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• avformat/mov : Fix parsing of saio/siaz atoms in encrypted content.

  7 décembre 2017, par Jacob Trimble

  avformat/mov : Fix parsing of saio/siaz atoms in encrypted content.
  This doesn't support saio atoms with more than one offset.
  Signed-off-by : Jacob Trimble <modmaker@google.com>
  
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavformat/isom.h
  • [DH] libavformat/mov.c

• Feeding content of an X-Window to a virtual camera

  11 mai 2022, par Ingo

  I want to feed a virtual webcam device from an application window (under Linux/Xorg). I have so far just maximised the window and then used ffmpeg to grab the whole screen like this :

  


  ffmpeg \
    -f x11grab -framerate 15 -video_size 1280x1024 -i :0+0,0 \
    -f v4l2 -vcodec rawvideo -pix_fmt yuv420p /dev/video6


  


  where /dev/video6 is my v4l2loopback device. This works and I can use the virtual camera in video calls in chrome. This also indicates that the v4l2loopback module is correctly loaded into the kernel.

  


  Unfortunately, it seems that ffmpeg can only read the whole screen, but not an application window. gstreamer on the other hand can. Playing around with gst-launch-1.0, I was hoping that I could get away with something like this :

  


  gst-launch-1.0 ximagesrc xid=XID_OF_MY_WINDOW \
    ! "video/x-raw" \
    ! v4l2sink device=/dev/video6


  


  However, that complains that Device '/dev/video6' is not an output device.

  


  Given that ffmpeg seems happy to write to /dev/video6 I also tried piping the gst output to ffmpeg like this :

  


  gst-launch-1.0 ximagesrc xid=XID_OF_MY_WINDOW \
    ! "video/x-raw" \
    ! filesink location=/dev/stdout \
    | ffmpeg -i - -codec copy -f v4l2 -vcodec rawvideo -pix_fmt yuv420p /dev/video6


  


  But then ffmpeg complains about Invalid data found when processing input.

  


  This is running inside an xvfb headless environment, so mouse interactions will not work. This rules out obs as far as I can see.

  


  I'm adding the chrome tag, because I see that chrome in principle would also provide a virtual camera via the --use-fake-device-for-media-stream switch. However, it seems that this switch only supports a static file rather than a stream.

  


  Although I don't see why, it might be relevant that the other "application window" window is simply a second browser window. So the setup is google meet (or similar) in one browser window and the virtual camera gets fed vrom a second browser window.

  


• avcodec/nvdec : Add support for decoding HEVC 4:4:4 content

  7 octobre 2018, par Philip Langdale

  avcodec/nvdec : Add support for decoding HEVC 4:4:4 content
  The latest generation video decoder on the Turing chips supports
  
  decoding HEVC 4:4:4. Supporting this is relatively straight-forward ;
  
  we need to account for the different chroma format and pick the
  
  right output and sw formats at the right times.
  There was one bug which was the hard-coded assumption that the
  
  first chroma plane would be half-height ; I fixed this to use the
  
  actual shift value on the plane.
  We also need to pass the SPS and PPS range extension flags.
  

  • [DH] libavcodec/hevcdec.c
  • [DH] libavcodec/nvdec.c
  • [DH] libavcodec/nvdec_hevc.c