Abstract: This paper addresses the problem of power consumption in multimedia system architectures and presents an algorithmic optimization technique to achieve the goal of power reduction in the context of real time processing. The technique is based on a mixed speed-setting and shutdown policy. We address the problem from both a theoretical and practical point of view, by presenting a power efficient implementation of a MPEG-layer3 real-time decoder algorithm designed for wearable devices as a case study. The target system is the Hewlett-Packard's SmartBadgeIII prototype of wearable system based on the StrongARM1100 processor. Theoretical analysis as well as quantitative results of power measurements are provided to show the effectiveness of this technique. The experimental set-up is also described.