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• FFMPEG Applying Mux Operation to All Files in Folder Structure

  28 septembre 2023, par EURSCVA MembroFoto

  I have two identical folder structures containing video files (containing varying audio channels) - one has the originals, one has proxy (lower res) versions.
The process of making the proxies messed with the sample rate of the audio, so now I need to replace the audio from each proxy clip with the audio of the respective original clip.

  


  It seems like that is something I can do with ffmpeg without transcoding all of the files again :

  


  $ ffmpeg -i original_clip.mov -i proxy_clip.mov -c copy -map 0:0 -map 1:1 proxy_new.mov


  


  The issue is I have no idea how to make this happen for all files in a folder structure, and with the output also ending up in an identical folder structure. Any help is really appreciated, this issue has caused quite a mess...

  


• how the packuswb instruction works ? (in low level bit operation)

  17 avril 2019, par MaikonNascimento

  Studying ffmpeg convertion from yuv to rgb , I came across the equation being implemented in assembly, yuv2rgb_template.c located in ffmpeg/libswscale/x86.

  I want to know how the instruction packuswb works ? Google says it :

  Converts 4 signed word integers from mm and 4 signed word integers from mm/m64 into 8 unsigned byte integers in mm using unsigned saturation.

      DEST[7:0] ← SaturateSignedWordToUnsignedByte DEST[15:0];
  
      DEST[15:8] ← SaturateSignedWordToUnsignedByte DEST[31:16];
  
      DEST[23:16] ← SaturateSignedWordToUnsignedByte DEST[47:32];
  
      DEST[31:24] ← SaturateSignedWordToUnsignedByte DEST[63:48];
  
      DEST[39:32] ← SaturateSignedWordToUnsignedByte SRC[15:0];
  
      DEST[47:40] ← SaturateSignedWordToUnsignedByte SRC[31:16];
  
      DEST[55:48] ← SaturateSignedWordToUnsignedByte SRC[47:32];
  
      DEST[63:56] ← SaturateSignedWordToUnsignedByte SRC[63:48];

  Since I dont know Assembly x86, it is even hard to simulate it or debug the current code.

  I want to know how they fit 16 bits in 8 bits ?

• ValueError : I/O operation on closed file with ffmpeg

  22 mars 2018, par AstroCoda

  I’m trying to get this (minimal working example) code to compile in a virtual environment on Anaconda which I’ve set up in a supercomputing cluster :

  import numpy as np
  
  import matplotlib
  
  matplotlib.use("Agg")
  
  import matplotlib.pyplot as plt
  
  import matplotlib.animation as manimation
  
  
  
  FFMpegWriter = manimation.writers['ffmpeg']
  
  metadata = dict(title='Movie Test', artist='Matplotlib',
  
              comment='Movie support!')
  
  writer = FFMpegWriter(fps=15, metadata=metadata)
  
  
  
  fig = plt.figure()
  
  l, = plt.plot([], [], 'k-o')
  
  
  
  plt.xlim(-5, 5)
  
  plt.ylim(-5, 5)
  
  
  
  x0, y0 = 0, 0
  
  
  
  with writer.saving(fig, "writer_test.mp4", 100):
  
      for i in range(100):
  
          x0 += 0.1 * np.random.randn()
  
          y0 += 0.1 * np.random.randn()
  
          l.set_data(x0, y0)
  
          writer.grab_frame()

  The thing is, this code works absolutely fine on my local machine (MacOSX) - Anaconda distribution ; Python 2.7 ; same matplotlib and numpy version, and I have ffmpeg on Anaconda ; I have ffmpeg on the cluster as well, albeit at a different version to the one on Python (but no issue with this on my local machine). When I run the code on the cluster, I get :

  Traceback (most recent call last):
  
    File "movie_test.py", line 25, in <module>
  
      writer.grab_frame()
  
    File "~/anaconda2/envs/test_movie/lib/python2.7/contextlib.py", line 35, in __exit__
  
      self.gen.throw(type, value, traceback)
  
    File "~/anaconda2/envs/test_movie/lib/python2.7/site-packages/matplotlib/animation.py", line 241, in saving
  
      self.finish()
  
    File "~/anaconda2/envs/test_movie/lib/python2.7/site-packages/matplotlib/animation.py", line 367, in finish
  
      self.cleanup()
  
    File "~/anaconda2/envs/test_movie/lib/python2.7/site-packages/matplotlib/animation.py", line 405, in cleanup
  
      out, err = self._proc.communicate()
  
    File "~/anaconda2/envs/test_movie/lib/python2.7/site-packages/subprocess32.py", line 927, in communicate
  
      stdout, stderr = self._communicate(input, endtime, timeout)
  
    File "~/anaconda2/envs/test_movie/lib/python2.7/site-packages/subprocess32.py", line 1713, in _communicate
  
      orig_timeout)
  
    File "~/anaconda2/envs/test_movie/lib/python2.7/site-packages/subprocess32.py", line 1769, in _communicate_with_poll
  
      register_and_append(self.stdout, select_POLLIN_POLLPRI)
  
    File "~/anaconda2/envs/test_movie/lib/python2.7/site-packages/subprocess32.py", line 1748, in register_and_append
  
      poller.register(file_obj.fileno(), eventmask)
  
  ValueError: I/O operation on closed file
  
  </module>

  All the searches I’ve made correspond to relatively simple text write in/out operations, but not for videos. Thanks in advance for the help !