Indivision AGA MK2 - Forcing 4:3 modes

 
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This is a quick Amiga tutorial which explains how to get the Indivision AGA MK2 scandoubler to display 4:3 screen modes on a 16:9 monitor, while preserving the correct aspect ratio.  Have in mind that one of the HDMI inputs of a Funai LCD TV is used here (via DVI to HDMI adapter).

After installing a Indivision AGA MK2 in my second Amiga 1200, I connected it to the VGA input on my TV, where I had some problems with getting the PAL modes to display properly the way I wanted it to. The main issue was that I couldn't use the 768 x 576 VGA mode, since it was unsupported by the monitor. So then I decided to try connecting to a HDMI input instead, which worked much better. Now I was able to use the VGA mode I prefer, since it seems like the Funai will simply upscale almost any mode I throw at it.



There was one problem though - the displayed image was stretched to the sides, and while some people are just fine with this, I quite simply cannot stand it. Because I really need 4:3 images to be displayed with the correct aspect ratio! After fiddling around for a while with both the TV settings and the Indivision Preferances program - without having any success, I was starting to feel a bit disappointed with my Indivision AGA adapter. But I finally figured out what to do.



The answer to the problem was to simply make the Indivision use a 16:9 VGA mode for the PAL screens, but since there are no suitable widescreen modes with a 576 pixels height among the default VGA Mode presets, it meant I had to try making a custom one instead. First I had to figure out the new width, where I did the following calculation:
 
   576  /  9  *  16  =  1024
 
This meant that I now had to create a new custom 1024 x 576 VGA mode, and to do this I first selected Config > VGA Modes from the menu of the Indivision Preferances program, which brought up the window below. Here I chose the  "768x576 60Hz"  mode from the left list, and then clicked the Copy button



This made a new  "copy 768x576 60Hz"  entry at the bottom of the list, which I then selected and renamed to  "copy 1024x576 60Hz".  Next, I changed the value in the Pixles/Line box from 768 to 1024 and finally clicked the Apply button.



Back in the main Indivision Preferences window, I now selected the  "PAL-interlace"  Amiga Mode, and then the  "copy 1024x576 60Hz"  VGA Mode. Just to see if the new settings would work, I then clicked the Test button in order of opening a test screen. Since everything seemed to be fine, I just finished off by clicking the Apply button.





And finally I had a display for my Amiga 1200 that I was satisfied with.




Other Amiga Modes
There are also some third-party Monitor drivers for the Amiga, which is supported by the Indivision range of scandoublers. If you want to use any of those, and you also want them to look correct on a 16:9 monitor as well (in case aspect ratio is wrong), you can see how I have configured them in the table below. Just have in mind that I haven't tested the SuperPlus driver, so the 16:9 mode mentioned here is only a guesstimate.
 
Amiga Mode VGA Mode VGA Mode - 16:9 Comment
PAL 768x576 1024x576 See the instructions above.
HD720 1280x720 1280x720 This one is already 16:9, but since 1280x720 wasn't in the VGA Mode list, I had to create a custom mode by copying & editing the 1280x768 one (for best result).
HighGFX 1024x768 1368x768 This 16:9 mode is already present in the VGA Mode list.
SuperPlus 800x600 1066x600 Mode is not supported by the Indivision AGA MK2 core, so it isn't tested.
XTREME 1280x1024 1820x1024 This one is a bit unstable on my Amiga since it locks up the system, so in my case it's probably not safe to use it for the Workbench screen (both modes were tested).



Calculating 16:9 Modes
The way I figured out the new 16:9 widths mentioned in the table above, was by using the following formula:  Height  /  9  *  16  =  Width

With SuperPlus and XTREME I had to round off the numbers, since the orignal results was 1066.66 and 1820.44. One important thing to have in mind when dealing with screen sizes, is that both the width and height should always end with a zero or an even number. This is the reason why 1067 should not be used with SuperPlus for example (1068 would be better).

Once the new widths were calculated, it was just a matter of finding the most suitable modes among the VGA Mode presets, and then copy & modify them in the same way as described further up on this page.





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