title: Python ffmpeg on Windows
body: <p>I had installed ffmpeg in <strong>WIN7 64bit</strong>. When I use 
  <code>os.system("ffmpeg -i      rtsp://218.204.223.237:554/live/1/66251FC11353191F/e7ooqwcfbqjoo80j.sdp -c copy dump.mp4")</code> in my program by the <strong>PyCharm</strong>,it can also run but I can`t play the <strong>dump.mp4</strong>. I can run the same command in <strong>CMD</strong> or <strong>Python(command line)</strong> and get the <strong>dump.mp4</strong> successfully.Why? How can I solve this problem?Can you help me ? I just use Python not long before.</p>