Help! NTSC aspect ratio

(Trying to provide more details.)

I am keeping aspect ratio.

NTSC doesn't seem to work properly. What I would expect in NTSC mode is that the viewable area within the 960x540 window is still of 4:3 aspect ratio and that the NTSC screen would be stretched to fill it (NTSC has non-square pixels). What actually happens is that the viewable area is not of 4:3 aspect ratio, which means that either the screen is not being stretched properly, the screen is going off of the bottom of the viewable area, or both.

Also, the launcher seems to be inconsistent in how it saves video options. If you change NTSC option from the main menu, you have to save, but if you change the zoom option from the settings menu, you cannot save.

Now that I think of it, getting NTSC to work with zoom would be complicated. In order to get an exact integer pixel ratio, on a 1920x1080 screen, you need to specify a zoom window that is 540 pixels tall (704x540) and the window will be scaled vertically by exactly 2 so it fits in the screen vertically. But to give NTSC the correct aspect ratio and non-square pixels, ithe screen would have to be stretched vertically before any zoom. If it's stretched vertically, that raises the question of how to specify the zoom window--is it in pre-stretch pixels or post-stretch pixels? At any rate, you could not get an exact integer ratio in both directions, but in order to get it to be an exact ratio horizontally, you would have to pick 704x540 where the 540 is measured in post-NTSC-stretch pixels. Each Amiga pixel would then end up 2 pixels wide and 2.4 pixels high.

I also suggest having three aspect ratio settings: Don't keep aspect ratio, keep 1:1 square pixels, and keep original aspect ratio. The latter two entries would be the same on PAL but different on NTSC.

(Actually, pixels aren't *exactly* square even on PAL, but they're close enough.)

[jbl007]

From my understanding, "Zoom" doesn't stretch anything, it just crops pixels to provide more/less overscan.

Originally Posted by arromdee

Each Amiga pixel would then end up 2 pixels wide and 2.4 pixels high.

If you need to do this, you can set the options "scale_x=2" and "scale_y=2.4" for fullscreen 1920x1080. Press F11 (this is the zoom option) until you get a nice screen.

[FrodeSolheim]

Hi @arromdee, you are correct about the keep aspect option. It doesn't really do what it says, it is really currently a "use square pixels" option (which as you note, isn't that far off for PAL).

@jbl007 is also correct in that the zoom option is really a crop option. What FS-UAE does (by default) is:
1. Crop the Amiga display (unless full frame "zoom" is chosen)
and then, depending on the keep_aspect option:
2a. Stretch the cropped image to fill the entire screen
or
2b. Scale the cropped image to fill as much as possible of the screen while maintaining the same x/y scaling factor (or put another way, don't change the pixel aspect ratio).

So:
- cropping is determined by the zoom option (in combination with the viewport option when zoom=auto)
- how stretching is performed is determined by keep_aspect.
- how much to scale the Amiga display is determined by scale_x / scale_y options. Positive values means scaling relative to cropped source, (absolute of) negative values are relative to the screen size. Default scaling factors are -1.0 (which means fill the entire screen).

So yes, you can play around with the scale and zoom options to get any result, really. But as you've discovered, some options can only be set globally in the launcher, so you won't get your desired behavior suitable for both PAL *and* NTSC at the same time, unless FS-UAE implements a proper aspect ratio option...

Originally Posted by arromdee

Also, the launcher seems to be inconsistent in how it saves video options. If you change NTSC option from the main menu, you have to save, but if you change the zoom option from the settings menu, you cannot save.

For usability reasons (not technical reasons), some options are classified as "settings" in FS-UAE launcher, while others are classified as per-configuration options. In general, options affecting the *emulation* are per-configuration, while other options are classified as global settings.

(NTSC mode affects the emulated Amiga, while the zoom (crop) option does not)

I'm aware the current solution isn't ideal The short version is that it is a bit difficult to create a good UI visualizing config options overriding global settings (in turn overriding application defaults), and I want the .fs-uae configuration files to contain as few options as possible (not repeat all options in all .fs-uae config files == possible config nightmare).

Originally Posted by jbl007

From my understanding, "Zoom" doesn't stretch anything, it just crops pixels to provide more/less overscan.

If you need to do this, you can set the options "scale_x=2" and "scale_y=2.4" for fullscreen 1920x1080. Press F11 (this is the zoom option) until you get a nice screen.

I was about to say thanks, but I tried it and it doesn't quite work. With NTSC on, 704x540, fullscreen, and x_scale=2 and y_scale=2.4, the pixels are the shape I expect, but the viewing area is not what I expect. In fact, doing this with 704x540 produces a viewing area that is *smaller* than the viewing area I get if I use 640x480 because it has a black area at the bottom. Pausing with F12 shows that the viewing area is too low and both starts after the start of the actual display and ends after the end of the actual display.

I can compensate for this with min_first_line_ntsc, but I really shouldn't need to do that, because if the viewing area didn't start too low, even the default value of min_first_line_ntsc would work.

(With PAL it is worse, but I don't expect it to produce a useful result for PAL.)

[jbl007]

It doesn't make much sense to set the output to 704x540.
Normal ntsc amiga res. is 640x200 (640x400 with line doubling from the emulator).
Max. overscan you can use in normal workbench is 724x241 (724x482).
This much overscan is not supported by many games/demos. So if you set it to 704x540 you will get some "garbage" pixels because they just do not exist.

Originally Posted by jbl007

It doesn't make much sense to set the output to 704x540.
Normal ntsc amiga res. is 640x200 (640x400 with line doubling from the emulator).
Max. overscan you can use in normal workbench is 724x241 (724x482).
This much overscan is not supported by many games/demos. So if you set it to 704x540 you will get some "garbage" pixels because they just do not exist.

That is not the problem. Rather, the problem is that it's offset by too much. The viewable area starts too late and ends too late, so I get a screen that is vertically off-center. If it started earlier and ended earlier, it would neither be off-center nor have any black area at the bottom.

You can actually pause the emulator and see a 3D view of the screen starting before the viewable area.

Also, I don't think you understand the purpose of using 704x540. 704x540 is half of a 1920x1080 monitor vertically, so if you use 704x540 it will scale by an integer multiple when scaling that area to the monitor. Furthermore, since I'm using a factor of 2.4 Y scale and the 704x540 area is only scaled by a factor of 2 to fit to the monitor, it's only really displaying 540 / (2.4/2) = 450 stretched pixels anyway, which is less than 482.