As Virtual Reality (VR) applications gain more momentum recently, the social and communication aspects of VR experiences become more relevant. In this paper, we present some initial results of understanding the type of applications and factors that users would find relevant for Social VR. We conducted a study involving 91 participants, and identified 4 key use cases for Social VR: video conferencing, education, gaming and watching movies. Further, we identified 2 important factors for such experiences: interacting within the experience, and enjoying the experience. Our results serve as an initial step before performing more detailed studies on the functional requirements for specific Social VR applications. We also discuss the necessary research to fill in current technological gaps in order to move Social VR experiences forward.

Virtual Reality (VR) and 360-degree video are reshaping the media landscape, creating a fertile business environment. In 2016 many new 360-degree cameras and VR headsets entered the consumer market. Distribution platforms are being established and new production studios are emerging. VR is a hot topic in research and industry, and many new and exciting interactive VR content and experiences are emerging. The biggest gap we see in these experiences is the lack of social and shared aspects of VR usage, as today's VR applications tend to be an isolated endeavour. In this paper, we present TogetherVR, a web-based framework for the creation and evaluation of social and shared VR experiences in which users can communicate with a high degree of presence and in photo-realistic video quality. We further elaborate on three multiuser VR cases: watching TV together in VR, social collaboration in VR, and social VR conferencing in a mixed reality setting.

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Abstract-With the deployment of IPTV reliability for multicast is becoming an important research topic again. Even though it has been intensively investigated before, there is now an understanding of the deployment scenario and the application requirements that allows solutions to be evaluated in detail. We describe how to design a fast retransmission cache based on recent extensions of RTP. We have implemented a prototype intended for deployment in an access node and explain the necessary trade-offs in the design. The paper also contains a performance evaluation which shows the efficiency of the retransmission functionality to handle losses and its performance in congested networks.Index Terms-IPTV, QOS, ARQ, RTP. I. INTRODUCTIONlow packet loss rate is essential to provide good quality for IPTV services. Because of the error propagation properties of interframe video coding a single lost packet can cause quality degradations that can last in the order of a second depending on the encoding parameters. Even if an operator uses quality of service mechanisms that make losses unlikely within its own network, losses may occur in home networks, which are usually not quality of service aware. It is beneficial for the operator to handle also these losses to maximize the customer satisfaction and make the customers more inclined to buy IPTV services. A customer that experiences bad quality due to problems in the home network is not likely to buy IPTV services.For IPTV services sent by multicast an end-to-end retransmission scheme would lead to feedback implosion when receivers notify the source about what packets they need to get retransmissions of. An alternative solution is to use forward error correction (FEC) end-to-end so that the receivers can recover a certain amount of losses [1]. However, in a multicast solution the amount of added parity information is identical for all users, which means that when the loss rates vary for the different receivers there will either be some users with remaining losses or bandwidth will be wasted in large parts of the network where the loss rate is low. Another solution is to use local loss recovery for smaller parts of the multicast tree. By introducing a fast retransmission function in an access node, losses can be recovered rapidly and the quality for the users can be maintained. The proposed retransmission function can use the play-out buffer at the receiver to handle retransmissions of lost packets. In contrast to link layer retransmissions, retransmissions on the transport layer also recover losses occurring within the home network. Retransmission can also be combined with FEC to a hybrid ARQ solution where multiple packets are encoded together to save bandwidth in a multicast retransmission scenario.Much effort has been spent on developing solutions for loss recovery for multicast video transmission [2]. However, it is not until recently that multicast video transmission is getting widely deployed due to the commercial interest in IPTV. Now we can design the solutions in det...

The media industry is being pulled in the often-opposing directions of increased realism (high resolution, stereoscopic, large screen) and personalisation (selection and control of content, availability on many devices). Within the EU FP7 project FascinatE, a capture, production and delivery system capable of allowing end-users to interactively view and navigate around an ultra-high resolution video panorama showing a live event is being developed. In this paper we report on the latest developments of the FascinatE delivery network. We build upon an initial version of this delivery network architecture and its constituent functional components and propose a hybrid element to combine the two underlying delivery mechanisms that have previously been reported on. This hybrid aspect enables the delivery network to function in an end-to-end live delivery scenario.