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• Unable to save Matplotlib animations using ffmpeg

  23 décembre 2017, par jtpointon

  I have installed ffmpeg and added it to path, and checked it works in command prompt, but I am still unable to save animations. I have tried creating a sin wave that will animate when I don’t try to save it, but throws an error when I do to demonstrate ;

  from __future__ import division
  
  
  
  import numpy as numpy
  
  from matplotlib import pyplot as pyplot
  
  from matplotlib import animation
  
  
  
  fig = pyplot.figure()
  
  ax = pyplot.axes(xlim=(0, 2), ylim=(-2, 2))
  
  line, = ax.plot([], [], lw=2)
  
  
  
  def init():
  
      line.set_data([], [])
  
      return line,
  
  
  
  def animate(i):
  
      x = numpy.linspace(0, 2, 1000)
  
      y = numpy.sin(2 * numpy.pi * (x - 0.01 * i))
  
      line.set_data(x, y)
  
      return line,
  
  
  
  anim = animation.FuncAnimation(fig, animate, init_func=init, frames=200, 
  
      interval=20, blit=True, repeat=False)
  
  
  
  FFwriter = animation.FFMpegWriter()
  
  anim.save('animation_testing.mp4', writer = FFwriter)
  
  
  
  pyplot.show()

  When I try to run this it throws the same errors over and over again, I assume as it iterates through each frame ;

  Traceback (most recent call last):
  
    File "c:\users\james\appdata\local\enthought\canopy\user\lib\site-
  
  packages\matplotlib\backends\backend_wx.py", line 212, in _on_timer
  
      TimerBase._on_timer(self)
  
    File "c:\users\james\appdata\local\enthought\canopy\user\lib\site-
  
  packages\matplotlib\backend_bases.py", line 1273, in _on_timer
  
      ret = func(*args, **kwargs)
  
    File "c:\users\james\appdata\local\enthought\canopy\user\lib\site-
  
  packages\matplotlib\animation.py", line 910, in _step
  
      still_going = Animation._step(self, *args)
  
    File "c:\users\james\appdata\local\enthought\canopy\user\lib\site-
  
  packages\matplotlib\animation.py", line 769, in _step
  
      self._draw_next_frame(framedata, self._blit)
  
    File "c:\users\james\appdata\local\enthought\canopy\user\lib\site-
  
  packages\matplotlib\animation.py", line 787, in _draw_next_frame
  
      self._pre_draw(framedata, blit)
  
    File "c:\users\james\appdata\local\enthought\canopy\user\lib\site-
  
  packages\matplotlib\animation.py", line 800, in _pre_draw
  
      self._blit_clear(self._drawn_artists, self._blit_cache)
  
    File "c:\users\james\appdata\local\enthought\canopy\user\lib\site-
  
  packages\matplotlib\animation.py", line 840, in _blit_clear
  
      a.figure.canvas.restore_region(bg_cache[a])
  
  KeyError: 

  Since it mentioned an error in _blit_clear I tried changing blit to False in FuncAnimation, but then it wouldn’t animate in the pyplot.show() when I didn’t try to save.

  I’m unsure as to where the error could be and so can’t work out how to fix this.

  I’m using Windows 10, python 2.7.6 and matplotlib version 1.4.2

  Many Thanks !

• Videos which is only played by particular app, need help to save it

  19 septembre 2015, par Kumar

  There’s a app(i can’t disclose the app name) which plays video stored in memory card and videos have no extension, by viewing the file sizes im assuming that they are the videos + I also check changing the extension with mp4 flv 3gp etc but no success. I then decompiled the app and saw that app is using ffmpeg-jni to play the videos. Anybody can help me in this ? and yeah all videos have IGN in their meta tag.

  Thanks

• FFMPEG not save logs when converting to audio format

  27 mars 2017, par PUXIII

  The command does not save or even create a file :

  ffmpeg -i "video.mp4" -f mp3 "audio.mp3" -vstats_file "log_file.log"

  And if you convert to a video file, everything normally creates and writes :

  ffmpeg -i "video.mp4" -f mp3 "video.avi" -vstats_file "log_file.log"

  Goal : to pull out the time from the log file and bind it to the process bar.

  There are no problems with video, everything works. But with the sound does not work.

  I tried the command :

  ffmpeg -i "video.mp4" -f mp3 "video.avi" >2 "log_file.txt"
  But there are other problems popping out. Since I run it all from the python using the subprocess

  ffmpegProc = subprocess.Popen(ffmpegCommand, startupinfo=startupinfo, shell=True)
  , I can not kill the running process, because it is started with the attribute shell=True, and only the shell is killed.and only the shell is killed.