The best high-end mobile games rival console games, but the price of these high-end graphics is high power consumption by the GPU, meaning your gaming session will be severely limited if you want to make it to the end of the day.
Now Microsoft Research Asia (MSRA) and Korea Advanced Institute of Science & Technology (KAIST) have developed a new system, called RAVEN, to reduce the power consumption of mobile games without compromising user experience.
RAVEN is based on the insight that while most games are rendered at 60 fps, up to 50% of those frames look nearly exactly the same as the other frames, meaning processing power was wasted generating them.
RAVEN is a novel system which leverages human visual perception for scaling the rate of rendering frames. To accomplish this, RAVEN is introducing the use of perception-aware scaling (PAS) of frame-rendering rates. This energy-saving methodology reduces a game’s rate of rendering frames whenever succeeding frames are predicted to be perceptually similar enough.
The RAVEN system consists of three major components which collectively scale the rate of game-frame rendering: Frame Difference Tracker (F-Tracker), Rate Regulator (R-Regulator), and Rate Injector (R-Injector). The system works in a pipelined fashion. First, F-Tracker measures perceptual similarity between two recent frames. Then, R-Regulator predicts the level of similarity between the current and next frame(s). The prediction is done based on how similar the current frame and the previous frame(s) are. If the next frames are similar enough (determined by a threshold) to the current one, R-Injector limits frame-rendering rates by injecting certain delay in a rendering loop and skip graphics processing for unnecessary frame(s). Presently, RAVEN can skip up to a maximum of three frames, and thus, inflict a frame-rate drop down to 15 FPS.
The researchers first developed an energy-efficient method to measure perceptual similarity based on the susceptibility of human eyes to the color difference which leverages the difference in the luminance component between frames.
Second, the researchers built a virtual display, cloned from the mobile device main display but with a much lower resolution (e.g., 80 x 45 pixels). The system reads the graphical contents of the virtual display for the similarity measurement. Because the resolution of the virtual display is significantly smaller, the computational and energy overheads are also much smaller. The two techniques together effectively reduce the energy overhead of RAVEN.
In a real-life test on a Nexus 5 phone and 11 gamers showed an average 21.8% up to a high of 34.7% reduction in energy-per-game session while maintaining quality, user experiences.
Microsoft has published the research in a paper called “RAVEN: Perception-aware Optimization of Power Consumption for Mobile Games” . It is not known yet if the technology has been licensed out t0 any gaming company yet, but if implemented it could mean gaming sessions could last up to 1/3 longer than previously without any impact on the experience.
Read more at Microsoft Research here.