Fan-Made Street Fighter V Netcode Fix Might Help With Artificial Lag and Rollback

A Street Fighter V netcode fix has been released by Altimor, and initial tests and feedback suggest that it might have fixed the multiplayer artificial lag and rollback issues. The creator announced and released the patch via Reddit, with this adjustment to the code apparently fixing a four-year-old problem in “a bit over 2 days.” People who download and apply it can still play with other people online, though the fix will only improve their own experience and not the other player’s.

Here is Altimar’s explanation of what this Street Fighter V netcode fix does.

SFV has a bug where one player’s game can lag behind the other’s online. This can cause artificial lag and one sided rollback for the other player.

When the players’ "clocks" are synced, if there is e.g. a 4 frame packet round trip time between them, each player should be 2 frames ahead of the time of the last received input from their opponent, and experience 2 frame rollbacks.

If one player lags behind, the other player will receive inputs from farther "in the past" (up to 15 frames!) than they should, causing unnecessarily big rollbacks and artificial lag, while the player that’s behind may even be receiving inputs that appear to be "in the future" to their game and never experience rollbacks at all.

This fix ensures your "clock" never gets more than half of your packet round trip time ahead of your opponent’s so that you never experience more rollback than them.

In a follow-up question to someone asking about this potential fix, Altimar said, “This was primarily tested by using two of my machines with various configurations of artificially induced latency/packet loss (using clumsy) and attempting to cause clock desync by momentarily speeding up/slowing down the game on one side.”

This is a mod, so there could be issues for people using it. Capcom could decide to ban people who use this to modify their multiplayer experience. It is also a new Street Fighter V netcode fix and hasn’t had extensive testing yet. Early reports from some people in the Reddit thread where it launched have some people saying that there can be problems in matches where one person is on a PC and the other is on a PlayStation 4. (Apparently, the player on the PlayStation 4 would experience things like rollback.)

To show how this Street Fighter V netcode fix works in action, Just UltraDavid uploaded this video showing it in action.

I’ll have a more in depth dive tomorrow, but here are some clips from a match I played tonight from my apartment in CALIFORNIA vs a player in SAUDI ARABIA using the new SFV PC netcode mod. Here are some highlights. It’s so good. Sooo gooooood pic.twitter.com/NDSyT7QAdn

— Just UltraDavid (@ultradavid) January 9, 2020

Street Fighter V is available for the PlayStation 4 and PC.