title: executing a subprocess from python
body: <p>I think something is getting subtly mangeled when I attempt to execute a subprocess from a python script</p>
  
  <p>I attempt to execute vlc with some (a lot) of arguments. </p>
  
  <p>the instance of vlc that arises complains:</p>
  
  <blockquote>
    <p>Your input can't be opened:
    VLC is unable to open the MRL ' -vvv rtsp://192.168.1.201:554/ch0_multicast_one --sout=#transcode{acodec=none}:duplicate{dst=rtp{sdp=rtsp://:5544/user_hash.sdp},dst=display} :no-sout-rtp-sap :no-sout-standard-sap :ttl=1 :sout-keep'. Check the log for details.</p>
  </blockquote>
  
  <p>Here is the python code</p>
  
  <pre><code>pid = subprocess.Popen(["vlc "," -vvv rtsp://%s" % target_nvc.ip_address + ":554/ch0_multicast_one --sout=#transcode{acodec=none}:duplicate{dst=rtp{sdp=rtsp://:5544/user_hash.sdp},dst=display} :no-sout-rtp-sap :no-sout-standard-sap :ttl=1 :sout-keep" ], stdout=subprocess.PIPE, stderr=subprocess.PIPE, stdin=subprocess.PIPE)
  </code></pre>
  
  <p>I have examined the output of the subprocess function (using a shell), and if I copy paste that string into my cmd window, the vlc instance works fine... Is this a privilege thing?</p>