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• avcodec/vc2enc : Simplify writing dirac golomb codes

  8 mars, par Andreas Rheinhardt

  avcodec/vc2enc : Simplify writing dirac golomb codes
  The earlier code used a loop to determine the number of bits used
  
  and called ff_log2() on a power of two (and it would be easy to
  
  keep track of the exponent of said power-of-two) ; neither GCC nor
  
  Clang optimized the loop away or avoided the ff_log2().
  
  This patch replaces the loop and the log2 with a single av_log2().
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
  

  • [DH] libavcodec/vc2enc.c

• 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

• 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... ?