[Libva] Disabling sync on vblank

[Xiang, Haihao]

Hi Yann,

vaPutSurface() is calling  DRI2SwapBuffers on X11 to display the image,  the behavior is controlled by  display server. You may check xf86-video-intel for how is DRI2SwapBuffers implemented.

Thanks
Haihao


>-----Original Message-----
>From: Libva [mailto:libva-bounces at lists.freedesktop.org] On Behalf Of Yann
>Dirson
>Sent: Sunday, June 26, 2016 11:11 PM
>To: libva at lists.freedesktop.org
>Subject: [Libva] Disabling sync on vblank
>
>Hello,
>
>When I'm decoding a video (using i965-va-driver, libva 1.7.0) and
>displaying frames using
>vaPutSurface, it looks as if the latter was syncing on vblank: i
>observe the frame rate of my
>program to be exactly that of the video mode refresh.
>
>I would like to test if we can do triple-buffering rather than sync on
>vblank, and see the
>influence on the result.
>
>It does not look like any parameter honored by other software pieces
>(Option VSync of the X intel
>driver, XV_SYNC_TO_VBLANK, glx's vblank_mode) has any influence.
>I cannot find any explicit reference to vsync or vblank in the libva
>or va-driver source code,
>and at first read (followed Broadwell path, admitedly quickly) it is
>not obvious that the
>intel-vaapi-driver exlicitly requires any synchro.  Can anyone shed some light ?
>
>Best regards,
>--
>Yann
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