Game Gear maintain aspect ratio scaling

[Former user]

Original [issue 179](https://code.google.com/p/genplus-gx/issues/detail?id=179) created by westonlast on 2011-08-10T18:42:04.000Z:

I'm requesting an option that scales Game Gear games to fit the screen while maintaining the aspect ratio.

[Former user]

Comment # 1 originally posted by ekeeke31 on 2011-08-11T08:20:02.000Z:

As described in the user manual, the options are already there:

In Video Settings, disable border emulation and set Aspect ratio to SCALED. With default scale value (0,0), it will make Game Gear games fit the screen while more or less maintaining aspect ratio (the Game gear LCD screen has approx. 4:3 dimensions)

Some quick calculations: Full screen height being 224 lines (this is the default value when YSCALE = 0), the 160x144 Game Gear screen should be upscaled to 160 \* 224/144 = 248 x 224. With default XSCALE value (0), width is 640 Wii pixels which represents 256 Master System or Game Gear pixels, so 248 pixels equal 248\*640/256 = 620 pixels. With that in mind, setting XSCALE to (620-640)/2 = -10 should give you the exact original aspect ratio.

[Former user]

Comment # 2 originally posted by westonlast on 2011-08-12T00:06:37.000Z:

With both sets of settings I notice scaling artifacts in Sonic 2 (and all games). Pixels appear and disappear in the ground texture when walking down a slope, for example.

[Former user]

Comment # 3 originally posted by ekeeke31 on 2011-08-12T08:03:18.000Z:

That's perfectly normal.

Artefacts are quite expected since the ratio between the original height (144 lines) and the fullscreen one (224 or 448 lines) is not an even number, so when you are upscaling, filtering is needed to hide this kind of artefacts.

In short, turn BILINEAR FILTERING option ON and use INTERLACED or PROGRESSIVE display.

[Former user]

Comment # 4 originally posted by westonlast on 2011-08-16T01:23:42.000Z:

I also see scaling artifacts in the Master System Sonic 2. This game was designed to be fullscreen...

[Former user]

Comment # 5 originally posted by ekeeke31 on 2011-08-16T08:54:35.000Z:

Did you read my previous comment ? You get scaling artefacts because you are upscaling with a non-integer ratio. If you don't want scaling artefacts, use the default ORIGINAL settings or enable filtering. Is that so complicated to understand ?

And NO master system games were ever designed to be fullscreen, I wonder why people constantly brag about this (maybe it's memory playing tricks or they never have played a real master system on TV before ?) This makes no sense, really, vertical resolution for ALL master system games is 192 lines, while full screen is approx. 224 lines for NTSC (268 lines for PAL), which is why you got vertical borders on all TV when playing Master System.

There are no magical stretching on TV and the ORIGINAL aspect ratio is called like this for a good reason, because it is the way those games were displayed and therefore "designed". If for an odd reason, you prefer games to look stretched, then you have to use filtering. Is that clear now ?

[Former user]

Comment # 6 originally posted by westonlast on 2011-08-16T12:40:02.000Z:

Thank you for taking the time to explain. You really know your stuff. ;)

I use ORIGINAL, ALL BORDERS, and DEFAULT 4:3, and Sonic 2 Master System looks "widescreen" with vertical borders, as it should, but I still see scaling artifacts. Is this normal?

[Former user]

Comment # 7 originally posted by ekeeke31 on 2011-08-16T13:05:55.000Z:

No, it isn't and it doesn't happen for me but I think I know what cause the issue for you : do you have a PAL or NTSC Wii ? What is the TV Mode option set to ? 60HZ or 50/60Hz ?

[Former user]

Comment # 8 originally posted by westonlast on 2011-08-16T13:18:54.000Z:

NTSC 60Hz.

[Former user]

Comment # 9 originally posted by ekeeke31 on 2011-08-16T13:36:27.000Z:

Ok.

What happens is that Sonic 2 is a PAL game (and as far as I know, never was released in the US). There are indeed some glitches when playing it on a NTSC system so the emulator automatically detects it and switch to PAL mode when loaded.

The problem is that IF your console is a NTSC one, the emulator will assume that your TV does not support 50hz to be safe, and will be configured to always output in 60hz. This is what explains the scaling artefacts issues, because the emulator needs to do some scaling to keep the original PAL aspect ratio while outputing in NTSC. In that specific case, filtering is also required because you are basically trying to mimic PAL output on a NTSC system (i.e larger vertical borders).

Now, if your TV supports both 50Hz and 60hz, you can change that by setting the TV Mode option to 50/60hz (which is automatically done on PAL Wii since they support both output) so it automatically matches the emulator mode and you won't have artefacts anymore while having the original PAL aspect ratio. This is actually the most accurate solution and the one to choose if you know your TV supports 50hz video signals.

Another solution is to force the emulated region to USA in SYSTEM OPTIONS but keep in mind that this particular game is known to have glitches on NTSC systems because of timing differences and the emulator is accurate enough to reproduce that. For this reason, it is not advised to do that.

Finally, you can leave the region setting to AUTO (thus still emulating PAL timings) and TV Mode to 60Hz (thus outputing NTSC signal) but set the Aspect Ratio to SCALED and modify the vertical scale value so that the output matches original height and litteraly disable any vertical scaling, thus reproducing aspect ratio of a NTSC master system. A value of -24 should be correct and remove any artefacts by the same way.

[Former user]

Comment # 10 originally posted by westonlast on 2011-08-16T19:56:56.000Z:

I wonder whether the Virtual Console NTSC release scales or fixes the resolution. Thank you. I'll try this when I get home.

[Former user]

Comment # 11 originally posted by ekeeke31 on 2011-08-16T21:14:29.000Z:

That's an interesting question.

According to this forum:

http://forums.sonicretro.org/index.php?showtopic=16550&view=findpost&p=330081

Sonic 2 VC release uses the known [V1] PAL dump but also includes a ROM patch that is applied by the emulator so maybe it was fixed in order to run at 60hz.

What is sure is that it displays NTSC aspect ratio and runs at 60hz, so no scaling.