Sonic 2 480i Square Pixels

[Mittens0407]

Just a little video showing Sonic 2 multiplayer scaled so it's proportionally accurate. I would've done this with my TV but it has the most useless sizing/scaling option ever (Scaling outwards doesn't move the black bars for 4:3 so it's useless for anamorphic stuff, and it can't squish inwards so it was useless for this), so I ended up using a cheap USB HDMI capture card and OBS, and at that point I thought that I might as well record it. I think Sega Smash Pack on the Dreamcast offered a feature that did this.

[Kirk_Johnston]

It's strange that the Genesis apparently never had the ability to use double height sprite and/or background tiles in this mode to compensate for the squishing effect that naturally occurs when running in 480i on these old consoles and TVs, as the games that used it could have had pixels that appeared normal height and also still taken up the full width of screen with that one little addition, which obviously would have looked much better. Unfortunately, this very noticeable squish of everything to half the height, was something that instantly put me off the mode in the couple of Genesis games that used it, as everything always just looked kinda off/wrong to me.

 

That two-player mode on Sonic 2 looks so much nicer when the pixels aren't vertically squished, as we can do on modern TVs and emulators and the like, and as perfectly demonstrated in your clip.

 

As it is on Genesis, it seems to work the same way as the SNES does when using interlacing in background modes 0-4 and 7. If it had worked similar to how SNES does in background modes 5 and 6 though, I think we probably would have seen way more Genesis games use this feature, which is a shame:

 

 

 

Interestingly, the SNES actually has both horizontal and vertical tile doubling in Modes 5 and 6 to overcome this squish, but that's because it can double both the horizontal and vertical resolutions, going from the standard 256x244 resolution to 512x448, whereas the Genesis would have only had to worry about it in the vertical direction in its 320x448 mode, as it doesn't have a mode for doubling the horizontal resolution anyway.

 

Shame SNES used the full 512x448 mode in-game on even less games that Genesis used its 480i mode. A handful of games did use if for titles screens and menus and such, but it was ultimately woefully underused, as was also the case with quite a few of the SNES' other background modes too.

 

I'd actually like to see more games use the 480i mode on both these consoles (along with the 512 horizontal resolution on SNES).

 

Edited December 15, 2022 by Kirk_Johnston

[Mittens0407]

19 hours ago, Kirk_Johnston said:

It's strange that the Genesis apparently never had the ability to use double height sprite and/or background tiles in this mode to compensate for the squishing effect that naturally occurs when running in 480i on these old consoles and TVs, as the games that used it could have had pixels that appeared normal height and also still taken up the full width of screen with that one little addition, which obviously would have looked much better. Unfortunately, this very noticeable squish of everything to half the height, was something that instantly put me off the mode in the couple of Genesis games that used it, as everything always just looked kinda off/wrong to me.

 

That two-player mode on Sonic 2 looks so much nicer when the pixels aren't vertically squished, as we can do on modern TVs and emulators and the like, and as perfectly demonstrated in your clip.

 

As it is on Genesis, it seems to work the same way as the SNES does when using interlacing in background modes 0-4 and 7. If it had worked similar to how SNES does in background modes 5 and 6 though, I think we probably would have seen way more Genesis games use this feature, which is a shame:

 

 

 

Interestingly, the SNES actually has both horizontal and vertical tile doubling in Modes 5 and 6 to overcome this squish, but that's because it can double both the horizontal and vertical resolutions, going from the standard 256x244 resolution to 512x448, whereas the Genesis would have only had to worry about it in the vertical direction in its 320x448 mode, as it doesn't have a mode for doubling the horizontal resolution anyway.

 

Shame SNES used the full 512x448 mode in-game on even less games that Genesis used its 480i mode. A handful of games did use if for titles screens and menus and such, but it was ultimately woefully underused, as was also the case with quite a few of the SNES' other background modes too.

 

I'd actually like to see more games use the 480i mode on both these consoles (along with the 512 horizontal resolution on SNES).

 

Yeah. Theoretically, you could use high res mode on the Megadrive for a better proportional picture, but you'd need double height sprite graphics and have to use double the amount of tiles. I guess devs assumed that essentially a 2 times memory cost for graphics wouldn't be worth it for the extra rows. Probably applies a lot to the SNES high res modes as well. It's easy to forget about what devs had to do to get their games to fit on cartridges of the time. No matter the capabilities of the system itself, it all boils down to ROM size limitations for large high resolution graphics. Interestingly, in the Japanese version of RPM Racing they actually downgraded the resolution, and by doing that it seems they were able to eek out a lot more variety in the tile art (It was probably more a RAM limitation in the case of RPM Racing though).

[Kirk_Johnston]

2 hours ago, Mittens0407 said:

Yeah. Theoretically, you could use high res mode on the Megadrive for a better proportional picture, but you'd need double height sprite graphics and have to use double the amount of tiles. I guess devs assumed that essentially a 2 times memory cost for graphics wouldn't be worth it for the extra rows. Probably applies a lot to the SNES high res modes as well. It's easy to forget about what devs had to do to get their games to fit on cartridges of the time. No matter the capabilities of the system itself, it all boils down to ROM size limitations for large high resolution graphics. Interestingly, in the Japanese version of RPM Racing they actually downgraded the resolution, and by doing that it seems they were able to eek out a lot more variety in the tile art (It was probably more a RAM limitation in the case of RPM Racing though).

Who knows what they were doing with that original 512x448 version of RPM Racing, but they definitely could have done a lot more visually. Even without any additional tiles, they could have at least used the full colours available in that mode, which isn't that much different to some of the other modes, 4bpp for the main layer and 2bpp for the other layer with still around 128 dedicated colours for both BG layers combined, and the standard 4bpp and 128 dedicated colours for sprites. They didn't use anywhere near the full colours, they wasted the second background layer, and the background tiles and sprites are just fugly. Disappointing.

 

I honestly think they could have actually gotten pretty close to what we saw in Rock N' Roll Racing in the 512x448 mode to be honest. Someone would need to put that to the test though.

 

There's a post here that goes into more detail on the perceived vs real limitations of Mode 5 and how it works on SNES, especially concerning VRAM (and it's coming from the guy who's actually working on a shmup game running in Mode 5, which is the most impressive implementation of it that I've seen to date): https://forums.nesdev.org/viewtopic.php?p=279032#p279032

 

Here's Kulor's Mode 5 shmup game again, which uses the SNES 512x448 resolution, just for reference:

 

 

So much prettier than RPM Racing. And I imagine he's just getting started there.

 

Note: The strange background shimmering/stuttering that happens occasionally there is a bug in the emulator. It runs smoothly on the real hardware.

Edited December 15, 2022 by Kirk_Johnston

[Kirk_Johnston]

By the way, are there any examples of Genesis using the 480i mode without the half-sized squished pixels? 

 

I'd really love to check out any games or demos of this mode in action and running at its full capability.

[maxxoccupancy]

Even at 320x224, the background tiles alone can eat up 35KB of VRAM out of the whole 64KB.  Once you add the foreground layer and sprites, there's almost nothing left in VRAM, and the DMA could only move so many tiles in from the game cartridge in the 16ms available to draw a frame. 

 

Right before releasing the Megadrive onto the Japanese market, SEGA decided to cut costs and reduce their 128KB of VRAM down to just 64KB, also cutting video memory bandwidth in half.  Tom Kalinske even cut the components in the system even more to get the price down from $189 to $149, so audio suffered.

IMHO, SEGA should've released a more powerful Genesis onto the market with a 12MHz 68000 (instead of the Sega CD), a 12MHz Z80 for audio, 128KB VRAM, a higher color Mode 6, and perhaps even the SVP DSP used for Virtua Racing.  320x448 (or 384x448 in hypothetical Mode 6 supported it) games might've become commonplace, and we might have seen the Genesis stick around for another generation.