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• ffmpeg : kmsgrab to v4l2 loopback device

  17 septembre 2020, par Vamshi Surabhi

  I've been trying to pipe my screen into a v4l2 loopback device (as a hack to share screen during calls on wayland). This is what I tried so far :

  


  $ sudo modprobe vl42loopback 
$ sudo ffmpeg -device /dev/dri/card0 -f kmsgrab -i - -vf 'hwmap=derive_device=vaapi,scale_vaapi=w=1920:h=1080:format=nv12' -f v4l2 /dev/video2 
ffmpeg version n4.3.1 Copyright (c) 2000-2020 the FFmpeg developers
  built with gcc 10.1.0 (GCC)
  configuration: --prefix=/usr --disable-debug --disable-static --disable-stripping --enable-avisynth --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-libsoxr --enable-libspeex --enable-libsrt --enable-libssh --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-nvdec --enable-nvenc --enable-omx --enable-shared --enable-version3
  libavutil      56. 51.100 / 56. 51.100
  libavcodec     58. 91.100 / 58. 91.100
  libavformat    58. 45.100 / 58. 45.100
  libavdevice    58. 10.100 / 58. 10.100
  libavfilter     7. 85.100 /  7. 85.100
  libswscale      5.  7.100 /  5.  7.100
  libswresample   3.  7.100 /  3.  7.100
  libpostproc    55.  7.100 / 55.  7.100
[kmsgrab @ 0x55f52ac85380] Using plane 55 to locate framebuffers.
[kmsgrab @ 0x55f52ac85380] Template framebuffer is 99: 3840x2160 32bpp 32b depth.
Input #0, kmsgrab, from 'pipe:':
  Duration: N/A, start: 1600327750.235546, bitrate: N/A
    Stream #0:0: Video: wrapped_avframe, drm_prime, 3840x2160, 29.83 tbr, 1000k tbn, 1000k tbc
Stream mapping:
  Stream #0:0 -> #0:0 (wrapped_avframe (native) -> rawvideo (native))
[video4linux2,v4l2 @ 0x55f52ac89e40] Unknown V4L2 pixel format equivalent for vaapi_vld
Could not write header for output file #0 (incorrect codec parameters ?): Invalid argument
Error initializing output stream 0:0 -- 
Conversion failed!


  


  Also tried adding -vcodec rawvideo -pix_fmt yuv420p as follows :

  


  sudo ffmpeg -device /dev/dri/card0 -f kmsgrab -i - -vf 'hwmap=derive_device=vaapi,scale_vaapi=w=1920:h=1080:format=nv12' -vcodec rawvideo -pix_fmt yuv420p -f v4l2 /dev/video2


  


  which failed with :

  


  ....
Stream mapping:
  Stream #0:0 -> #0:0 (wrapped_avframe (native) -> rawvideo (native))
Impossible to convert between the formats supported by the filter 'Parsed_scale_vaapi_1' and the filter 'auto_scaler_0'
Error reinitializing filters!
Failed to inject frame into filter network: Function not implemented
Error while processing the decoded data for stream #0:0
Conversion failed!


  


  How can I get this working ?

  


• lavu/buffer : add a convenience function for replacing buffers

  5 juin 2020, par Anton Khirnov

  lavu/buffer : add a convenience function for replacing buffers
  A common pattern e.g. in libavcodec is replacing/updating buffer
  
  references : unref old one, ref new one. This function allows simplifying
  
  such code and avoiding unnecessary refs+unrefs if the references are
  
  already equivalent.
  

  • [DH] doc/APIchanges
  • [DH] libavutil/buffer.c
  • [DH] libavutil/buffer.h
  • [DH] libavutil/version.h

• Using ffmpeg results in undesirable motion blur

  13 septembre 2020, par Oleg Yablokov

  I am trying to convert a video with the best quality possible. The problem is, no matter which command arguments I use, a motion blur appears (the first image is converted, the second is the original) :

  


  

  


  The ffprobe's output of the original video :

  


  ffmpeg version 4.2.2-1ubuntu1 Copyright (c) 2000-2019 the FFmpeg developers
built with gcc 9 (Ubuntu 9.3.0-3ubuntu1)
configuration: --prefix=/usr --extra-version=1ubuntu1 --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --arch=amd64 --enable-gpl --disable-stripping --enable-avresample --disable-filter=resample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libcodec2 --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libjack --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librsvg --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-lv2 --enable-omx --enable-openal --enable-opencl --enable-opengl --enable-sdl2 --enable-libdc1394 --enable-libdrm --enable-libiec61883 --enable-nvenc --enable-chromaprint --enable-frei0r --enable-libx264 --enable-shared
libavutil      56. 31.100 / 56. 31.100
libavcodec     58. 54.100 / 58. 54.100
libavformat    58. 29.100 / 58. 29.100
libavdevice    58.  8.100 / 58.  8.100
libavfilter     7. 57.100 /  7. 57.100
libavresample   4.  0.  0 /  4.  0.  0
libswscale      5.  5.100 /  5.  5.100
libswresample   3.  5.100 /  3.  5.100
libpostproc    55.  5.100 / 55.  5.100
Input #0, mpegts, from 'input.ts':
Duration: 00:00:30.24, start: 1.400000, bitrate: 26265 kb/s
Program 1
    Metadata:
    service_name    : Service01
    service_provider: FFmpeg
    Stream #0:0[0x100]: Video: mpeg2video (Main) ([2][0][0][0] / 0x0002), yuv420p(tv, top first), 1920x1080 [SAR 1:1 DAR 16:9], 25 fps, 25 tbr, 90k tbn, 50 tbc
    Stream #0:1[0x101](ita): Audio: ac3 ([129][0][0][0] / 0x0081), 48000 Hz, 5.1(side), fltp, 448 kb/s (clean effects)


  


  I've tried different combinations of the following arguments :

  


  ffmpeg \
-i input.ts \
-c:v libx264 \
-preset veryslow \
-qp 0 \
-minrate 25165824 \
-b:v 25165824 \
-r 25 \
-s 1920x1080 \
-aspect 16:9 \
-g 25 \
-crf 7 \
output.ts


  


  None of these settings helped. Please, could you tell me how to remove this motion blur ?

  


  EDIT : to be more specific, I leave a link to a shorten video ( 10 seconds). If you manage to convert it to hls (h.264 & .m3u8) without motion blur and with preserving the overall quality, it will be equivalent to the answer.