linux : Virtual Desktop webcam : error v4l2

[Sylvain-07]

Virtual Webcam Desktop don't work's

error in my terminal :
[code][sylvain-sa@SYLVAIN-SA Desktop]$ webcamoid
libv4l2: error getting pixformat: Argument invalide VideoCapture: Can't set format: "YUYV" [/code]

[sylvain-sa@SYLVAIN-SA Desktop]$ webcamoid -v
Webcamoid 8.5.0
[sylvain-sa@SYLVAIN-SA Desktop]$ ffmpeg -version
ffmpeg version N-91132-gcadf7a7f39 Copyright (c) 2000-2018 the FFmpeg developers
built with gcc 8.1.0 (GCC)
configuration: --prefix=/usr --extra-cflags=-I/opt/cuda/include --extra-ldflags=-L/opt/cuda/lib64 --extra-libs=-lpthread --disable-rpath --enable-gpl --enable-version3 --enable-nonfree --enable-shared --disable-static --enable-gray --enable-avresample --enable-alsa --enable-avisynth --enable-bzlib --enable-chromaprint --enable-frei0r --enable-gcrypt --enable-gmp --enable-gnutls --enable-iconv --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcelt --enable-libcdio --enable-libcodec2 --enable-libdc1394 --enable-libfdk-aac --enable-libflite --enable-fontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libiec61883 --enable-libilbc --enable-libjack --enable-libkvazaar --enable-libmodplug --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --disable-libopencv --enable-libopenh264 --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librsvg --enable-librubberband --enable-librtmp --enable-libshine --enable-libsmbclient --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libssh --enable-libtesseract --enable-libtheora --disable-libtls --enable-libtwolame --enable-libv4l2 --enable-libvidstab --enable-libvmaf --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs --enable-libxcb --enable-libxcb-shm --enable-libxcb-xfixes --enable-libxcb-shape --enable-libxvid --enable-libxml2 --enable-libzimg --enable-libzmq --enable-libzvbi --enable-lv2 --enable-lzma --enable-decklink --enable-libndi_newtek --enable-libmysofa --enable-openal --enable-opencl --enable-opengl --disable-openssl --enable-sndio --enable-sdl2 --enable-vapoursynth --enable-xlib --enable-zlib --enable-cuda-sdk --enable-cuvid --enable-ffnvcodec --enable-libdrm --enable-libmfx --enable-libnpp --enable-nvdec --enable-nvenc --enable-omx --enable-omx-rpi --enable-rkmpp --enable-v4l2-m2m --enable-vaapi --enable-vdpau
libavutil 56. 18.102 / 56. 18.102
libavcodec 58. 19.102 / 58. 19.102
libavformat 58. 15.100 / 58. 15.100
libavdevice 58. 4.100 / 58. 4.100
libavfilter 7. 24.100 / 7. 24.100
libavresample 4. 0. 0 / 4. 0. 0
libswscale 5. 2.100 / 5. 2.100
libswresample 3. 2.100 / 3. 2.100
libpostproc 55. 2.100 / 55. 2.100

[sylvain-sa@SYLVAIN-SA Desktop]$ v4l2-ctl --list-device
camoid (platform:v4l2loopback-000):
/dev/video2

Webcam C170: Webcam C170 (usb-0000:00:1a.0-1.4):
/dev/video0
/dev/video1

[Sylvain-07]

It's not work since i have upgrade my kernel to 4.16.9
before it work correctly.
i have reinstal ffmpeg, v4l2, webcamoid : not solve.
Since this upgrade my web cam has 2 dev :
/dev/video0 and /dev/video1 : it's the same webcam. : before /dev/video0

[hipersayanX]

It seems to be a bug in v4l2loopback it self, here is the related issue, you may report the bug there, there is a lot of people with the same exact issue.
For me, I'm about to finish writing the virtual camera for Windows, and start writing my own virtual camera for Linux and remove v4l2loopback as dependency.

Since this upgrade my web cam has 2 dev :
/dev/video0 and /dev/video1 : it's the same webcam. : before /dev/video0

I'm experiencing the same in Arch Linux but is not related to Webcamoid, it seems a bug related to Arch Linux, here is the related report, I did removed the v4l2loopback package and the phantom video device still persists.

Maybe this a problem of the 4.16 version of Linux kernel itself?

[Sylvain-07]

Today :
i have upgraded to kenel 4.16.11
recompile v4l2loopback-dkms-git
to patch soluce : https://github.com/umlaeute/v4l2loopback/blob/master/v4l2loopback.c#L2096
I have recompile webcamoid

manually Virtual Desktop webcam work correctly witch
ffmpeg -f x11grab -r 15 -s 1920x1080 -i :0.0+0,0 -vcodec rawvideo -pix_fmt yuv420p -threads 0 -f v4l2 /dev/video2

but it's alway's out witch webcamoid

[hipersayanX]

Some updates on virtual camera for Linux. From my previous comment:

For me, I'm about to finish writing the virtual camera for Windows, and start writing my own virtual camera for Linux and remove v4l2loopback as dependency.

I'm actually planning to keep support for v4l2loopback (for high performance), but at same I'm experimenting with fuse to create a user space virtual camera, may be much easier to maintain while giving support for other POSIX compliant operating systems for free.

[hipersayanX]

Fixed in 8.5.0.