Re: Linux video camera UVC driver with multiple cameras

[Roger Heflin]

udev and a rule similar to this:
ENV{SUBSYSTEM}=="video4linux", ENV{ID_TYPE}=="video",
ENV{ID_SERIAL_SHORT}=="0582C6D0", SYMLINK+="video-ibm2",
GROUP="video"
ENV{SUBSYSTEM}=="video4linux", ENV{ID_TYPE}=="video",
ENV{ID_SERIAL_SHORT}=="A6D77E9F", SYMLINK+="video-pr1",
GROUP="video"
ENV{SUBSYSTEM}=="video4linux", ENV{ID_TYPE}=="video",
ENV{ID_SERIAL_SHORT}=="9EAC29D0", SYMLINK+="video-pr2",
GROUP="video"

I don't know if that rule still works,I last used it 8 years ago.  But
something similar should still work.  And at least the logitech cams do
seem to have a serial number.

 udevadm info /dev/video0  will dump the info.  If you want to be avoid
udev, you could use the SN  from the info command and create another device
in /dev with the name you want and the same major/minor number (using the
mknod command) (major/minor is in the info command).  Say start at
/dev/video20 or something similar.

udev is the clean way to do it, but udev is more difficult to debug if it
does not work, and I have been burned by udev changing semantics enough to
do it the crude but easier to debug way.


On Tue, Mar 22, 2022 at 12:33 PM Steve Underwood <coppice12(a)gmail.com&gt;
wrote:

>  Hi,
>
>  The Linux UVC driver for USB video cameras names devices according to
>  the product name it gets from the USB device itself. This is fine if you
>  have different models of camera, as each gets a different name. However,
>  if you have, say, 3 Logitech C920 cameras, the device list in video
>  applications shows you have many devices called "HD Pro Webcam C920",
>  and you can't tell which is which. I looked in the driver source code to
>  see if there is a way to tag the cameras with unique names, but there
>  doesn't seem to be. Does anyone know if I missed something?
>
>  Regards,
>
>  Steve
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