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• FFMPEG filter 10 frames per second without running through all frames ?

  15 mars 2017, par Kitsune

  I’m trying to process a video through ffmpeg and only need 10 frames per second regardless of the FPS of the original movie file.
  I run the frames through a pipe then call a function to process the frame.

  So what I want is that it scans only 10 frames a second even if the movie runs at 30. So it would for example end up with every 3rd frames (per sec.)

  I’v tried -vf ’select=not(mod(t\,1/10))’ which does make it so that it sends less calls to my function (which reacts to each frames send to a pipe.)

  But the processing takes just as long as without the filter. Setting the -r FPS after the input I receive errors : "[image2pipe @ 0x7fb3d3008a00] Application provided invalid, non monotonically increasing dts to muxer in stream 0 : 788 >= 788" it also does not change the amount of frames being output.

  FFMPEG Commandline :
  FFMPEG_BIN = "ffmpeg"
  command = [ FFMPEG_BIN,
  ’-threads’, ’0’,
  ’-i’, filename,
  ’-f’, ’image2pipe’,
  ’-pix_fmt’, ’rgb24’,
  ’-vsync’, ’0’,
  ’-vf’, ’scale=320:180’, # ,select=not(mod(t\,10/1))
  ’-an’,
  ’-sn’,
  #’-r’, ’10’,
  ’-vcodec’, ’rawvideo’,
  ’-’
  ]
  pipe = sp.Popen(command, stdout=sp.PIPE, bufsize=10**8)

  I send the frames using : process_frame(pipe.stdout.read(width*height*3))
  So far no matter what I try, -r -vf filters.. It either does not speed up, or I still get the full amount of frames calling my function.

• avformat/hls : Pass a copy of the URL for probing

  29 juin 2020, par Michael Niedermayer

  avformat/hls : Pass a copy of the URL for probing
  The segments / url can be modified by the io read when reloading
  This may be an alternative or additional fix for Ticket8673
  
  as a further alternative the reload stuff could be disabled during
  
  probing
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavformat/hls.c

• ffmpeg output parse in batch script

  5 juin 2022, par vlad2005

  I am totally unfamiliar with scripts in Windows, but are forced to use such a script. I would like someone to help me with the following problem. I want to process the output from ffmpeg command to save information about access an webcam to be used later.
More precisely command is following :

  



  ffmpeg -stats -hide_banner -list_devices true -f dshow -i dummy


  



  and output is like this :

  



  [dshow @ 02cec400] DirectShow video devices (some may be both video and audio devices)
[dshow @ 02cec400]  "Microsoft LifeCam Studio"
[dshow @ 02cec400]     Alternative name "@device_pnp_\\?\usb#vid_045e&pid_0772&mi_00#6&2a15e69b&0&0000#{65e8773d-8f56-11d0-a3b9-00a0c9223196}\global"
[dshow @ 02cec400] DirectShow audio devices
[dshow @ 02cec400]  "Desktop Microphone (3- Studio -"
[dshow @ 02cec400]     Alternative name "@device_cm_{33D9A762-90C8-11D0-BD43-00A0C911CE86}\Desktop Microphone (3- Studio -"
[dshow @ 02cec400]  "Line In (High Definition Audio "
[dshow @ 02cec400]     Alternative name "@device_cm_{33D9A762-90C8-11D0-BD43-00A0C911CE86}\Line In (High Definition Audio "
[dshow @ 02cec400]  "Microphone (High Definition Aud"
[dshow @ 02cec400]     Alternative name "@device_cm_{33D9A762-90C8-11D0-BD43-00A0C911CE86}\Microphone (High Definition Aud"


  



  Typically, the first two occurence for ”Alternative name” from DirectShow correspond to video and audio, so for simplicity I want these two information saved in two variables.
In this example is :

  



  @device_pnp_\\?\usb#vid_045e&pid_0772&mi_00#6&2a15e69b&0&0000#{65e8773d-8f56-11d0-a3b9-00a0c9223196}\global


  



  and

  



  @device_cm_{33D9A762-90C8-11D0-BD43-00A0C911CE86}\Desktop Microphone (3- Studio -


  



  Can someone more experienced to help me with this task ?
Thanks in advance !