Energy-aware video streaming with QoS control for portable computing devices

We propose an energy-aware video streaming system for portable computing devices, in which the video can be played back for the specified duration within the remaining battery amount. To save power, we introduce techniques (i) to reduce playback quality of a video at an intermediate proxy and (ii) to shorten working time of the network I/F card using periodic bulk transfer of the video data on the wireless LAN. To enable playback for the specified duration, we have developed a power consumption model for portable devices using parameters on playback quality, playback duration, battery amount, and so on. We have also developed an algorithm to assign different playback quality among multiple video segments based on the user's preference.within the battery amount. Our experiments using PDAs and laptop PCs on 802.11b WLAN show that our system achieves less than 6 prediction error in playback duration while adapting playback quality among video segments.