Beam-racing vsync shearing problems

keith.f.kelly · 17 September 2018, 02:08

WinUAE 4.0.1, Win10 Pro x64, MSI GS65 Stealth Thin

Using the new beam-racing V-sync 50/60Hz option in any fullscreen 50Hz mode, games still exhibit shear lines within the top quarter or so of the screen while scrolling horizontally. The shear line does not move vertically, which tells me that the beam-racing is delivering an exact 50Hz match, it's just out-of-sync with the actual screen refreshes. CPU is not bottlenecking, and I've got winuae.exe set in the nVidia options to use the nVidia GPU rather than the integrated Intel graphics. Switching to the non-beam-racing 50/60Hz vsync option resolves it, so it's definitely something specific to the new beam-racing implementation.

I assume that during initialization someplace, the beam-racing implementation must need to sync itself to the real screen refresh, so that all the beam-racing math thereafter will actually be in sync with the display. Perhaps something is wrong with that initialization piece?

Toni Wilen · 17 September 2018, 08:22

I actually have similar laptop and it has odd behavior in top part of screen, page flipping is inhibited during that time. It probably is related to Intel/NVidia GPU interfacing or something like that. I couldn't find any workarounds. Except use of external display...

If you enable debugging colors (END+F9), you should see that first slice has different and static size.

17 September 2018, 02:08	#1
keith.f.kelly Registered User Join Date: Aug 2018 Location: Sammamish, WA, USA Posts: 13	Beam-racing vsync shearing problems WinUAE 4.0.1, Win10 Pro x64, MSI GS65 Stealth Thin Using the new beam-racing V-sync 50/60Hz option in any fullscreen 50Hz mode, games still exhibit shear lines within the top quarter or so of the screen while scrolling horizontally. The shear line does not move vertically, which tells me that the beam-racing is delivering an exact 50Hz match, it's just out-of-sync with the actual screen refreshes. CPU is not bottlenecking, and I've got winuae.exe set in the nVidia options to use the nVidia GPU rather than the integrated Intel graphics. Switching to the non-beam-racing 50/60Hz vsync option resolves it, so it's definitely something specific to the new beam-racing implementation. I assume that during initialization someplace, the beam-racing implementation must need to sync itself to the real screen refresh, so that all the beam-racing math thereafter will actually be in sync with the display. Perhaps something is wrong with that initialization piece?

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17 September 2018, 08:22	#2
Toni Wilen WinUAE developer Join Date: Aug 2001 Location: Hämeenlinna/Finland Age: 49 Posts: 26,502	I actually have similar laptop and it has odd behavior in top part of screen, page flipping is inhibited during that time. It probably is related to Intel/NVidia GPU interfacing or something like that. I couldn't find any workarounds. Except use of external display... If you enable debugging colors (END+F9), you should see that first slice has different and static size.

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