how create duplicate device0 and /dev/video1 who desn't have "Video Capture"?

[LaurentDelaon]

how create duplicate device0 and /dev/video1 who desn't have "Video Capture"?

[umlaeute]

the loopback camera is not a USB-device. it doesn't attempt to be one.

also, if your application requires a metadata device, then i think it is broken.

i'm closing this as "out-of-scope" resp "won't fix". sorry

[LaurentDelaon]

Hi Umlaeute

As I write is it perfectly work when I connect the application to video0 directly
but don't if I connect on video4 which is a copy of video0 thru v4l2loopback+ffmpeg
ffmpeg -f video4linux2 -i /dev/video0 -codec copy -f v4l2 /dev/video4

So how I can obtain via v4l2loopback the device video1 which isn't 'videocapture' ?

[umlaeute]

as i said, you cannot.

your assumption is, that your application works only with /dev/video0 because there is an accompanying /dev/video1 metadata device.
if this assumption is correct, then i believe the application is broken (because there is no valid reason why there has to be a metadata device at all. i have seen plenty of real hardware capture devices that do not have a metadata device).
in this case, i'm closing this bug-report as "out-of-scope".

if your assumption is wrong, then there is no reason to duplicate the metadata device, and the problem is something else. in this case i'm closing this bug-report as "off-topic" (because then you should start a new bug report, that describes the actual problem)

[umlaeute]

totally off-topic (and unrelated to your problem), but could you please explain why you chose to ignore the template-text of the bug-report? i try to get information about the environment early, because it is usually important.

i'm not asking you to provide this information right now, but wonder why you did not provide it in the first place.
i am asking because you are not alone, so i would like to improve my communication in this regard (to keep frustration levels low)

[LaurentDelaon]

I am not english well readers speaker.
I haven't clearly understand pre writing.
Suggest simpler way :
Put in terminal commands and send : sudo dmesg | grep -i v4l2loopback....

sudo dmesg  | grep -i v4l2loopback
[sudo] Mot de passe de laurent : 
[ 2444.843240] v4l2loopback: loading out-of-tree module taints kernel.
[ 2444.843337] v4l2loopback: module verification failed: signature and/or required key missing - tainting kernel
[ 2444.844988] v4l2loopback driver version 0.12.7 (0.12.7-412-g850a2e3) loaded
[ 8244.940513] v4l2loopback driver version 0.12.7 (0.12.7-412-g850a2e3) loaded
laurent@laurent-NL40-50GU:~/programme/lazarus/pblireUsbCamFfmpeg$ uname -a
Linux laurent-NL40-50GU 5.4.0-150-generic #167~18.04.1-Ubuntu SMP Wed May 24 00:51:42 UTC 2023 x86_64 x86_64 x86_64 GNU/Linux
laurent@laurent-NL40-50GU:~/programme/lazarus/pblireUsbCamFfmpeg$ lsb_release -a
No LSB modules are available.
Distributor ID:	Ubuntu
Description:	Ubuntu 18.04.6 LTS
Release:	18.04
Codename:	bionic