[RFC v2] Wayland presentation extension (video protocol)
jason at jlekstrand.net
Sat Feb 8 14:29:03 PST 2014
OK, that makes more sense. Thank you for stating it in terms of intervals.
I still need to think about it a bit more.
On Feb 8, 2014 4:14 PM, "Axel Davy" <axel.davy at ens.fr> wrote:
> On 08/02/2014, Axel Davy wrote :
> On 08/02/2014, Jason Ekstrand wrote :
>> For each surface with queued content updates and matching main
>> output, the compositor picks the update with the highest
>> timestamp no later than a half frame period after the predicted
>> presentation time. The intent is to pick the content update
>> whose target timestamp as rounded to the output refresh period
>> granularity matches the same display update as the compositor is
>> targeting, while not displaying any content update more than a
> I'm not really following 100% here. It's not your fault, this is just a
> terribly awkward sort of thing to try and put into English. It sounds to
> me like the following: If P0 is the time of the next present and P1 is the
> time of the one after that, you look for the largest thing less than the
> average of P1 and P2. Is this correct? Why go for the average? The
> client is going to have to adjust anyway.
> If you target t, and P0 and P1 are possible pageflips time,
> if P0<t<(1/2)P0+(1/2)P1 then you take the pageflip at P0
> if (1/2)P0+(1/2)P1<t<P1 then you take the pageflip at P1
> That way the length of the intersection of the interval (t,t+time between
> two pageflips) and 'time interval at which it is displayed' is maximized.
> Well it isn't really the reason why this is choosen (else one might say
> it would be better to maximize with (t-T/2,t+T/2) with T the time between
> two pageflips.).
> The reason is more that you want to minimize the time at when the pageflip
> happens and t, so the real presentation time and t doesn't differ more than
> Axel Davy
> wayland-devel mailing list
> wayland-devel at lists.freedesktop.org
-------------- next part --------------
An HTML attachment was scrubbed...
More information about the wayland-devel