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• Generating movie from python without saving individual frames to files

  31 juillet 2022, par Paul

  I would like to create an h264 or divx movie from frames that I generate in a python script in matplotlib. There are about 100k frames in this movie.

  



  In examples on the web [eg. 1], I have only seen the method of saving each frame as a png and then running mencoder or ffmpeg on these files. In my case, saving each frame is impractical. Is there a way to take a plot generated from matplotlib and pipe it directly to ffmpeg, generating no intermediate files ?

  



  Programming with ffmpeg's C-api is too difficult for me [eg. 2]. Also, I need an encoding that has good compression such as x264 as the movie file will otherwise be too large for a subsequent step. So it would be great to stick with mencoder/ffmpeg/x264.

  



  Is there something that can be done with pipes [3] ?

  



  [1] http://matplotlib.sourceforge.net/examples/animation/movie_demo.html

  



  [2] How does one encode a series of images into H264 using the x264 C API ?

  



  [3] http://www.ffmpeg.org/ffmpeg-doc.html#SEC41

  


• Generating movie from python without saving individual frames to files

  31 juillet 2022, par Paul

  I would like to create an h264 or divx movie from frames that I generate in a python script in matplotlib. There are about 100k frames in this movie.

  



  In examples on the web [eg. 1], I have only seen the method of saving each frame as a png and then running mencoder or ffmpeg on these files. In my case, saving each frame is impractical. Is there a way to take a plot generated from matplotlib and pipe it directly to ffmpeg, generating no intermediate files ?

  



  Programming with ffmpeg's C-api is too difficult for me [eg. 2]. Also, I need an encoding that has good compression such as x264 as the movie file will otherwise be too large for a subsequent step. So it would be great to stick with mencoder/ffmpeg/x264.

  



  Is there something that can be done with pipes [3] ?

  



  [1] http://matplotlib.sourceforge.net/examples/animation/movie_demo.html

  



  [2] How does one encode a series of images into H264 using the x264 C API ?

  



  [3] http://www.ffmpeg.org/ffmpeg-doc.html#SEC41

  


• Using ffprobe/ffmpeg to extract individual frames and types in encode order

  24 janvier 2018, par Hélder

  I am able to extract keyframes using ffmpeg. Something like this that I have been using :

  ffmpeg -i input.mp4 -vf "select='eq(pict_type\,I)" -vsync vfr -qscale:v 2 I-thumbnails-%02d.png -vf "select='eq(pict_type\,B)" -vsync vfr -qscale:v 2 B-thumbnails-%02d.png -vf "select='eq(pict_type\,P)" -vsync vfr -qscale:v 2 P-thumbnails-%02d.png

  Now the issue is, I would like these extracted frames to be in encode order, if possible, the way they are extracted should have a timestamp or any way to know that they start in a certain sequence, example, from start to end :

  IBBBIPPB......BI

  but in a way that I can sort the frames in the encode sequence.

  I want to use this to load in python to extract motion vectors but they should all follow the encoding sequence. Any help ?

  Edit :
  Changed playback to encode sequence(or order).