Frame-Based Dynamic Voltage and Frequency Scaling for an MPEG2 Player

This paper describes a dynamic voltage and frequency scaling (DVFS) technique for MPEG2 decoding to reduce the energy consumption while maintaining a quality of service (QoS) constraint. The computational workload for an incoming frame is predicted using a frame-based history so that the processor voltage and frequency can be scaled to provide the exact amount of computing power needed to decode the frame. More precisely, the required decoding time for each frame is separated into two parts: a frame-dependent (FD) part and a frame-independent (FI) part. The FD part varies greatly according to the type of the incoming frame whereas the FI part remains constant regardless of the frame type. In the DVFS scheme presented in this paper the FI part is used to compensate for the prediction error that may occur during the FD part such that a significant amount of energy can be saved while meeting the frame rate requirement. The proposed DVFS algorithm has been implemented on two platforms, a low performance StrongArm-1110 based evaluation board from Intel and a high performance XScale-based testbed designed at USC. Detailed current measurements in these two platforms demonstrate larger than 50% and 80% CPU energy saving for the DVFS technique, respectively.