Something else? I think (but can't remember for sure) that we might have showed one of the camera feeds instead of the holding slide after the second interuption.


The latest version of vMix 25 was installed and NDI 5 tools were installed. There is no additional security software installed on the computer, beyond what normally comes with Windows 10. I've never experienced this before with my own personal/business use of a similar setup (3 POE PTZ NDI cameras with vMix), though I don't normally use a holding slide for a half hour. Thoughts?

Thank you.

Can I use Studio Monitor to determine issues that could be impacting NDI Webcam input? If so, could you please detail how? Thank you.

Were you using NDI 5? And are you saying you rolled back to NDI 4.6?

Are you using NDI 4.6 with vMix 25? Thanks.

I have a similar issue - we have a laptop running NDI Desktop Capture that's used to display slides with song lyrics, this is added as an input in vMix on our primary desktop streaming computer (specs similar to one of the high-end reference machines). Intermittently we'll see that the NDI signal signal gets dropped, i.e. we advance to the next slide on the laptop, but the previous slide still shows in vMix. The two computers are literally side-by-side, connected to GigE ports on the same switch, same vlan etc, so I don't see an issue there. I did find one post about enabling IGMP snooping on that vlan, and that has been done. When this happens, we have to restart NDI Desktop Capture on the laptop for vMix to pick up the feed again. If anyone has suggestions for things to check other than network, I would appreciate it. Thanks in advance.