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<div class="moz-cite-prefix">On 08/02/2014, Axel Davy wrote :<br>
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<div class="moz-cite-prefix">Hi,<br>
<br>
<br>
On 08/02/2014, Jason Ekstrand wrote :<br>
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cite="mid:CAOFGe95Y+UJfph3rkuH2CofWa+ExMdy4r=3F6b66dgqcOBPUQg@mail.gmail.com"
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.8ex;border-left:1px #ccc solid;padding-left:1ex"> <br>
For each surface with queued content updates and
matching main<br>
output, the compositor picks the update with the
highest<br>
timestamp no later than a half frame period after
the predicted<br>
presentation time. The intent is to pick the
content update<br>
whose target timestamp as rounded to the output
refresh period<br>
granularity matches the same display update as the
compositor is<br>
targeting, while not displaying any content update
more than a<br>
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<div>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.<br>
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If you target t, and P0 and P1 are possible pageflips time,<br>
if P0<t<(1/2)P0+(1/2)P1 then you take the pageflip at P0<br>
if (1/2)P0+(1/2)P1<t<P1 then you take the pageflip at P1<br>
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.<br>
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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.). <br>
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 T/2.<br>
<br>
Axel Davy<br>
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