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• lavfi/vf_libplacebo : split and refactor logic

  5 mai 2023, par Niklas Haas

  lavfi/vf_libplacebo : split and refactor logic
  This commit contains no functional change. The goal is merely to
  
  separate the highly intertwined `filter_frame` and `process_frames`
  
  functions into their separate concerns, specifically to separate frame
  
  uploading (which is now done directly in `filter_frame`) from emitting a
  
  frame (which is now done by a dedicated function `output_frame`).
  The overall idea here is to be able to ultimately call `output_frame`
  
  multiple times, to e.g. emit several output frames for a single input
  
  frame.
  

  • [DH] libavfilter/vf_libplacebo.c

• How to input an audio file, generate video, split, crop and overlay to output a kaleidoscope effect

  29 septembre 2017, par wrrkkksstffrrg

  I need to create an FFMPEG script which reads in an audio file ("testloop.wav" in this example) generates a video from the waveform using the "showcqt" filter , and then crops and overlays the output from that to generate a kaleidoscope effect. This is the code I have so far - the generation of the intial video and the output section work correctly, but there is a fault in the split, crop and overlay section which I cannot trace.

      ffmpeg -i "testloop.wav" -i "testloop.wav" \
  
  -filter_complex  "[0:a]showcqt,format=yuv420p[v]" -map "[v]" \
  
          "split [tmp1][tmp2]; \
  
          [tmp1] crop=iw:(ih/3)*2:0:0, pad=0:ih+ih/2 [top]; \
  
          [tmp2] crop=iw:ih/3:0:(ih/3)*2, hflip [bottom]; \
  
          [top][bottom] overlay=0:(H/3)*2"\
  
  -map 1:a:0 -codec:v libx264 -crf 21 -bf 2 -flags +cgop -pix_fmt yuv420p -codec:a aac -strict -2 -b:a 384k -r:a 48000 -movflags faststart "${i%.wav}.mp4

• Python - Popen(shlex.split(command), shell=False) - not working with ffmpeg

  1er octobre 2014, par speedyrazor

  I am using Popen(shlex.split(command) to run an ffmpeg command which saves out wav files from a quicktime mov file and also save an ffmpeg log file at the same time. if I use this :

  command = './ffmpeg/ffmpeg -i /Users/me/Documents/MOVS/source.mov -map 0:1 -acodec pcm_s16le -y /Users/me/Documents/MOVS/source_01.wav'
  
  
  
  p = Popen(shlex.split(command), shell=False)

  Then the command completes correctly, but if I add the line which saves out a logfile then it no longer works, so if I use :

  command = './ffmpeg/ffmpeg -i /Users/me/Documents/MOVS/source.mov -map 0:1 -acodec pcm_s16le -y /Users/me/Documents/MOVS/source_01.wav 2> /Users/me/Documents/MOVS/lofFile.txt'
  
  
  
  p = Popen(shlex.split(command), shell=False)

  Then it no longer works. Using either command in the command line, without python, works fine. If I just use :

  p = Popen(command, shell=True)

  Then all works well, but I need to use the shell=False for other reasons.

  I just can’t understand why it breaks by adding the ’correct’ end line of 2> /Users/me/Documents/MOVS/lofFile.txt