How Modern Emulation Tech is Reducing Lag in Classic Games

It doesn’t take much computing power to actually run classic games, but things get a bit more complex when it comes to preserving — and even improving on — the details that defined history’s greatest titles. These small tweaks may seem tedious, but they guarantee that the classics will be appreciated for generations to come. Today, the dedicated developers that gave the world the RetroArch multi-system emulator have taken us one step further into the future of classic gaming.

Since the NES, game consoles have run user input logic during a frame’s rendering phase, rather than processing input between frames, like the Atari 2600. This may cause perceptible lag at 60 fps, as reactions to player input aren’t executed until at least the next frame after the command, and can be delayed by more than four frames.

The newest version of Retroarch addresses this issue. It’s outfitted with a prototype Input Lag Compensation mode, which works by emulating additional hidden frames after each input, and accelerating past the lag. For instance, the original Sonic the Hedgehog has an input lag of two frames. To correct that, instead of only processing one frame at a time, the emulator will rapidly process three frames every time the user taps a button or moves a stick. The first two frames aren’t displayed on screen, and the third assumes the place of the first.

Save states are used to keep the game’s logic in check during input compensation, while PCs with multiple cores can easily sift through and synchronize the audio output. The feature itself, dubbed “LAGFIX” by its creators, has been under development since early March. Improvements are ongoing, and anyone can modify the program’s code, as Retroarch is open source.

Thanks to this fix, the delays that pervaded classic games are history, and it is now possible to play Super Mario Bros. with less input lag than its NES version. The lag reduction comes at the cost of significant processing power, but the supercharged CPUs of today’s computers are generally equipped to handle it.

While LAGFIX is likely among the most monumental improvements to the classic console experience, it’s far from the first attempted modification. Solutions have been posed to sprite flickering on the NES, and others have attempted graphical upgrades using upscaling and polygonal modeling. A common theme among improvements, however, is their tendency to stoke uproar from authenticity fanatics who insist that games should be preserved exactly as they were, lagging pixels and all.