MAMEWorld Forums - EmuChat

Is it possible under MAME to underscan only the left and right sides of a 4:3 image without shrinking the width of the screen? Tried a couple of methods and do not see a way to achieve this correctly. The options tried shrink the entire width of the screen, not just the image.

It includes these options utilized under a full screen:

'Screen Horiz Stretch'
While overscan for the left and right sides can be performed properly leveraging this core option, underscan does not work properly. A value greater than 1 does as is expected and maintains a 4:3 aspect ratio while more and more of the image stretches and is removed off screen. However, the same option with a value less than 1, does not shrink just the image, but the entire width size of the screen area, so the aspect ratio of the screen changes, not just the image.

bgfx/crt-geom-deluxe/'Overscan X'
Similar behavior to the core option 'Screen Horiz Stretch'. A value less than 1.00 shrinks the entire screen width not just the image on the screen. There does not seem to be a setting where it maintains the screen effects of 'crt-geom-deluxe' at 4:3, while just shrinking the image width displayed against that screen effect. Results are the same of course under /crt-geom/ and /Fighters/ as well.

To see more clearly the issue - with or without BGFX (or HLSL) effects, set the brightness of a game considerable higher than default (I.E. Brightness 1.00 --> 1.20), then adjust the screen. As the image width shrinks, ideally there should become evident, off-black side bars matching the 1.20 brightness level, that continue to grow in size. Instead, the entire screen loses its 4:3 aspect ratio, as it is shrinking along with the image.

-Trebor