I've had vMix for about 3 months, and was excited to get going with multi camera switching. I'm running vMIx on a gaming laptop (specs below) and purchased a JVC HM200 that i connect to vMix via RTSP stream input. The JVC connects great and works awesome when there aren't wifi bandwidth issues. My problem has been with adding 2 USB logitech webcams. A C920 and a PTZ Pro. I can add them as inputs and they connect, but regardless of the video formats I use (Default vs. MJPG), the connection isn't solid. Typically the C920 looks OK but drops alot of frames. The PTZ looks really good when MJPG is selected, but either immediately or after a little while, starts glitching. Not sure what the technical term is, but the image with distort and go black. When both cameras are connected, the C920 will glitch too. This is very frustrating because I've read all the posts on this forum regarding webcams, and I've followed every suggested fix, with no success. I'm pulling my hair out at this point because I need to have multiple cameras to start making money with my streaming setup. Any help is much appreciated.

Here is what I've tried so far:

I've tried plugging each camera in to other USB ports on the laptop, no change. I've also tested both cameras on a different computer (Mac pro) and they work perfect.

I've opened the cameras in VLC on the laptop, and the cameras do not glitch.

I've tried changing the video format from Default to MJPG. Improves frame rate, but still glitches.

I've tried changing the resolution and frame rate of both the cameras and the main vMIx settings.

I've updated drivers in Device Manager to both UVC and back to Logitech drivers. No change


ASUS i7 2.7GHz
16 GB RAM
NVIDIA GeForce GTX 950M (2GB VRAM)
500 SSD
2 TB HD
Windows 10 updated
Fresh update to vMix 20
300/30 mbps LAN
vMix is configured to use NVIDIA graphics card


Here is a video of what is going on: https://drive.google.com...x3lztOjZqR2hlWE1GV2VMcFk

I'm not sure what you mean about the resources. The reason the CPU got near 90% was because i had the additional desktop capture input and of course i was recording. When i connect just even one webcam, say the C920, the CPU goes to maybe 5% vMix and 10% Total, even in 1080. vMix is recognizing the camera but is dropping alot of frames. The PTZ seems better, but does have the glitching issue. This seems silly to me that I'm having trouble connecting even 2 webcams.

I tried dropping the project output to 720 30p instead of 1080, it seems to help a bit but it still glitched.
And the NVIDIA gtx 950m is set to default card.

Is this laptop really not up to the task of 2 1080 USB webcams and 1 1080 RTMP stream?

Any help from @admin or @sinc747 would be much appreciated.

Is looks like you're having issues with the USB bus when connecting two cameras. That's not uncommon. Is the host connection on the laptop USB 2.0 or USB 3.0?

I also have the C920 and PTZ Pro. I have no trouble using two USB cameras connected to a USB 3.0 hub, onward to a USB 3.0 port on my desktop.

Even using MJPEG, you probably can't use two cameras connected to a USB 2.0 port. A single bus just isn't fast enough to be reliable.

Laptops can be troublesome as they may only expose one USB bus. That's why I bought my Airtop PC. It's a small, fanless desktop with an i7, GTX GPU, and tons of ports.

Just as a matter of curiosity... did you try creating a new project in vMix (not relying on a copy of another project)?

I recently had a choppy webcam (one of three webcams attached to the computer), and it got resolved when I recreated the project from scratch.

vMix has a built-in tool to display that CPU usage in the lower left corner of the app. That will tell you if the system is CPU constrained.

I can tell you that my Lenovo X1 Carbon (2013) with an i5-3427U dual-core CPU cannot handle 1080p30 reliably. It does well enough at 720p30 with one external webcam.

It has one USB 3.0 port and one USB 2.0 port. By definition these are different controllers, so I can connect two cameras and know that they're on different buses.

With a USB 3.0 hub I've used two webcams on the USB 3.0 bus. Two webcams at 720p30 MJPEG is fine. Anything more starts to drop frames.

It occurred to me that I haven't tried vMix on the X1C in about 6 months. I see now that operating at 720p30 vMix required about 15% of CPU, the entire system running at around 30-35%. If I were to use vMix External output to emulate a webcam to a Hangout the system would be close to unstable.