[Xine-vdpau] Questions about thread synchronisation in video_out_vdpau.c

[Andreas Auras]

Hi,

first a big Thanks to your fantastic work on vdpau support for xine!!

I am currently developing some patches for support of frame grabbing for
the vdpau driver and i need
some help to continue my work.

Starting from revision 263 the "XLockDisplay/XUnlockDisplay" calls have
been made completly optional.
I don't understand why synchronisation between "vdpau_display_frame" and
"vdpau_gui_data_exchange" is
not neccesary because these features could be called from different
threads and "vdpau_gui_data_exchange"
does destroy/create vdpau objects.
Second i don't understand why there is (now optional) synchronisation on
"vdp_decoder_render" because this
would prevent executing the expensive render and video mixer calls in
parallel.

Please could you give me a short explanation?
 
- Andreas