Native res. for Neo-Geo on Wii build

lordviper63 · 15 January 2017 03:27

Hi. Just tried the new build for Wii and these native resolutions looks great! Only issue I noticed is that there doesn’t seem to be a native resolution for the Neo-Geo core. The closest is 320x224, but from what I’ve read, the proper res. should be 304x224. The main issue is that there are weird scrolling issues when using the double-strike modes with point filtering and the incorrect resolution - a wavy effect. Bilinear filtering fixes the scrolling problem but of course the image isn’t as sharp. Is there a way to add this resolution in the future (if I’m right about that). Also, might there be a way to disable any type of filtering entirely when using the double-strike mode? Is point filtering even needed when you are displaying a scanlined image? I wonder if disabling the filtering would fix the problem as well. Thanks a bunch, and great work on the emulator! So nice to finally play these games with the proper display.

system · 15 January 2017 04:12

These are all the texture filters available in libogc for GX -

http://libogc.devkitpro.org/group__texfilter.html#gab3c71309b1cd91c6a6680c06efc5ed1a

#define GX_NEAR 0

Point sampling, no mipmap

Point sampling is what we refer to as ‘point filtering’. It should be the closest thing there is to having no filtering applied - especially in combination with setting VI Trap on/off.

Anyway, I can add that resolution for you - 304x224 that is.

lordviper63 · 15 January 2017 04:12

Cool thanks. I looks forward to trying that resolution. Again, from what I’ve seen, 304x224 should be the correct one. Funny thing - on Virtual console, Metal Slug 1 and X look fine and scroll properly, but they must have used the wrong resolution for Slug 3 because you get that weird warping of the pixels when the screen scrolls. I should correct what I said earlier - it seems like when you have the proper native resolution set, there is no difference between bilinear and point filtering. I actually just tested a real snes and genesis and compared to retroarch and it looks identical, so I guess the filtering makes no difference at all. And when I say “identical” I mean pixel-perfect.
Unbelievable how much difference double-strike makes. Anyways, thanks again for looking into this!

lordviper63 · 15 January 2017 04:13

One more question and comment about these resolutions. For SNES, I’m using 256x224p. If I set it to 512x224p, it looks sharper, and upon closer inspection, it looks just as crisp to the actual SNES version (via S-video). I noticed the same thing with Genesis at 640x224p as opposed to 320x224, and also with the Neo-Geo games that work at this resolution. Why would using the higher resolution look more accurate compared to the natives? Doesn’t the image have to be scaled all the way to fit the 640 NTSC signal anyways? How did the original consoles accomplish this scaling? Just curious because I noticed it when I was testing to see what resolutions worked for some of the Neo games. Also, since using the doubled horiz. res. seems to be the way to go, can you also add 608x224p? Some games work at 320x224p and 640x224p, some don’t. It looks like the Neo-Geo actually had 2 resolutions. Thanks again for a great emulator!

system · 15 January 2017 04:13

lordviper63:

One more question and comment about these resolutions. For SNES, I’m using 256x224p. If I set it to 512x224p, it looks sharper, and upon closer inspection, it looks just as crisp to the actual SNES version (via S-video). I noticed the same thing with Genesis at 640x224p as opposed to 320x224, and also with the Neo-Geo games that work at this resolution. Why would using the higher resolution look more accurate compared to the natives? Doesn’t the image have to be scaled all the way to fit the 640 NTSC signal anyways? How did the original consoles accomplish this scaling? Just curious because I noticed it when I was testing to see what resolutions worked for some of the Neo games. Also, since using the doubled horiz. res. seems to be the way to go, can you also add 608x224p? Some games work at 320x224p and 640x224p, some don’t. It looks like the Neo-Geo actually had 2 resolutions. Thanks again for a great emulator!

Yeah, nintygaming on RetroArch Wii actually discovered the reason for this when he emailed Eke-Eke about it -

Eke-Eke:

“the Wii always output the same resolution signal, which is 720x480 (720x576 for PAL) interlaced/progressive or 720x240 (720x288 for PAL) non-interlaced (also called double strike or “Original” in emulators). the maximal active screen SIZE (size that can be rendered by the Wii GPU in one pass) corresponds to the size of the embedded framebuffer (EFB) and is 640x528. the video hardware can then be configured to position (generally centered but it´s up to the developer) your rendered screen (640x448 or 640x224 for example) in the video signal window (720x480 or 720x240 as explained first), the “inactive” pixels being output to black. what i do in “original” mode is to render the emulated active screen (320x224 for most Genesis games but some games use 256x224 and Master System or Game Gear games do as well) then DOUBLE it horizontally to 640x224 or 512x224 inside the embedded framebuffer, using Wii GPU texture hardware (GX) scaling. GX scaling by default applies heavy bilinear filtering when upscaling so I have to disable hardware filtering if I want the image to remain sharp and not blurry. The fact that the screen width is simply doubled prevents scaling (generally visible when games are scrolling if you use a non-integer scaling ratio with no filtering). This other way is to use a feature of the Wii Video encoder which is able to upscale horizontally the framebuffer rendered by the Wii GPU up to the max. resolution (720 pixels), without any noticeable filtering ( understand, not blurry). So what I do is taking the rendered frame buffer, 640x224 (384x224 with overscan emulated) or 512x224 and let the Video Encoder upscale it to a COMMON and FIXED size (something like 644 pixels, which comes from my calculation based on Genesis and Wii pixel clocks, and match my observation against my real Genesis output on the same TV). And yes, the 256x224 original screen also needs to be upscaled to that common width because pixels in this mode wasn’t square pixels at all on the real thing, while Wii pixels always are. Similarly, pixels in 320x224 mode aren’t exactly square, which is why the screen is still upscaled to little than simply 640 pixels. All of this is because of the different pixels used on Genesis in the different resolution modes and on the Wii. i don’t know how retroarch handle those “resolution” modes, as i said, Wii resolution is fixed, only active screen size can be changed, scaled, etc lack of sharpness [when in 256 horizontal and not 512] is undoubtedly due to filtering being applied, either through software or through hardware:”

Nintygaming:

So there you have it . I think what he said about the hardware possibly using filtering would be correct, because I believe that the Wii’s Virtual Console does the same thing you do, and that is uses 640 or 512 horizontal. Why? Because it has the “exact” same sharpness and crispness as the “Original” modes in the GX emulators and 640/512 in Retroarch (very noticeable in games like Donkey Kong Country). So the Wii’s hardware probably filters “true” 256 and 320, as he mentioned above with hardware possibly filtering 256 or 320 horizontal.

I’ve also come to notice that VI Trap filtering actually sharpens the picture even more when turned on in “Original” modes. When turned off, colors tend to bleed more and the overall image gets slightly more fuzzy.

So essentially, if we want to prevent “hardware” filtering, we need to use 512 for NES and SNES, and 640/512 for Genesis. This however presents a problem for Genesis, because some games like Splatterhouse 3 use both 256 and 320, and thus, Retroarch needs to “decide” when to switch between the two, otherwise things get distorted. Genesis Plus GX (the standalone version) is designed to “know” when to switch.

Anyway, RetroArch should allow you the flexibility to set it however you like.

I’ll add those extra modes before releasing the new version of RetroArch Wii today/tomorrow.

lordviper63 · 15 January 2017 04:13

Thanks for the explanation. Would doubling 384x224 for CPS1/2 be impossible in that case, since it exceeds 720? Maybe even a 576x224p mode for some of those Konami games (TMNT, Simpsons, etc.) Its just too bad that none of the newer consoles support, or likely will ever support 240p again. I’d love to see some proper CPS3. Thank you once again for putting so much effort into this and accepting feedback. Can’t wait to try the new Neo modes!

lordviper63 · 15 January 2017 04:13

Just tried the new build, and that new Neo resolution fixed the scrolling problems with some of the games. If 320x224p doesn’t work, 304x224p does. Its basically just trial and error. Thanks for adding that!

system · 15 January 2017 04:13

We’re going to have Eke-Eke take a look over our Wii video code - it might be possible that all these ‘resolution lists’ will have to be either downscaled or removed - it’s entirely up to his judgement. We will want to aim for accurate scaling without distorting the picture and without any potentail for breakage.

lordviper63 · 15 January 2017 04:14

Sounds great, as long as there’s the option for the two resolution for neo games, unless its possible to do it on a game by game basis. One thing I just noticed is that most Neo Geo games on Virtual Console have scrolling problems…not just Metal Slug 3. Getting back to what I asked about earlier, I actually A and B’d a lot of these resolutions with 2 Wii’s hooked up. 512x224 looked better than 256x224 for SNES of course, but there doesn’t seem to be a difference with say 320x224 and 640x224 for Genesis and Neo. I swore 640 looked better when I was using just one console, but my eyes were playing tricks on me. All of these resolutions look identical to the original consoles anyway, and believe me, I’ve compared them all. Even the CPS2 and Neo Geo games look the same, all tested with the original arcade boards hooked up to my TV with a Supergun. The original picture may have to be scaled up to Wii’s 720x240, but original consoles had to scale them up anyways to fit the 4:3 ratio on a CRT. If I’m not mistaken, the US NTSC signal is 720x480i for a CRT, which I’m sure is why Nintendo went with that resolution for Wii. I can only assume this is why they look the same. In the end, who cares - it looks great!

system · 15 January 2017 04:14

The maximum resolution for the internal framebuffer of the Wii (EFB) is 640 x 528. You can’t go any higher than that. Display output resolution is a different thing entirely.

Troy_McClure · 15 January 2017 04:14

The picture isn’t actually scaled to 720 if you read Eke Eke’s answer closely. Rather, most of the difference between 640-720 is made up of inactive pixels, similar how the difference between 224 and 240 should be made of blank lines.This makes sense if Wii pixels are always square, since 720x480 isn’t 4:3 in such a case.