Dosbox and scanlines in non native resolution \ VOGONS

Dosbox and scanlines in non native resolution

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First post, by theelf

Posted on 2016-02-01, 18:10

theelf Offline

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Joined: 2011-09-25, 19:39

Greetings!

Im having trouble with dosbox in my CRT screen. I want to use a resolution that have over 1000 pixels in height, for example 1280x1000 or 1280x1200 or 1280x1400 or 320x1000 or 640x1600 is the same if i want to play a 320x200 game

Plus scanlines (normal ones, black line) for CGA and EGA games

Because my CRT is a 20" one, if the resolution is less than 960px show small thin scanlines (less resolution, bigger they are), but over 960 lines, the screen is sharp, and great for scanline emulation

My best will be 320x1200 or 640x1200 or 1280x1200 and scanlines.... is possible in dosbox?

Thanks a lot for any ideas

Reply 1 of 4, by realnc

Posted on 2016-02-01, 18:38

realnc Offline

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Since you have a CRT, you don't need to emulate scanlines. That's for LCD users who want to make the image look more like a CRT.

So what's stopping you from actually running it at 320x200?

Reply 2 of 4, by theelf

Posted on 2016-02-01, 19:02

theelf Offline

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realnc wrote:
Since you have a CRT, you don't need to emulate scanlines. That's for LCD users who want to make the image look more like a CRT.

So what's stopping you from actually running it at 320x200?

I dont need to emulate scanlines for VGA games at all, i can use native resolution, but yes for CGA and EGA ones to simulate 15khz screen

Scanlines is not just for TFT users only, for 31khz CRT users is great too

Reply 3 of 4, by Lo Wang

Posted on 2016-02-04, 17:24

Lo Wang Offline

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For a standard 320x200 CGA display, you should upscale the image to 1600x1200 (aspect ratio-corrected) or 1600x1000 (aspect ratio correction must be done from from the monitor itself). Problem is, DosBox doesn't have an option for overlaying custom patterns on top of the output image.

15khz should be about one black line per pixel row, which perhaps the tv scaler can do.

"That if thou shalt confess with thy mouth the Lord Jesus, and shalt believe in thine heart that God hath raised him from the dead, thou shalt be saved" - Romans 10:9

Reply 4 of 4, by theelf

Posted on 2016-02-05, 02:02

theelf Offline

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Lo Wang wrote:
For a standard 320x200 CGA display, you should upscale the image to 1600x1200 (aspect ratio-corrected) or 1600x1000 (aspect ratio correction must be done from from the monitor itself). Problem is, DosBox doesn't have an option for overlaying custom patterns on top of the output image.

15khz should be about one black line per pixel row, which perhaps the tv scaler can do.

Thanks, yes, i preffer non 4:3 resolutions, because i already use 1600x1200 for other emulators, but is ok, i realize dosbox dont support non integer resolutions

Anyways, my problem is.... (nvidia 8600GT)

surface ---> impossible to scale to 1600x1200
ddraw ---> have bilinear
overlay --> bilinear + dont scale
openGL --> bilinear + dont scale very well
openGLnb --> bilinear + dont scale very well

The only output metod that reescale to fullscreen a 320x200 game is ddraw, all others fail to scale if I use more than 640x480

SVN Daum Dosbox in OpenGL or D3D works great, scale to fullscreen without bilinear, and apply scanlines, but i preffer to use official build if possible

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