Demystifying the magic of cache thresholds in the Android media framework

Mobile video streaming has gained growing popularity with the rapid adoption of mobile devices (e.g., smart-phones, tablets, pads). In the market of mobile devices, a large portion were installed with Google´s Android as the default operating system. A clear understanding of the Android media framework is of great importance for the performance optimization of mobile video streaming. In this paper, we focus our attention on demystifying the magic of cache thresholds in the Android media framework. As the key control parameters, cache thresholds play an important role in regulating the downloading behavior of a mobile device, which directly affects the cost and quality of mobile streaming. We built a dedicated testbed and conducted a measurement study to measure the cost and quality of mobile video streaming when varying cache thresholds. Our measurements pointed out that, the sunk cost incurred by user viewing abortion will grow with the increase of either high or low threshold. More battery energy can be saved if lowering the low threshold. In addition, the freezing phenomenon can be mitigated significantly by increasing the low threshold. It is also interesting to observe that there exists a clear cost-quality tradeoff when varying cache thresholds. It implies that the current static cache management scheme is unsuitable to achieve the best cost-quality tradeoff. We finally discussed a few implications of our results on cache optimization of mobile video streaming.