invmem fake video codec module

invmem fake video codec module

This module make possible uses libvlc as output (not input as vmem) for
video stream rendering in aplication ... motivation to create this patch can
find at http://forum.videolan.org/viewtopic.php?f=32&t=53256

Usage is similar to vmem output module. We need next vlc_argv[] options:
   "--codec", "invmem",
   "--invmem-width", width,
   "--invmem-height", height,
   "--invmem-lock", clock,
   "--invmem-unlock", cunlock,
   "--invmem-data", cdata,
and calling libvlc_media_new with "fake://" access string:
   libvlc_media_new(libvlc, "fake://", &ex);

Signed-off-by: Rémi Denis-Courmont <rdenis@simphalempin.com>