智慧型手機的快速發展，無形中也加速了無線網路的普及，因此手機節能議題廣為眾人所探討。各種相依於網路的應用需求逐漸提高，其中一項應用即是串流服務，過往SVC影像編碼的串流研究透過改善CPU運算及降低網路流量達到節能的目的，但沒考慮到手機上同樣占大多數耗能的螢幕元件。本文提出並實現一個基於網路訊號強度預測之SVC影像編碼的視訊調適與螢幕背光控制的複合式即時串流服務。首先，透過預測使用者網路訊號強度調整適合當下環境的影片品質以達到有效率地傳輸；而對於螢幕節能方面，本文提出了背光調降比來描述畫格(frame)對比度與螢幕背光亮度的關聯性，並藉由背光調降比調整目前使用者的螢幕背光亮度。為了減少調降螢幕背光所產生之對比度下降的問題，每張畫格會透過雙直方圖均化方法來增強原始對比度。實驗結果證明本文所提之機制在使用者進行串流服務時能有效降低系統耗能。

With the rapid evolution of smartphone, the issue of prolonging the battery’s life time has become a major challenge. As the network service becomes popular, the demand of streaming also grows. Many researchers have already proposed works about energy efficient streaming methods through different aspects such as bandwidth control, packet scheduling etc. Those works usually focus on reducing the energy consumption of CPU and wireless network. However, the screen also drains lots of energy, and thus the energy consumption of screen indeed needs to be considered if we want to further extend the battery’s life. In this paper, we proposed an energy efficient streaming system which combined the SVC coding and backlight control mechanism. We used Non-parametric Signal Prediction method to forecast the network condition and then adjust the encoder’s parameters to fit capable network bandwidth. For backlight control, we applied Histogram Equalization to compensate the loss of Image’s contrast owing to reducing the backlight. Experiment results demonstrate that our streaming system can save energy consumption, especially when the user is making a live streaming.

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