I. Introduction
Video-on-demand providers continue to grow their dominance in the area of subscription-based online video streaming services. These providers target a variety of customers distributed around the world. This diversity of customers poses a huge technical challenge in providing a high level of Quality of Experience (QoE) globally. As the underlying transmission medium characteristics can vary quite dramatically, these providers encode their video content into a discrete number of quality levels and implement an adaptive video content delivery mechanism to maximise QoE. Currently, the most prominent adaptive video streaming technology is HTTP Adaptive Streaming.