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• ffmpeg scale 4k video and add subtitles

  29 novembre 2020, par goodkid38

  I am having trouble scaling video from 4k to 1080 while still retaining the video sub titles. These subtitles are PGS based and therefore need to be baked into the output video. In order to scale the video I am using ffmpeg with a filter_complex like so :

  


  '-filter_complex', `[0:v][0:s:randomSubtitleHere]scale=1920:1080[scaled];[scaled][0:s:0]overlay[v]`, 
'-map', '[v]', '-map', 
`0:a:${movieTitle['audioSelect']}`,


  


  This will give me the video at 1080, but it i still am not seeing the subtitles I have selected.

  


• ffmpeg selects shortest movie but leaves full length audio

  26 octobre 2015, par Stan James

  I’ve created a tool to create a grid of movies, like in the Brady Bunch opening. It’s a cool, funny effect.

  Here’s a sample movie showing the grid.

  

  The problem is that ffmpeg is choosing the shortest movie to determine the maximum length of overlaid videos, but still using the full length of the first audio track to determine the overall output movie length.

  So all my videos stop moving when the shortest one ends, but the audio plays on for full length of the first movie.

  How can I either (1) set the length of the output movie to the longest input movie or (2) match the audio length to the shortest movie length as well ?

  Gist of my script.

  Based on this ffmpeg example usage which exhibits the same audio problem :

  ffmpeg
  
      -i 1.avi -i 2.avi -i 3.avi -i 4.avi
  
      -filter_complex "
  
          nullsrc=size=640x480 [base];
  
          [0:v] setpts=PTS-STARTPTS, scale=320x240 [upperleft];
  
          [1:v] setpts=PTS-STARTPTS, scale=320x240 [upperright];
  
          [2:v] setpts=PTS-STARTPTS, scale=320x240 [lowerleft];
  
          [3:v] setpts=PTS-STARTPTS, scale=320x240 [lowerright];
  
          [base][upperleft] overlay=shortest=1 [tmp1];
  
          [tmp1][upperright] overlay=shortest=1:x=320 [tmp2];
  
          [tmp2][lowerleft] overlay=shortest=1:y=240 [tmp3];
  
          [tmp3][lowerright] overlay=shortest=1:x=320:y=240
  
      "
  
      -c:v libx264 output.mkv

• 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