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#1902 VICE still stutters...
To reproduce:
Load VSYNC.PRG
https://github.com/Zibri/C64_Stable_Raster/raw/main/vsync.prg
Before running it issue:
POKE 2126,154
This makes the screen scroll up one line per frame.
On areal C64 this is very smooth.
On VICE it stutters.
What speed are you running the emulator at? What is the refresh rate of your monitor?
emulator in normal speed.
monitor in standard speed (60hz)
but AFAIK, 50hz on 60hz can be shown without stuttering.
for example by inserting a black frame every 5. But there are other methods too.
Last edit: Zibri 2023-06-23
Is it similar to the scroll in Giana Sisters start screen (on Vice C64-PAL 50Hz emulation)?
This is due to the standard 60Hz (or greater) for Windows desktop resolution.
For me, it is enough to manually add the frequency for the windows graphics card (1920x1080 50Hz) and then it is much smoother in PAL mode.
When running your program, switching the Windows desktop to 50Hz gives me a noticeable improvement.
the scroller in Giana Sisters stutters even on a real C64 :)
When I have a desktop at 60Hz, it jumps like a kangaroo.
Thats nonsense of course - it has been THE testcase for anything scrolling in emulators for decades. If you dont trust Giana Sisters, try the attract screen of Starpaws.
P.S.
Even setting VICE to 60hz (120% speed) it still stutters. (but way less)
Apparently once every 25/50 frames.
Last edit: Zibri 2023-06-23
Are you using the 60Hz option in VICE or setting the speed of a PAL machine to 120%? Those two aren't the same
yes.. sorry for the confusion.. 60hz option. (which stes the speed to 120% too) but I used the option.
The only way to have 100% stutterfree scrolling like on a C64 is when the Monitor is using the exact same refresh rate as the emulator. And that has been working perfectly fine for a long time now.
so why if I put the emulator to 60hz (and my monitor is 60hz ) I still see it stutter?
what OS, CPU and GPU do you have? does changing the sound settings (also try disabling sound) change anything? SDL or GTK?
Also make sure to enable vsync in VICE AND the video driver.
Am closing this fruitless "bug report".