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MFCs easier at certain bpms. Why?

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Post #41 · Posted at 2016-01-05 10:13:42pm 8.2 years ago

Offline Storm_x8
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Reg. 2015-06-08

Quote: Silverhawke
in general the number of frames between each beat in a song would vary, but some BPMs cause the number of frames between each beat to be constant, which may have contributed to those BPMs being easier to MA.

So..er...back to this. From silverhawke's earlier post, we know 150/180/200 songs are special because the number of frames between each beat is constant, and this is a result of (60 frames per sec)/(# beats per sec for song) being an integer number for those bpms. This should hold true for 120 and 225 then, too, according to this theory (120 = exactly 30 frames per beat, and 225 = exactly 16 frames per beat). Can anyone say anything about how easy it is to MA 120/225 songs? Has Arrabbiata (225bpm) been widely MFCed on easier difficulties?

Post #42 · Posted at 2016-01-06 05:30:13am 8.2 years ago

Offline Dr.D
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Last updated: 2016-01-06 05:30am
What doesn't make sense is you are seeming to suggest is that your most comfortable read speed is where you will MA the best regardless of the song's BPM. That would be saying that me reading 180BPM on 3.5x (630) and 140BPM on 4.5x (630) would feel no different since both are read at my comfortable read speed.

However, what we are pointing out in this thread is that the above example does not yield the same experience.

It seems like silverhawke is on to something with what he posted.

To go a step further, I would say there are certain tiers of BPMs that are easy to MA.

Tier 1
180
150
200
120
225

Tier 2
160
155
175

Tier 3
130
140
165
170
145
135


The first tier I'm confident and am sure every MA play in Japan would agree. The next two tiers are from my own personal experience and might not have any way to measure.

Edit: Just read this

Quote: Storm_x8
Quote: Silverhawke
in general the number of frames between each beat in a song would vary, but some BPMs cause the number of frames between each beat to be constant, which may have contributed to those BPMs being easier to MA.

So..er...back to this. From silverhawke's earlier post, we know 150/180/200 songs are special because the number of frames between each beat is constant, and this is a result of (60 frames per sec)/(# beats per sec for song) being an integer number for those bpms. This should hold true for 120 and 225 then, too, according to this theory (120 = exactly 30 frames per beat, and 225 = exactly 16 frames per beat). Can anyone say anything about how easy it is to MA 120/225 songs? Has Arrabbiata (225bpm) been widely MFCed on easier difficulties?

OMG! Just read this and WOW. In my mind this is now solved using that logic. Arrabbiata Expert is in fact sitting at 1p. When I first saw that I was shocked beyond belief because I never thought of 225 being one of the special BPMs. But, since you were able to extrapolate the logic used to find out why 150, 180, and 200 were special and it includes 120 and 225, IT ALL MAKES SENSE NOW.

Originally I haven't included 120 in the tier 1 but that's probably either based on my own experience or probably the sample size of songs available at that BPM (basically just the PYFIMs). But to go along with your question, yes, most of the 120BPM songs are MFCed.
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Post #43 · Posted at 2016-01-06 05:42:06am 8.2 years ago

Offline Silverhawke
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3DS Friend Code: 3496-9710-9426
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from my personal experience, yes, Arrabbiata is kinda easier to MA since i got a ridiculously low perfect count for a chart like that.
my homepage → silverhawke.xyz

Post #44 · Posted at 2016-01-06 06:29:11am 8.2 years ago

Offline Storm_x8
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Well, cool to see that there's a plausible explanation for all this now!

There's a few followup thoughts/questions going through my mind now:

-We still have the question of why the effect is more noticeable on the newer white/black cabinets versus, say, SN2 cabinets. Also, is the effect still there in CS versions as well? I have no idea about the programming software that goes into these games, but perhaps that's related?

-At those special bpms, PFCs would also be easier, right? I would think so by the same logic that MFCs are easier. From my experience, this seems true, too - the most difficult songs I have PFCed are 12s, and I've only PFCed two: Super Driver (200bpm) and Happy Angel (180bpm), each with a slightly better MA than I usually get.

-So, going back to silverhawke's post where he mapped out what frames would contain the 16th note marvelous window for different bpms: essentially, for the non-special bpms, because the # of frames in each beat isn't constant, the marvelous window will actually sometimes shift by one frame between beats, so the 16th notes aren't...well, true 16th notes, being offset by this tiny amount. To me, this sounds a bit similar to how triplets in non-SN2 weren't quantized correctly, but just on a much more micro scale, which is weird to think about.

Post #45 · Posted at 2016-01-06 07:07:25am 8.2 years ago

Offline Silverhawke
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Last updated: 2016-01-06 07:13am
Quote: Storm_x8
-We still have the question of why the effect is more noticeable on the newer white/black cabinets versus, say, SN2 cabinets. Also, is the effect still there in CS versions as well? I have no idea about the programming software that goes into these games, but perhaps that's related?

i think the effect should still be there in SN2 cabinets as well. though back then when i played on one i don't have good enough MA to notice it -- but i believe it's there.

it's... probably in CS versions as well, though you have to deal with input lag, which if i recall correctly, was the reason they enlarged the perfect window slightly in CS.

Quote: Storm_x8
-At those special bpms, PFCs would also be easier, right? I would think so by the same logic that MFCs are easier. From my experience, this seems true, too - the most difficult songs I have PFCed are 12s, and I've only PFCed two: Super Driver (200bpm) and Happy Angel (180bpm), each with a slightly better MA than I usually get.

technically yes, but the perfect window is pretty wide compared to marvelous window. the 2 frame window is pretty much the reason why a frame of difference means a lot and hence, this effect manifests itself more significantly in marvelous count. it's just not that noticeable in PAing due to the relatively wider perfect window compared to marvelous.

Quote: Storm_x8
-So, going back to silverhawke's post where he mapped out what frames would contain the 16th note marvelous window for different bpms: essentially, for the non-special bpms, because the # of frames in each beat isn't constant, the marvelous window will actually sometimes shift by one frame between beats, so the 16th notes aren't...well, true 16th notes, being offset by this tiny amount. To me, this sounds a bit similar to how triplets in non-SN2 weren't quantized correctly, but just on a much more micro scale, which is weird to think about.

yeah, that's pretty much how it is, i think. it's an artifact of using frames to determine timing windows VS using milliseconds. so it's pretty similar to how the misquantization of notes in EXTREME~SN2 (side note though: they fixed I'LL MAKE LOVE TO YOU in SN2 but for some reason not others) is an artifact due to how the engine handled 64ths VS a smaller subdivision (this was also the reason Poseidon's note after the stop was hard to time properly since it's a 64th off. tiny amount, but noticeable. X fixed it by making it either a 128th off or 192nd off, can't remember which)

also, here are the round BPMs that give a whole number of frames per beat:
400.00 (9 frames)
360.00 (10 frames)
300.00 (12 frames)
240.00 (15 frames)
225.00 (16 frames)
200.00 (18 frames)
180.00 (20 frames)
150.00 (24 frames)
144.00 (25 frames)
120.00 (30 frames)
100.00 (36 frames)
90.00 (40 frames)
80.00 (45 frames)
75.00 (48 frames)
72.00 (50 frames)
60.00 (60 frames)

they are all divisors of 3600. you can plug in 3600 / [number of frames in a beat] to find the corresponding BPM, though obviously, if the number of frames isn't a divisor of 3600 you won't get a nice number (and it's unlikely to get a song like that).

also, here's a thing: https://ideone.com/fork/ouvF1x
plug in your BPM in the input (stdin) section, one line at a time. it only accepts whole numbers though.
run it and you'll the the number of frames per beat and the location of the marvelous window for 16ths.
my homepage → silverhawke.xyz

Post #46 · Posted at 2016-01-06 08:24:05am 8.2 years ago

Offline Dr.D
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Last updated: 2016-01-06 08:28am
I haven't noticed any difference in CS mixes but it wouldn't surprise me if it is.

As for the difference on the machine, that is a burning question I want to know if there is a reason for it.

The special BPMs do still have an effect on Red Machines (SN-SN2). It is definitely easier to MA those BPMs compared to similar songs at slightly different BPMs. However, I still contest that the effect is far greater when playing on newer machines, ie. the ones with LCD screens. I can only give my evidence through my many years of playing and experience on all types of machines. I can promise you there would be no way I'd ever be able to do the following on a Red Machine. (Noticed all songs are 180BPM played on a white machine.)



Lastly, as far as PFCs also becoming easier at those BPMs, I haven't noticed it to be honest. In fact, sometimes I feel the perfect window might be smaller. In my head I imagine that the perfect window is shrinking a little and BOTH the marvelous and great windows increase. But honestly, I don't think that is truly the cause, just something that runs in my mind because I already know there are some fishy things about those BPMs and it's probably my way of justifying when I get greats on them Tongue.
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Post #47 · Posted at 2016-01-06 10:56:17pm 8.2 years ago

Offline Storm_x8
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Quote: Silverhawke
2 frame window

Can we just clarify this? A lot of people say the marvelous window is only 1 frame, but others say it's 2. I thought that it was agreed upon that the marvelous window is 0.01666... seconds, which is equivalent to 1/60 second = 1 frame. On the other hand, that wouldn't make sense if it was only 1 frame since by our previous explanation, that 1 frame window would jump around between beats making MAing most songs extremely difficult.

Post #48 · Posted at 2016-01-14 04:55:46pm 8.2 years ago

Offline Dr.D
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Anyone have more ideas yet?
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Post #49 · Posted at 2016-01-21 06:00:06pm 8.1 years ago

Offline Zowayix
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Last updated: 2016-01-21 06:01pm
Quote: Storm_x8
Quote: Silverhawke
2 frame window

Can we just clarify this? A lot of people say the marvelous window is only 1 frame, but others say it's 2. I thought that it was agreed upon that the marvelous window is 0.01666... seconds, which is equivalent to 1/60 second = 1 frame. On the other hand, that wouldn't make sense if it was only 1 frame since by our previous explanation, that 1 frame window would jump around between beats making MAing most songs extremely difficult.
The Marvelous window offset is 1 frame (~17 ms) away from the ideal center, making it 2 frames (~33 ms) wide in total. Similar to how ITG has a Fantastic window of 21.5 ms (on each side of the center), making it 43 ms wide in total.

Post #50 · Posted at 2016-03-08 04:43:30am 8 years ago

Offline Dr.D
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Reg. 2008-03-01

This isn't directly related, however, I want to share this.

People have mentioned this before and I've experienced this a few times myself. This is the first time I experienced this back to back and on camera.



The video that I posted is my playing pierce the sky back to back. On the first play, I immediately noticed the sync was funny. You'll notice a lot of slow perfects and great. Especially at the end because I gave up trying to fight it and just played it how it sounded. I then play it again on Extra stage and there is no sync issue whatsoever.


I am hoping this video can be used to showcase this strange phenomenon and hopefully someone better than me can find a way to analyze the footage to see exactly what's going on.
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