Video Output Width

[trebor68]

Is there interest and availability to add screen borders or/and adjustable video output width? The 7800 consoles video output typically does not stretch fully across a 4:3 display.

For current simulation/emulation reference examples:

1. MiSTer handles this correctly. Below is a capture of MiSTer on the left and Test7800 on the right

2. A7800/MAME has the ability to modify the screen width (Taking the 1.000 setting and adjusting down to ~0.935 - 0.950) mimics the width of original hardware output very closely. Effectively, filling ~93.5% - 95% of the screen.

Attached are some CRT examples of various games demonstrating not stretching across the full width of the display.

[JetSetIlly]

I could scale the image so that the aspect ratio is a little taller but it wouldn't look good without custom filtering. Either, the width of the pixels wouldn't be even or there would be visible but uneven anti-aliasing across the image. CRT emulation would produce the best results but I wanted to avoid that for Test7800.

I'll keep this issue open until I decide what the long term future of Test7800 is. The Gopher2600 engine can do this already, so if I added 7800 emulation to that it would be solved problem already.

[trebor68]

Understood. Thank you for explaining.

[JetSetIlly]

I'm having another look at this issue because it's directly related to another problem I'm working on.

I've found a good/easy way around the problem I mention above. A couple of quick example images:

Square pixels:

Narrower pixels (horizontally scaled by 0.93)

[JetSetIlly]

Here's an animated GIF that hopefully shows the difference better. The taller image is the new version with the aspect bias of 0.93 applied

[trebor68]

The Aspect Ratio definitely looks better. Just a little concern over the way it was implemented. It appears the screen is being stretch vertically as opposed to narrowed horizontally.

When stretching vertically, instead of narrowing horizontally to account for the left and right screen borders, games that leverage a higher number of scanlines: Tank Command and Water Ski from the original Retail line for example, may have some data or intended to be seen image removed from the visible area. In addition to the mentioned original retail titles, post original retail/homebrews, may also be impacted: Froggie (Full screen setting), Donkey Kong XM, Pac-Man: Double Feature, 1942, Mario Bros. (OldStyle), Tiger-Heli.

Ideally, the height average of 224 scanlines should be visible for NTSC titles: http://atariage.com/forums/topic/261266-testing-crt-screen-size/#entry3676087

[JetSetIlly]

The Aspect Ratio definitely looks better. Just a little concern over the way it was implemented. It appears the screen is being stretch vertically as opposed to narrowed horizontally.

It amounts to the same thing I believe. The number of scanlines isn't changing.

What's happening is that the width is being reduced but then the entire image is being scaled so that it best fits into the window. Because the window is taller than it is wide, it looks like the width isn't changing.

Here's the same example but when the window is wider than it is tall.

If the emulation is running full-screen then it would look more like this example.

[trebor68]

That looks great. Thank you!