Logitech C920 performance issues - Rpi4

Hello,

 

I'm finding I have trouble when connecting to my C920 webcam over virtualhere - interestingly it's fine in the logitech configuration app - but opening the videostream in zoom, meet or the camera app causes the virtualhere connection to tank, with mouse and keyboard movements barely registering or missing entirely. the webcam itself shows a frame every second or two. This persists until the window is closed and the webcam image is dropped.

 

Both devices are connected over ethernet, and the top reading from the rpi shows no more than 40-50% CPU usage when the camera is on. What could be choking this so badly?

 

Cheers,

Jacob

#2

Can you explain your setup a bit more.

So you have the camera and mouse/keyboard plugged into the pi4.  That runs virtualhere server. And the virtualhere client is running on a remote windows pc. Everything is connected via ethernet. On the remote windows pc you are running zoom and trying to have a conference call. Then it gets poor performance on the window client side?

#3

Absolutely correct - there's also a USB sound device connected to the Pi too. Client end is a desktop windows 11 machine, well specced so no hardware issues I can see. Everything works well until an application on the client windows device is using the webcam, such as zoom or similar. Once this happens the virtual here performance is very poor with inputs hanging and missing completely, and poor audio with pops and skips from the sound device too. Closing the application that's using the webcam fixes the issue. It doesn't seem to occur in apps that only show a small webcam preview like the windows settings app, or the logitech configuration app.

 

Hope that helps, it's a curious one!

#4

I tried a similar setup just then with my Logitech Brio camera (at 1920x1020), and a USB mouse keyboard with no issues. I think its specific to your setup.

If you remove the sound device from the setup is it smooth then? It might be trying to sync the sound feed with the video feed and the video is taking all the "isochronous" bandwidth and the sound feed is being starved...

Also is the mouse a normal USB mouse or a gaming mouse?  A gaming mouse has much higher polling rates and so you would need to lower the polling rate in the mouse properties on the client side.

#5

As you suspected - running with no usb audio the camera performs correctly. With USB audio going - everything chokes when the camera is accessed. Is there a way round this? I'd be happy with less resolution but that's the only camera I have to hand at the mo! Or lower audio bitrate! Interestingly - when I pulled the USB audio cable out while the camera was up I bluescreened the machine - with a WDF_Violation stop code.

#6

You might not be able to remember but was WDF_Violation in the driver vhusb3hc.sys or another driver?

Anyway im surprised it tries to sync the audio with the video like that. The video is taking all the bandwidth.  This is a guess but plug the camera into the usb 3 ports and the audio into the usb 2 ports on the pi4 because they are completely different USB Busses. Maybe that will help.

#7

I snapped a pic of the BSOD - but it doesn't specify - just gives the WDF Violation stop code. 

I'll give the USB ports a shuffle and see where we're at. I forgot to mention - I'm using an MX Master Mouse from Logitech - I don't think it has a particularly crazy polling rate - but I may be wrong!