Pixel Perfect - 1080p vs. 480p

[PhilExile]

The thing is, when talking about CRT TVs, it's completely redundant to refer to horizontal resolution. These displays don't have a horizontal resolution since the display is not made up of pixels, it's made up of horizontal lines. Each line is approximately one pixel tall so the number of lines used vertically does conform to the native vertical resolution of the hardware (except every other line is blank hence the scanlines). However the native horizontal resolution of the hardware is irrelevant since, however many pixels there are, they will always be stretched to the full length of the line. So in order to replicate this with an emulator we need to set the vertical size to a multiple of the native vertical resolution of the system (hence giving the correct number of 'lines') and then we just need to decide how long our lines are going to be, since this is determined by the display and is different for every TV; there is no 'perfect' value.

 

I know from working with these games on a PVM, that unless you set the horizontal size 'perfectly' there will be a distortion. For instance, when I tried to set a game like SALAMANDER to stretch to fill the screen through the emulator and go beyond 512 pixels - you will see these 'waves' that your ship will fly through. Its almost like a wrinkle in the screen. I'm not denying that in the arcade this game is stretched edge-to-edge most of the time. However, I think this is similar to the NES/SNES were there was something in the hardware that acted like an upscaler in some ways. It wasn't something that was specific to the CRT technology - as far as I know.

 

The best thing (and I don't know if this is possible) would be to build a second pass scale into an emulator. For instance:

 

1. You set your perfect pixel screen size or just set it to double the pixel size of the arcade rom - 256x224 becomes 512x448

2. Set your TV's resolution to 4:3 in the preferences

3. When you launch the game, the emulator scales the image to 640x448 to fit your screen*

 

*I believe this is what BSNES does.

 

And in case you're wondering about rotated arcade games. The above still applies since it's just a regular monitor turned on its side, so the vertical lines now appear to the player to run horizontally across the screen. The 'height' of the lines is still determined by the display and will still always be the same size.

 

Yes, I know. I play a lot of MS. PAC-MAN, T. I actually have a PVM set on its side for vertical games only.

 

The SUPER MARIO WORLD is a great example. Again, I'm not arguing with what you are saying. Its just the way these emulators are built, if you don't find the 'perfect pixel' width - there is distortion introduced. There must be a way to stretch the image horizontally, after its been set, to fill the screen.

 

Talk soon

 

PS - I still plan on doing 'research' at the bar/arcade. Don't try to stop me, T!

Edited September 19, 2011 by PhilExile

[+ T +]

I know from working with these games on a PVM, that unless you set the horizontal size 'perfectly' there will be a distortion. For instance, when I tried to set a game like SALAMANDER to stretch to fill the screen through the emulator and go beyond 512 pixels - you will see these 'waves' that your ship will fly through. Its almost like a wrinkle in the screen. I'm not denying that in the arcade this game is stretched edge-to-edge most of the time. However, I think this is similar to the NES/SNES were there was something in the hardware that acted like an upscaler in some ways. It wasn't something that was specific to the CRT technology - as far as I know.

You're right. The image is horizontally stretched somewhat in the hardware prior to reaching the screen. You'll see this if you plug an original system's video output into a capture card. But to emulate this would be almost impossible without altering the Xbox's video output. Also, no CRT display would display a game at the equivalent of 640 pixels wide, that's simply too big. If you want a close approximation of a system's outputted width in pixels then it will be somewhere between 570 and 600 for most displays. Wii VC seems to use around 576 which is a good horizontal value.

 

With an Xbox emulator you will never escape the fact that the image needs to be upscaled. So the best and most practical method of achieving a display as close to accurate as possible is to use hardware filtering to eliminate those distortions and scale the screen to the appropriate vertical size and a fixed horizontal size. 256x224 becomes 576x448, 320x240 becomes 576x480, etc.

 

Trying to set pixel-perfect horizontal sizes is just a waste of time since it won't get you anything like an accurate display. So this is the approach I'm taking with FBL to get the scanlines working properly across as many games as possible. For most games FBL will be sized to be double the native vertical resolution and all games will use the same horizontal size (probably around 576), thus creating as arcade-accurate an image as it's possible to achieve with this hardware.

[+ T +]

PS - I still plan on doing 'research' at the bar/arcade. Don't try to stop me, T!

Stop you? I'd join you if I could.

[PhilExile]

Never say never, T.

 

I was just thinking about 10x11 pixel mode. Basically, that mode compresses the screen by (I think) outputing pixels that are taller than they are wider. Would it be possible to reverse this, in effect creating a 11x10 pixel mode? With this new mode the pixels would be wider than they were tall, thus helping with the black bar issue.

 

What do you think?

[Cospefogo]

Never say never, T.

 

I was just thinking about 10x11 pixel mode. Basically, that mode compresses the screen by (I think) outputing pixels that are taller than they are wider. Would it be possible to reverse this, in effect creating a 11x10 pixel mode? With this new mode the pixels would be wider than they were tall, thus helping with the black bar issue.

 

What do you think?

 

 

Hey Phil!

 

I already had this idea in the past!

I asked MadMab about this and the answer is no!

Pixel Aspect Ratio 10x11 is a hardware/video thing.

It is not a function or a bit of coding added for the programmer guys...

There is no way to invert it!

=)

 

C.

[Cospefogo]

Trying to set pixel-perfect horizontal sizes is just a waste of time since it won't get you anything like an accurate display. So this is the approach I'm taking with FBL to get the scanlines working properly across as many games as possible. For most games FBL will be sized to be double the native vertical resolution and all games will use the same horizontal size (probably around 576), thus creating as arcade-accurate an image as it's possible to achieve with this hardware.

 

Hey guys!

 

Well, if I take - right now, under 480p/720p in a LCD TV:

 

- Any NeoGeo game, like for example Metal Slug

- Apply the scanlines

- Apply point filtering (no bilinear, no blur, sharp as hell)

- Double the original height (pixel perfect)

- And apply *any given horizontal width* the game - even with the scanlines will not present a perfect scrolling horizontal. There will be waves totally noticeable on the screen. When you are out of the correct width is super easy to see the problem.

 

However, if I change the hardware filtering to bilinear or trilinear, the waves are gone. The problem is masked, diguised, but the screen becomes so blurry that I feel I am needing glasses to play. The pixels are completely smoked!

 

Mybe under the real 240p the width could not matter at all, but under a progressive 480p/720p in a emulator I think it should not be left behind. Also, there are some games that really had narrow old crt sceens. Stretching them to fill the modern display will present a "bad aesthetic" result... fat charecters!

=)

 

Well, my cents!

 

Regards,

Cospefogo.

[+ T +]

Yes, Cospefogo has hit the nail on the head. That's what I was referring to when I said to emulate the internal stretching would be impossible without altering the Xbox's video output. The 10x11 mode is a built-in function of the Xbox graphics adapter just like the flicker filter and display softening. An emulator can tap into these functions and make use of them, but it can't alter them unfortunately.

[PhilExile]

OK, thanks, Cos. I wonder if there is another way to somehow stretch the image, almost like the opposite CoinOps's widescreen fix.

 

What I'm thinking is:

 

1. You set the boundaries of your monitor's video - just like CoinOps/MAME, instead of creating a perfect pixel setup (512x448)

2. Set every game to automatically scale by x2 for 480p, x3 for 720p and center on the screen

3. There could then be an option to stretch the screen based on the user defined screen boundaries

 

Example: (512) screen width size / (610) defined screen size = percentage to stretch horizontally (8.4%)

 

Although, this too may lead to distortions in the image. Its all hypothetical and I don't know anything about programming, so please take this with a grain of salt.

[PhilExile]

Very interesting. By the way, what the heck does 'soften' do? I've never been able to discern a difference whether its on or off.

 

Yes, Cospefogo has hit the nail on the head. That's what I was referring to when I said to emulate the internal stretching would be impossible without altering the Xbox's video output. The 10x11 mode is a built-in function of the Xbox graphics adapter just like the flicker filter and display softening. An emulator can tap into these functions and make use of them, but it can't alter them unfortunately.

[Gilou9999]

There's some systems where the displays can fit the screen totally WITH pixel perfect settings like on a real CRT TV:

 

sega genesis/32x/sega cd

 

most time games native resolution is 320*224 typically for a genesis game so pixel perfect on a sdtv is 640*448

After set the screen size to 640*448 and NO hardware or software filter, in this case (and only in this case) i use the 10*11 pixel ratio trick:

the result is a screen with 448 pixels height (fit perfectly the screen) and ~600 pixels width (fit perfectly the game horizontally)

 

also neo geo since most games are 302 pixels width native, on the xbox 604 is a perfect width

if the neo geo game is 320 native i use 10*11 pixel ratio trick (and only in that case)

 

for nes/snes/master system, you will always have blackbars on left and right margin if you want to achieve the pixel perfect screen , that's perfectly normal,

but as far as im concerned in the case of nes/snes/master system etc..., the black bars are quite thin and doesn't bother me...

 

You'll also achieve a screen that match the real crt output with pcsxbox since native output is 640*480, so with the 10*11 pixel trick again, it will works perfectly

and also winstonX (atari st) as a native 640*400 output so you can use the 10*11 pixel trick with this one

[PhilExile]

I'm going to experiment some more and see what I can figure out. I may also do NES comparisons sometime this week.

 

Also, here are two other newer RGB/Composite comparison pages from Chris Covell's site:

 

http://www.chrismcovell.com/gotRGB/rgb_compare.html & http://www.chrismcovell.com/gotRGB/rgb_compare2.html

 

 

 

There's some systems where the displays can fit the screen totally WITH pixel perfect settings like on a real CRT TV:

 

sega genesis/32x/sega cd

 

most time games native resolution is 320*224 typically for a genesis game so pixel perfect on a sdtv is 640*448

After set the screen size to 640*448 and NO hardware or software filter, in this case (and only in this case) i use the 10*11 pixel ratio trick:

the result is a screen with 448 pixels height (fit perfectly the screen) and ~600 pixels width (fit perfectly the game horizontally)

 

also neo geo since most games are 302 pixels width native, on the xbox 604 is a perfect width

if the neo geo game is 320 native i use 10*11 pixel ratio trick (and only in that case)

 

for nes/snes/master system, you will always have blackbars on left and right margin if you want to achieve the pixel perfect screen , that's perfectly normal,

but as far as im concerned in the case of nes/snes/master system etc..., the black bars are quite thin and doesn't bother me...

 

You'll also achieve a screen that match the real crt output with pcsxbox since native output is 640*480, so with the 10*11 pixel trick again, it will works perfectly

and also winstonX (atari st) as a native 640*400 output so you can use the 10*11 pixel trick with this one

[+ T +]

One thing I found really interesting on that website is how programmers deliberately designed graphical elements in games to take advantage of how they would appear when viewed through a composite output. Check out the waterfall in Sonic on the screenshots page. Very cool stuff and definitely lends weight to the argument that the only way to play old games is on an old crappy TV.

Edited September 19, 2011 by + T +

[cba.gy]

Im confused, i always thought people knew that composite is rubbish (not to be confused with component, surely).

Also confused about the 1080p from an original xbox, mentioned in the title of the topic.

[+ T +]

Apparently it's not as rubbish as previously thought. Take a look for yourself (scroll down to the Genesis shots):

http://www.chrismcovell.com/gotRGB/screenshots.html#sms

 

See how the line dithering in Vectorman shows up as a solid colour in composite? Well that's a colour that the Genesis would be incapable of displaying otherwise. Also the line dithering beneath the spotlights in the same shot actually show up as a blue glow in composite mode (as they are intended to) whereas in RGB and the emulator shot, all you see are the dithering lines. And look at how the waterfall in the Sonic shot actually looks like water whereas the clearer images show it as just a bunch of vertical lines.

 

I'm sure there are other examples to be found of how programmers took advantage of composite blurring to achieve otherwise impossible effects in games, but these are great ones. I'm seriously tempted to hook my Xbox up with composite cables now just to see if these effects still work. And who knows? I may even leave it that way.

Edited September 20, 2011 by + T +

[PhilExile]

Im confused, i always thought people knew that composite is rubbish (not to be confused with component, surely).

 

Not always, the NES has good, sharp composite output. Its just a matter of opinion. I actually prefer the colors from a NES composite signal to an RGB.

 

Also confused about the 1080p from an original xbox, mentioned in the title of the topic.

 

It wasn't just a comparison between 1080p and 480p in terms of emulation. My first post I didn't even touch an Xbox. It was just to show that Xbox is enough and you don't need 1080 or even 720p for these old games.