I have testet your patch with the current xinelib and df-patches. But it wont work with a ati card.
I have startet like you write it in the Readme.vaapi
xine -V vaapi
So xine wont start it beak
The second problem is wenn i start xine with -V xv SD will work but HD dont work.
Please can you fix it that ati also can use the vaapi