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

[Christophe Thommeret]

Le Saturday 20 June 2009 11:35:35 yak54 at gmx.net, vous avez écrit :
> Hi,
>
> first a big Thanks to your fantastic work on vdpau support for xine!!

Thanx.

> 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 completely optional. I don't understand why synchronization
> between "vdpau_display_frame" and "vdpau_gui_data_exchange" is not
> necessary because these features could be called from different threads and
> "vdpau_gui_data_exchange" does destroy/create vdpau objects.

VDPAU is meant to be thread-safe.

> Second i don't understand why there is (now optional) synchronization on
> "vdp_decoder_render" because this would prevent executing the expensive
> render and video mixer calls in parallel.

Because of a bug in libx11/xcb.
This bug has been fixed in recent distro, like ubuntu 9.04, so locking is now 
optionnal.

> Please could you give me a short explanation?
>
> - Andreas


-- 
Christophe Thommeret