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• How to export mestimate filter motion vectors into a separate file with ffmpeg binary ?

  20 juin 2022, par Hitokage

  So mestimate filter can be used to compute the motion vectors in a video. They can also be displayed. Is there a way to export them into a separate file using the ffmpeg binary ? I would love to have them for example in an image like 2-component color values representing the 2D vectors for each block (so the resolution would be the original one divided by the block size) or something.
Given a sequence of png frames, I can do :

  


  ffmpeg -i %04d.png -vf "mestimate" test.mkv


  


  And as I understand it, the vectors are then stored in the frames' side data which can be extracted using libav. Is there a simple way with the ffmpeg tool alone ? Thanks.

  


• moviepy ffmpeg stderr to tkinter interface

  1er avril 2018, par Alexander Perlman

  Hi stackoverflow community,

  I’m a novice python hobbyist. I wrote a python / ffmpeg script using moviepy that batch concatenates videos. I then designed an interface using tkinter.

  Now I want to redirect the stderr output from FFMPEG to the tkinter interface so that users can review the progress directly in app instead of needing the Sublime text console.

  I’ve done a lot of research but I’m in way over my head. Any tips would be greatly appreciated.

  Here’s the moviepy component. The gui is pretty cut and dry

  #import video clips 
  
  mainvid = VideoFileClip(fullpath, audio=True)
  
  intro = VideoFileClip("intro.mp4", audio=True)
  
  black = VideoFileClip("black1s.mp4", audio=True)
  
  
  
  #concatenate video clips 
  
  final = concatenate_videoclips([black, intro, mainvid, black]) final.fps=24 
  
  
  
  #actually write file 
  
  final.write_videofile(output, audio=True, audio_fps=48000, ffmpeg_params=[ "-r","24000/1001", "-b:v", "50M", "-level:v", "4.1", "-c:a", "libvo_aacenc", "-b:a", "256K", "-colorspace", "bt709"])

• How to write a filter for ffmpeg that burn subtitles using a subtitle stream directly

  20 mars 2014, par Filimindji

  Let say I have an MKV with a video stream, an audio stream and a subtitles stream.

  I would like to burn this subtitle into my video directly from the subtitle stream.

  so far, this is my command line :

  ffmpeg.exe -i "MyMovie.mkv" -map 0:0 -map 0:1 -vf subtitles=sub.srt out.mkv

  So far so good. But, my subtitles are inside the movie and I need to extract them before. I used this :

  ffmpeg.exe -i "MyMovie.mkv" -f srt sub.srt

  But this operation is too long : 25 sec on my PC for a 2.5Go MKV. I need something faster because I need to start streaming the output to an app as soon as possible. (I did not mentioned the others command line arguments I used to achieve this streaming properly because my question is not about that.)

  I know it is not possible to get the stream directly like this :

  ffmpeg.exe -i "MyMovie.mkv" -map 0:0 -map 0:1 -vf subtitles=[0:s:0] out.mkv

  But this is something I would love.

  edit :

  But I already know this kind of command line do not exist. (But if I'm wrong, please, let me know.)

  Now, I would like to write this kind of filter myself, and compile ffmpeg with it.
  But I have no idea where to start.

  Can anyone help me to start ?

  Thank you