QoE-aware inter-stream synchronization in open N-screens cloud

The growing popularity and increasing performance of mobile devices is transforming the way in which media can be consumed, from single device playback to orchestrated multi-stream experiences across multiple devices. One of the biggest challenges in realizing such immersive media experience is the dynamic management of synchronicity between associated media streams. This is further complicated by the faceted aspects of user perception and heterogeneity of user devices and networks. This paper introduces a QoE-aware open inter-stream media synchronization framework (IMSync). IMSync employs efficient monitoring and control mechanisms, as well as a bespoke QoE impact model derived from subjective user experiments. Given a current lag, IMSync's aim is to use the impact model to determine a good catch-up strategy that minimizes detrimental impact on QoE. The impact model balances the accumulative impact of re-synchronization processes and the degree of non-synchronicity to ensure the QoE. Experimental results verify the run-time performance of the framework as a foundation for immersive media experience in open N-Screens cloud

Closing the gap: human factors in cross-device media synchronization

The continuing growth in the mobile phone arena, particularly in terms of device capabilities and ownership is having a transformational impact on media consumption. It is now possible to consider orchestrated multi-stream experiences delivered across many devices, rather than the playback of content from a single device. However, there are significant challenges in realising such a vision, particularly around the management of synchronicity between associated media streams. This is compounded by the heterogeneous nature of user devices, the networks upon which they operate, and the perceptions of users. This paper describes IMSync, an open inter-stream synchronisation framework that is QoE-aware. IMSync adopts efficient monitoring and control mechanisms, alongside a QoE perception model that has been derived from a series of subjective user experiments. Based on an observation of lag, IMSync is able to use this model of impact to determine an appropriate strategy to catch-up with playback whilst minimising the potential detrimental impacts on a users QoE. The impact model adopts a balanced approach: trading off the potential impact on QoE of initiating a re-synchronisation process compared with retaining the current levels of non-synchronicity, in order to maintain high levels of QoE. A series of experiments demonstrate the potential of the framework as a basis for enabling new, immersive media experiences

BCI to Potentially Enhance Streaming Images to a VR Headset by Predicting Head Rotation

While numerous studies show that brain signals contain information about an individual’s current state that are potentially valuable for smoothing man–machine interfaces, this has not yet lead to the use of brain computer interfaces (BCI) in daily life. One of the main challenges is the common requirement of personal data that is correctly labeled concerning the state of interest in order to train a model, where this trained model is not guaranteed to generalize across time and context. Another challenge is the requirement to wear electrodes on the head. We here propose a BCI that can tackle these issues and may be a promising case for BCI research and application in everyday life. The BCI uses EEG signals to predict head rotation in order to improve images presented in a virtual reality (VR) headset. When presenting a 360° video to a headset, field-of-view approaches only stream the content that is in the current field of view and leave out the rest. When the user rotates the head, other content parts need to be made available soon enough to go unnoticed by the user, which is problematic given the available bandwidth. By predicting head rotation, the content parts adjacent to the currently viewed part could be retrieved in time for display when the rotation actually takes place. We here studied whether head rotations can be predicted on the basis of EEG sensor data and if so, whether application of such predictions could be applied to improve display of streaming images. Eleven participants generated left- and rightward head rotations while head movements were recorded using the headsets motion sensing system and EEG. We trained neural network models to distinguish EEG epochs preceding rightward, leftward, and no rotation. Applying these models to streaming EEG data that was withheld from the training showed that 400 ms before rotation onset, the probability “no rotation” started to decrease and the probabilities of an upcoming right- or leftward rotation started to diverge in the correct direction. In the proposed BCI scenario, users already wear a device on their head allowing for integrated EEG sensors. Moreover, it is possible to acquire accurately labeled training data on the fly, and continuously monitor and improve the model’s performance. The BCI can be harnessed if it will improve imagery and therewith enhance immersive experience

Experiencing virtual reality together: Social VR use case study

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 user

Design, Development and Assessment of Control Schemes for IDMS in a Standardized RTCP-based Solution

[EN] Currently, several media sharing applications that allow social interactions between distributed users are gaining momentum. In these networked scenarios, synchronized playout between the involved participants must be provided to enable truly interactive and coherent shared media experiences. This research topic is known as Inter-Destination Media Synchronization (IDMS). This paper presents the design and development of an advanced IDMS solution, which is based on extending the capabilities of RTP/RTCP standard protocols. Particularly, novel RTCP extensions, in combination with several control algorithms and adjustment techniques, have been specified to enable an adaptive, highly accurate and standard compliant IDMS solution. Moreover, as different control or architectural schemes for IDMS exist, and each one is best suited for specific use cases, the IDMS solution has been extended to be able to adopt each one of them. Simulation results prove the satisfactory responsiveness of our IDMS solution in a small scale scenario, as well as its consistent behavior, when using each one of the deployed architectural schemes.This work has been financed, partially, by Universitat Politecnica de Valencia (UPV), under its R&D Support Program in PAID-01-10. TNO's work has been partially funded by European Community's Seventh Framework Programme (FP7/2007-2013) under Grant Agreement No. ICT-2011-8-318343 (STEER Project). CWI's work has been partially funded by the European Community's Seventh Framework Programme (FP7/2007-2013) under Grant Agreement No. ICT-2011-7-287723 (REVERIE Project).Montagud Aguar, M.; Boronat Segui, F.; Stokking, H.; Cesar, P. (2014). Design, Development and Assessment of Control Schemes for IDMS in a Standardized RTCP-based Solution. Computer Networks. 70:240-259. https://doi.org/10.1016/j.comnet.2014.06.004S2402597

Inter-Destination Multimedia Synchronization; Schemes, Use Cases and Standardization

Traditionally, the media consumption model has been a passive and isolated activity. However, the advent of media streaming technologies, interactive social applications, and synchronous communications, as well as the convergence between these three developments, point to an evolution towards dynamic shared media experiences. In this new model, geographically distributed groups of consumers, independently of their location and the nature of their end-devices, can be immersed in a common virtual networked environment in which they can share multimedia services, interact and collaborate in real-time within the context of simultaneous media content consumption. In most of these multimedia services and applications, apart from the well-known intra and inter-stream synchronization techniques that are important inside the consumers playout devices, also the synchronization of the playout processes between several distributed receivers, known as multipoint, group or Inter-destination multimedia synchronization (IDMS), becomes essential. Due to the increasing popularity of social networking, this type of multimedia synchronization has gained in popularity in recent years. Although Social TV is perhaps the most prominent use case in which IDMS is useful, in this paper we present up to 19 use cases for IDMS, each one having its own synchronization requirements. Different approaches used in the (recent) past by researchers to achieve IDMS are described and compared. As further proof of the significance of IDMS nowadays, relevant organizations (such as ETSI TISPAN and IETF AVTCORE Group) efforts on IDMS standardization (in which authors have been and are participating actively), defining architectures and protocols, are summarized.This work has been financed, partially, by Universitat Politecnica de Valencia (UPV), under its R&D Support Program in PAID-05-11-002-331 Project and in PAID-01-10, and by TNO, under its Future Internet Use Research & Innovation Program. The authors also want to thank Kevin Gross for providing some of the use cases included in Sect. 1.2.Montagud, M.; Boronat Segui, F.; Stokking, H.; Van Brandenburg, R. (2012). Inter-Destination Multimedia Synchronization; Schemes, Use Cases and Standardization. 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Automatic Measurement of Play‐out Differences for Social TV, InteractiveTV, Gaming and Inter‐destination Synchronization

Inter-destination media (play-out) synchronization for social TV has gained attention from research and industry in recent years.Applications include social TV and interactive game shows. To motivate further research of inter-destination synchronization technologies, pilot measurements of play-out differences in different TV-broadcasting systems are desirable. However to our knowledge no broadly applicable measurement system exists. This paper fills this gap by presenting and implementing a robust system that can detect constant or slowly varying differences in media play-out between different receivers without accessing receiver hardware or network. The measurements are relevant in various use-cases such as football watching, social TV, inter active game shows around TV-content, TV input lag comparison for gaming and validation of current inter-destination synchronization technologies. The robustness of the system is demonstrated in a working prototype

Network delay and bandwidth estimation for cross-device synchronized media

Driven by the growth in mobile phone and tablet ownership, recent years have witnessed an increasing trend towards coordinated media experiences across multiple devices. The quality of experience (QoE) over such new generation applications is dictated by the Quality of Service (QoS) of underlying networks. Inevitable network delay and bandwidth fluctuations affect the communications and media synchronization between connected devices. Therefore, network measurement is becoming the key to providing essential information for the QoE assurance of cross-device synchronized media. Among many network measurement techniques, packet probing is considered as the most effective for end-to-end evaluations. Packet probing may seem straightforward but it requires a good understanding of the methodologies and how the results should be interpreted. This chapter provides a guidance and some best practices in packet probing, accompanied with a use case where delay measurement enhances cross-device media synchronization and the QoE of an immersive media application

Influence of Photorealism and Non-Photorealism on Connection in Social VR

Traveling for business meetings is not only costly but also has a negative influence on the environment. Many video conferencing platforms have tried to reduce the need to travel, but people still find it relevant to meet face-to-face. Remote meetings via virtual reality (VR) allow users to still have the feeling of being together in the same space. In VR, avatars are used as digital user representations. This study investigated whether photorealistic avatars influence the connection users feel with each other during a VR remote meeting, and whether congruence between environment and avatar realism influences this connection. A 2x2 within-subject experiment was conducted whereby twelve participants had remote meetings in VR with photorealistic and non-photorealistic avatars and environments. Results indicate that when both participants are represented by live video footage of themselves (photorealistic), they feel more connected with each other than when they are represented by a non-photorealistic avatar. Congruence between the avatar and environment did not seem to influence connection. These results may help to improve the value of future remote business meetings