Energy-Aware MPEG-4 FGS Streaming

In this paper, we propose an energy-aware MPEG-4 FGS video streaming system with client feed-back. In this client-server system, the battery-powered mobile client sends its maximum decoding capability (i.e., its decoding aptitude) to the server in order to help the server determine the amount of data (in the form of enhancement layers on top of the base layer) per frame that it sends to the client, and thereby, set its data rate. On the client side, a dynamic voltage and frequency scaling technique is used to adjust the decoding aptitude of the client while meeting a constraint on the minimum achieved video quality. As a measure of energy efficiency of the video streamer, the notion of a normalized decoding load is introduced. It is shown that a video streaming system that maintains this normalized load at unity produces the optimum video quality with no energy waste. We implemented an MPEG-4 FGS video streaming system on an XScale-based test bed in which a server and a mobile client are wirelessly connected by a feedback channel. Based on actual current measurements in this test bed, we obtain 20% communication energy reduction at the client by making the MPEG-4 FGS streamer energy-aware.