On 11/26/20 1:04 PM, Thomas Steen Rasmussen via freebsd-usb wrote:
Hello USB friends :)
I am having a hard time trying to get two webcams working simultaneously
on FreeBSD 12.2-STABLE r367109 GENERIC amd64.
Each webcam works by itself, for example when taking a snapshot with
pwcview:
sudo pwcview -h -c 1 -o foo.jpg -d /dev/video0
The webcam creates two video devices, video0 and video1. When I plug in
the second webcam video2 and video3 are created. But trying to use the
device doesn't work, pwcview hangs forever and multimedia/motion
complains about timeouts when speaking to the camera.
If I swap the cameras around then "the other one" works, so I know both
cameras are fine.
It seems somehow webcamd or maybe something in the usb system doesn't
like having two cameras in my setup.
Hi Thomas,
Try setting the resolution or framerate down, because high resolution
webcams need a lot of USB bandwidth! We currently don't have so many
checks for excess bandwidth usage in the USB stack in FreeBSD, but I
believe this is the root cause.
Or make sure the webcams are connected to different USB host controllers.
I recently bought a couple of USB 3.0 capable webcams to resolve the
issue I had on my setup.
USB 2.0 is only 480 MBit/s and many webcams simply send raw data :-)
Both are connected to a USB hub, but I have tried connecting one
directly to the computer, which is a pcengines APU3C4 btw. It did not
make a difference.
What can I try to troubleshoot/debug this? Any more info needed?
--HPS
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