Error when trying to open (wrong?) video device

[bodograumann]

I’m trying to use weffe on arch-linux.
Honestly not sure which version was installed (with yay). It says it would install 1.0.0.r1.g449d0db-1, but now says 1.0.1.r4.gf0418fb-1 is installed 🤷 .
It fails with an error:

ffmpeg version n4.4.1 Copyright (c) 2000-2021 the FFmpeg developers
  built with gcc 11.1.0 (GCC)
  configuration: --prefix=/usr --disable-debug --disable-static --disable-stripping --enable-amf --enable-avisynth --enable-cuda-llvm --enable-lto --enable-fontconfig --enable-gmp --enable-gnutls --enable-gpl --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libdav1d --enable-libdrm --enable-libfreetype --enable-libfribidi --enable-libgsm --enable-libiec61883 --enable-libjack --enable-libmfx --enable-libmodplug --enable-libmp3lame --enable-libopencore_amrnb --enable-libopencore_amrwb --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-librav1e --enable-librsvg --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libssh --enable-libsvtav1 --enable-libtheora --enable-libv4l2 --enable-libvidstab --enable-libvmaf --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxcb --enable-libxml2 --enable-libxvid --enable-libzimg --enable-nvdec --enable-nvenc --enable-shared --enable-version3
  libavutil      56. 70.100 / 56. 70.100
  libavcodec     58.134.100 / 58.134.100
  libavformat    58. 76.100 / 58. 76.100
  libavdevice    58. 13.100 / 58. 13.100
  libavfilter     7.110.100 /  7.110.100
  libswscale      5.  9.100 /  5.  9.100
  libswresample   3.  9.100 /  3.  9.100
  libpostproc    55.  9.100 / 55.  9.100
Input #0, video4linux2,v4l2, from '/dev/video0':
  Duration: N/A, start: 362449.130468, bitrate: 147456 kb/s
  Stream #0:0: Video: rawvideo (YUY2 / 0x32595559), yuyv422, 1280x720, 147456 kb/s, 10 fps, 10 tbr, 1000k tbn, 1000k tbc
Input #1, png_pipe, from '/usr/share/weffe-git/static/blur_portrait.png':
  Duration: N/A, bitrate: N/A
  Stream #1:0: Video: png, rgba(pc), 1920x1080 [SAR 999:999 DAR 16:9], 25 fps, 25 tbr, 25 tbn, 25 tbc
Stream mapping:
  Stream #0:0 (rawvideo) -> split
  Stream #1:0 (png) -> alphaextract
  format -> Stream #0:0 (rawvideo)
Press [q] to stop, [?] for help
[video4linux2,v4l2 @ 0x555cea26ce40] Unable to open V4L2 device '/dev/video7'
Could not write header for output file #0 (incorrect codec parameters ?): No such file or directory
Error initializing output stream 0:0 -- 
Conversion failed!

[intermezzio]

This means that the virtual device on /dev/video7 has not been initialized yet. Have you run weffe -a first?

[bodograumann]

Of course I forgot that m(
When I try it, I get the following error though:

modprobe: FATAL: Module v4l2loopback not found in directory /lib/modules/5.16.2-arch1-1

[intermezzio]

That can be one of two things. v4l2loopback-dkms is a dependency of weffe and should've been installed with it if you used yay. You can confirm this by running pacman -Qs v4l2loopback-dkms.
This may also be because you don't have kernel headers for the kernel you're running. If that is the case you'll have to install linux-headers. Let me know if this solution fixes it, as I may need to find a way to add linux-headers as a dependency if this is the case.

[bodograumann]

v4l2loopback-dkms was installed. linux-headers was not. After I added it, it seems to work.
So it should definitely be a dependency.
Also, why not simply run the setup automatically, if the device file does not exist?

[intermezzio]

Glad to hear it worked. I am looking into a better solution for activating the webcam - there's a way to store the virtual camera module and have it automatically enabled on boot, so I plan to put that in the installation script.

[bodograumann]

Ah, so currently I have to run weffe -a after every reboot?

[intermezzio]

At the moment, yes, because it's a kernel module. By adding the configuration to the installation, however, I should be able to make the virtual camera initialize on boot.

[intermezzio]

I've added scripts to install.sh to manually add the configuration for manual installation from source, but adding the configuration in the installation section of the PKGBUILD doesn't seem to work for me. I won't merge anything into the main branch until I can figure out how that gets installed, and I'll also change the flag weffe -a to allow a user to change the virtual camera name(s) and reactivate them at the same time.

[intermezzio]

As a side note here's why you saw a different version number on the weffe-git PKGBUILD https://unix.stackexchange.com/questions/149231/how-package-managers-update-packages-installed-using-git-packages#149296