MAME, Neo Geo, HLSL and OCD

[NightShadowPT]

Hi,

This one may be a bit tricky to explain, but I'll do my best.

Here is the setup:

• Arcade Cabinet witha 19" LCD Monitor, using HLSL to simulate a CRT
• Emulator: MAME 0.220
• Emulated System: Neo Geo MVS

The problem (besides my OCD :)):

• Some Neo Geo games seem to be slightly cropped (?) on the sides while others seem to use the whole screen.
• The problem is that the ones that are slightly cropped, ruin the "3D" illusion of having a CRT because some of the HLSL effects are not applied to the sides of the image (only to the top and bottom).

To illustrate the problem, I am attaching two pictures. 

• The first one was taken while the NeoGeo was booting up, occupying the whole screen. Note the top-left corner. It is rounded and the line on the side has a fading to black effect.
• The second one, was taken after the game loaded. If you look at the top left, the corner is no longer rounded (because the side is cropped) and because of that, the line does not get the fading to black effect.

I know I cannot play with the screen adjustments in MAME because that would move the whole screen, not just the "emulated image" inside.

Is there any solution/option I can use to remediate this and extend the emulated image to the whole screen?

Apologies if I'm not making much sense, but any help will be much appreciated.

Happy to answer any questions.

Thanks in advance.