Energy efficient video encoding using the tegra K1 mobile processor

Abstract

Energy consumption is an important concern for mobile devices, where the evolution in battery storage capacity has not followed the power usage requirements of modern hardware. However, innovative and flexible hardware platforms give developers better means of optimising the energy consumption of their software. For example, the Tegra K1 System-on-Chip (SoC) offers two CPU clusters, GPU offloading, frequency scaling and other mechanisms to control the power and performance of applications. In this demonstration, the scenario is live video encoding, and participants can experiment with power usage and performance using the Tegra K1's hardware capabilities. A popular power-saving approach is a "race to sleep" strategy where the highest CPU frequency is used while the CPU has work to do, and then the CPU is put to sleep. Our own experiments indicate that an energy reduction of 28 % can be achieved by running the video encoder on the lowest CPU frequency at which the platform achieves an encoding frame rate equal to the minimum frame rate of 25 Frames Per Second (FPS).