webcamd, usb and two webcams - only one works

[Thomas Steen Rasmussen]

On 11/26/20 1:18 PM, Hans Petter Selasky wrote:
> 
> Hi Thomas,
> 
> Try setting the resolution or framerate down, because high resolution 
> webcams need a lot of USB bandwidth! 

Hi,

Thanks for the reply. How can I set the resolution or framerate lower?

I first connect both webcams, and then try for example with the pwcview 
command:

$ sudo pwcview -h -c 1 -o foo.jpg -d /dev/video0 -s xga
Webcam set to: 640x480 (xga) at 5 fps
$

$ sudo pwcview -h -c 1 -o foo.jpg -d /dev/video2 -s xga
Webcam set to: 640x480 (xga) at 5 fps
^C
$

And only the first (video0+1) works, the second (video2+3) never 
returns. Can I maybe tell webcamd to set fps and resolution somehow or 
how would I do it?

The webcams are connected to a externally powered USB3 hub which is 
connected to a USB3 XHCI controller. I would think the 5 gbit/s offered 
by USB3 would be enough for this.

The onboard usb3 controller:
usbus0 on xhci0
usbus0: 5.0Gbps Super Speed USB v3.0
ugen0.1: <0x1022 XHCI root HUB> at usbus0
uhub1: <0x1022 XHCI root HUB, class 9/0, rev 3.00/1.00, addr 1> on usbus0

When I plugin the external USB hub it shows both a usb 2 and a usb3 hub 
for some reason?

ugen0.2: <VIA Labs, Inc. USB2.0 Hub> at usbus0, cfg=0 md=HOST spd=HIGH 
(480Mbps) pwr=SAVE (0mA)
ugen0.3: <VIA Labs, Inc. USB3.0 Hub> at usbus0, cfg=0 md=HOST spd=SUPER 
(5.0Gbps) pwr=SAVE (0mA)

uhub5 on uhub1
uhub5: <VIA Labs, Inc. USB2.0 Hub, class 9/0, rev 2.10/2.21, addr 1> on 
usbus0
uhub5: 4 ports with 4 removable, self powered
uhub6 on uhub1
uhub6: <VIA Labs, Inc. USB3.0 Hub, class 9/0, rev 3.00/2.21, addr 2> on 
usbus0
uhub6: 4 ports with 4 removable, self powered

So when I plug in the webcams how do I know which "uhub" device they are 
plugged into? These are the messages after plugging in the webcams:

=====================================
ugen0.4: <Jieli Technology USB PHY 2.0> at usbus0
uaudio0 on uhub5
uaudio0: <USB Microphone> on usbus0
uaudio0: No playback.
uaudio0: Record[0]: 48000 Hz, 1 ch, 16-bit S-LE PCM format, 2x8ms buffer.
uaudio0: Record[0]: 44100 Hz, 1 ch, 16-bit S-LE PCM format, 2x8ms buffer.
uaudio0: Record[0]: 16000 Hz, 1 ch, 16-bit S-LE PCM format, 2x8ms buffer.
uaudio0: Record[0]: 8000 Hz, 1 ch, 16-bit S-LE PCM format, 2x8ms buffer.
uaudio0: No MIDI sequencer.
pcm0: <USB audio> on uaudio0
uaudio0: No HID volume keys found.
ugen0.5: <Jieli Technology USB PHY 2.0> at usbus0
uaudio1 on uhub5
uaudio1: <USB Microphone> on usbus0
uaudio1: No playback.
uaudio1: Record[0]: 48000 Hz, 1 ch, 16-bit S-LE PCM format, 2x8ms buffer.
uaudio1: Record[0]: 44100 Hz, 1 ch, 16-bit S-LE PCM format, 2x8ms buffer.
uaudio1: Record[0]: 16000 Hz, 1 ch, 16-bit S-LE PCM format, 2x8ms buffer.
uaudio1: Record[0]: 8000 Hz, 1 ch, 16-bit S-LE PCM format, 2x8ms buffer.
uaudio1: No MIDI sequencer.
pcm1: <USB audio> on uaudio1
uaudio1: No HID volume keys found.
=====================================

"uhub5" is the usb2 external hub. Could this be the reason for my timeouts?

Thanks!

/Thomas