Cannot save matplotlib animation with ffmpeg

Question

I am trying to save a simple matplotlib animation from Jake Vanderplas, but I keep getting `OSError: [Errno 13] Permission denied`. I should note that I made two small modifications to Jake Vanderplas's example. I installed ffmpeg from MacPorts so I added the line `plt.rcParams['animation.ffmpeg_path'] = '/opt/local/bin'` and I ran into the problem discussed in (Using FFmpeg and IPython), so I added `FFwriter = animation.FFMpegWriter()`. Here is the code: ``` import numpy as np from matplotlib import pyplot as plt from matplotlib import animation plt.rcParams['animation.ffmpeg_path'] = '/opt/local/bin' fig = plt.figure() ax = plt.axes(xlim=(0, 2), ylim=(-2, 2)) line, = ax.plot([], [], lw=2) def init(): line.set_data([], []) return line, def animate(i): x = np.linspace(0, 2, 1000) y = np.sin(2 * np.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) FFwriter = animation.FFMpegWriter() ani…

Accepted Answer

So it turns out there were two issues.

Issue #1: The path to ffmpeg was wrong. I thought I needed to provide the path to the directory that ffmpeg resides in, but I needed to provide the path all the way to the ffmpeg binary.

Issue #2: Prior to testing out my code to generate videos, I sometimes would import a module with the setting `plt.rcParams['savefig.bbox'] = 'tight'`. (I did not think much of it, because I did not use the module, but rcParams persist until you restart the python interpreter.) This `plt.rcParams['savefig.bbox'] = 'tight'` causes the video file to save without any errors, but the frames are all garbled when you try to play the video. Although it took me all evening to track this down, it turns out this is a known issue.

Here is the updated solution that creates a video file for me with a nice, translating, sine wave.

```
import numpy as np
from matplotlib import pyplot as plt
from matplotlib import animation
plt.rcParams['animation.ffmpeg_path'] = '/opt/local/bin/ffmpeg'

fig = plt.figure()
ax = plt.axes(xlim=(0, 2), ylim=(-2, 2))
line, = ax.plot([], [], lw=2)

def init():
    line.set_data([], [])
    return line,

def animate(i):
    x = np.linspace(0, 2, 1000)
    y = np.sin(2 * np.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)

FFwriter = animation.FFMpegWriter(fps=30, extra_args=['-vcodec', 'libx264'])
anim.save('basic_animation.mp4', writer=FFwriter)
```

Cannot save matplotlib animation with ffmpeg

Solution

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