It has something to do with the multithreading support in ffmpeg or libav. vlc git disables ffmpeg-hw support when a ffmpeg mt is detected, that's true for both current ffmpeg or libav now. The vlc 1.1 branch does not have got that detection and just crashes. So basically you can currently forget vlc as player with vaapi support. xbmc is basically working, but just like mplayer vaapi it does not decode h264 l5.1. I dont know if libva reports an error that those apps just ignore to add a fallback or if that is not possible. I also want to test the pcom mode of mplayer vaapi, but i think that part of the source is not open. Also i dont think that the xvba-video 0.8.0 binary was compiled with pcom support, no idea how to compile it on my own to try it. It is really pointless to advertise h264 support via vaapi and then it does not play certain files. vdpau is not perfect too, with mplayer 2 i had got about 10 vdpau decoder errors while watching a m2ts movie, but at least it worked for most of the time. mplayer 2 also supports m2ts subtitles now, mplayer vaapi does not.