Empty .mp4 file created after making video from matplotlib using matplotlib.animation
<p>I found this little code, and I am able to save a video (random colors changing in a grid) using it:</p>

<pre><code>import numpy as np
import matplotlib
matplotlib.use("Agg")
import matplotlib.pyplot as plt
import matplotlib.animation as animation
from scipy import rand

Writer = animation.writers['ffmpeg']
writer = Writer(fps=15, metadata=dict(artist='xy'), bitrate=3600)

fig = plt.figure()
frames = []
for add in np.arange(15):
    base = rand(10, 10)
    frames.append((plt.pcolormesh(base, ),))

im_ani = animation.ArtistAnimation(fig, frames, interval=500, repeat_delay=3000,
                               blit=True)
im_ani.save('Vid.mp4', writer=writer)
</code></pre>

<p>I tried to insert it into my simulation, I get no errors, but the video is empty, the whole picture is white. Can you help me with that? This is the simplest case where I got it:</p>

<pre><code>class Dummy():

    def __init__(self):
        self.video=[]

    def addFrame(self):

        Frame=rand(10,10)
        print (Frame)
        self.video.append((plt.pcolormesh(Frame),))

    def saveVideo(self):

        Writer = animation.writers['ffmpeg']
        writer = Writer(fps=15, metadata=dict(artist='XY'), bitrate=3600)
        fig = plt.figure()

        im_ani = animation.ArtistAnimation(fig, self.video, interval=500, repeat_delay=3000,
                               blit=True)
        im_ani.save('myVid.mp4', writer=writer, dpi=dpi)
</code></pre>

<p>You can try it out:</p>

<pre><code>from scipy import rand

foo=Dummy()

for i in range(20):
   foo.addFrame()

foo.saveVideo()
</code></pre>

<p>Your <code>self.video.append((plt.pcolormesh(Frame),))</code> line is fine. You just changed the order of statements.</p>

<pre><code>import matplotlib
matplotlib.use("Agg")
import matplotlib.pyplot as plt
import matplotlib.animation as animation
import numpy as np


class Dummy():
    def __init__(self, fname):
        self.fname = fname
        self.video = []
        self.fig, self.ax = plt.subplots()  # Create new figure here

    def addFrame(self):
        Frame = np.random.rand(10, 10)
        self.video.append((self.ax.pcolormesh(Frame), ))

    def saveVideo(self):
        Writer = animation.writers['ffmpeg']
        writer = Writer(fps=15, metadata=dict(artist='XY'), bitrate=3600)
        im_ani = animation.ArtistAnimation(self.fig, self.video, interval=500,
                                           repeat_delay=3000, blit=True)
        im_ani.save(self.fname, writer=writer)


foo1 = Dummy('foo1.mp4')
for i in range(20):
   foo1.addFrame()
foo1.saveVideo()

foo2 = Dummy('foo2.mp4')
for i in range(40):
   foo2.addFrame()
foo2.saveVideo()
</code></pre>

python numpy video matplotlib simulation