Legitimacy of "lagless"

[PROMETHEUS]

This thread as a reply to third_strike from DOJ High Score discussion : http://shmups.system11.org/viewtopic.ph ... 84#p668784

What do you mean ? I didn't follow the "shmup chat". Is it because "lagless" is considered a cheat now since PCBs aren't lagless ?

Here is where is the problem and you put still more clear to me, MaMe emulates the pcb correctly. Lagless hacks mame to give a advantage to player, this advantage will assist the player during all run.
Think now:
- Can I slowdown gp meter in a hacked MaMe version?
- Can I give 5 bomb stock to Exy in a hacked MaMe version?
- can I speed up the bomb style in a hacked MaMe version?
- And If I reduce the rank effect to do the game more playable?
- Meybe invincibility to don't break the chain? LOL

Since now know this features is not in pcb.
Lagless is pretty close to a bootleg.

I am convinced now, I don't like my later score. Please jpj change my score to this did today in Wolfmame 0141 this need be easy to you now since I will stay in same place:
Third_strike - 739,650,470 - A-E - 2-3 - 2634 Hit


PROMETHEUS if you don't agree with me I can discuss about this in other topic.

I don't agree with you third_Strike. I don't think it matters that the effect was achieved through a hack.

A shmup is a game where you have to dodge crazy patterns and execute very precise actions. Less input lag equals tighter controls, allowing the player to better express their skill in the game. The PCBs have a small flaw in that regard. They shouldn't be considered the perfect reference because they are not perfect.

Now however, for the sake of trying to put everyone kind of on an even ground, it is arguable that players should prefer a version of MAME closer to the PCB. That said, I personally regard any score made with a lagless version as perfectly valid, and I regard the lagless MAME as a version that allows the players to perform to the best of their ability, thanks to (very slightly) tighter controls.

Ideally, we would want PCBs to be lagless, because lagless is preferable.
Whereas more lives / slowed down chaining or similar modifications would change the game and make it more shallow and weak. That's the basis of my thinking.

[PROMETHEUS]

Oh by the way can it be confirmed that PCBs aren't lagless because I've heard it from a few people, but has it been measured? Does it depend on the PCB ? I always thought they were lagless before.

Preliminary Answer :
PCBs still have less lag than lagless MAME, because of PC hardware and emulation limitations.

If confirmed, this nullifies the debate and makes lagless MAME completely legit.

Sources :

As for actual numbers, pulsewidth has done some preliminary testing a few months ago with a photodiode and an optimal MAME setup (a game with 0 frames with a very fast response screen) and IIRC he got around 40ms of lag, this same game on PCB has 16ms at most (displays on the next frame), this means lagless mame would have to remove two frames of lag and be used in an optimal PC setup to be as responsive as pcb.

Currently lagless mame removes only one frame, which means it still isn't as responsive as pcb even with an optimal setup.

keep in mind these numbers are preliminary and more actual testing would be needed, but these numbers give us a good idea.

I realise nimitz has also mentioned this, but it seems that people need to be reminded that MAME needs to:

a) Get input from the host, which commonly uses the USB stack (laggy) or PS/2 (little to no lag since it's IRQ-controlled).
b) Simulate the guest code until vblank then render a frame (possible vsync delay here).
c) Push out the video driver's buffer (not much latency here, AdvancedMAME does away with this step afaik).
d) The driver then pushes it out to the framebuffer (lag).
e) The VDU will then receive the frame and display it (lag).

So really, unless you have an ideal host+display which doesn't have these issues (and it's possible but does not exist right now) it's very silly to say that MAME accurately emulates the latency of the PCB. It's going to be a few frames latency due to the host at the very least. Worst of all, this varies from system to system, so some people might be at an advantage without others even knowing it. The lagless patch sacrifices visual accuracy (rendering the sprite buffer without waiting a frame) for more accurate latency in comparison to the PCB on a real host. Theoretically, you can make a close-to-ideal host but not right now so it's a moot point -- i.e., MAME is always laggier than the PCB and would need adjustment to become more accurate in that manner.

[Chaos Phoenixma]

I see no problem with it, but it's not like I'm going to be submitting any decent scores for anything?

Plus, since I'm not even using the keyboard to play, wouldn't this also make normal MAME even worse for me and the lagless version making it closer? I'm pretty sure if you're using a controller/gamepad/stick on the PC, you're getting some extra lag from it.

[ptoing]

Why would a stick going in the same port as a keyboard have more lag?

[sikraiken]

Less lag than PCB is cheating.

[MathU]

If the original game had more input lag, then yeah, it's definitely cheating.

At the very least you shouldn't be comparing scores between the hack and properly emulated version.

[Aquas]

If the original game had more input lag, then yeah, it's definitely cheating.

At the very least you shouldn't be comparing scores between the hack and properly emulated version.

+1

[Lance Boyle]

I wonder why he insists on camel-casing MAME.

EDIT: Also, this

Think now:
- Can I slowdown gp meter in a hacked MaMe version?
- Can I give 5 bomb stock to Exy in a hacked MaMe version?
- can I speed up the bomb style in a hacked MaMe version?
- And If I reduce the rank effect to do the game more playable?
- Meybe invincibility to don't break the chain? LOL

is strawman argument bullshit and isn't worth regarding. Losing one frame of input lag is ridiculously dissimilar to those examples.

[Vyxx]

If the original game had more input lag, then yeah, it's definitely cheating.

At the very least you shouldn't be comparing scores between the hack and properly emulated version.

This.

[LeeVanCleef]

A shmup is a game where you have to dodge crazy patterns and execute very precise actions. Less input lag equals tighter controls, allowing the player to better express their skill in the game. The PCBs have a small flaw in that regard. They shouldn't be considered the perfect reference because they are not perfect.

If I remember correctly, developers add input lag to some of there games. By taking that lag out of gameplay you are changing the way the game is intended to be played. If my first statement is correct, the lag may have been put into the game to possibly mimic the movement(physics) of a flying vehicle. You admit by this statement "A shmup is a game where you have to dodge crazy patterns and execute very precise actions. Less input lag equals tighter controls, allowing the player to better express their skill in the game" that lagless helps players to achieve what they may not be able to achieve on a PCB. So in short, lagless may enhance performance of players.

The way I look at it, a score using a hacked version to reduce lag should not be valid against a PCB or an official MAME version for that matter.

[third_strike]

don't agree with you third_Strike. I don't think it matters that the effect was achieved through a hack.

Ideally, we would want PCBs to be lagless, because lagless is preferable.

If less lag was a priority the developers will do the max to put it at zero.

A shmup is a game where you have to dodge crazy patterns and execute very precise actions. Less input lag equals tighter controls, allowing the player to better express their skill in the game.

Having the lag how a new difficult will advantage other of player attributes like: attention and memorization.

The PCBs have a small flaw in that regard. They shouldn't be considered the perfect reference because they are not perfect.

PCB is the perfect reference, the players want the game as close as it can be of the pcb. And if the equality is possible then we can't let the comfort ( ) interfere in this.

lagless MAME as a version that allows the players to perform to the best of their ability, thanks to (very slightly) tighter controls.

To me ability to play determined game is not only in shake fingers. Concentration, knowledge about the game, self control and luck deserves respect too. And how much you about a game less useless dodges you will do contrariwise you will set your ship in a position which will advantage the dodge.

[austere]

If I remember correctly, developers add input lag to some of there games. By taking that lag out of gameplay you are changing the way the game is intended to be played.

Rarely ever true. In this case it's due to do the electronics (the VDP) and the sprite buffer.

I realise nimitz has also mentioned this, but it seems that people need to be reminded that MAME needs to:

a) Get input from the host, which commonly uses the USB stack (laggy) or PS/2 (little to no lag since it's IRQ-controlled).
b) Simulate the guest code until vblank then render a frame (possible vsync delay here).
c) Push out the video driver's buffer (not much latency here, AdvancedMAME does away with this step afaik).
d) The driver then pushes it out to the framebuffer (lag).
e) The VDU will then receive the frame and display it (lag).

So really, unless you have an ideal host+display which doesn't have these issues (and it's possible but does not exist right now) it's very silly to say that MAME accurately emulates the latency of the PCB. It's going to be a few frames latency due to the host at the very least. Worst of all, this varies from system to system, so some people might be at an advantage without others even knowing it. The lagless patch sacrifices visual accuracy (rendering the sprite buffer without waiting a frame) for more accurate latency in comparison to the PCB on a real host. Theoretically, you can make a close-to-ideal host but not right now so it's a moot point -- i.e., MAME is always laggier than the PCB and would need adjustment to become more accurate in that manner.

So really, there's nothing wrong with scores which use the lagless patch as far as latency goes. The problem Haze et. al. have is the fact that, due to the advantage it gives players, many would gladly sacrifice visual accuracy for lower latency. I think that if someone finds the visual difference between lagless and MAME to be obvious, the latency difference between MAME and the PCB should be obvious to them as well. After all, in these kind of games, overall reaction time is king.

[Despatche]

No one should consider scores made with the original game and scores made with an emulator as equal. This goes for anything.

[nimitz]

Saying that "lagless mame" is cheating is like saying that a fast response screen is cheating.

With current pc hardware limitations it is impossible to make lagless mame respond faster than pcb.

[austere]

No one should consider scores made with the original game and scores made with an emulator as equal

Not really, if it's an actual emulation (more on this word later) of the original game, it's entirely legitimate.

[Despatche]

Yes, but those are incredibly rare. That definition may as well be "incorrect".

[austere]

Like I said, more on that word later.

[captpain]

Keep on fighting the good fight for sloppy controls. This is the most asinine thing ever.

[louisg]

I'd be surprised if a PCB would have more lag considering 1.) inputs are not going through USB as part of a multitasking OS and 2.) most have a consistent refresh mechanism unlike most emulators (e.g., draw, do input/logic, draw, do input/logic, repeat-- vs. using a framerate-independent timer or other mechanism). Where does this assertion come from? Has this been measured? What was the methodology?

[LeeVanCleef]

If I remember correctly, developers add input lag to some of there games. By taking that lag out of gameplay you are changing the way the game is intended to be played.

Rarely ever true. In this case it's due to do the electronics (the VDP) and the sprite buffer...

Saying that "lagless mame" is cheating is like saying that a fast response screen is cheating.

With current pc hardware limitations it is impossible to make lagless mame respond faster than pcb.

Both statements have been duly noted. With that being said, if "lagless" builds give players an advantage over official MAME builds then I do not believe the scores should be compared. I know this gets tricky with all the different versions out there but this seems fair to me.

Simply put:
MAME vs MAME
Shmupmame vs Shmupmame
PCB vs PCB
and so on...

[austere]

Worst of all, this varies from system to system, so some people might be at an advantage without others even knowing it.

So basically, by your modus operandi, scores on a particular computer configuration should be separated out from scores on a different one.

You're going to have a thousand score boards with a single entry in each one except for the PCB version. Even then, shall we have different score boards for different arcade sticks and buttons? How about the display, for people using superguns and a video converter on a laggy display?

I think it's much more reasonable if all scores are comparable. What you might want to do is note which version of MAME you used, that's all.

[sikraiken]

sikraiken vs. sikraiken

[LeeVanCleef]

Worst of all, this varies from system to system, so some people might be at an advantage without others even knowing it.

So basically, by your modus operandi, scores on a particular computer configuration should be separated out from scores on a different one.

You're going to have a thousand score boards with a single entry in each one except for the PCB version. Even then, shall we have different score boards for different arcade sticks and buttons? How about the display, for people using superguns and a video converter on a laggy display?

I think it's much more reasonable if all scores are comparable. What you might want to do is note which version of MAME you used, that's all.

I do not disagree with your suggestion. Obviously doing such things as comparing scores on different configs and such is too broad. But, if members on the scoring threads do not approve of certain builds, I believe the person in charge of the thread can use his discretion to include or disclude builds. That is how this got started. So in turn, you can have one section(of the scoring thread) for lagless builds if you see fit. This may help if players feel that "lagless" builds give an advantage.

[Bananamatic]

it's all in your head

[ED-057]

With current pc hardware limitations it is impossible to make lagless mame respond faster than pcb.

So far in this thread these sources of lag have been identified:
USB stacks / input lag (I believe this would include the old style DB15 game ports)
double or triple buffering by the video renderer/drivers
LCDs

But can`t all of the above be eliminated? What about a system running MAME under DOS and driving a CRT at the same frequency as the original game? Under this best-case scenario, could it still not beat any PCBs?

[mjclark]

Saying that "lagless mame" is cheating is like saying that a fast response screen is cheating.

With current pc hardware limitations it is impossible to make lagless mame respond faster than pcb.

Since (as I am constantly reminded) "When used in conjunction with images of the original arcade game's ROM and disk data, MAME attempts to reproduce that game as faithfully as possible on a more modern general-purpose computer ", whichever version of MAME, lag/lagless, most closely emulates the response of the PCB is by it's own definition the legitimate version.
Once we've established which MAME version's lag comes closest to that of the arcade board, then that should surely be the version used for scoring since that will be the most faithful version as well as being the one closest to the MAME Project's own mission statement.

[Zengeku3]

I don't notice much difference between lagless and regular mame but I wouldn't consider using the lagless version to be cheating at all. I agree with ProMeTheus on that a shmup is a test of skill and having the tools to better express that skill isn't cheating at all.

[DocHauser]

What we need here is some proper science and statistics. Playing a few times on each version isn't good enough, so the kind of thing that needs to happen is:

Play a game 100 times on the PCB
Play the same game 100 times on regular MAME
Play it another 100 times on lagless MAME

Then you'd get a mean and standard deviation for your score on each version, which should tell you whether or not lagless MAME gives you a statistically significant advantage compared to the PCB. Otherwise, the argument is mostly hypothetical. Anyone willing to be a guinea pig and try it out?

[Subterranean Sun]

Less lag than PCB is cheating.

^^This.

Anyway, thirdstrike, where did you get the information that the lag in regular MAME is indeed there in PCB version? I'm not sure about Cave titles but I really don't think the PCB version of Garegga is that laggy.

I don't really have a lot of problem playing with that 1 frame input lag though. Guess I just have to go back to vanilla MAME.

[emphatic]

Playing 360 ports on a CRT is basically cheating then. The response of controls compared to a PCB on the same screen is noticeably faster.