ValueError: Could not find a backend to open path with iomode `wI` 解决

运行如下语句时报错

imageio.mimwrite(os.path.join(savedir, 'video.mp4')

报错信息：

ValueError: Could not find a backend to open `video.mp4`` with iomode `wI`.
Based on the extension, the following plugins might add capable backends:
  FFMPEG:  pip install imageio[ffmpeg]
  pyav:  pip install imageio[pyav]

一开始没看懂这两条是什么意思，以为是要pip install imageio，执行后仍然报错。

FFMPEG:  pip install imageio[ffmpeg]
pyav:  pip install imageio[pyav]

后来才知道是要pip install imageio-ffmpeg，解决。