Re: [hatari-devel] Display problem in Paradox latest demo

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Le 28/12/2013 17:53, Anders Eriksson a écrit :


just wanted to inform that Hatari doesn't display Paradox newest STe
demo properly (released today).

As far as I can tell, the entire demo runs at 60 Hz, which is a bit
unusual in itself, but the final screen also appear to remove the lower
border at 60 Hz. I think Neochrome Master might be the only other
program to do that?

I think it's to reduce color flickering with the 2 different dithering pictures ? A higher framerate can slightly limit it (I remember the old TEX's spectrum 512 slideshow was running in 60 Hz too).

The result is that Hatari freaks out pretty bad, it jumps from
low/medres randomly (set Hatari without zoom then you'll see the window
change size constantly) and there is garbage graphics displayed as well..

Hatari handles bottom border's removal in 60 Hz since quite some time ; I didn't check neochrome master, but leaving terramis is using it (the kind of spectrum 512 picture displayed while loading next level).

A 60 Hz screen has only 263 hbl, but I see the demo is switching to med res on hbl 259, so the last 4 lines of the screen are displayed in med res, I don't see the point. Maybe something is displayed on a real STE that we don't see on Hatari ? But it's just seem to show some garbage lines.

Anyway, the problem is that the timing they chose for bottom border removing is really tight. The 50/60 Hz switch sometimes goes back to 60 Hz at cycle 500, while Hatari considers the min value should be 504, else no removal should occur.

This is what I once measured on real STE, but I only checked in 50 Hz, and as 60 Hz lines start 4 cycles earlier, this could explain the differences ; I would need to write a more complete version of my test program later to check all those timings again.

For now, I added a 4 cycles tolerance to this case, so the demo should now run OK :)

Thanks for reporting it


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