pSize           X      x    Maximum period between keyframes.  GOP
                                   stands for  &quot;group of pictures&quot; in MPEG
                                   lingo.  Supported by most ffmpeg
                                   codecs.  To see whether a particular
                                   codec uses the gopSize parameter, run
                                   the testGopSize function in the tests/
                                   subdirectory (NOTE: very few Dir