Turbo speed & frameskip, continued

update, May 2011

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I previously did some research on frameskip patterns in Vampire Savior. Here's the followup.

To reiterate, an n in the frameskip pattern means on the nth frame, advance two frames instead of one. So a pattern of 3,3,3,... means every third frame advances two, and every fourth frame is skipped.

SF2 series

Game	Timer count/frame addresses	Frames per count
sf2	0xFF8ACE-F	30
sf2ce, sf2hf	0xFF8ABE-F	40
ssf2	0xFF8CCE-F	40
ssf2t	0xFF8DCE-F	40
hsf2	0xFF8BFC-D	40

hsf2	Frameskip pattern
TURBO 0	n/a
TURBO 1	5,5,6,5,5,6,...
TURBO 2	3,3,3,3,4,3,3,3,3,4,...
TURBO 3	2,2,2,3,2,2,3,...

There's no discernible pattern for sf2hf or ssf2t so I have averaged a full round's worth of skip data:

Game	Average frameskip interval
sf2hf	~6
ssf2t, TURBO 0	3.7
ssf2t, TURBO 1	3.1
ssf2t, TURBO 2	2.7
ssf2t, TURBO 3	2.2

It doesn't seem like ST is twice as fast as HF. Maybe there's more to the speed than frameskip.

There's no speed settings or frameskip for sf2, sf2ce, or ssf2.

Rufus has compiled the frameskip data for SSF2T: HD Remix, which was derived by looking at video of Chun Li's roundhouse lightning legs frame by frame and watching for missing frames. He points out that all of the patterns fit into a cycle of 32 visible frames, which is a clue to how the frameskip might be implemented by the game code.

Speed	Frameskip pattern
TURBO 0	n/a
TURBO 1	5,5,6,5,5,6
TURBO 2	5,5,4,5,4,5,4
TURBO 3	4,4,4,4,4,4,4,4
TURBO 4	4,3,4,3,4,3,4,3,4

SFA series

Game	Timer count/frame addresses	Frames per count
sfa	0xFFAE09-A	79,59,44,29
sfa2, sfz2al	0xFF8109-A	59,49,39,29
sfa3	0xFF8109-A	74,59,44,29

sfa, sfa2, sfz2al, sfa3	Frameskip pattern
NORMAL	n/a
TURBO 1	4,4,5,4,4,5,...
TURBO 2	3,3,3,3,...

Darkstalkers series

Game	Timer count/frame addresses	Frames per count
dstlk	0xFF9409, 0xFF9415	42,37,32
nwarr	0xFF8E09, 0xFF8E15	60,52,46,42,38,34,28,20
vsav, vhunt2, vsav2	0xFF8109-A	134,109,89,74

dstlk	nwarr	vsav	vhunt2, vsav2	Frameskip pattern
TURBO 1	NORMAL	NORMAL	ノーマル	n/a
			ターボ1	7,7,7,...
	TURBO			5,5,5,6,5,5,5,6,...
TURBO 2		TURBO 1	ターボ2	4,4,5,4,4,5,...
		TURBO 2		4,3,4,3,4,4,3,4,3,4,3,4,4,3...
TURBO 3		TURBO 3	ターボ3	3,3,3,3,...

dstlk and nwarr are more chaotic than suggested here. The frameskip patterns seem to be affected by the timer speed setting or maybe other factors like the stage or characters. The patterns here were measured at default timer speed.

Super deformed series

Game	Timer count/frame addresses	Frames per count
spf2t	0xFF8109-A	60
sgemf	0xFF8189-A	59,49,39,29

sgemf	Frameskip pattern
TURBO 1	n/a
TURBO 2	15,15,15,...
TURBO 3	7,7,7,...
TURBO 4	4,4,5,4,4,5,...

spf2t does have speed settings but doesn't use frameskip.

Marvel series

Game	Timer count/frame addresses	Frames per count
xmcota	0xFF4808-9	127,70,55,40,35,25,15,5
msh	0xFF4808-9	80,70,60,50,45,40,35,30
xmvsf	0xFF5008-9	120,110,100,90
mshvsf	0xFF4808-9	120,110,100,90
mvsc	0xFF4008-9	120,110,100,90

msh	xmvsf	mshvsf, mvsc	Frameskip pattern
NORMAL	NORMAL	NORMAL	n/a
TURBO	TURBO 1		10,10,10,...
	TURBO 2	TURBO 1	6,6,6,...
		TURBO 2	4,4,4,...

There's no speed settings or frameskip for xmcota.

Comments

[Rufus]

I have the frameskip patterns for SSF2T:HDR - derived from looking at video of Chun Li's roundhouse lightning legs. At least there, the frameskip cycle has a period of 32 visible frames.

Turbo 0: Skips no frame
Turbo 1: 5,5,6,5,5,6
Turbo 2: 5,5,4,5,4,5,4
Turbo 3: 4,4,4,4,4,4,4,4
Turbo 4: 4,3,4,3,4,3,4,3,4

[dammit]

Thanks, I'll add that in.