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• Cutting movie with ffmpeg result in audio/video desync

  15 mai 2020, par T4ng10r

  I've concate long ago set of movies taken during some lecture. Now I want to cut them for each question/answer.

  



  I do it like this.

  



  


  ffmpeg -ss 00:00:34.7 -t 00:10:44.6 -y -i input_movie.mp4 -vcodec copy -acodec copy output_1.mp4

  
 


  ffmpeg -ss 00:11:22.2 -y -i input_movie.mp4 -vcodec copy -acodec copy output_2.mp4

  


  



  Yet, for the second part I can't set proper starting point so audio and video would be in sync.
  
Usually I could fix it with small tweeks in cut start time (like .1, .2, and so on). For this case this doesn't work.
  
When I play second cut in mplayer video is few second behind audio (where audio is cut properly). When I jump forward and back - all is again in sync.

  



  Where's the problem ? How to fix it ?

  


• Handling an arbitrary number of start and stop time pairings to cut a movie file down

  9 juin 2019, par Kieran

  I am writing a function that takes a list of tuples and a file path string as arguments and outputs a cut down video that only includes the frames that fall inside the start/stop pairings provided.

  I’m getting stuck because I am not sure whether the .trim() method of the ’infile’ object is altering the existing object or or creating a new one or doing something else entirely.

  the list of start/stop frame pairings can be arbitrarily long, every example I have found has been for a specific number of start and stop pairings and I can’t find anything describing what data structure needs to be passed back to ffmpeg.concat().

  My code is displayed below :

  import ffmpeg
  
  
  
  frameStamps = [(50,75),(120,700),(1250,1500)]
  
  videoFilePath = 'C:/Users/Kieran/Videos/testMovie.mp4'
  
  outputFolder = 'C:/Users/Kieran/Videos/'
  
  
  
  def slice_video(frameStamps, videoFilePath, outputFolder):
  
  
  
      originalFile = ffmpeg.input(videoFilePath)
  
  
  
      for stamp in frameStamps:
  
          ffmpeg.concat(originalFile.trim(start_frame=stamp[0], end_frame=stamp[1]))
  
  
  
  
  
      ffmpeg.output(outputFolder + 'testoutput.mp4')
  
      ffmpeg.run() 
  
  
  
  slice_video(frameStamps, videoFilePath, outputFolder)

  Now I am able to get the following when I individually print out originalFile.trim() which are getting recognised in the console as "FilterableStream" objects

  trim(end_frame=75, start_frame=50)[None] <29b4fb0736ec>
  
  trim(end_frame=700, start_frame=120)[None] <c66c4e1a48f5>
  
  trim(end_frame=1500, start_frame=1250)[None] &lt;13e0697a5288>  
  
  </c66c4e1a48f5>

  and I have tried passing them back as a list, dictionary and tuple and haven’t been able to get it working

  Output Errors :

    File "C:/Users/Kieran/Example.py", line 21, in slice_video
  
  ffmpeg.output(outputFolder + 'testoutput.mp4')
  
  
  
    File "C:\ProgramData\Anaconda3\lib\site-packages\ffmpeg\_ffmpeg.py", line 94, in output
  
  return OutputNode(streams, output.__name__, kwargs=kwargs).stream()
  
  
  
    File "C:\ProgramData\Anaconda3\lib\site-packages\ffmpeg\nodes.py", line 282, in __init__
  
  kwargs=kwargs
  
  
  
    File "C:\ProgramData\Anaconda3\lib\site-packages\ffmpeg\nodes.py", line 170, in __init__
  
  self.__check_input_len(stream_map, min_inputs, max_inputs)
  
  
  
    File "C:\ProgramData\Anaconda3\lib\site-packages\ffmpeg\nodes.py", line 149, in __check_input_len
  
  raise ValueError('Expected at least {} input stream(s); got {}'.format(min_inputs, len(stream_map)))
  
  
  
  ValueError: Expected at least 1 input stream(s); got 0

• FFMPEG hold multiple frames and use as a movie

  18 juin 2019, par Cole

  I have a video that I’m trying to create jump shots from. For example I want the output of my command to show frame 5 of the original clip for 30 frames, and frame 25 of the OG clip to show for 30 frames.

  assuming the OG clip is 30 FPS

  ffmpeg -t 1 -i og_clip.mp4 -filter_complex "
  
      [0]select=eq(n\,5)[H1];[0][H1]overlay[O1];
  
      [0]select=eq(n\,25)[H2];[0][H2]overlay[O2];
  
      [O1][O2]concat=n=2[Merge]" -map "[Merge]" out.mp4

  The above doesnt work right.

  What I’ve been doing up until now has been a two part command :

  ffmpeg -i og_clip.mp4 -vf "select=eq(n\,5)" -vframes 1 -y out_0.png
  
  ffmpeg -i og_clip.mp4 -vf "select=eq(n\,25)" -vframes 1 -y out_1.png
  
  ffmpeg -t 1 -i og_clip.mp4 -i out_0.png -i out_1.png -filter_complex "
  
      [0][1]overlay[H1];[0][2]overlay[H2];
  
      [H1][H2]concat=n=2[Merge]" -map "[Merge]" out.mp4

  Which has been working for me. The only problem is that the process of converting to a png first for each frame I want to use, takes too long. I’m trying to condense it all into one command. I figure that the encoding of the png is what takes so long.

  Any help would be much appreciated !