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Old 05-04-2010, 03:42 PM   #1
TheAnyKey
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Default DosBox: Big black bar at the bottom in full screen mode

Hi,

whenever I maximize dosbox I have a big black horizontal bar at the bottom of the screen. It's about 1/4 of the screen big. The bar is not present in windowed mode. The black bar occurs with all games.

Does anybody know what the reason for this could be?

Thanks a lot.
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Old 05-04-2010, 07:56 PM   #2
Eagle of Fire
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It is the first time I ever heard about something so strange. Seems to me like it is an issue with your monitor. You probably have a huge monitor which have trouble to fit the tiny DOS resolution and thus is cutting some of the screen off.

Does the image or screen you get seem good to you? Could you actually play on it?
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Old 05-04-2010, 08:11 PM   #3
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Is the game's screen completely visible or does the bar obscure part of it?
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Old 05-04-2010, 08:13 PM   #4
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did you try playing with the [sdl] settings in dosbox.conf? (for example output method, or screen resolution ...) i;m pretty sure you can fix it by playing with the settings
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Old 06-04-2010, 01:12 AM   #5
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Look at this example, it may be enough for you to understand the (likely) problem:

http://www.abandonia.com/vbullet/sho...837#post354837

Specially click on the image link at the bottom.
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Old 06-04-2010, 11:31 PM   #6
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OK I had very little time yesterday. First of all, try if this solves the problem:

Quote:
Originally Posted by Japo View Post
A small tip for the road. Maybe you like to play in fullscreen, but when you try you see a small game image surrounded by a big black frame. To fix this go to "Start > Programs > DOSBox-X.XX > DOSBox.conf". Here you can change DOSBox's settings, but we didn't mention it to keep things simple. Right now don't worry about all the garble inside and just search (Ctrl+F) for "fullresolution", and change what's to the right of the "=" to "640x480":


Make sure to save the changes. When you run DOSBox in fullscreen again, the image should occupy the whole width, if your graphic card supports the 640x480 resolution. (You can eliminate the black strips that may appear along the top and bottom of the screen depending on the game, by changing "aspect=false" to "aspect=true" instead; but I don't recommend that because it can be very processor-consuming, and what's worse you'll lose image definition. Besides what in the world's wrong with those cool retro Cinemascope strips?)
Now let me explain:

1) First there's the resolution the game has. Most very old games have 320x200 pixels, more recent ones 640x400, and then 640x480.

2) Then DOSBox scales this original image into the resolution defined in that "fullresolution" parameter. The default setting is "original", meaning to leave it be, not to scale the image but pass it to the graphics hardware unscaled.

3) Also if the "aspect" parameter is set to "true", the image will be stretched so that it always fills the whole fullresolution. This means losing a lot of definition, and probably stretching both dimensions differently so that squares become rectangles etc.

On the other hand if "aspect" is set to "false", the image can be scaled into a different resolution, but preserving the aspect ratio and definition at 100 per cent. That means a 320x200 can only be scaled into 640x400, 960x600, 1280x800, etc. The rest of the "fullresolution" if any, is filled with black, but DOSBox kindly centres the scaled image in it.

4) Finally the graphics hardware takes the image created by DOSBox (at "fullresolution" pixels). The problem is, if the hardware doesn't support "fullresolution", it will fall back into a supported resolution, probably the closest larger; but it won't probably centre the image served by DOSBox, but leave it at the left top.

And modern hardware never support 320x200 nor 640x400. With luck they will continue supporting 640x480 for legacy purposes. So if you leave "fullresolution=original", your graphics hardware will probably chose a tricky resolution and screw you. If you change it to "fullresolution=640x480", a 320x200 or a 640x400 will be scaled into filling the whole width and leaving two black frames at the top and bottom, and the image definition will be preserved 100 per cent.

In this example the original image (from Windows 3.1) was 640x480, and I had tested "fullresolution=768x480":


(click to enlarge)


5) But there's more! Actually I wouldn't recommend "fullresolution=640x480" any longer, if you bear with me. Because 640:480 = 4:3 (old TV set/screen aspect ratio), but modern panoramic screens or TV sets usually have a 16:9 aspect ratio (for example 1920:1080). So even if DOSBox didn't modify the aspect ratio, it will be modified when displaying a 4:3 image on a 16:9 screen--the number of pixels would be right and the definition would be perfect, but each pixel wouldn't be square.

The best solution depends on the resolutions your hardware supports, and how it behaves. You can always make "fullresolution" equal to the native resolution of your hardware (the one you're using in Windows, that should have the same aspect ratio as the physical dimensions of the screen) and call it a day. Perhaps this would be the most recommendable option.
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Old 08-04-2010, 12:56 PM   #7
TheAnyKey
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Thanks so much Japo. It works with 640x480 for me, I have an old 4:3 screen.

Really, thanks a lot for all your efforts.
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Old 08-04-2010, 08:24 PM   #8
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NP, lots of people have similar problems, now I can link here when they ask in the future.
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