In one of the more intriguing statements around cloud gaming, one of Google’s chief engineers has said that Google’s predictive work will be able to deal with any potential lag between the client and server. Their term for it? Negative latency.
In an interview in the latest Edge UK magazine, which PCGamesN grabbed at the newsagent, Google’s VP of engineering Madj Bakar reckons Stadia will be faster and more responsive than gaming on local hardware “in a year or two”. I’d normally call bullshit, but here’s the full quote from Bakar going into bat for the cloud.
“Ultimately, we think in a year or two we’ll have games that are running faster and feel more responsive in the cloud than they do locally regardless of how powerful the local machine is,” Bakar is quoted as saying.
So how do you make a cloud game “feel” more responsive than something on local hardware? The answer, apparently, is through “negative latency”. Apart from the bit where it sounds like Google has reinvented the passage of time, negative latency is effectively a buffer where Stadia applies certain techniques to combat lag. It might include predicting user inputs in some scenarios, or a rapid increase in FPS to lower latency, but the general idea is that the cloud gaming model will actively work in the background to identify and combat areas of high lag before they happen.
There’s certainly some quibbles about how rooted in reality the idea of “negative latency” actually is as a term. The principle isn’t too dissimilar from some techniques and netcode implementations we’ve seen in video games, though. The GGPO rollback netcode that was built by the EVO fighting game championship creators predicts and simulates frames before they happen, rolling the game back to the most recently accurate state if the predictions are wrong:
GGPO uses speculative execution to eliminate the perceived input delay for each local player. Instead of waiting for all inputs to reach a player’s simulation before executing a frame, GGPO will guess what remote players will do based on their previous actions. This eliminates the lag experienced by the local player created by the traditional frame-delay method. The local player’s avatar is just as responsive as when playing offline. Though the actions of the other players cannot be known until their inputs arrive, the prediction mechanism used by GGPO ensures that the game simulation is correct most of the time.
Another technique was the one used by hacknet creator Matt Trobbiani for Wrestledunk Sports, where the game runs in a 240fps deterministic space. “Every frame, you send your inputs across the network directly to the partner’s machine. Whenever you inputs from your partner in, I roll the entire game simulation back in time to when that button was actually pressed, add in all the inputs, then re-simulate back up the the present,” Trobbiani told Kotaku Australia.
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So the idea isn’t as farfetched as it sounds … although it probably wouldn’t hurt if Google could come up with a name that didn’t sound like they were reinventing physics.