- Sep 22, 2008
- WinMelee, Australia
BACKGROUND and INTRODUCTION
In his memorable thread, Izaw revealed to the world video evidence of the mechanic that was first known as "frame cancelling". In the video Izaw proposed a hypothesis for the mechanic which revolved around hitting with the first frame of the aerial and then fast falling during hitlag. While everyone was thrilled to see that such a thing was possible, the explanation didn't sit right with some people, myself included. The thread moved forward, and the underlying mechanic became better understood. Hitlag and landing lag were seen to be overlapping i.e. 'syncing' when this technique was performed correctly. (For the purposes of this article, the technique will be referred to by the preferred name 'frame syncing', as that name more appropriately fits the nature of its behavior.) Unfortunately, the thread lost momentum before the mechanic was fully understood and most people moved on with their lives.
Dr. Tuen was one such person who, like me, never fully moved on, and so over the last year or so we've been discussing and testing frame syncing on and off via PM's. The information found in this thread represents the conclusion we finally came to. We must have changed our minds half a dozen times, but at this stage we're finally confident that we know exactly how frame syncing works.
In more recent times a thread was created claiming to understand the underlying mechanism for this technique. The author inferred these mechanisms through the article that was translated by Source Gaming, but as shall be shown, the conclusions that were reached are inaccurate. This thread inspired us to take yet another look at frame syncing through an examination of the claims made in the thread. That effort solidified our conclusions, which are presented below.
Before giving you the definitive explanation for frame syncing however, we must address the many common misconceptions about it, or in other words, "You must unlearn what you have learned."
Frame Syncing Misconceptions
"Frame syncing means that you land on the frame you hit the opponent with an aerial."
First of all, this is impossible; the game does not allow it. Only one of two things can happen on a single frame with a normal aerial if you try to hit an opponent and land at the same time; either the aerial will hit the opponent on your last airborne frame, or you'll land, at which point there can be no aerial to hit with. Second of all, most known examples of frame syncs don't even land on the frame immediately following the aerial hitting an opponent. The most well known example, the Falco Dair frame sync, has Falco landing not on the frame after the Dair hits, but on the frame after that (i.e. the third frame of hitlag). Then there are examples of frame syncs such as Toon using Uair such that it hits on the last airborne frame of his short hop, which has Toon landing on the 9th frame of hitlag.
"You need to connect with the first frame of the aerial."
Technically you can connect with any frame of the aerial, it's just that it's much much easier to connect with the first frame of the aerial on your last airborne frame, otherwise you're more than likely to simply hit the opponent before your last airborne frame. Speaking of which...
"You must hit the opponent on the last airborne frame."
Technically no, though in practice this will usually be true. If there are extreme circumstances (e.g. involving a rising platform) there's no reason why you need to hit the opponent on your last airborne frame, though you'll get a worse frame sync if you don't.
- Try using Ganondorf's down air on an opponent standing on the rising platform on Kongo Jungle 64. It can frame sync on various airborne frames, not just the last one.
"In order to frame sync you need to fast fall during hitlag."
Fast falling during hitlag is impossible, and in any case hitting down on the joystick any number of times during hitlag will not affect whether you get a frame sync or the degree to which you do frame sync.
"In order to frame sync you need to fast fall."
There are examples of frame syncs working without the need to fast fall at all, such as the Toon Uair one mentioned above or a Ganon using Dair on the 15th airborne frame of a SH. In many instances however, fast falling will be required as part of a 'setup' or will in any event make the already existing frame sync better, but I'll touch more on that later.
- Note that the Toon Link Up air frame sync can be set up by buffering an air dodge during the jump-squat frames of a short hop then buffering the Up air out of the air dodge.
"Vibration during hitlag is what causes you to land."
This is the conclusion that was drawn from the Source Gaming article and which was for a long time before that considered to be one of the better explanations for frame syncing. However, a few observations will show that this is not so.
First, vibration decreases over time during the hitlag (for example, Captain Falcon stops vibrating after about six frames when he uses his forward air). Combine this with the fact that there are many examples of frame syncs that have the character land toward the end of their hitlag, e.g. Toon using Uair as above and landing on the 9th frame of hitlag out of a total of 11 frames of hitlag. If it was the vibrating that caused the character to land, one would expect it to increase over time during hitlag until Toon Link landed.
Second, the article refers to the vibration as a camera zoom dependent mechanic. The character in question vibrates more if the camera is zoomed out to make the effect visible when there are many characters on the screen. If the vibration caused the frame syncing mechanic, one would then expect that frame syncing would be made easier if the camera is zoomed out. However this is not the case and characters will not land earlier or later during hitlag.
- You can test this yourself by executing Toon Link's Up air frame sync in training mode. Try it with the camera zoomed all the way in, or all the way out on a large stage. The result will be the same. Toon will always land on the 9th frame of hitlag when the frame sync is performed identically.
"But the attacking character doesn't vibrate when they hit a shield with their aerial, so that explains why you can't frame sync when hitting a shield!"
Actually, the attacking character does vibrate when they hit a shield... so... yeah.
"It's the aerial animation that is responsible for frame syncs. On the frame the hitbox comes out, the aerial moves the character into the ground and therefore makes you land."
While it is true that the aerial you use can in fact play a part (in some instances, a large part), if it was the sole reason why frame syncing worked, it would be impossible to frame sync during the latter hitlag frames when aerial animations play a smaller role. Additionally, if this had any large significance for the cause of frame syncs, there would be no explanation for why frame syncs don't work on shields.
"What matters is that the character visually looks like their body touches the ground, and so certain aerials that don't have any limbs extending into the ground are impossible to frame sync."
What actually matters is the root bone of the character which is unaffected by where your character's limbs are during an aerial. Link's Nair can frame sync just as well as any of his other aerials even though his character model is visually nowhere near the ground on the last airborne frame. In fact, there is a setup which works for all his aerials (except Dair of course) where you're able to get a perfect frame sync, i.e. one frame better than the classic Falco Dair example.
- To do this, buffer a Double Jump during Link's jump-squat frames, then it's just a matter of timing the aerial of your choice such that you hit the opponent on your last airborne frame.
"Only non-floaty characters can get frame syncs, or at least it is easier for them to get frame syncs."
There is no reason for this to be true, and in any case, characters such as Kirby and Jiggs have demonstrated the frame sync mechanic just fine with the right setup.
How Frame Syncing WorksFrame syncing is a combination of a few things, but in essence it all hinges upon one previously unknown factor: the fact that characters actually continue to move during hitlag, just very very slowly. This effect is mentioned in the article. Sakurai states that the vibration does not affect hurtboxes, but the character moves slowly throughout hitlag. It was previously assumed that characters froze completely and only began to move once hitlag had ended.
This knowledge simplifies the explanation for frame syncing. The character using the aerial hits the opponent extremely close to the ground just before they land, they enter hitlag and continue to slowly fall toward the ground during hitlag, then at some point during hitlag they land, at which point their landing lag begins to occur at the same time that they continue to wait out their remaining hitlag frames (i.e. a synchronization of those two lag types).
You can see this very slow movement during hitlag yourself by using a fast falling character in training mode, standing alongside e.g. the ladder on Palutena's Temple, then fast falling an aerial and hitting a character with it, preferably an aerial with a lot of hitlag. Skip forward two frames at a time by tapping L while using '1/4 hold', and just as the vibrating during hitlag is settling down, for the remainder of the hitlag you will be able to see undeniably that the character actually moves ever so slowly and slightly downwards as they continue to fall. The vibrating unfortunately masks this movement toward the start, but you'll see the movement nonetheless.
Using this method we captured two screen shots that display this movement. The first picture represents the point the vibrations were definitely finished, then the second picture represents somewhere toward the end of the hitlag. I still recommend testing it yourself as it is much more readily apparent, but here you go.
Note that Game and Watch naturally continues to vibrate throughout the hitlag, so ignore his position. What you want to be looking at is Falcon's position in relation to the ladder rungs in the background.
"Does this mean that any aerial can frame sync?"
I had assumed the answer was yes and that any failure to frame sync an aerial was due to the very specific nature of the tech leading to a failure to find the right setup. However, recently Arthur (https://twitter.com/BenArthur_7) demonstrated that not all aerials are made equally, and that there is a specific parameter in the coding of each aerial that decides whether or not you will continue to move during hitlag:
"Set to 0: Allows animation to continue (slowly) during hitlag.
This allows landing during hitlag frames
Set to 1: No animation occurs during hitlag."
So yes, Ryu is incapable of frame syncing because all his aerials are set to 1.
"So then, why doesn't frame syncing work on shields?"
A good question! And the answer is quite simple really. As has been shown, characters continue to move very slowly during hitlag, allowing them to continue to fall. However, the attacking character does not continue to move if they hit a shield. Instead they get frozen solid for the duration of the shield hitlag (aside of course from the vibrating, which is purely a cosmetic visual) and do not continue to fall if they were falling before they connected the aerial with the shield.
How to Frame Sync
Now that the mechanic itself has been explained, we'll look at what is required to set frame syncs up. There are a few key things that you can adjust to get a frame sync to work.
- Characters need to get as close to the ground as possible before the aerial hits to reduce the distance that will be required to travel downwards during hitlag in order to reach the ground and land. This is by far the most important factor contributing towards why a frame sync will or will not work. For most characters the last airborne frame in a standard SH or FH simply will not be anywhere near close enough to the ground. I'll explain further in a moment.
- Aerials with a lot of hitlag frames are best as they will have more hitlag frames to slowly fall to the ground with and then more frames of hitlag for syncing with their landing lag once they have landed. Aerials with low hitlag can definitely still work just fine, but they will require a better setup to get the last airborne frame close enough to the ground such that the character will land during those few hitlag frames.
- Aerials that position the character slightly closer to the ground may yield frame syncs in circumstances where other aerials won't. The effect this will have will depend upon the aerial. Often there will be little to no difference, while other times you'll have a more extreme example such as Falcon's Uair which can be very difficult to frame sync, though not impossible. What this means is that certain setups, especially ones that aren't optimised, may either not work well or not work at all for some aerials.
- You actually need to use an aerial that allows movement during hitlag. Here's the link again: https://docs.google.com/spreadsheets/d/1bTgV0ogNCOK2oZ1t51ERzGzPXgICk0vzb5VXPlZJTz4/edit#gid=0
Most frame syncs will require a setup. This generally means fast falling on a specific frame or doing a footstool or a double jump or making use of a platform or something to get your character in an 'abnormal' position relative to the ground. Here's an extremely simplified explanation of this:
Imagine that Smash is divided into segments like on an X and Y graph. Imagine that your character moves exactly 5 units downwards per frame while falling. For the sake of this explanation, we'll say that '0' represents landing on stage. In a standard SH then, the last few positions of your character would be something like '15, 10, 5, then 0', with '5' being your position relative to the ground on the last airborne frame. This isn't anywhere near close enough to the ground to get a frame sync. But let's say that when you fast fall you instead travel 7 units down per frame. Therefore, if you fast fall on the 4th to last airborne frame, your last few character positions per frame will instead be '15, 8, 1, then 0', this time with '1' being your position relative to the ground on the last airborne frame. What you want to do then is get your aerial to hit the opponent on that last airborne frame, and then the final '1 to 0' distance can be covered during hitlag.
Now obviously this is deliberately over simplified and the distance covered during hitlag is minuscule etc, but it is a helpful way to understand how the game actually works. To sum it up, in order to frame sync you need to find a way to get into an abnormal aerial position such that your last airborne frame is (much) closer to the ground than normal. The better the setup, the closer to the ground you'll be on your last airborne frame, the better the frame sync, the more frames you'll save.
It is hoped that having imparted a correct understanding of the frame sync mechanic, the community will be empowered to do more research into their own characters and find even more ways to make this tech user-friendly, such as finding more buffered setups. Take for example the footstool setup for Ganondorf that can lead to a guaranteed frame synced down air that pretty much leads to... whatever you want.
Feel free to ask questions in the comments below about the research, the results, or anything related to the frame sync technique.
All the best,
Foxy & Tuen.
The technique known as 'the frame sync' is not to be confused by another technique which gives similar results but functions very differently. There are some aerials that generate a hitbox when they land which causes an overlapping of hitlag and landing lag frames, and it works on shields. Bowser Junior's Dair is one such case that benefits from this greatly, though moves like Zero Suit Samus' down air and Sheik's down air technically benefit too.
While conducting frame sync tests with Ganon's Dair on Kongo Jungle 64, I noted while trying to force a frame sync on a shield that even though Ganon didn't continue to fall slowly during the shield hitlag as noted above, and even though the platform moved up during hitlag and actually carried Ganon further upwards while he was still in hitlag, he refused to actually land while still in hitlag, yes, even though the platform was actually moving him upwards. There are any number of explanations for this, but for now my theory is that it has something to do with specifically being programmed to stay perfectly still (disregarding the vibrating) and not continue to fall, therefore perhaps not being open to the possibility of landing.
Finally, one quirk to do with training mode held us back for quite some time there. There was a point at which, regardless of what we tried, we could not get Falco to frame sync his Dair in training mode. Eventually we decided to ask Izaw if he could provide us with a video of a standard Falco Dair frame sync and slow it down so that we could see it frame by frame. Using the video we replicated it frame perfectly in training mode, and still it would not frame sync. At this point, having ruled out all other explanations, I knew that the fault had to lie in training mode somehow. What I found was that the frame sync would not work when skipping forwards by two frames using 1/4 hold, while it would work when skipping forwards by three frames at a time using 1/2 hold. We've tested numerous frame syncs over the past year or so, and this is the only example we've encountered where using 1/4 hold made any difference whatsoever. As for why this occurred, I'm not sure, but we've been on the look-out for differences since then and have had no further trouble using 1/4 hold frame skips.