In this paper, a closed-loop approach to control the power consumption of multimedia mobile devices is presented, such that the feedback signal is an estimation based on monitored system events. First, the power estimation method is presented and validated. Afterwards, prior to the implementation of the real-time control system, off-line estimation data are used to get a system model, which enables the application of classic control-theory methods to analyze and design an integral controller whose behavior is then simulated. The target system is a video decoder running in an embedded development platform. The simulation results show how the controller achieves null average steady-state error with short settling times, even in the presence of estimation noise or disturbance, thus predicting promising results for the closed-loop approach to the final real-time system implementation.