The main motivation for VAAPI (Video Acceleration API) is to enable 
hardware accelerated video decode/encode at various entry-points 
(VLD, IDCT, Motion Compensation etc.) for the prevailing coding 
standards today (MPEG-2, MPEG-4 ASP/H.263, MPEG-4 AVC/H.264, and 
VC-1/VMW3).  Extending XvMC was considered, but due to its original 
design for MPEG-2 MotionComp only, it made more sense to design an 
interface from scratch that can fully expose the video decode 
capabilities in today's GPUs.