Game Categorization for Deriving QoE-Driven Video Encoding Configuration Strategies for Cloud Gaming

Cloud gaming has been recognized as a promising shift in the online game industry, with the aim of implementing the “on demand” service concept that has achieved market success in other areas of digital entertainment such as movies and TV shows. The concepts of cloud computing are leveraged to render the game scene as a video stream that is then delivered to players in real-time. The main advantage of this approach is the capability of delivering high-quality graphics games to any type of end user device; however, at the cost of high bandwidth consumption and strict latency requirements. A key challenge faced by cloud game providers lies in configuring the video encoding parameters so as to maximize player Quality of Experience (QoE) while meeting bandwidth availability constraints. In this article, we tackle one aspect of this problem by addressing the following research question: Is it possible to improve service adaptation based on information about the characteristics of the game being streamed? To answer this question, two main challenges need to be addressed: the need for different QoE-driven video encoding (re-)configuration strategies for different categories of games, and how to determine a relevant game categorization to be used for assigning appropriate configuration strategies. We investigate these problems by conducting two subjective laboratory studies with a total of 80 players and three different games. Results indicate that different strategies should likely be applied for different types of games, and show that existing game classifications are not necessarily suitable for differentiating game types in this context. We thus further analyze objective video metrics of collected game play video traces as well as player actions per minute and use this as input data for clustering of games into two clusters. Subjective results verify that different video encoding configuration strategies may be applied to games belonging to different clusters.