title: GPL - How does it impact my project? Do I need to publish my code?
body: <p>for one of my project I'm using FFmpeg, which is a library under GPL license.</p>
  
  <p>My program is written in C# and I start FFmpeg.exe using command line like this:</p>
  
  <p><code>Process Convert = new Process();
  Convert.StartInfo = new ProcessStartInfo("DLL\\FFmpeg.exe", "-i Source.avi -f mp4 Dest.mp4");
  Convert.Start();</code></p>
  
  <p>I would like to know what is the impact on my project of using a GPL library.
  Do I need to use GPL license for my program? (And therefore publish all my code)</p>
  
  <p>Or GPL only apply to FFmpeg if I wanted to modify the code?</p>
  
  <p>Thanks a lot </p>