title: FFMPEG error with Python Popen on Windows 10
body: <p>I'm trying to extract key-frames from a video called "twws.mp4" using FFMPEG and Python's Popen. However, I'm getting some error. This error has popped up recently.</p>
  
  <p>I've been using <a href="https://github.com/chexov/image2pipe" rel="nofollow noreferrer">https://github.com/chexov/image2pipe</a> repository for frame extraction. However, even the examples mentioned in this code have stopped working.</p>
  
  <pre class="lang-py prettyprint-override"><code>    cmd = "ffmpeg -v error -skip_frame nokey -i twws.mp4 -vsync 0 -r 30 -s 
      300x300 -pix_fmt rgb24 -f image2pipe -"
  
      args = shlex.split(cmd)
  
      frame_ext_proc = subprocess.Popen(args,stdout=subprocess.PIPE, 
      stdin=subprocess.DEVNULL,bufsize=10**8)
  </code></pre>
  
  <p>The error I received is as follows:</p>
  
  <pre><code>  File ".\test.py", line 97, in &lt;module&gt;
      decoder.start()
    File "C:\Users\g_host\AppData\Local\Programs\Python\Python36\lib\multiprocessing\process.py", line 105, in start
      self._popen = self._Popen(self)
    File "C:\Users\g_host\AppData\Local\Programs\Python\Python36\lib\multiprocessing\context.py", line 223, in _Popen
      return _default_context.get_context().Process._Popen(process_obj)
    File "C:\Users\g_host\AppData\Local\Programs\Python\Python36\lib\multiprocessing\context.py", line 322, in _Popen
      return Popen(process_obj)
    File "C:\Users\g_host\AppData\Local\Programs\Python\Python36\lib\multiprocessing\popen_spawn_win32.py", line 65, in __init__
      reduction.dump(process_obj, to_child)
    File "C:\Users\g_host\AppData\Local\Programs\Python\Python36\lib\multiprocessing\reduction.py", line 60, in dump
      ForkingPickler(file, protocol).dump(obj)
  AttributeError: Can't pickle local object 'images_from_url.&lt;locals&gt;.&lt;lambda&gt;'
  PS C:\Users\g_host\Desktop\wxTest&gt; Traceback (most recent call last):
    File "&lt;string&gt;", line 1, in &lt;module&gt;
    File "C:\Users\g_host\AppData\Local\Programs\Python\Python36\lib\multiprocessing\spawn.py", line 99, in spawn_main
      new_handle = reduction.steal_handle(parent_pid, pipe_handle)
    File "C:\Users\g_host\AppData\Local\Programs\Python\Python36\lib\multiprocessing\reduction.py", line 87, in steal_handle
      _winapi.DUPLICATE_SAME_ACCESS | _winapi.DUPLICATE_CLOSE_SOURCE)
  PermissionError: [WinError 5] Access is denied
  av_interleaved_write_frame(): Invalid argument
      Last message repeated 3 times
  Error writing trailer of pipe:: Invalid argument
  </code></pre>