vblank timestamps and page flipping in DRI2
Saulius Krasuckas
saulius2 at ar.fi.lt
Sun Feb 13 11:33:48 CST 2011
There are some news on the $Subject: [1].
(have a look at the chapter "Fine tuned")
I thought it could help Wine fixing such bugs as 6086, 13085, 17260, 22362
[2].
I'll paste the text in just for archiving purposes:
--- quote ---
Fine tuned
The kernel hackers have extended the DRM infrastructure to include
"precision vblank timestamps", which are explained in detail in the commit
comment and are relevant to OpenML (Open Media Library) conformity. This
feature enables the kernel to provide timestamps with an accuracy of a few
microseconds, allowing applications to detect when the rendering of a new
image has started ("double-buffer swap"). This can, for instance, be
relevant for applications where it is important to precisely co-ordinate
the audio output, or the control of other devices, with the rendering of
the image. The technology was first implemented for experimental
psychology and neuroscience applications, but it can also be applied to
provide (more) jerk-free video playback, animations or desktop effects.
Such timestamps can also be utilised by the new page flipping feature
available via DRI2. This feature improves the way the kernel synchronises
the release of an updated image with the moment the graphics hardware
starts rendering the new image (Vsync). Synchronising the release avoids
such distortions as flickering, tearing or incomplete rendering, as it
prevents situations where one half of a displayed image is part of the old
image while the other half is part of the new image . for instance with
individual movie frames. In kernel version 38, the graphics driver support
required for both features will be available via the AMD drivers (1, 2)
and the Intel drivers (1, 2). The NVIDIA drivers currently only support
page flipping (1, 2).
--- quote ---
S.
[1] http://www.h-online.com/open/features/Kernel-Log-Coming-in-2-6-38-Part-1-Graphics-1176900.html?artikelseite=1;page=2
[2] http://bugs.winehq.org/show_bug.cgi?id=6086
http://bugs.winehq.org/show_bug.cgi?id=13085
http://bugs.winehq.org/show_bug.cgi?id=17260
http://bugs.winehq.org/show_bug.cgi?id=22362
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