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• Is H.264 used with CRF 0 really strictly lossless ?

  23 décembre 2017, par Mephisto

  I am surprised by how small files are when encoded in ffmpeg with the libx264 codec in Constant Rate Factor mode equals zero (-crf 0) that, according to the documentation, is "lossless".

  I would like to make sure what the word "lossless" here means. I would like to know if it follows my personal definition of lossless video : After encoding a video, you can confidently bet the life of your mother that, once you play it, the numerical values in the pixels of the restored video will be identically equal (within maybe a factor 0.00001 due to the floating point arithmetic) to the original.

  Does the H.264 lossless encoding follow my definition, or do they call it "lossless" because it is visually very close, very beautiful, whatever... ?

• Video Edit with FFMpeg

  22 octobre 2020, par Max

  I have been trying to figure out small video editing with FFmpeg in Android.

  


  I want to make video to be stopped in some seek position with overlay for a few seconds.

  


  For example, there is original video, and overlay image file.

  


  After 3 seconds, the video will be looked as stopped with overlay for a few seconds (there will not be audio).
In a word, 5 seconds of video needs to be 8 seconds of video. (certain frame needs to be inserted with overlay for 3 seconds.)

  


  How can I solve this with FFMpeg ? If anyone know FFMpeg command for this edit, please help me.

  


• How can I save an animation from matplotlib as a mp4 video file ? [duplicate]

  19 décembre 2018, par Manza

  This question already has an answer here :

  • How can I overcome this key word error ?
    
    4 answers
    

  I’m trying to render a animation.ArtistAnimation object into a 24 fps video file in format mp4.

  I have search about and I reached this. However, even after compiling ffmpeg I get this error message :

  C:\Users\trite\OneDrive\Documentos\MusiTex\Python\venv\Scripts\python.exe 
  
  "C:/Users/trite/OneDrive/Documentos/MusiTex/Python/venv/Saving Animation.py"
  
  Traceback (most recent call last):
  
    File "C:\Users\trite\OneDrive\Documentos\MusiTex\Python\venv\lib\site- 
  
  packages\matplotlib\animation.py", line 161, in __getitem__
  
      return self.avail[name]
  
  KeyError: 'ffmpeg'
  
  
  
  During handling of the above exception, another exception occurred:
  
  
  
  Traceback (most recent call last):
  
    File "C:/Users/trite/OneDrive/Documentos/MusiTex/Python/venv/Saving 
  
  Animation.py", line 20, in <module>
  
      FFMpegWriter = manimation.writers['ffmpeg']
  
    File "C:\Users\trite\OneDrive\Documentos\MusiTex\Python\venv\lib\site- 
  
  packages\matplotlib\animation.py", line 164, in __getitem__
  
      'Requested MovieWriter ({}) not available'.format(name))
  
  RuntimeError: Requested MovieWriter (ffmpeg) not available
  
  
  
  Process finished with exit code 1
  
  </module>

  What is the problem with ?

  I would really appreciate if you can help me. Actually, if there is other ways to saving/render this kind of object into a video file (preferably mp4) I will be delighted to hear them.

  Thank you very much