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• ffmpeg with partial motion detection

  2 mars 2021, par Silentfury

  I have video files from a static surveillance camera and I try to re-encode them using some sort of motion detection filter (keeping the movements, droping the stills) in order to save space and play time.

  


  I have successfully tried the two below filter options but it still feels not good enough. :

  


  

  • mpdecimate e.g. -vf "mpdecimate=hi=6480:lo=6420:frac=0.1,setpts=N/(15*TB)"

  


  • select (e.g. -vf "select=gt(scene,0.4)")

  


  


  The main problem is a moving bush in the camera view, that I would like to exclude from the motion detection.

  


  Is there other/better ways of applying motion detection (and stills dropping) to ffmpeg ?
Is there any way to mask areas of the video that will be ignored in the above mentioned (or any other) motion detection filter/method ?

  


  Many thanks in advance !

  


  Edit :
in the mean time I found this excellent answer from Gyan

  


  I am testing this now but would still appreciate other ideas

  


• matplotlib funcanimation save issue

  20 avril 2015, par Richie Abraham

  I have been trying some animation recently using matplotlib animations. It has been going great, i create an ffmpeg writer and save it as a video file. However i face an issue whenever the function that FuncAnimation calls returns more than one object.

  Below is a small snippet of my code base. When I return both im0 and im1, the video file created only has im1 , although the plt.show command works as expected ( showing both the videos ). If i return just a single im0, then it works as expected. IT also works as expected if i return both im0 and im1 with alpha=0.5.

  Can anyone shed some light on what is happening underneath the hood ?

  fig, ax = plt.subplots(1)
  
  def animate(i):
  
      im0=ax.imshow(np.ma.masked_array(imgl[i][:,:,0], mask=get_blob(i)),cmap='cubehelix')
  
  
  
      im1=ax.imshow(imgl[(i-100)%len(imgl)][:,:,0],cmap='cubehelix')
  
  
  
      return [im1,im0]
  
  
  
  
  
  
  
  ani = animation.FuncAnimation(fig, animate, frames=200,
  
                                interval=10, blit=True,repeat=False)
  
  ani.save('ps.mp4', writer=writer)
  
  plt.show()

• FFmpeg convert single image into video Android

  15 mai 2014, par berserk

  I am trying to convert a single image into a video using FFmpeg. I have tried following the files :

  "ffmpeg  -analyzeduration 2147483647 -probesize 2147483647 -i " + packat.get(i).path +"-r 25 -t 1000 -y op.mp4"
  
  
  
  "ffmpeg -loop 1 -r 23.976 -i input.jpg -t 00:00:02 -vcodec qtrle -an output.mov"
  
  
  
  "ffmpeg -i c:\rawvideo\mask.bmp -loop 1 -r 29.97 -s 720x480
  
          -aspect 4:3 -t 00:04:05 -vcodec mjpeg -vb 11261600 -an
  
          c:\rawvideo\fullmask.avi"

  But all of them give me this annoying error :

   Can not process SOS before SOF, skipping marker parser used 0 bytes (0 bits) decode frame unused 0 bytes decoding for stream 0 failed 
  
  Could not find codec parameters for stream 0 (Video: mjpeg): unspecified size
  
  Consider increasing the value for the 'analyzeduration' and 'probesize' options /storage/sdcard0/cblVE/temp/0.jpg: could not find codec parameters 
  
  exit_program: 1 

  Please help. I have searched for a solution from a week, but I have found nothing.