Macbook下ffmpeg下载失败问题解决

问题描述

在MacBook下pyCharm的Terminal使用

pip install moviepy

后，运行一段测试代码：

# coding: utf-8

from moviepy.editor import *
video = VideoFileClip("0.mp4")
result = CompositeVideoClip([video])
result.write_videofile("new.mp4") 

发现提示错误：

Imageio: 'ffmpeg-osx-v3.2.4' was not found on your computer; downloading it now.
Error while fetching file: <urlopen error [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:727)>.
Error while fetching file: <urlopen error [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:727)>.
Error while fetching file: <urlopen error [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:727)>.
Error while fetching file: <urlopen error [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:727)>.
Traceback (most recent call last):
  File "test_ffmpeg.py", line 3, in <module>
    from moviepy.editor import *
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/moviepy/editor.py", line 30, in <module>
    imageio.plugins.ffmpeg.download()
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/imageio/plugins/ffmpeg.py", line 79, in download
    get_remote_file(fname=fname, directory=directory, force_download=force_download)
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/imageio/core/fetching.py", line 130, in get_remote_file
    _fetch_file(url, filename)
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/imageio/core/fetching.py", line 189, in _fetch_file
    % os.path.basename(file_name)
IOError: Unable to download 'ffmpeg-osx-v3.2.4'. Perhaps there is a no internet connection? If there is, please report this problem.

根据提示逐个文件进行回溯，发现是因为imageio需要实时下载ffmpeg，但是该链接时常断掉，所以程序认为现在没网。

问题解决

事情变得明朗，我们只需要找到ffmpeg-osx-v3.2.4是从哪里下载到哪里的，然后手动操作一次即可。
找到ffmpeg的资源：ffmpeg in github
在目录下找到需要的文件：ffmpeg-osx-v3.2.4，下载到本地。
现在我们需要知道Macbook下应该把这个文件放到哪里，才能使得imageio找到它并进行下一步操作。
根据错误提示，逐个回溯文件，到达fetching.py，发现

def _fetch_file(url, file_name, print_destination=True):
	print(
	        "Imageio: %r was not found on your computer; "
	        "downloading it now." % os.path.basename(file_name)
	    )

这里会输出文件错误的信息，可见file_name即为我们所需要的下载到本地的文件路径。修改代码：

def _fetch_file(url, file_name, print_destination=True):
	print(
        "Imageio: %r was not found on your computer; "
        "downloading it now.\n %r"
        % (os.path.basename(file_name), file_name)
    )

再次运行测试代码（见上文），获取到本地的文件路径，把我们下载的ffmpeg-osx-v3.2.4复制到对应目录：

cp -R /Users/_your_account_/Downloads/ffmpeg-osx-v3.2.4 /Users/_your_account_/Library/Application\ Support/imageio/ffmpeg/

再次运行测试代码，可以看到成功了。