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• ffmpeg in the use of libardrone by python

  13 mai 2016, par Chao Wang

  Recently I am trying to do a vision-based control using AR.drone 2.0. I meet a problem in the first step that is to import video seen from drone to my PC. I searched online and there is a library called libardrone. I tried to used it but when I do the first step that is to intialize. I wrote

  drone = libardrone.libardrone.ARDrone(True)

  The problem rises in the installation of ffmpeg. I actually installed and set ffmpeg\bin in my path, but I don’t know why it keeps jumping out this error

  The error turns out to be

  Traceback (most recent call last) :

  File "C:\Python27\dronetest.py", line 7, in <module>
  
      drone=libardrone.ARDrone(is_ar_drone_2=True,hd=True)
  
    File "C:\Python27\lib\site-packages\libardrone\libardrone.py", line 126, in __init__
  
      self.network_process = arnetwork.ARDroneNetworkProcess(com_pipe_other, is_ar_drone_2, self)
  
    File "C:\Python27\lib\site-packages\libardrone\arnetwork.py", line 45, in __init__
  
      self.ar2video = ar2video.ARVideo2(self._drone, libardrone.DEBUG)
  
    File "C:\Python27\lib\site-packages\libardrone\ar2video.py", line 37, in __init__
  
      self.h264 = h264decoder.H264Decoder(self, drone.image_shape)
  
    File "C:\Python27\lib\site-packages\libardrone\h264decoder.py", line 82, in __init__
  
      raise Exception("You need to install ffmpeg to be able to run ardrone")
  
  Exception: You need to install ffmpeg to be able to run ardrone
  
  </module>

  The related code in h264decoder.py is

   if (H264Decoder.which('ffmpeg') is None):
  
                      raise Exception("You need to install ffmpeg to be able to run ardrone")
  
  
  
  ....
  
  
  
  
  
  def which(program):
  
          def is_exe(fpath):
  
              return os.path.isfile(fpath) and os.access(fpath, os.X_OK)
  
  
  
          fpath, fname = os.path.split(program)
  
          if fpath:
  
              if is_exe(program):
  
                  return program
  
          else:
  
              for path in os.environ["PATH"].split(os.pathsep):
  
                  path = path.strip('"')
  
                  exe_file = os.path.join(path, program)
  
                  if is_exe(exe_file):
  
                      return exe_file
  
  
  
          return None

• Anomalie #3590 : Si on recharge la page après avoir changé le statut d’un article, il y a un messa...

  28 février 2016, par realet RealET

  Une précision, quand je parle de simple rafraichissement de la page, je par le de F5 ou rechargement d’une session.

  Et si le navigateur m’affiche temporairement une page blanche avec une boite de dialogue me demandant si je veux renvoyer les données du formulaire, avec juste OK ou Annuler, je ne sais pas franchement quoi faire. Dans le doute, je fais OK.

  Mais c’est à chaque fois un grand moment de solitude.

• Export sprites/images from movie

  7 octobre 2014, par Dr.Kameleon

  OK, here’s the situation :

  • I have a .mov video, recorded using QuickTime
  • I want to split it into images (which I will use in a js animation)

  ---

  JS Code :

  function pad(num, size) {
  
      var s = num+"";
  
      while (s.length < size) s = "0" + s;
  
      return s;
  
  }
  
  
  
  
  
  $(function(){
  
      var currentIndex = 1;
  
  
  
  
  
      setInterval(function(){
  
         $("#theImage").attr("src","img/video"+pad(currentIndex,3)+".png");
  
         currentIndex++;
  
      }, 1000/24);
  
  
  
  });

  ---

  So, I tried with FFMpeg :

  ffmpeg -i "video.mov" -f image2 -vf fps=24 video%03d.jpg

  This works. But the quality of the sprites is very low.

  ffmpeg -i "video.mov" -f image2 -vf fps=24 video%03d.png

  This works too. But the quality/size of the sprite is HUGE. I mean every sprite is around 110KB, with a grand total far above the video’s size (100MB > 2MB !)

  What’s going on ?

  How can I achieve that, without losing any quality and still not having too deal with huge filesizes ?