This is part of Digital Foundry’s current coverage for the Xbox Series X. You can find the rest here:
The full specifications of the Xbox Series X! How powerful is the new generation console?
How big is the Xbox Series X compared to the Xbox One X?
Xbox Series X: the difference in ray tracing and efficient design
Xbox Series X: Why Faster SSD Storage Changes Everything
Xbox Series X: How Old Games Work Better on Next Generation Console
The fight against the displacement and uprooting of inputs
Microsoft’s X-Series speed policy is also leading to a radical overhaul of input processing to reduce latency for every imaginable part of the games pipeline. This means that the time between the press of the button and the resulting response on the screen should decrease considerably. Microsoft has already mentioned the dynamic latency entry, but only shows the extent of the work here. It starts with the controller, where the typical 8ms latency at the analog controller input is now drastically reduced by transferring the last inputs, just before the game needs it. Digital inputs such as key presses are time stamped and sent to the game, reducing latency without increasing polling rate, while pads connected via USB immediately transmit digital inputs to the console. To simplify all this, the entire input software stack has been rewritten, which further improved latency.
Latency was a crucial variable but invisible to developers. As game engines become more complex and parallel, it’s not easy to keep an eye out for additional delays – something else Microsoft is trying to fix with DLI. “We’ve made it easy for game developers to optimize game latency. Xbox games give you an ID for each frame as it goes through the engine,” Goossen says. “When the controller input is queried, this Frame ID is tied to the timing of the input. When rendering is complete for that frame, this ID is passed to the system along with the full information from the forward buffer. This mechanism can be used to do this. The system therefore now determines the total in-game latency for each frame. ”
According to Microsoft, a system has been provided that allows developers to track engine input delays as easily as frame rate. The metric has been added to the internal Pix performance analysis tool. The latest item from DLI is Xbox Series X support for the new wave of 120Hz HDMI 2.1 displays that are now hitting the market. The company has already started testing this feature at resolutions below 4K on supported HDMI 2.0 displays on Xbox One S and Xbox One X. As the displays update twice as fast as their 60Hz counterparts, users should have a faster response time. A problem that should also apply to VRR (Variable Refresh Rate) modes. Microsoft has also launched ALLM modes for its existing devices, so the console can tell the screen to automatically switch to game mode.
Microsoft is also working on innovations in screen tearing. Usually a new frame is displayed during scanning to reduce latency. Triple buffering can then flatten the junk in the frame rate, but also mean additional lag. But with the X series, there is an evolution here. “We’ve redesigned the display API that games use to send full frames to TV,” said Andrew Goossen. “We decoupled the traditional connection between double or triple buffering and latency. Until now, triple buffering has been used to absorb drops in frame rates, but it also meant increased latency. Frame – Buffering and latency have been completely decoupled and games can use triple buffering while the desired latency is determined separately, so that the image processor start time and the image GPU start can be defined specifically in microseconds and no longer in V-Syncs. ”
“This allows developers to precisely control the latency between the CPU and GPU until bubbles form or the GPU is idle because the CPU is not delivering fast enough. The routines then provide the game with detailed latency statistics to help them keep the dynamic adjustments up to date. With this mechanic, games can reduce game latency as much as possible and very easily. ”
Even though the new Series-X controller shines with improvements, optimizations and a share button, it’s still good news that DLI technology will be compatible with existing controllers. These are then updated with a simple firmware update.