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Jittery

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Re: Jittery

Postby wkitty42 » Tue May 29, 2018 2:55 am

PINTO wrote in Mon May 28, 2018 8:14 pm:Heres a gif with text scrolling at 15FPS, 30FPS, and 60FPS. There is a plain difference between all three.

not over here there isn't... the text for each line comes in at the same time for all three, travels across at the same rate and exits at the same time... there is no difference between them that can be seen over here by several sets of eyes ranging from 10yo to 80+yo...
"You get more air close to the ground," said Angalo. "I read that in a book. You get lots of air low down, and not much when you go up."
"Why not?" said Gurder.
"Dunno. It's frightened of heights, I guess."
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Re: Jittery

Postby wkitty42 » Tue May 29, 2018 2:59 am

WoodSTokk wrote in Mon May 28, 2018 8:18 pm:
wkitty42 wrote in Sat May 26, 2018 5:05 pm:i don't understand why folks want to run their FPS faster than the human eye can see... ~30fps is all the human eye can see and register changes... anything more is just pure overkill for overkill's sake...

This comes from the old shooter games.

uh, no... it actually comes from film projectors... nothing as gauche as digital stuffs :mrgreen:

remember when watching real films? the projector always made that clacking sound? that was when the frame passed through the light projection window and the shutter opened and closed before the next frame moved into place...
"You get more air close to the ground," said Angalo. "I read that in a book. You get lots of air low down, and not much when you go up."
"Why not?" said Gurder.
"Dunno. It's frightened of heights, I guess."
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Re: Jittery

Postby Thorsten » Tue May 29, 2018 5:16 am

The eyes-can-only-see-30Hz thing is largely believed to be a myth. The USAF studied this by flashing a picture of an aircraft for 1/220th if a second - participants were able to ID the plane repeatedly and reliably.


Oh, the eyes can perceive a one-time change at a faster timescale just fine, they just can't update to a second change any faster.

You get the same phenomenon when you record images on a camera at, say, 20 fps - if you flash something at 1/250 of a second, you'll see it in the exposure of one frame - but if you flash 10 such things, all you see is garbage.

It's not rocket science... the eyes work by pigments reacting to exposure to light, just as an old-fashioned film did.

Here is a an article nicely explaining why movies work fine at 24 fps, why in tests video gamers could not distinguish between 30 fps and higher (just like myself in fact) and why 60 fps in video games are primarily needed for anti-aliasing and why anything above 60 fps with a normal monitor when you don't saturate peripheral vision is bogus.
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Re: Jittery

Postby Thorsten » Tue May 29, 2018 7:36 am

Heres a gif with text scrolling at 15FPS, 30FPS, and 60FPS.


You seriously believe that an animated gif gets its own 3d rendering context from the Window Manager such that it can do a consistent update at its own framerate?

I sure don't.

Whatever update time is baked into the gif is completely at the mercy of when the Window Manager receives an update event and displays it, and the update will generally be slower than what it proposes to be. That gif is not what you see when you have your own 3d rendering context.
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