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When trying to run a simple animation example code in python, I am getting an error which I am not able to resolve.

Traceback (most recent call last):
File "D:/CG/dynamic_image2.py", line 29, in <module>
    ani.save('dynamic_images.mp4')
File "C:\Python27\lib\site-packages\matplotlib\animation.py", line 127, in save
    self._make_movie(filename, fps, codec, frame_prefix)
File "C:\Python27\lib\site-packages\matplotlib\animation.py", line 164, in _make_movie
    stdout=PIPE, stderr=PIPE)
File "C:\Python27\lib\subprocess.py", line 679, in __init__
    errread, errwrite)
File "C:\Python27\lib\subprocess.py", line 893, in _execute_child
    startupinfo)
WindowsError: [Error 2] The system cannot find the file specified

I found similar situations (link1 , link2 ) but still I don't know how to resolve mine...

I am using: Python 2.7.2 |EPD 7.2-2 (32-bit)| (default, Sep 14 2011, 11:02:05) [MSC v.1500 32 bit (Intel)] on win32

I hope somebody can help me!

Community
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carla
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  • I found out I can run the code and get the animation, if I change line 163 from **C:\Python27\Lib\site-packages\matplotlib\animation.py** from `proc = Popen(command, shell=False, stdout=PIPE, stderr=PIPE)` to `proc = Popen(command, shell=True, stdout=PIPE, stderr=PIPE)`. – carla Feb 10 '12 at 14:37
  • However, I am not sure how "safe" is this change in the **animation.py** file... [more info here](http://docs.python.org/library/subprocess.html#frequently-used-arguments) – carla Feb 10 '12 at 14:48

1 Answers1

3

I had the same situation, but the sollution is simple if you just want to look at the animation. Your proglem is related to ani.save('dynamic_images.mp4'), which isn't needed for the animation itself. Just comment it out. Your code crashes due to lack of installed codec (most likely). animation.py contains the code below. If the argument codec to _make_movie is None, ffmpeg (google it) is used, then you need to have this one installed and available in your path. Otherwise you can use mencoder which also needs to be installed and in path.

def ffmpeg_cmd(self, fname, fps, codec, frame_prefix):
    # Returns the command line parameters for subprocess to use
    # ffmpeg to create a movie
    return ['ffmpeg', '-y', '-r', str(fps), '-b', '1800k', '-i',
        '%s%%04d.png' % frame_prefix, fname]

def mencoder_cmd(self, fname, fps, codec, frame_prefix):
    # Returns the command line parameters for subprocess to use
    # mencoder to create a movie
    return ['mencoder', 'mf://%s*.png' % frame_prefix, '-mf',
        'type=png:fps=%d' % fps, '-ovc', 'lavc', '-lavcopts',
        'vcodec=%s' % codec, '-oac', 'copy', '-o', fname]

def _make_movie(self, fname, fps, codec, frame_prefix, cmd_gen=None):
    # Uses subprocess to call the program for assembling frames into a
    # movie file.  *cmd_gen* is a callable that generates the sequence
    # of command line arguments from a few configuration options.
    from subprocess import Popen, PIPE
    if cmd_gen is None:
        cmd_gen = self.ffmpeg_cmd
    command = cmd_gen(fname, fps, codec, frame_prefix)
    verbose.report('Animation._make_movie running command: %s'%' '.join(command))
    proc = Popen(command, shell=False,
        stdout=PIPE, stderr=PIPE)
    proc.wait()
Håvard
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  • You are right. In fact, I had ffmpeg instaled but it was not on my python path... This [stackoverflow question](http://stackoverflow.com/questions/9256829/how-can-i-save-animation-artist-animation/9281433#9281433) gave me already that hint! Thanks for your help! – carla Mar 07 '12 at 10:31
  • may I ask how you "added ffmpeg to python path"? `PYTHONPATH` is only for importing modules, so `PATH` would make more sense. My ffmpeg installation already is in `PATH` but I still get this error when I try to `import matplotlib.animation` – N4ppeL Oct 18 '19 at 11:50