Low latency tearless mode for 60hz screens?

[Dr.Venom]

Hi Toni,

Lately I've been making more use of my portable device for gaming than my desktop setup, and the one thing with these portable devices is that their screen refresh rate is (sadly) forced to 60hz only. Since the Amiga is so dependant on using 50hz, it makes a smooth low latency experience with WinUAE kind of difficult. I've been trying all kinds of stuff to add a 50hz mode but with no luck.

So on 60hz screens, we're either doomed to using no vsync, which because of the tearing is a no go, or use full-window mode, but that adds a (too) large amount of input latency.

To alleviate that problem could you consider adding a swap method that:

- does not sync to the screen refresh rate
- flips the screen in the nearest available vblank

Basicly it would cherrypick the vblank that is nearest available to where it would be supposed to swap, to achieve a tearingless mode on 60hz screens with the lowest amount of input latency.

Of course it would lead to minimal judder when using a 60hz screen, but it could probably still be miles better than using no vsync (ugly tearing) or windowed mode (high input latency).

I guess it would be closest to Microsofts full-window mode (no tearing on 60hz screens), but then done in a smarter way / without large buffers

[Toni Wilen]

It should be possible but I expect it to look horrible

[Dr.Venom]

Yeah it will probably be kind of unlike real Amiga, but hopefully it will not be unbearably horrible

[Dr.Venom]

Originally Posted by Toni Wilen

It should be possible but I expect it to look horrible

Would you expect it to look like Full Window mode (as that forces swapping in the vblank also)?

Because in my experience that looks quite OK when used with slower scrolling / moving games, e.g. with battle squadron it's not even THAT noticable that it's running on 60hz.

Of course for something like pinball dreams it's very noticable, but in the end there are enough games with slow scrolling or still screens for it to be of use when the input latency wouldn't be so bad.

Just curious how it will look, I'm weary of your comment that it will look horrible, which suggest something worse than full-window mode forced syncing...

[Toni Wilen]

What happens if you use cru (https://www.monitortests.com/forum/T...on-Utility-CRU ? Did the mode appear but selecting it didn't work? (black screen, doubled frames etc?)

Apparently it should work with most laptops, at least those with Intel (with or without switchable Nvidia) GPUs, as long as it is still supported by Intel because apparently it was only fixed in 2017 drivers..

Don't bother with Intel control panel, it always complains about invalid timings...)

[Toni Wilen]

I tested using old Acer (with Intel i5-5257U). Default Windows driver (dated 2016) didn't work but latest driver (15.40.38.4963) worked fine, CRU created 50Hz mode appeared and worked fine in WinUAE.

Oddly enough default driver was version 20.something and new driver (which was supposed to be 15...) become 20.19.15.4963 date 21.2.2018. It also needed manual install (normal install complained that it was not validated by manufacturer. Unpacked exe using 7zip, installed it via device manager). I also got black screen after login but alt-tab and exit fixed it so there may be issues if driver is not from manufacturer..

New MSI GS65 (that has 144Hz panel but only available refresh rates are 60Hz and 144Hz) also worked fine with 50Hz CRU mode after installing latest Intel driver.

EDIT: Quick CRU instructions:

Select 60Hz mode you want to use as a base for new 50Hz mode. Click Detailed Resolutions Edit-button. Click Copy. Cancel to close window. Click Detailed Resolutions Add, Click Paste. Change refresh rate to 50Hz (Make sure Timing is Manual, don't touch any other values). Ok to close window, Ok. Reboot. (I didn't try standard resolutions but usually detailed has at least 1 slot free)