Fortnite Team Explains Decision to Cap PS4 and PS4 Pro at 30 FPS in Update 1.8

October 25, 2017Written by Chandler Wood

Fortnite update 1.8 is still a few hours away, but already there has been some push back to one of the changes listed in the patch notes. Specifically, the patch notes call out that they have “re-enabled capped 30 FPS on PS4 and PS4 Pro to maintain a smooth experience,” and now the team has made additional comments on their decision to re-implement that cap.

In short, uncapping the framerate was an accident that released with update 1.5, however it introduced a bigger problem with the game stuttering as it waffled between various frame rates. In blind tests, players were “pretty universal in their preferences” of what Epic is about to release in update 1.8, so the good news is that the game will actually play the best that it can. Essentially what it boils down to is that a capped frame rate provides the best experience to players, all benefits and drawbacks accounted for. If you’re looking for more of the technical details on what led to this decision though, Epic has you covered.

TLDR: We’re really, really sorry to players who appreciated the higher frame rates under certain conditions. Unlocking frame rate was an accidental change with some unusual benefits and drawbacks. We feel that capping consoles to 30 fps will provide the best experience based on our internal metrics and blind play testing. We’ll be looking forward to your feedback and continually working to make the experience awesome!

In addition, we are also working on improvements over the next couple of weeks, including locking the “front end” UI and lobby screens at 60fps, and investigating adding a “display options” menu on consoles.

More Background/Technical Info:

  • At launch we had significant problems with frame syncing which was due to the way we were synchronizing the game and render threads with the GPU at 30fps. Digital Foundry made an excellent video that highlights the problem (which was awesome!) and we began work on fixing that.

  • While fixing the frame syncing problem our engineers also identified that in addition to frame syncing, we also had significant input latency because of how we are handling parallel rendering on consoles. This introduced latency as high as 120ms and made the experience on both consoles poor.

  • While working on a fix for this, we inadvertently released a build that uncapped framerate on PS4 and PS4 Pro with our 1.5 release. This was actually a happy mistake, as it hid a lot of the issues with frame syncing and input latency compared to what we launched with and did mean that we hit 60fps in some scenes. However, that also introduced significant variations in frame rate, and we never really reached or could maintain a 60fps lock for longer than a few frames. In general, our data says that average fps on PS4 Pro for Save the World, for example, was around 45fps with a range between 20fps and 55fps. Those dips under 30fps would often get compounded over multiple subsequent frames causing an even worse experience. In addition, it could cause “stuttering” of frames. Your TV can display a new frame 60 times every second, but often would be forced to display the same image twice in a row because the game was rendering at a lower rate. This made smooth camera movements appear “jumpy” as the time between frames oscillated back and forth.

  • Since then, we’ve been working on the real fix to both frame pacing and input latency and doing significant testing on what would provide the best user experience. One of the many measures we use to track performance is what we call “MVP30” or Missed VSync Percentage at 30fps. In simplified terms, how many frames did we miss rendering compared to perfectly rendering every frame at 30fps. At launch we hovered around 5% missed frames. Our last internal performance test had that number at 1% or less.

  • We have also reduced overall input latency from 120ms to around 76ms in typical gameplay, which was achieved by limiting the time between the simulation thread kicking off and the frame being presented to the display.

  • Our hope was that fixing the frame syncing and input latency bugs would introduce a much better player experience at a consistent frame rate for all players. We have run multiple blind playtests with all of the variations, unlocked framerate on PS4 Pro and PS4, locked framerate on Xbox One, along with the correct fix for both, and players were pretty universal in their preference for what we’re about to ship with 1.8.

  • We do intend to cap framerate up to 60fps in our “front end” UI and lobby screens in the short term, and we are constantly striving for optimizing the engine and game code to provide the best experience.

  • We’re also investigating adding a menu for capping and uncapping fps and other types of display options, but want to make sure we think through that sufficiently. There’s always a balance between optimizing and striving for the best, most consistent, user experience while allowing players the ability to play the way they want. We also have to consider the competitive balance implications.

  • As always, we welcome and value your feedback so please let us know your thoughts!

What do you think of Fortnite being capped at 30 fps on PS4 and PS4 Pro? Do you appreciate Epic for making difficult changes like this one that are actually in the best interest of the game experience?

[Source: Epic Games]