Better than reality: New emulation tech lags less than original consoles ~ USA Latest Games

This video comparison shows how RetroArch emulation can actually react to button inputs more quickly than original NES hardware.

Here at Ars, we've previously written about how difficult it is to perfectly emulate classic video game consoles even with powerful modern computer hardware. Now, the coders behind the popular RetroArch multi-emulator frontend are working to make their emulation better than perfect, in a way, by removing some of the input latency that was inherent in original retro gaming hardware.

While early game consoles like the Atari 2600 sample and process user inputs between frames, consoles since the NES usually run that game logic while a frame is rendering. That means the game doesn't output its reaction to a new input until the next frame after the button is pressed at earliest. In some games, the actual delay can be two to four frames (or more), which can start to be a noticeable lag at the usual 60 frames per second (or about 17 ms per frame).

An experimental Input Lag Compensation mode being rolled out in new versions of RetroArch fixes this issue by basically fast-forwarding a few hidden frames behind the scenes before displaying that first "reaction" frame in the expected spot. So in a game like Sonic the Hedgehog, which has two frames of input lag, the game will quickly emulate two additional, hidden frames after every new input. Then, the emulator actually shows the third post-input frame (where Sonic first shows a visible reaction) timed for when the first post-input frame would naturally appear, cutting out the delay a player would usually see.

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