v4l2loopback ?

[kris777]

Can we count on adding a module to the future kernel... I mean: v4l2loopback 🙂

[robertoj]

Does this package exist? (sorry I am away from my armbian device)

https://packages.debian.org/bookworm/v4l2loopback-dkms

[kris777]

sudo apt install v4l2loopback-dkms
Czytanie list pakietów... Gotowe
Budowanie drzewa zależności... Gotowe
Odczyt informacji o stanie... Gotowe   
v4l2loopback-dkms is already the newest version (0.12.7-2).
0 aktualizowanych, 0 nowo instalowanych, 0 usuwanych i 8 nieaktualizowanych.
root@orangepi3-lts:~# sudo modprobe v4l2loopback
modprobe: FATAL: Module v4l2loopback not found in directory /lib/modules/6.12.35-current-sunxi64

 

[Ryzer]

It is not an internal module so modprobe will not work. It appears to need to built separately: https://github.com/v4l2loopback/v4l2loopback You should be able to build this if you have the kernel headers that match, the just load it by using sudo insmod instead.

[kris777]

I can't build it from GitHub, or rather I've built it but it doesn't work because the kernel headers don't seem to match and it can't be loaded. I guess you have to compile the entire kernel with this module  🙂  ..uppss

Quote

modinfo /lib/modules/6.12.35-current-sunxi64/updates/v4l2loopback.ko | grep vermagic
vermagic:       6.12.35-current-sunxi64 SMP mod_unload aarch64
modinfo /lib/modules/$(uname -r)/updates/v4l2loopback.ko
filename:       /lib/modules/6.12.35-current-sunxi64/updates/v4l2loopback.ko
alias:          char-major-10-255
license:        GPL
version:        0.15.1
author:         Vasily Levin, IOhannes m zmoelnig <zmoelnig@iem.at>,Stefan Diewald,Anton Novikovet al.
description:    V4L2 loopback video device
srcversion:     45D4A1AED5D88ED1EEB4704
depends:        videodev
name:           v4l2loopback
vermagic:       6.12.35-current-sunxi64 SMP mod_unload aarch64
parm:           debug:debugging level (higher values == more verbose) (int)
parm:           max_buffers:how many buffers should be allocated [DEFAULT: 2] (int)
parm:           max_openers:how many users can open the loopback device [DEFAULT: 10] (int)
parm:           devices:how many devices should be created (int)
parm:           video_nr:video device numbers (-1=auto, 0=/dev/video0, etc.) (array of int)
parm:           card_label:card labels for each device (array of charp)
parm:           exclusive_caps:whether to announce OUTPUT/CAPTURE capabilities exclusively or not  [DEFAULT: 0] (array of bool)
parm:           max_width:maximum allowed frame width [DEFAULT: 8192] (int)
parm:           max_height:maximum allowed frame height [DEFAULT: 8192] (int)

sudo modprobe v4l2loopback
insmod /lib/modules/6.12.35-current-sunxi64/updates/v4l2loopback.ko
insmod: ERROR: could not insert module /lib/modules/6.12.35-current-sunxi64/updates/v4l2loopback.ko: Invalid module format

Edited August 6, 2025 by kris777

[robertoj]

Uninstall the debian v4l2loopback package

Did you add the build parameter to build for your specific kernel version?

Did you do the final "make install" step?

 

https://github.com/v4l2loopback/v4l2loopback?tab=readme-ov-file#build-for-a-different-kernel

 

Search in the raspberry pi forum also

[kris777]

OK...I think it worked in OrangePi3 LTS 🙂 ...first, clean up the remnants:

.................................................................

sudo apt purge v4l2loopback-dkms

sudo apt autoremove

...............................................................

armbian-config

then I had to switch to a different kernel: edge:6.15.4-edge-sunxi64 ....then update the system: apt update / upgrade / reboot ! install from GitHub:  v4l2loopback and then:

cd ~/v4l2loopback

....................................................................
VERSION=$(grep -oP 'PACKAGE_VERSION="\K[^"]+' dkms.conf)

sudo cp -r . /usr/src/v4l2loopback-$VERSION
sudo dkms add -m v4l2loopback -v $VERSION
sudo dkms build -m v4l2loopback -v $VERSION
sudo dkms install -m v4l2loopback -v $VERSION

dkms status
sudo modprobe v4l2loopback
ls /dev/video*

...................................................................
I guess it's OK now:

................................................................

Quote

ls /dev/video*
/dev/video0 /dev/video1 /dev/video2 /dev/video3 /dev/video4
root@orangepi3-lts:~/v4l2loopback# lsmod
Module Size Used by
v4l2loopback 45056 0
uinput              16384 1
bnep                 16384 2
hci_uart            106496 1
btqca 16384  1 hci_uart
btrtl 20480    1 hci_uart
btintel 36864 1 hci_uart
btbcm 20480 1 hci_uart

But in my opinion the module is not working properly 😞

I'll be more precise, it works OK... but OrangePi3LTS is a weak device and the option/module: v4l2loopback and the ffmpeg program that transmits/splits the image to two programs (motion/ustreamer) causes high CPU usage... but it works OK, so my problem is solved

 

Edited September 8, 2025 by kris777