Support for power efficient mobile video playback on simultaneous hybrid display

Mobile devices, such as smartphones, e-books, and tablets, have limited battery capability because of the constraint of battery size and mobility requirement. However the large color displays on those devices put more tensions on this situation as the displays consume a large portion of the total battery power. A TOLED-EPD hybrid display that integrates a transparent OLED (TOLED) with an electrophoretic display (EPD) has been emerging to reduce the energy usage of displays. The technology displays information selectively on one of the displays based on the update rate of content, thus reduces the energy usage. In this paper, we propose a design of mobile video playback, Decoder4Hybrid, for the hybrid displays. The proposed approach supports encoded video playback based on the update frequency of each block, which is exploited by the hybrid display controller to determine which display should be used to show a MPEG encoded block. A fast DCT-based heuristic algorithm is proposed to detect the changes between frames at block level with minimal computation cost. Experimental results show that the proposed approach can save up to 40% power with acceptable video quality.