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• Translating ffmpeg command line to C++ codec settings

  6 mars 2014, par pacificator

  I've been doing some work in ffmpeg for a while in C++.
  Most of the help regarding encoder settings is explained as command line options.
  For example (taken from the ffmpeg site) :

  -mbd rd -trellis 2 -cmp 2 -subcmp 2 -g 100 -pass 1/2’ 

  but beware the ’-g 100’ might cause problems with some decoders. Things to try :

   ’-bf 2’, ’-flags qprd’, ’-flags mv0’, ’- flags skiprd.

  This is not really usefull when you want to set these options in C.
  For example I managed to find int trellis ; in the AVCodecContext struct so that is one solved, but what about the others ?

  Is there a way to determine what command line parameters correspond to what AVCodecContext members ?
  I tried setting them like this :

  AVCodecContext* c;
  
  av_opt_set_int(c->priv_data, "cmp", 2, 0);

  But this returns an error code that the option does not exist.
  I've also tried :

    av_opt_set(c->priv_data, "cmp", "2", 0);

  I still get the error that the option does not exist.

  So, is there a way to determine what AVCodecContext members I should set that are equivalent to the ffmpeg command line parameters above ?

• Pipe each ffmpeg output to command line

  6 septembre 2016, par Max13

  I would like to output a screenshot every X seconds of a video using ffmpeg, but I also would like to pipe each output to another command.

  Here is my screenshot command : ffmpeg -i video.mp4 -vf fps=1/5 sh%03d.png (one image every 5 seconds).

  I would like to do as find’s argument -exec do, allowing the user to execute a command for each output. Is this possible ? This is the first time I’m using ffmpeg, thanks for your help.

• trailing options found on command line ffmpeg

  1er juillet 2016, par asad

  ffmpeg complains about trailing options. What parameters are out of the order. I am unable to find any. Please point out some.

   /home/ec2-user/bin/ffmpeg -thread_queue_size 1024 -probesize 18M 
  
      -re -f rawvideo -framerate 1 -pixel_format rgb32 -video_size 1920x1080 
  
      -i pipe:0 -i /home/ec2-user/logo.png 
  
      -i /home/ec2-user/testdata/audio.m4a -ss 0 -t 20 
  
      -filter_complex "[0:v]vflip[main];[1:v]scale=1920/10:-1[si], [main][si]overlay=5:5:format=rgb,format=yuv420p" 
  
      -c:v libx264 /home/ec2-user/output.mp4 
  
      -c:v copy -shortest