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• How can I preview and republish a webcam stream with ffmpeg and PowerShell ? (Non-blocking buffered named pipe in Powershell)

  30 octobre 2020, par Marvin Irwin

  My question is a duplicate of this, except for powershell, however in the interest of avoiding the XY problem I'll describe my objective.

  


  I'd like to use ffmpeg to create a preview of my webcam, while broadcasting to another process which would like to use the video.

  


  I figure I'll created a named pipe in PowerShell, and use ffmpeg to preview the webcam with sdl while writing the output to the pipe and letting other process eavesdrop on it.

  


  $pipe = New-Object System.IO.Pipes.NamedPipeServerStream('webcam', [System.IO.Pipes.PipeDirection]::Out);

ffmpeg.exe `
-y `
-f dshow `
-i "video=vide_source:audio=audio_source" `
-f mjpeg \\.\\pipe\\webcam `
-pix_fmt yuv420p -window_x 0 -window_y 0 -f sdl :0 


  


  After running this command for a few seconds, ffmpeg warns me that my real-time buffer is full.

  


  How can I accept a pipe which accepts and emits/discards data immediately ?

  


• inline asm : fix arrays as named constraints.

  7 mai 2014, par Matt Oliver

  inline asm : fix arrays as named constraints.
  Signed-off-by : Michael Niedermayer <michaelni@gmx.at>
  

  • [DH] libavcodec/x86/cabac.h
  • [DH] libavcodec/x86/h264_i386.h
  • [DH] libavcodec/x86/idct_sse2_xvid.c
  • [DH] libavcodec/x86/lpc.c
  • [DH] libavutil/x86/asm.h
  • [DH] libswresample/x86/resample_mmx.h
  • [DH] libswscale/x86/yuv2rgb_template.c

• FFMPEG filter using named pipe for I/O to a forked program and legal consideration [closed]

  17 septembre 2021, par alexbuisson

  I would like to develop a ffmpeg filter to have an easier and better integration of the ffmpeg functionalities in case of complex command lines.

  



  Imagine an ffmpeg command line in which you can configure a filter that will use to configure a 3rd party executable to fork and use named pipe to pass video through that external tools.

  



  Technically I can write it, but the question is, is it legal from FFMPEG license point of view (FFMPEG can be GPL or LGPL depending of how it has been built). As far as I understand, if I have an executable called "my_video_transformation.exe" (no relationship with ffmpeg, it just read input pipe and write to output pipe)

  



  It's ok for a user to run the following :

  



  


  (FFMPEG GPL or LGPL).exe decoding_args | my_video_transformation.exe | (FFMPEG GPL or LGPL).exe encoding_args

  


  



  But it's not ok if a user can run something similar to :

  



  


  (FFMPEG GPL or LGPL).exe filter="my_video_transformation.exe" transcoding_args

  


  



  from my understanding of https://www.gnu.org/licenses/gpl-faq.html#GPLPlugins

  



  As soon as you write in a GPL or LGPL executable something that can fork and communicate with 3rd party and by the way maybe a commercial executable, it doesn't respect the license ?

  



  Maybe not the correct place to ask, but would like to have some feedback before starting that project. FFMPEG dev community will reject my code proposal if it's not legal or even border line.

  



  Regards