OSError: [Errno 22] Invalid argument,Error saving

Question

I use jupyter notebook to write my code, and I use HTML(anim.to_html5_video()) to show my answer gif on the notebook. But it always have a bad problem. Here is an example:

import numpy

import seaborn

from matplotlib import pylab as plt

from matplotlib import animation

from IPython.display import HTML

nx=40

nt=25

dx=2/(nx-1)

dt=.025

c=1

u=numpy.ones(nx)

u[int(.5/dx):int(1/dx+1)]=2

uu=numpy.ones(nx)

fig=plt.figure(figsize=(8,5))

ax = plt.axes(xlim=(0,2), ylim=(1,2))

plt.xticks(fontsize=14)

plt.yticks(fontsize=14)

line = ax.plot([], [], color='#003366', ls='-', lw=3)[0]

def convection(i):

    x=numpy.linspace(0,2,nx)

    line.set_data(x,u)

    uu=u.copy()

    u[1:]=uu[1:]-c*dt/dx*(uu[1:]-uu[0:-1])

anim = animation.FuncAnimation(fig, convection,frames=nt, interval=100)

HTML(anim.to_html5_video())

The error is:

OSError Traceback (most recent call last)

OSError: [Errno 22] Invalid argument

During handling of the above exception, another exception occurred:

OSError: Error saving animation to file (cause: [Errno 22] Invalid argument) 

Stdout: b'' StdError: b"Unknown encoder 'h264'\r\n". It may help to re-run 

with --verbose-debug.