title: linux run ffmpeg within c++ code
body: <p>the O.S. is Linux.
  I have an old c++ code that writes raw SDI input from a capture device to a file.
  My intent is to modify this program and redirect the raw video from the SDI source to the stdin of ffmpeg.
  How can I do that?
  Is better to run ffmpeg within the c++ source code (how can I do that?)?
  Thank you very much.</p>