Nadia scrolls too well

[Former user]

Original [issue 185](https://code.google.com/p/genplus-gx/issues/detail?id=185) created by [e-mail] on 2011-09-05T01:35:52.000Z:

What steps will reproduce the problem? 1. Load up Nadia (No-Intro name Fushigi no Umi no Nadia (Japan).md). (Either the fan translation or the original Japanese version will work.) 2. Start a game and just keep going through all the dialog boxes until you get control of your character and can move around in the city. 3. Move around in the city and find a place where you can scroll up and down and where there are several characters on the screen. The easiest place is all the way at the left end before the drunk (you can only scroll a limited amount since the drunk blocks you.)

What is the expected output? What do you see instead?

On a real machine, scrolling horizontally is smooth but scrolling vertically is jerky. On the emulator, both scrolling horizontally and vertically are smooth. Obviously this is not a game-breaking problem, since the emulator works better than the real machine; however it is a difference.

What version of the emulator are you using (official, SVN revision,...)?

1.60. The real machine is a Japanese Mega Drive with language switch running an Everdrive.

Please provide any additional information below (Video settings, Console region,...)

US NTSC Wii, 4:3 mode.

[Former user]

Comment # 1 originally posted by [e-mail] on 2011-09-05T02:44:14.000Z:

Oh, the Mega Drive is a non-TMSS model 1, if that matters, hooked up to a 32X and model 2 Sega CD.

[Former user]

Comment # 2 originally posted by ekeeke31 on 2011-09-21T12:12:34.000Z:

I tried the translated ROM on my PAL Mega Drive and did not notice the jerky vertical scrolling you mentioned, it works exactly as with the emulator for me.

I suspect you are using a LCD TV (I have CRT TV) and for some reason it does not display this game very well. What are the video settings you are using in the emulator ? Try switching to ORIGINAL with FILTERING OFF and use the same kind of video cable.

[Former user]

Comment # 3 originally posted by [e-mail] on 2011-09-22T03:24:08.000Z:

I am away from home for a while and can't check my settings, but I can tell you at the moment that I definitely have filtering off (I hate filtering and always disable it on emulators) and I \*think\* it's original mode, my TV is LCD, and my Mega Drive is NTSC. I wouldn't be surprised if this only had jerky scrolling on NTSC.

Also, the problem does not require the translation--the untranslated ROM does the same thing.

[Former user]

Comment # 4 originally posted by ekeeke31 on 2011-09-22T08:23:59.000Z:

It's not only the filtering but the video mode. LCD generally works better with INTERLACED or PROGRESSIVE output, which you might have been using with the emulator. The original Mega Drive outputs a non-interlaced video signal, which the Wii can also outputs if you select ORIGINAL video mode.

I don't think the difference comes from PAL or NTSC as my Mega Drive is switched and outputs 60Hz video signal, which is similar to NTSC. Only difference is the cable I'm using (SCART RGB) and the TV (real CRT).

What is sure is the game does not do anything special in that part and does not require any more accurate emulation that what is actually done, the issue with real hardware most likely comes from your TV equipement (TV mode, vcideo connector, etc), not from the game or console itself.

That's why I told you to use the SAME type of video cable for the Wii as you are using with your Mega Drive (I guess it's a basic composite cable) and switch to ORIGINAL (i.e non-interlaced) video mode in genesis plus gx video settings + disable any kind of filter. I'm pretty sure you will notice the same jerkyness with scrolling

[Former user]

Comment # 5 originally posted by [e-mail] on 2011-09-26T13:01:04.000Z:

I got home and tried it on my actual machine. You are correct, it's just a bad TV. I had original \*aspect ratio\* on the Wii but output was progressive; using original video mode and a composite cable like for the Mega Drive will produce the same jerky scrolling on the Wii. I tried another MD game on the real MD and it also had jerky scrolling.

[Former user]

Comment # 6 originally posted by thiagoalvesdealmeida on 2011-11-03T15:00:24.000Z:

Hi ekeeke, if you don't mind, I would like to use this topic to ask you something.

I'm helping the author of Mednafen-Wii in the implementation of a 240p mode, but since Mednafen works with a lot of systems, each one using a different resolution, we are having a hard time finding the best method.

At first, the emulator was using the fbwidth as 640. So, it looks perfect with Genesis games (for an obvious reason), but not good with NES and PC Engine games that use 256 pixels as the horizontal resolution, since the GPU is upscaling from 256 to 640, which is a non-integer upscale.

Of course, using 512 as the fbwidth will fix this issue for NES and PCE games - but it will break Genesis games that use 320 pixels.

I noticed that Genesis Plus looks perfect no matter what the horizontal resolution the game is using (320; 256 or 160).

Could you please tell how that was achieved? Genesis Plus is probably using the GPU to double the horizontal resolution and the video hardware to fill the rest of the screen, but I was wondering if the emulator somehow auto-detect the horizontal resolution and adjust the fbwidth accordly, in order to look good without GX filtering.

Thanks.

[Former user]

Comment # 7 originally posted by ekeeke31 on 2011-11-03T18:17:33.000Z:

Yes, it does indeed detect emulated resolution mode changes and changes fb\_width accordingly, which is logical in the sense, by definition, the emulator does know when mode is changing.

And as already said in your other topics about this subject:

1) to get minimal filtering, fb\_width should be equal or twice the width of the generated image (which is used as texture by GX rendering), so that NO bilinear filtering is applied by GX because of non-integer scaling ratio.

2) to get accurate aspect ratio, the rendered framebuffer should be upscaled (if necessary) to Wii fullscreen using VIDEO hardware, by setting vi\_width to 640 (if you want no filtering at all in 320 pixels width modes) or, to be more accurate, a little wider, how much wide depending on each emulated console and more precisely, its pixel aspect ratio, which is determined by original console dot clock and active width length...

Indeed, the filtering applied by VI encoder when upscaling fb\_width to vi\_width is much less destructive than the heavy bilinear filtering applied by GX on scaled textures.

[Former user]

Comment # 8 originally posted by thiagoalvesdealmeida on 2011-11-03T19:49:58.000Z:

Thanks ekeeke. The author of Mednafen-Wii will work on this.

By the way, when using the 240p mode, I noticed that Genesis Plus GX is the only emulator which a few pixels of horizontal resolution are hidden by the overscan area of my TV.

When using others emulators (Snes9x, FCEU, etc.), including playing Genesis games in Mednafen or Virtual Console, I can see all the horizontal pixels on my TV (unlike Genesis Plus).

Of course, this can be adjusted using the service menu of my TV. But regulating the screen size only for Genesis Plus will mess it for everything else.

Anyway. It's nothing major. Just a few pixels. But I was just wondering how it looks on your TV (or when using a real Genesis). If you can see all the horizontal resolution or not, compared to others emulators.

[Former user]

Comment # 9 originally posted by ekeeke31 on 2011-11-03T21:17:46.000Z:

It's probably because by default (original aspect ratio) I'm not using 640 pixels as vi\_width (like other emulators) but a little wider (654 actually), to accurately match aspect ratio observed on my Mega Drive.

On my TV (32" CRT Sony Wega), I only get hidden pixels if I let the TV in 16:9 mode with Aspect Ratio set to ORIGINAL (and not ORIGINAL with 16:9 compensation) as the display got horribly stretched, but otherwise I always see the full width and even some part of horizontal border, just like with my original Mega Drive.

If your TV is hiding some pixels and you don't like it, you can switch into SCALED aspect ratio and eventually adjust XSCALE/XOFFSET default values.

Out of curiosity, what kind of TV are you using ?

[Former user]

Comment # 10 originally posted by thiagoalvesdealmeida on 2011-11-03T23:43:35.000Z:

All right. Using SCALED fixed my problem. I was using 4:3 aspect ratio before. Also, using 4:3 with the borders turned off was clipping even more pixels compared with borders turned on.

BTW, using SCALED and turning off the vertical border with Master System games is horribly stretching the screen. And with Game Gear, also using SCALED, turning off the vertical or the horizontal border will stretch the screen too. Not sure if this is a know behaviour.

I'm using a 27" CRT Sony Wega. Great TV, but with horrible geometry issues. Seems to be a common problem with flat TVs. I wish I had a curved screen instead.

[Former user]

Comment # 11 originally posted by ekeeke31 on 2011-11-04T09:22:43.000Z:

yes, SCALED is meant to be like that, fill the screen. Though you are right and vertical scaling should not be applied for Master System games as it is actually, it's not right and should be fixed. thanks for pointing that out.