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Street Fighter 5's input lag actually fluctuates mid match according to findings of French computer science PhD

From four to seven frames at any given moment

Posted by John 'Velociraptor' Guerrero • July 15, 2018 at 3:55 p.m. PDT • Comments: 85

If you've experienced more than 10 minutes of Street Fighter 5 you've almost certainly heard someone complain about input lag affecting their ability to win, and according to the recent findings of Loïc "WydD" Petit there may be more legitimacy than you think to said salty claims.

Petit, who holds a PhD in computer science, has intricately investigated input lag of fighting games on PlayStation 4 while specifically using a PS4 Pro. His findings show that not only does SF5 have an average input lag of nearly 6 frames but that said lag actually fluctuates over the course of a single round.

Petit uses the term "stability" to measure this and defines it as "the probability of having the same input lag with the same timing." He attributes stability percentages to the fourteen games he tested and notes, "A stability of 100% means that when you press a button, the input lag is entirely predicable. A stability of 50% means that when you press a button, the input lag can vary by one frame even knowing the right timing."

Street Fighter 5 came in last place with a stability score of 43%. Street Fighter 30th Anniversary Collection titles Alpha 3, Super Turbo and Hyper Fighting were the next lowest with respective scores of 60%, 55% and 57%. All other games scored 88% or higher.

Furthermore WydD found that SF5's input lag changes appear to come in waves. Fluctuations between four and seven frames of lag happen almost constantly, but there are clear windows of time wherein you're more likely to have seven frames and others where you're more likely to have four.

The images below depict these findings visually. The first shows input lag and stability scores for all fourteen titles, the second depicts input lag fluctuation over time with the X-axis measuring time (in frames), and the third shows more specific results for SF5:

Input Lag WydD image #1 Input Lag WydD image #2 Input Lag WydD image #3
Click images for larger versions

DisplayLag took to Twitter to back the results found by Petit, stating, "We can confirm this also. SF5 has always been problematic with consistent input lag timings, which shows up in our input lag tests as well."

The latest Street Fighter's high input lag has been a sore spot for the game since its release in February of 2016. The additional information that said lag is also inconsistent will undoubtedly serve as yet another strike against the popular series for many.

Capcom reduced the initial input lag, which clocked in around 8 frames, towards the end of the game's first year and since then there have been no known alterations to the infamous delay.

Many have speculated that the inclusion of said delay was intentional for the sake of bridging the gap in experiences of online and offline play though Capcom has never confirmed or denied this.

You can see Petit's full dissertation on the matter right here wherein he explains his investigative process in greater detail.

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