"Widescreen Amiga"

Posted: 05 April, 2021

This weekend's been the Revision Demo Party, probably the world's largest, pure demoscene event. I didn't get to watch much of it live, but I've spent much of the morning sofa-sceneing, catching up with the competitions. The 16:9 OCS demos really sparked my interest.

I go to Assembly Partly regularly, and, like Revision, they show the demo entries on a Widescreen 4k projector at one end of a massive hall. The soundsystem is earth-shakingly powerful and there's really nothing quite like being huddled with a few hundred devs, oohing and ahhing as people set the hall on fire with their latest work. But, the old-school demos tend to struggle a little, as a 4:3 display loses some of the majesty.

Revision started to offer a 16:9 output for the Amiga compo a few years ago, and I was wondering how they did it. More importantly, I was wondering how I could do it, and setup WinUAE to always give me a 16:9 output, say, when I'm developing.

The screen setup turns out to be quite easy, and Revision already has this in their rules: on a standard PAL (320x256) screen, either render into the middle 320x180 pixels (vert aligned) or use DIWSTRT,$5281 / DIWSTOP,$06c1

The WinUAE side took me a little longer to figure out. There are a bunch of display settings you can configure, but they're mainly how to handle the WinUAE screen/window, not what the Amiga's doing internally. But, it's possible to setup a filter, and it turns out this is where the magic happens. By setting WinUAE to null filter with Automatic Scaling, it'll just "do the right thing". I tested this by pulling down the ADF of Nah's Revision 2021 entry; On Fire, which is 16:9. When I hit ctrl-F12 and go to full screen, I get the demo with no borders, exactly as intended. When I set WinUAE up to open in a 16:9 window, the demo is also edge-to-edge in that window.

So yeah, much simpler than I was expecting. I'm going to edit my dev WinUAE config to always open in 16:9, and swap out my screen setup to move over to it. I'd much rather have larger square pixels on modern monitors, than side-borders or, even worse, a stretched out 4:3 :/

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