Reply To: Scaling, Aspect Ratio and Resolutions

[patrickm]

“Both SNES emulators cores have a native resolution 256 x 239.”

I’ve explained this.

The SNES is 239 when padded with the black borders. Minus padding, the SNES image is 224 horizontal lines or 1120 at 5x scale.

Just for kicks though let’s say that the SNES was supposed to display the full 1196 lines.

1196 – 1080 = 116, divided by 5 for 5x scale, is 23.2. As mentioned, the overscan area is 10%. 10% of 239 lines is 23.9. 23.2 is less than 23.9 so the amount that is cropped is within the overscan area.

The image was only drawn to 1120 lines though. 1120-1080 = 40, or 8 pixels at 5x scale. So you lose 4 lines from the top and bottom- again, this is well within the range of what actual CRTs would have done.

“Of course may be a CRT cuts off some lines from the picture, but I do not think that has anything to do with overscan.”

Padding and overscan aren’t the same thing. Padding relates to the extra part of the image put out by the console that wasn’t meant to be displayed. Overscan had to do with the TV.

I’ve also explained the following more than once:
On an NTSC TV, up to 10% of the picture would be cropped from top and bottom. The amount being cropped on SNES and Genesis is well within these parameters.

“Screenshots and especially when at FFV the Black / White / Grey frame with your settings 1536×1120 just missing the top and bottom.
I think that was certainly not planned by the programmer.”

I’m afraid you are simply incorrect in your assumption, here. The frame would indeed be cut off on many CRTs- as I’ve demonstrated via direct logical explanation as well as empirical evidence in a side by side comparison with an actual CRT (my Sanyo).

What you need to look at are things like life meters, heads up displays, etc. These were never placed in the overscan area and thus will never be cut off with a 5x vertical scaling. There is no single correct way to display these games since the CRTs varied so widely in how they were calibrated- there is only “incorrect.”

The programmer could only expect a certain range. Thus, occasionally on a real crt graphics would be cut off, but important graphics were always places within the “safe zone”

“With Integerscale 5 : 4 you can see everything from the picture but the aspect ratio is not correct and against the image on a CRT TV, in which I assume that the image is stretched to 4 : 3, is too wide”

I have also already explained this.

The aspect ratio is an arbitrary consequence of the display tech being used. The actual output frame was never 4:3. It would be stretched to a 4:3 image in a variety of different ways by CRTs, which cropped widely different amounts off the sides and top/bottom. Thus, how “wide” or “thin” individual sprites or pixels were on a crt varies widely and there is no single standard here, only a correct range. And as I’ve explained more than once, the pixel dimensions in 6×5 on NES and SNES are well within this correct range. In fact, you said that Mario looked too fat in the 6×5 scale image when in reality he is thinner there than in the 4:3 aspect image.

I posted a side by side comparison showing the super Mario bros title screen in 6×5 emulated on a PC and on an actual crt showing that the 6×5 scale image is completely within the correct range for CRTs.

The fact is that the amount you saw varied on a crt. Some CRTs would show all the overscan. Most cropped this off. Some, like my Sanyo CRT, cropped off even slightly more than the overscan area. This is the reason why SNES and Genesis had those black bars at the top/bottom, so that the actual picture wasn’t cropped off. But sometimes, the crt cropped off a bit more than this and you would lose a couple lines off the picture.

In fact, the developers did not intend for the overscan to be displayed, and they certainly didn’t intend for the game to be displayed letterboxed on your TV. They also did not intend for you to see the black bars/padding that were part of the SNES and Genesis output frame. If you’re playing at 4x scale you’re seeing a bunch of stuff that you weren’t supposed to see, while at 5x you crop off a few pixels on the SNES and Genesis and this is well within the normal range for CRTs.