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• Silence h264 decoding warnings when called from OpenCV in Python

  26 juillet 2018, par Raubtaube

  I have the following script with which I read RTSP streams from withing Python3 using OpenCV.

  cap = cv2.VideoCapture(ID)
ret, frame = cap.read()

  The streams are encoded using h264 and I get tons of warnings and error messages.

  [h264 @ 0x7f74cc430c80] co located POCs unavailable
[h264 @ 0x7f74b4258160] error while decoding MB 38 2, bytestream -19

  I tried to silence them using a context manager for redirecting stdout and stderr but with no success :

  class SilenceOutput(object):
  
      def __enter__(self):
  
          self._original_stdout = sys.stdout
  
          self._original_stderr = sys.stderr
  
          sys.stdout = None
  
          sys.stderr = None
  
  
  
      def __exit__(self, exc_type, exc_val, exc_tb):
  
          sys.stdout = self._original_stdout
  
          sys.stderr = self._original_stderr

• Anomalie #4402 (Fermé) : Liste de notices

  12 février 2021, par cedric -

  je ferme ce ticket, car un ticket qui référence un wiki qui liste des patches, ça commence à ressembler à un jeu de pistes
  + depuis novembre 2019 ces notices ont été corrigée
  + maintenant proposer une PR pour chaque cas quand on tombe dessus ça sera beaucoup plus efficace

• The proper way to limit framerate when recording screen on macOS

  5 juillet 2024, par jsx

  macOS 14.5, FFmpeg 7.0.1. To record the screen, if I use the code from Wiki, that is,

  


  ffmpeg -f avfoundation -i 1 output.mp4


  


  the frame rate seems to be so high that when I press q to stop recording, the following message persists until my MacBook Pro starts to noise by its cooler : "[q] command received. Exiting."

  


  My current solution is to add -r after -i :

  


  ffmpeg -f avfoundation -i 1 -r 24 output.mp4


  


  But I heard that a more correct solution is to replace -r with -framerate and to put it before instead of after -i :

  


  


  ffmpeg -f avfoundation -framerate 24 -i 1 output.mp4


  


  Note that I used -framerate as an input option instead of -r 24 as an output option, so I'm telling avfoundation to record at 24fps instead of recording at the default fps and then forcing FFmpeg to drop or duplicate frames to give you the desired 24.

  


  


  This doesn't work for me currently, and appears to be the same as I don't use -r at all.

  


  And so, what is the proper way to fix the "too high framerate" issue when recording the screen on macOS ? Do we need -r or instead -framerate, and where to put it, before or after -i ?

  


  Just in case, here is the log of ffmpeg -f avfoundation -i 1 output.mp4 -v verbose :

  


  https://github.com/jsx97/test/blob/main/ffmpeg.log