Re: [Algorithms] vrefresh jumpiness

[Nils P. <np...@in...>]

Madoc Evans wrote:

>I've noticed that whenever framerates drop below the monitor refresh rate
>renderings look they're jumping back and forth, it basically looks like
>there are more offset images overlayed. The problem is most noticeable with
>vsync enabled. This problem is visible in all programs and hardware I've
>seen and it's _really ugly_. I'm puzzled that I've never seen it mentioned.
>  
>

I think it's slightly offtopic.. I have no algorithm to offer, but an 
explanation:

I absolutely know what you're talking about. I guess most console 
developers also know what you're talking about because they get very 
sensitive to graphics that are not 100% in sync with the vertical 
refresh over the years.

You start to see "ghost images". My argument is, that from watching TV 
the eye is conditioned to see 50/60 frames at the same refresh-rate, 
always 100% in sync. The eye will start to see these kinds of illusions 
when framerate and refresh-rate differs.

If you go into a cinema and watch a movie with 24 or 25 fps you don't 
see the ghost images. On the other hand if you watch a 25fps movie on a 
50hz tv-screen you'll see them. The refresh-rate is much worse in the 
cinema , but your eye/brain is not conditioned for this framerate, thus 
it does not expect the high framerate and can compensate better.

PC players will most probably not notice it as hard as you do, and 
europeans will not notice it because we have a lot of frame-rate 
converted ntsc-movies on the tv (those jerk horrible if you look at them).

  Nils