title: Matplotlib save animation with many frames
body: <p>I'm trying to save the animation from matplotlib with:</p>
  
  <pre><code>...
  an = anim.ArtistAnimation(fig, frames, interval=500, blit=True, repeat_delay=2000)
  Writer = anim.writers['ffmpeg']
  writer = Writer(fps=5, metadata=dict(artist='Me'), bitrate=1800)
  an.save(file_name, writer=writer, fps=5)
  </code></pre>
  
  <p>When I save about 5 - 8 frames it works ok, but when I calculate 100 frames and try to save them the saved animation contains only the last frame. It's length is as it should be... but every frame is the same.
  I show the animation with pyplot.show() and there it looks fine.
  So I'm wandering what's the problem? </p>
  
  <p>Thanks in advance.</p>