Date: Thu, 26 Nov 2020 13:18:39 +0100 From: Hans Petter Selasky <hps@selasky.org> To: Thomas Steen Rasmussen <thomas@gibfest.dk>, usb@freebsd.org Subject: Re: webcamd, usb and two webcams - only one works Message-ID: <9a382539-c90d-91b9-bfac-f36c0f19d3f7@selasky.org> In-Reply-To: <c11c1a2f-306f-3cd9-825f-4c39fd250d50@gibfest.dk> References: <c11c1a2f-306f-3cd9-825f-4c39fd250d50@gibfest.dk>
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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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