  Streaming services gradually support high-quality videos for better user
experience. However, streaming high-quality video on mobile devices consumes a
considerable amount of energy. This paper presents the design and prototype of
EVSO, which achieves power saving by applying adaptive frame rates to parts of
videos with a little degradation of the user experience. EVSO utilizes a novel
perceptual similarity measurement method based on human visual perception
specialized for a video encoder. We also extend the media presentation
description, in which the video content is selected based only on the network
bandwidth, to allow for additional consideration of the user's battery status.
EVSO's streaming server preprocesses the video into several processed videos
according to the similarity intensity of each part of the video and then
provides the client with the processed video suitable for the network bandwidth
and the battery status of the client's mobile device. The EVSO system was
implemented on the commonly used H.264/AVC encoder. We conduct various
experiments and a user study with nine videos. Our experimental results show
that EVSO effectively reduces energy consumption when mobile devices use
streaming services by 22% on average and up to 27% while maintaining the
quality of the user experience.
