Showing papers by "Enrico Masala published in 2017"

Foveated video streaming for cloud gaming

Abstract: Good user experience with interactive cloud-based multimedia applications, such as cloud gaming and cloud-based VR, requires low end-to-end latency and large amounts of downstream network bandwidth at the same time. In this paper, we present a foveated video streaming system for cloud gaming. The system adapts video stream quality by adjusting the encoding parameters on the fly to match the player's gaze position. We conduct measurements with a prototype that we developed for a cloud gaming system in conjunction with eye tracker hardware. Evaluation results suggest that such foveated streaming can reduce bandwidth requirements by even more than 50% depending on parametrization of the foveated video coding and that it is feasible from the latency perspective.

Optimized Upload Strategies for Live Scalable Video Transmission from Mobile Devices

Abstract: Sharing live multimedia content is becoming increasingly popular among mobile users. In this article, we study the problem of optimizing video quality in such a scenario using scalable video coding (SVC) and chunked video content. We consider using only standard stateless HTTP servers that do not need to perform additional processing of the video content. Our key contribution is to provide close to optimal algorithms for scheduling video chunk upload for multiple clients having different viewing delays. Given such a set of clients, the problem is to decide which chunks to upload and in which order to upload them so that the quality-delay tradeoff can be optimally balanced. We show by means of simulations that the proposed algorithms can achieve notably better performance than naive solutions in practical cases. Especially the heuristic-based greedy algorithm is a good candidate for deployment on mobile devices because it is not computationally intensive but it still delivers in most cases on-par video quality compared to the more complex local optimization algorithm. We also show that using shorter video segments and being able to predict bandwidth and video chunk properties improve the delivered video quality in certain cases.

A New Architecture for Cross-Repository Creation and Sharing of Educational Resources

Abstract: A large amount of educational resources are currently available in the Internet, covering educational needs for many school grades. However, using such wealth of material, typically dispersed in several repositories, in a simple and effective way, is rather challenging due to the difficulties encountered by teachers in learning the peculiar access and operational procedures that each repository system requires. Therefore, it is important to provide the teachers with a centralized, integrated, simple system that can address most of their needs so that every operation (search, edit, share, download) can be done from a single location. This work follows this direction by designing and presenting both an architecture to integrate different repository systems using the Content Management Interoperability Services (CMIS) API and an integration layer that provides a simple web interface suitable for the needs of both the content creators (teachers) and the users of the contents (learners). Results have been evaluated both quantitatively, i.e., using performance indicators such as response time, and qualitatively, on the basis of the user experience evaluated through a questionnaire. Both type of results show that the platform adequately addresses user needs therefore it has the potential to be embraced by a large user community.

Analysis of HEVC transform throughput requirements for hardware implementations

Abstract: Hardware implementations can provide significant speedup and saving for video compression applications. In this work we focus on the transform coding sub-module analyzing the performance required by actual encoder implementations. We show that the throughput assumption about the transform sub-module in most research works is overly optimistic since it does not consider the complexity of a rate-distortion optimized video coding process. Many HEVC coding options are compared in terms of impact on quality and throughput, so to recommend the most efficient settings without excessively penalizing quality. Moreover, comparisons with the AVC standard show that, in general, HEVC presents much higher complexity to deliver its claimed compression advantages. Finally, a practical case study is shown to highlight how the proposed transform throughput analysis could be used to determine the throughput for a transform sub-module hardware design.

Foveated Video Streaming for Cloud Gaming

Abstract: Good user experience with interactive cloud-based multimedia applications, such as cloud gaming and cloud-based VR, requires low end-to-end latency and large amounts of downstream network bandwidth at the same time. In this paper, we present a foveated video streaming system for cloud gaming. The system adapts video stream quality by adjusting the encoding parameters on the fly to match the player's gaze position. We conduct measurements with a prototype that we developed for a cloud gaming system in conjunction with eye tracker hardware. Evaluation results suggest that such foveated streaming can reduce bandwidth requirements by even more than 50% depending on parametrization of the foveated video coding and that it is feasible from the latency perspective.