Enhancing mobile multimedia services

The deep penetration of mobile smart devices, e.g., smartphones, tablets, and wearable devices, has significantly enriched the multimedia services on the Internet and undoubtedly reshaped the way that users access them. The unique user interactions and the featured user interfaces of the mobile smart devices has brought both opportunities and challenges to delivering today’s multimedia services. In this thesis, we present our studies on understanding and enhancing multimedia services on mobile platforms. First, we present a measurement and enhancement study on instant video clip sharing, an emerging mainstream multimedia service. We systematically investigate its distinct mobile interface, service framework, and user watching behaviors, revealing how this service type differentiates from its traditional counterparts, based on which we formulate and solve the optimization problem to maximize the viewing experience as well as the cost efficiency. Second, by utilizing the touch screen user interactions on mobile devices, we design and build a mobile-friendly HTTP middleware, which interprets user input gestures and optimizes the HTTP download of media contents for dynamic-viewport mobile applications, a class of mobile Internet applications that download contents beyond the user’s viewing region. Further, we jointly consider user behaviors and application features to optimize the steaming of 360-degree videos, a novel type of multimedia contents. We propose the viewport-aware adaptive 360-degree video streaming framework with robust viewport prediction and QoE-based rate adaptation optimization. Finally, we attempt to improve mobile multimedia services by leveraging cloud resources. We closely examine the performance and energy efficiency of offloading realtime video applications to cloud, propose a scheduling algorithm that makes adaptive offloading decisions at a fine granularity in dynamic wireless network conditions, and verify its effectiveness through real-world case studies with advanced mobile platforms and practical applications.