Perfectly Smooth Scrolling

In order to get perfect scrolling in (PAL) Amiga games, your display must run with a refresh rate of 50Hz (*) and you must have video synchronization enabled in FS-UAE.

Video synchronization will automatically be enabled if FS-UAE detects that your display runs at 50Hz and you have enabled video sync in preferences. In case it doesn’t detect it, you can force full video sync with the video_sync option. If you force this, and the display isn’t running at 50Hz, the emulation will instead run at incorrect speed and you will get issues with sound.

(*) When running NTSC Amiga emulation, your display must be running at 60Hz.

Enabling 50Hz Modes

Depending on your system and display, this can be either easy or difficult to get 50Hz modes working. If you have have a 1920×1080 monitor which announces it’s support for 50hz properly, it can be as easy as just switching the refresh rate with the control panel on your system.

In other cases you may be able to create a custom 50Hz mode for your monitor. For Linux, you can tweak modelines in Xorg.conf, and for Mac OS X, you can use a tool such as SwitchResX.

Windows users may be able to use a program called Powerstrip to create a 50Hz mode for the monitor – if a 50Hz mode is not already available.

50Hz Modes in Linux with nVIDIA

With LCDs and nVIDIA drivers, getting a working 50Hz mode can be a bit difficult in some cases, so I have written a how-to on 50Hz display modes on linux with nVIDIA drivers.

4 thoughts on “Perfectly Smooth Scrolling

  1. Many thanks for FS-UAE! How does it work with a 100 Hz monitor? Should i force video sync or is it ok?

    • Hi, FS-UAE does not (yet) support syncing emulation to a 100 Hz display mode (it would have to sync to every other refresh cycle in that case). Your 100Hz monitor probably supports 50Hz as well, so for perfect scrolling, you should switch to a 50Hz mode (and enable the video sync options in FS-UAE Launcher settings).

      • Thanks! Can’t wait for 100Hz v-sync, it will be great on my monitor.
        I have some questions.
        1) Why “Low latency video sync”, by default, is off?
        2) I did a test: running SWOS 96/97 (PAL game, 50Hz & 50 fps) at 60 Hz with v-sync on. I saw it wasn’t synced, is it normal? I know PAL > 50Hz and NTSC > 60Hz, it was just a test.

        • 1) Because it requires a faster computer (much less time available when both emulation and rendering has to occur within the same 20 ms interval).
          2) Yes, you only enable the “possibility” of vsync – FS-UAE checks the display mode, and if the display refresh rate is 60 and the Amiga runs at 50, FS-UAE will not enable full vsync (it will then only syncronize buffer swaps to avoid tearing).

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