Get media descriptor's elementary streams description Note, you need to
play the media _one_ time with --sout="#description" Not doing this will
result in an empty array, and doing it more than once will duplicate the
entries in the array each time.
Enable, disable or set an integer marquee option Setting
libvlc_marquee_Enable has the side effect of enabling (arg !0) or disabling
(arg 0) the marq filter.