[Mesa-dev] What use do swap interval > 1 and OML_sync_control divisor and remainder have?

Alexander E. Patrakov patrakov at gmail.com
Wed Jan 29 08:33:23 PST 2014

[Just for the sake of argument]

2014-01-28 Pekka Paalanen <ppaalanen at gmail.com>:
> Hi Ian and Jason
> On Mon, 27 Jan 2014 12:26:23 -0700
> Ian Romanick <idr at freedesktop.org> wrote:
>> There are a number of theoretical uses, but I don't know that we've
>> ever seen any in the wild.
>> One is video playback.  You likely want 30fps there.
> I would hope that no video player will use swap interval as a means of
> target timing, because the buffer queueing protocol I'm planning is
> supposed to be superior for accurately timed video presentation. The
> protocol will also be usable with EGL provided content, if the EGL
> implementation can cope with buffers being reserved by the display
> server for longer than usual.

One more argument would be that video players actually don't want
30fps here, and do that only because of constrained resources. Every
Smart TV sold nowadays has the motion-interpolation feature, which is
(unlike frame-doubling, and at least from the viewpoint of some
people) the proper way to display low-fps content on high-fps panels.
PC-based video players don't have this feature because nobody so far
has written the code that works on anything else than NVidia GPUs.

Alexander E. Patrakov

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