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How did the TV Aspect option come about? #43682 08/09/08 08:41 AM
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Josh7289 Offline OP
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From what I can tell, the TV Aspect option in View -> Screen Size just scales the horizontal resolution of whatever NES game you're playing by a multiple of 1.125, while leaving the vertical resolution completely alone. So, for example,

256 x 240 would become 288 x 240,

256 x 224 would become 288 x 224,

512 x 480 (256 x 240 scaled by a multiple of 2 on both axes) would become 576 x 480,

and so on.

But, how did this number, 1.125, come about? How was it determined that scaling the horizontal resolution by a multiple of 1.125 would cause NES games being played on a computer monitor with an emulator to be displayed in the same aspect ratio as they'd be displayed in on a normal TV connected to an actual NES?

Re: How did the TV Aspect option come about? [Re: Josh7289] #43804 08/15/08 06:35 AM
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blargg Offline
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A ruler? That's the least affected by subtle math errors. Take any large rectangle displayed in a game and measure its width and height, do the same in pixels in an emulator, then compare the aspects of each to find the correction factor.

There's also NewRisingSun's more rigorous calculation posted to Nesdev.

Re: How did the TV Aspect option come about? [Re: blargg] #43822 08/16/08 07:28 AM
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After reading that post, my head asplode! I just don't fully understand it...especially about the NES having a resolution of 282 x 243...? And what, and huh, and eh?

If anyone wants to help me understand this stuff better (including those calculations NewRisingSun did), then please, go ahead.

But also, I was wondering if the Super NES is the same way...? I mean, regarding what you have to do to the 256 x 240 emulator resolution to get it in the correct aspect ratio. Does anyone know?

Re: How did the TV Aspect option come about? [Re: Josh7289] #43828 08/16/08 01:38 PM
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It's easy to visually prove. Run NST in a window with TV Aspect off. You'll notice the game screen is perfectly square. Now go look at an NTSC television. Notice that it's wider than it is tall. Turn on TV Aspect and the shape will now match the TV. This is because NTSC TVs have rectangular pixels; they're slightly wider than they are tall. PCs have square pixels. You gotta translate to make one look like the other.

And yes, the same thing applies to SNES.

Re: How did the TV Aspect option come about? [Re: R. Belmont] #43835 08/16/08 05:29 PM
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Ah, that's interesting, about the SNES thing. Nintendo ignored this aspect ratio correction on their GBA port of A Link to the Past. I'm sure they did it with their other SNES to GBA ports/remakes, too. Even Square-Enix has got Chrono Trigger DS running in the wrong aspect ratio... I guess all this would not only make things look slightly weird, but it would also screw up movement, wouldn't it? I mean, it would make it seem like moving a character vertically is faster than moving them horizontally, since the game is expecting a slight horizontal stretch to even things out... mirite??!1

Re: How did the TV Aspect option come about? [Re: Josh7289] #43839 08/16/08 10:26 PM
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Most ports are just making a quick buck on an old game. They rarely attempt to preserve even the behavior of the original game.

Hell, the NES games on Wii Virtual Console use a FCE-like emulator, even though the Wii is more than capable of running a perfectionist emulator like Nestopia. I was even disappointed that the effects of the NES NTSC output weren't preserved.

Re: How did the TV Aspect option come about? [Re: Mike S.] #43841 08/17/08 12:04 AM
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blargg Offline
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Originally Posted By "R. Belmont "
This is because NTSC TVs have rectangular pixels; they're slightly wider than they are tall. PCs have square pixels.

Actually, CRT-based NTSC composite and PC multisync displays have no pixels, just scanlines. The width of the pixels is determined by the device encoding the video signal. It just happens that most/all of the older consoles had rectangular pixels.

Originally Posted By "Josh7289"
Nintendo ignored this aspect ratio correction on their GBA port of A Link to the Past. I'm sure they did it with their other SNES to GBA ports/remakes, too. Even Square-Enix has got Chrono Trigger DS running in the wrong aspect ratio... I guess all this would not only make things look slightly weird, but it would also screw up movement, wouldn't it? I mean, it would make it seem like moving a character vertically is faster than moving them horizontally, since the game is expecting a slight horizontal stretch to even things out... mirite?

More likely the GBA and DS's hardware support for square tiles is the reason. To fix the aspect ratio, they'd have to be done in software, but the systems aren't fast enough for that. And on the TV-based consoles, characters most likely do move faster horizontally than vertically, due to pixels being wider than tall.

Re: How did the TV Aspect option come about? [Re: blargg] #43875 08/17/08 08:54 PM
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Originally Posted By blargg
More likely the GBA and DS's hardware support for square tiles is the reason. To fix the aspect ratio, they'd have to be done in software, but the systems aren't fast enough for that. And on the TV-based consoles, characters most likely do move faster horizontally than vertically, due to pixels being wider than tall.

I guess that's possible, but I was thinking that the programmers would have compensated for the rectangular pixels, by programming the characters to move slightly slower in the horizontal direction than in the vertical direction. That way, when the image gets stretched horizontally on the TV, the character would appear to move at the same speed in any direction.

Of course, if they ignored the fact that the image would be stretched horizontally when displayed on a TV, and they programmed the character to have the same speed in both the horizontal and vertical directions on a screen with square pixels, then yes, a character in a game like that would appear to move more quickly in a horizontal direction than in a vertical direction when displayed on a TV.

Any idea which of these was more popular back in the day? That is, did programmers generally compensate for this TV horizontal stretch or did they not?


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