Comparison of 4th generation ("8/16-bit") system hardware

[maxi]

http://www.4shared.com/video/C5cXpSr...a_preview.html
Can someone explain to me why Sega CD can't run the special stages as fast as this? This version is at the same speed as mode-7 games.

[TmEE]

VDP DMA limit is hit so you would not not be able to reach 50/60FPS unless the area is very small. Special stages could have easily been 25FPS in PAL though due to much higher VDP bandwidth

[Kamahl]

You can also reach a good frame rate in NTSC. Adventures of Batman and Robin and SoulStar both have rather high framerates while updating much more than needed for the Sonic CD special stages. Never 60fps though.

[Sik]

15 FPS is a good framerate? =P

But yeah, if theoretically it takes four frames to update the entire screen, and the floor is just half it (sprites are not done by the ASIC), then it should only take two frames to update, right? (at which framerate do the special stages go, actually?)

[Kamahl]

15 FPS is a good framerate? =P

If they're running at 15 FPS they fake it pretty well. AOB&R does drop a lot of frames when there's a ton of stuff, but when it's the entire screen with just the car and a few powerups it seems to run at 30 fps. Same goes for soulstar, it's updating 1 background plus a ton of sprites at 24 fps (seems like 30 during the on-rails stages, more like 15 in the robot stages).

[Sik]

If they're running at 15 FPS they fake it pretty well. AOB&R does drop a lot of frames when there's a ton of stuff, but when it's the entire screen with just the car and a few powerups it seems to run at 30 fps.

I've checked with Fusion before, it's always 15 FPS (occasionally it gets in a frame a bit earlier, but otherwise it's almost solid 15 FPS, period).

Remember Virtua Racing (SVP) is 15 FPS too. Here's the deal: if you have nothing else to compare the framerate to, and everything is constantly moving fast (which is the case of both games), you can't tell it's actually going at 15 FPS and it seems smoother than it actually is. This same effect is pretty much why games running at low framerates can feel playable.

Not gonna comment on Soulstar since I never checked it out.

[Kamahl]

Virtua Racing seems to be running at a much lower framerate then AOB&R .

[Sik]

Virtua Racing seems to be running at a much lower framerate then AOB&R .

Checked in Fusion, Virtua Racing runs at 15 FPS =P (and Virtua Racing Deluxe runs at 20 FPS)

[Kamahl]

Just goes to show that cleverness always wins. (When you can make 15 FPS look like much more than 15 FPS).

[sheath]

I'd swear when I counted frames in video captures of Virtua Racing it dipped below 10FPS at times. It's been a while though, I could be wrong.

-edit-

Nope, I recalled wrong, it's 15FPS.

[kool kitty89]

I've checked with Fusion before, it's always 15 FPS (occasionally it gets in a frame a bit earlier, but otherwise it's almost solid 15 FPS, period).

Remember Virtua Racing (SVP) is 15 FPS too. Here's the deal: if you have nothing else to compare the framerate to, and everything is constantly moving fast (which is the case of both games), you can't tell it's actually going at 15 FPS and it seems smoother than it actually is. This same effect is pretty much why games running at low framerates can feel playable.

Not gonna comment on Soulstar since I never checked it out.

Soul Star and Thunderhawk/Thunderstrike run at 20 FPS (at least in fusion). That's compared to 12 FPS for BC Racers and Battlecorps. (both of the latter use dual layer rendering with no optimization for sprites -1 layer is used for the BG/ground and the other is for "sprites", so a lot more DMA overhead vs Thunderhawk rendering everything on a single 16 color layer and Soul star using only 1 BG layer and scaled animation on hardware sprites -and only part of the BG layer is used by the ASIC at most, like for warped ground, with the rest used only for plain 2D tile scroll layers)

I forget how fast Wing Commander runs, but I think that only uses 1 16 color layer too (as far as ASIC rendering), and I don't think it makes any use of sprites for ASIC rendering


Sonic CD's special stage runs at 15 FPS . . . it could have been much faster if they'd been willing to clip the screen a bit (mostly for DMA time -not so much for decreasing the window size), though the bigger disappointment was the lack of scaled sprites/objects. (if it had had nicely scaled objects, 15 FPS would have been more acceptable IMO)


Another bad example (after actually seeing it in action on real hardware -and emulation) is Joe Montana NFL . . . it's really choppy (only 12 FPS peak in fusion), especially for a sports/action game and it shouldn't have had to be if they'd made some reasonable compromises (they barely clipped the screen, and it's rendering the scaled animation to the entire screen, so basically a full 248x216 4bpp framebuffer).

They did a nice job with the color optimization (given the 16 color limit) and the overall 3D/scaling effects/models/objects too. (and the sound -though having the commentary only between plays was a bit odd -they seem to have used 32 kHz 8-bit PCM, so the overhead for that may have been an issue, though it also seems like they had enough space to cut it to fit as CDDA too)

If they'd just been willing to clip the screen enough to get that to 20 FPS, it could have been really nice. (aside from the non-technical criticism of the actual game mechanics as a Football game -though Sheath refuted some of those iirc, at least compared to the general quality standards of contemporary Genesis games)
256x192 should have been fine -since everything was on 1 tile layer, no additional tile/sprite updates- (or higher res for H40, though VRAM space would be an issue -304x176 would use as much space as 248x216, but could run at 30 FPS).

Optimizing for sprites like Soul Star would have been nice (mainly for some added color), but that would add to bandwidth since you'd still need a full BG layer (since full-screen scaling was used), unlike games like Battlecorps or BC Racers where hardware sprites could have significantly reduced DMA overhead compared to using a full-screen tile layer for sprites (plus another layer for the ground -though only on 1/2 the screen with the other 1/2 a plain horizontal scroll section, similar to mode-7 games).

I'd swear when I counted frames in video captures of Virtua Racing it dipped below 10FPS at times. It's been a while though, I could be wrong.

-edit-

Nope, I recalled wrong, it's 15FPS.

Maybe you're thinking of Star Fox? (it peaks at 15 FPS iirc, but slows down a lot . . . certainly less than 10 FPS in some areas)

[Sik]

That's compared to 12 FPS for BC Racers and Battlecorps.

I swear it was 15 FPS... Guess I'll recheck later again, don't have the game here right now. But I was pretty sure it was 1 frame updating the objects, 1 updating the floor/BG, and 2 frames idle.

Sonic CD's special stage runs at 15 FPS . . . it could have been much faster if they'd been willing to clip the screen a bit

Actually, they could have easily bumped it up to 20 FPS as-is. Didn't check the exact height (so I can't be sure), but maybe even 30 FPS was doable without cutting anything =|

Maybe you're thinking of Star Fox? (it peaks at 15 FPS iirc, but slows down a lot . . . certainly less than 10 FPS in some areas)

10 FPS seems to be Star Fox's average speed x_X

[kool kitty89]

I swear it was 15 FPS... Guess I'll recheck later again, don't have the game here right now. But I was pretty sure it was 1 frame updating the objects, 1 updating the floor/BG, and 2 frames idle.

They both stagger the bg and sprite updates . . . and at first glance I thought it was 24 FPS (doing frame advance), but then noticed that only part of the screen (just the BG or just the "sprites") were updating at a time. (it usually takes 4 frames before the sprites update and then another frame for the BG, though it seems to take 6 frames total once in a while)

Actually, they could have easily bumped it up to 20 FPS as-is. Didn't check the exact height (so I can't be sure), but maybe even 30 FPS was doable without cutting anything =|

Don't forget bandwidth needed for tile and sprite updates other than the ASIC rendered segment. (especially if you want a solid framerate without slowdown -and thus have enough bandwidth for the worst cases of having many objects animated on-screen and extra bandwidth in cases with less on-screen)

Virtua Racing should manage up to 20 FPS in that context, if it was just the 256x192 polygon tile layer to consider. (but it's got an additional layer for the far BG -which may require dynamic updates, plus possible animation updates for the sprite overlay)

[Sik]

Don't forget bandwidth needed for tile and sprite updates other than the ASIC rendered segment. (especially if you want a solid framerate without slowdown -and thus have enough bandwidth for the worst cases of having many objects animated on-screen and extra bandwidth in cases with less on-screen)

I meant 20 FPS with some margin. 30 FPS would be pushing it. Remember most stuff stays in VRAM, so the only other things that change are the sprite table, the scrolling and the tiles for Sonic's sprite (which aren't many).

Virtua Racing should manage up to 20 FPS in that context, if it was just the 256x192 polygon tile layer to consider. (but it's got an additional layer for the far BG -which may require dynamic updates, plus possible animation updates for the sprite overlay)

I think it was around 10 MHz where speed stabilized for the SVP (over that it stuck at 15 FPS, below that it started slowing down), and the real SVP speed is around that, so it may be SVP capped actually and Sega set the framerate around that.

[kool kitty89]

I think it was around 10 MHz where speed stabilized for the SVP (over that it stuck at 15 FPS, below that it started slowing down), and the real SVP speed is around that, so it may be SVP capped actually and Sega set the framerate around that.

If that was the case, they shouldn't have needed to clip the screen so much at all. (if it was just for reducing screen size/draw area/VRAM use, then it would have made sense to clip horizontally too rather than only vertically, like 240x208 with a much less noticeable boarder)