[FFmpeg-user] A question on KMS and kmsgrab

[Dennis Mungai]

Hello there,

Can kmsgrab be used with NVIDIA GPUs?
I ask because running the sample command in the docs:

ffmpeg -loglevel debug -f kmsgrab -i - -vf 'hwdownload,format=bgr0'
output.mp4

Results in failure:

ffmpeg -loglevel debug -f kmsgrab -i - -vf 'hwdownload,format=bgr0'
output.mp4
ffmpeg version N-94423-ga0c1970781 Copyright (c) 2000-2019 the FFmpeg
developers
  built with gcc 7 (Ubuntu 7.4.0-1ubuntu1~18.04.1)
  configuration: --pkg-config-flags=--static --prefix=/home/brainiarc7
--bindir=/home/brainiarc7/bin --extra-cflags=-I/home/brainiarc7/include
--extra-ldflags=-L/home/brainiarc7/lib --enable-cuda-nvcc --enable-cuvid
--enable-libnpp --extra-cflags=-I/usr/local/cuda/include/
--extra-ldflags=-L/usr/local/cuda/lib64/ --enable-nvenc
--extra-cflags=-I/opt/intel/mediasdk/include
--extra-ldflags=-L/opt/intel/mediasdk/lib
--extra-ldflags=-L/opt/intel/mediasdk/plugins --enable-libmfx
--enable-libass --enable-vaapi --disable-debug --enable-libvorbis
--enable-libvpx --enable-libdrm --enable-opencl --enable-gpl --cpu=native
--enable-opengl --enable-libfdk-aac --enable-libx264 --enable-libx265
--enable-openssl --enable-librtmp --enable-libv4l2 --enable-libpulse
--enable-pic --extra-libs='-lpthread -lm -lz -ldl' --enable-nonfree
  libavutil      56. 32.100 / 56. 32.100
  libavcodec     58. 55.100 / 58. 55.100
  libavformat    58. 30.100 / 58. 30.100
  libavdevice    58.  9.100 / 58.  9.100
  libavfilter     7. 58.100 /  7. 58.100
  libswscale      5.  6.100 /  5.  6.100
  libswresample   3.  6.100 /  3.  6.100
  libpostproc    55.  6.100 / 55.  6.100
Splitting the commandline.
Reading option '-loglevel' ... matched as option 'loglevel' (set logging
level) with argument 'debug'.
Reading option '-f' ... matched as option 'f' (force format) with argument
'kmsgrab'.
Reading option '-i' ... matched as input url with argument '-'.
Reading option '-vf' ... matched as option 'vf' (set video filters) with
argument 'hwdownload,format=bgr0'.
Reading option 'output.mp4' ... matched as output url.
Finished splitting the commandline.
Parsing a group of options: global .
Applying option loglevel (set logging level) with argument debug.
Successfully parsed a group of options.
Parsing a group of options: input url -.
Applying option f (force format) with argument kmsgrab.
Successfully parsed a group of options.
Opening an input file: -.
[kmsgrab @ 0x5639923b7ec0] Failed to open DRM device.
pipe:: Invalid argument