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Pixel Perfect 1280 x 1000 resolution?

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First post, by TomVDJ

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I rediscovered "Lemmings" and would like to play it pixel perfect with DosBox. The original resolution of Lemmings is 320 x 200. With aspect correction to 640 x 480 it means that 20% is added to the height.

What I'd like to get, is pixels of 4 x 5. So a full-screen resolution of (320 x 4) 1280 by (200 x 5) 1000 pixels (with 14 pixel black bands on top and bottom and 320 pixel black bands left and right, since my screen is 1920 x 1280). This way I would almost have the correct 4:3, but in theorie, the pixels all should "translate" into "4 x 5 pixel" on my screen, right? I don't seem to be able to do this, though. I have been playing around with all the settings in the config file, using DosBox ECE r4301 (last one supporting pixel perfect scaling, as far as I know). When specifying a 1280 x 1000 resolution, I end up with a 1280 x 1000 screen with a 20 pixel black band on top and bottom, leaving the "classic" 1280 x 960 resolution.

Somebody can help me out here? What am I missing? Suggested config file settings are very welcome...

Reply 1 of 28, by Ant_222

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TomVDJ wrote on 2021-01-13, 14:32:

I rediscovered "Lemmings" and would like to play it pixel perfect with DosBox. The original resolution of Lemmings is 320 x 200. With aspect correction to 640 x 480 it means that 20% is added to the height.

What I'd like to get, is pixels of 4 x 5.

Ideal aspect correction would be not 4x5 but 5x6 (if your display permits it).

So a full-screen resolution of (320 x 4) 1280 by (200 x 5) 1000 pixels (with 14 pixel black bands on top and bottom and 320 pixel black bands left and right, since my screen is 1920 x 1280). This way I would almost have the correct 4:3, but in theorie, the pixels all should "translate" into "4 x 5 pixel" on my screen, right?

Right.

I don't seem to be able to do this, though.

In the original plain-vanilla DOSBox, try in windowed mode:

windowresolution = 1280x1000
fullscreen = false
output = openglnb
scaler = none
aspect = false

I have been playing around with all the settings in the config file, using DosBox ECE r4301 (last one supporting pixel perfect scaling, as far as I know). When specifying a 1280 x 1000 resolution, I end up with a 1280 x 1000 screen with a 20 pixel black band on top and bottom, leaving the "classic" 1280 x 960 resolution.

You never have to specify a resolution for pixel-perfect mode. Try in ECE:

fullresolution = desktop
fullscreen = true
output = openglpp
aspect = true

If you still fail to make it work, show me your config and provide a link to your version of ECE, so I can test it on my side. As a last resort, I can set up Lemmings in my own version of ECE and the whole setup back to you, and Bob's your uncle (if Windows is your OS).

Reply 2 of 28, by jmarsh

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Lemmings uses a resolution of 640x350, not 320x200.

Reply 3 of 28, by TomVDJ

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Thanks for the quick answer! I'll test it out tomorrow (it's already very late over here). Made a mistake about my monitor. It's off course a 1028 x 1920 one, not 1280 x 1920, so 5x6 pixels is no option.

Reply 4 of 28, by TomVDJ

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Oh man, I don't seem to manage. I think I missed some parameter in my config. I now got a small screen with artefacts around it. In attachment my lemmings.conf file (I start it with a bat file that calls dosbox ece with this config file). I've put machine=vgaonly (instead of svga_s3) since this renders the colors as the original.

I use Dosbox ECE r4301 (downloaded from the archive folder on the ECE website). Also use the CD-rom version of lemmings + oh no more lemmings, but that will not make a difference versus the normal floppy disk version, I guess. The CD only adds CD-audio...

Reply 5 of 28, by TomVDJ

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jmarsh wrote on 2021-01-13, 23:23:

Lemmings uses a resolution of 640x350, not 320x200.

Yep, you're right. At least the menu screen and screen with the level explanation are. The actual resolution while playing is 640x400 (so 2 times 320 x 200, I was testing things out with SpaceQuest which actually is 320 x200, hence the confusion).

I guess that could be a problem for the pixel perfect patch, since it can't multiply with a natural number to generate rectangular pixels... Hight can only be multiplied by 2 on my screen (when it would actually have been 320 x 200, it could have been multiplied by 5).

Still curious how to make this work with SpaceQuest (an actual 320 x 200 game) if it would not be possible with Lemmings.

Reply 6 of 28, by Ant_222

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TomVDJ wrote on 2021-01-14, 07:48:

Oh man, I don't seem to manage. I think I missed some parameter in my config. I now got a small screen with artefacts around it. In attachment my lemmings.conf file (I start it with a bat file that calls dosbox ece with this config file). I've put machine=vgaonly (instead of svga_s3) since this renders the colors as the original.

Your config has:

output=surfacenp

instead of

output=openglpp

Why did not you configure it as I recommended?

Reply 7 of 28, by TomVDJ

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Ah, damn, yeah, I tried with different output values there, none of them seemed to work. Also not openglpp. Could you just let me know what settings SHOULD work for the [sdl] and [render] section of the config file? If you just cut and paste those two complete sections with the correct settings, it should work over here too, right?

I have looked for a "template" config file for Dosbox ECE with the pixel perfect patch enabled, but didn't find one, so I tried to "interprete" the readme of your patch, but not too well, apparently...

Reply 8 of 28, by BardBun

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output=openglnb
aspect=false

Pixel perfect resolutions are:

Native game resolution: 320x200
Then: 640x400 \ 1280x800 \ 1600x1000 \ 1920x1200 \ 2240x1400 \ 2560x1600 \ 3200x2000 \ 3840x2400

Native game resolution: 320x240 or 640x480
Then: 1280x960 \ 1920x1440 \ 2560x1920 \ 3200x2400 \ 3840x2880

To get it centered in fullscreen mode you gotta adjust the horizontal value.

For example, you have a 1920x1080 FullHD Monitor, your choice would be the 1600x1000 resolution.
In DOSBox you have to enter
fullresolution=1920x1000

Then it will be 1600x1000 in the middle with black bars around.

This works for every resolution, for example 2560x1400 for monitors with 2560x1440.

For 640x480 games on a 2560x1440 monitor you can just leave it at 2560x1440, it'll be centered already, no need to adjust here.

---

Some games also change between resolutions when it comes to the menu and actual ingame resolution.

Reply 9 of 28, by Ant_222

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TomVDJ wrote on 2021-01-14, 10:29:

Ah, damn, yeah, I tried with different output values there, none of them seemed to work. Also not openglpp. Could you just let me know what settings SHOULD work for the [sdl] and [render] section of the config file?

Not until tomorrow evening. In the mean time, post screnshots of DOSBox ECE and its log window with the following settings:

fullresolution = desktop
fullscreen = true
output = openglpp
aspect = true

I have looked for a "template" config file for Dosbox ECE with the pixel perfect patch enabled, but didn't find one.

You can delete the existing config file, and DOSBox will generate a new default one at startup, if launched without any command-line arguments.

Reply 10 of 28, by Ant_222

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BardBun, the problem is not the centering of the image, but the scaling algorithm. I don't think you can always achieve correct integer scaling in full-screen by changing fullresolution. LCD displays must always work at their native resolution for a sharp image.

Reply 11 of 28, by TomVDJ

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OK, generated a "blank" config file by DosBox itself and just changed the above settings, and I got the result in attachment.

In the meanwhile I also tried the dosbox version from here: https://github.com/bladeSk/DOSBox-pixel-perfect and I was able to get what I wanted (see other attachment "Pixel Perfect Patch") but only this does not work with "vgaonly". Only works with svga_s3, which results in some colors being off, especially in the screens where the levels are explained (see attachment "colors").

Reply 12 of 28, by Ant_222

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Thanks for the screenshots. Your DOSBox ECE does not seem to work correctly in pixel-perfect mode. I will test it on my side. I also asked you to post a screenshot of its log output window. Can you do that?

Reply 13 of 28, by TomVDJ

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BardBun wrote on 2021-01-14, 10:53:

Native game resolution: 320x200
Then: 640x400 \ 1280x800 \ 1600x1000 \ 1920x1200 \ 2240x1400 \ 2560x1600 \ 3200x2000 \ 3840x2400

Yeah, but then you will have pixels that are 2x2 or 4x4,... I want to have pixels that are 4 width and 5 heigh, so the aspect ratio is (more or less) correct. See the one attachment in my previous post: all pixels there are 4x5, but I have no clue how to achieve this in DoxBox ECE r4301.

Reply 14 of 28, by TomVDJ

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Ant_222 wrote on 2021-01-14, 11:33:

Thanks for the screenshots. Your DOSBox ECE does not seem to work correctly in pixel-perfect mode. I will test it on my side. I also asked you to post a screenshot of its log output window. Can you do that?

I got this in the DosBox window (I guess that's the output window). Seems openglpp is not supported. (stderr.txt and stdout.txt stayed blank)

DOSBox version SVN
Copyright 2002-2019 DOSBox Team, published under GNU GPL.
---
CONFIG: Loading primary settings from config file lemmings.conf
"openglpp" is not a valid value for variable: output.
It might now be reset to the default value: surface
MIDI: Opened device:win32

To be clear: I used the Dosbox ECE version r4301 I found here: https://dosboxece.yesterplay.net/ in the archive folder, since I read here on Vogons it was the last version supporting Pixel Perfect. Maybe that statement was not correct? (Found it here: Re: DOSBox ECE (for Windows & Linux))

Reply 15 of 28, by imi

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jmarsh wrote on 2021-01-13, 23:23:

Lemmings uses a resolution of 640x350, not 320x200.

only the menus... which has giving me headaches trying to capture it, because my capture card doesn't like switching between these resolutions sometimes ^^

1600x1200 would be the correct pixel perfect scaling resolution, as someone else said, 1280x1000 is 4x5 pixels and not quite 4:3 while 1600x1200 is 5x6 pixels and 4:3

Last edited by imi on 2021-01-14, 13:25. Edited 1 time in total.

Reply 16 of 28, by TomVDJ

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imi wrote on 2021-01-14, 12:23:

1600x1200 would be the correct pixel perfect scaling resolution, as someone else said, 1280x1000 is 4x5 pixels and not quite 4:3 while 1600x1200 is 6x5 pixels and 4:3

Yes, indeed, but my monitor is only 1920 x 1080, so I'd be more than happy with 1280 x 1000 (so 4x5 pixels instead of 5x6), and an aspect ratio that's just a tiny bit off. So that I got this result (but then with, if possible, a recent version of DosBox / DosBox ECE and also if possible with vgaonly instead of svga_s3):

Reply 17 of 28, by Ant_222

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TomVDJ wrote on 2021-01-14, 11:59:

To be clear: I used the Dosbox ECE version r4301 I found here: https://dosboxece.yesterplay.net/ in the archive folder, since I read here on Vogons it was the last version supporting Pixel Perfect. Maybe that statement was not correct? (Found it here: Re: DOSBox ECE (for Windows & Linux))

Very likely so. I recommend that you try ealier versions, where openglpp is available.

Edit: Your question about DOSBox ECE is best asked in that thread rather than here.

Reply 18 of 28, by TomVDJ

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Yep, the version before that works fine (R4296). For space quest it does exactly what I want. For Lemmings however it gives me this result: A screen of 960 x 800 with 4x3 pixels. While the aspect ratio is perfect, I'd prefer to have a 5x4 pixels with an aspect ratio that's slighlty off, but covering a much bigger part of my screen. Is this possible with your patch Ant_222? Is it able to scale with "halfs"?

So width would scale 2 and height 2,5, resulting in the original 640 x 400 becoming 1280 x 1000. The patch mentioned (https://github.com/bladeSk/DOSBox-pixel-perfect) seems to be able to do this, but fails on supporting the vgaonly option... 🙁.

Reply 19 of 28, by Ant_222

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TomVDJ wrote on 2021-01-14, 13:59:

Yep, the version before that works fine (R4296). For space quest it does exactly what I want. For Lemmings however it gives me this result: A screen of 960 x 800 with 4x3 pixels. While the aspect ratio is perfect,

The ratio is 3:4 (width:height), and it is far from perfect, because it yields an emulated display of 960x800 with an aspect ratio of 6:5 instead of the standard 4:3. In fact, 4:5 pixels are much closer to the ideal for a 320x200 game than 3:4 ones.

I'd prefer to have a 5x4 pixels with an aspect ratio that's slighlty off, but covering a much bigger part of my screen. Is this possible with your patch Ant_222?

Are you running Lemmings and Space Quest with the same config? Screenshots here show that Lemmings use a 320x200 graphical mode. I remember the was a problem with vgaonly which imitated doublescan, causing the input resolution to be perceived as 320x400. Naturally, you cannot upscale 320x400 into 12800x1000 using integer scaling factors. I vaguely remember that I had to use svga_s3 to bypass exactly that problem, you say it spoils the colors. See if you can disable doublescan in DOSBox in any other way.

To answer your question precisely, I need to see the debug output either as stderr.txt or as a separate console window usually created together with the DOSBox main window. Maybe they can help you activate it at the ECE thread.