- Mul timedia systems typically include audiovisual (AV) content that stimulates only the senses of sight and hearing. However, stimulating other senses beyond these two can provide more realistic and immersive multimedia experiences, as well as help improve the user’s quality of the media consumption experience (QoE). The research community has been working for years on the development of so-called mulsemedia systems, which include sensory effects metadata associated with AV content, allowing those effects to be generated during the experience, thereby stimulating all the users’ senses. Examples of effects include scents, flavors, vibration, pressure, wind, lighting, temperature or fog. Existing solutions and standards (e.g., MPEG-V) already enable the integration of sensory effects generation devices into multimedia systems. However, most of them are not openly available or have been designed for and evaluated in desktop scenarios. Moreover, many of them use non-commercial generation devices, developed ad hoc to generate specific effects. This article proposes an MPEG-V standard-compliant platform based on web technologies and IoT-related devices for the distribution and consumption of multisensorial content, enabling the use of typical commercial effect generation devices. It also allows a 3D simulation of the effects generation and the location from which they are generated. A prototype implementation is presented, the operation of which has been subjectively validated by 40 users and media contents of different genres. All participants confirmed, among other things, that they perceived a good synchronization between sensory effects and AV content playout, that the inclusion of sensory effects adds value to the AV content, improving enjoyment, immersion, realism, and, therefore, the QoE during media consumption, and rated the usability of the developed prototype’s graphical interface as ‘excellent’ (82.3 in SUS scale) .

The use of Smart TVs and companion devices is gaining momentum, enabling personalised and enhanced media experiences. A new wave of enriched services, and even new business models, is now possible. This is particularly relevant to TV operators and other stakeholders, since the (linear) broadcast TV content can be augmented by on-demand media content delivered via broadband technologies. Nevertheless, despite the efforts from some initiatives to drive hybrid broadcast/broadband TV media services, the current solutions still do not fully exploit the potential and opportunities that hybrid TV media services can offer. Existing companion-screen (CS) apps typically remain confined to 2D interfaces. However, AR/VR head-mounted displays have matured sufficiently to enable a transition from the use of physical 2D interfaces to a more immersive scenario, allowing many virtual companion screens around the smart TV. This paper presents the preliminary results of a recently conducted study on how users perceive the enhancement of linear TV services with AR/VR in hybrid broadcast/broadband TV scenarios. A prototype of a typical ARTV service has been implemented and tested by 41 participants, who declared ARTV services as the future of TV, considering them useful, informative, desirable, and fun.

Abstract Thanks to the improvements experienced in technology during the last few years, most especially in virtual reality systems, the number and potential of networked virtual environments or NVEs and their users have been increasing. NVEs aim to give distributed users a feeling of immersion in a virtual world and the possibility of interacting with other users or with virtual objects inside it, just like when they interact in the real world. Being able to provide that feeling and natural interactions when the users are geographically separated is one of the goals of these systems. Nevertheless, this goal is especially sensitive to different issues, such as different connections with heterogeneous throughput or particular network latencies, which can lead to consistency and synchronization problems and, thus, to a worsening of the users’ quality of experience or QoE. With the purpose of solving these issues, researchers have proposed and evaluated numerous technical solutions, in fields like network architectures, data distribution and filtering, resource balancing, computing models, predictive modeling and synchronization in NVEs. This paper gathers and classifies them, summarizing their advantages and disadvantages, using a new way of classification. With the current increase in the number of NVEs and the multiple solutions proposed so far, this paper aims to become a useful tool and a starting point not only for future researchers in this field but also for those who are new to NVEs development, in which guaranteeing a good users’ QoE is essential.

This paper presents an end-to-end Dynamic Adaptive Streaming over HTTP (DASH) platform, developed by using open-source components. It includes and allows the configuration of all the required steps along the end-to-end media delivery chain, from the encoding, segmentation and storage of the media content at the server side, to the delivery and adaptive consumption of the media content at the client side. A key component of this platform is the DASH client, developed using the GStreamer framework. It includes a module with a novel adaptive algorithm for switching between the available representations (i.e., qualities) of the media content at the server side, based on the available bandwidth and on internal conditions and features of the client (such as the buffer occupancy level, the battery level, its charging state and the CPU load). It also includes different modules to simulate specific values for these parameters, and to visualize their values and the value of the selected quality in real-time. A preliminary evaluation has proved the satisfactory performance of the overall platform. Finally, links to demo videos are provided to demonstrate the satisfactory performance and capabilities of this platform.

Inter-Destination Multimedia Synchronization(IDMS) is a key requirement to enable satisfying group shared media experiences. This paper presents the design and simulation of a Distributed Control Scheme (DCS) for IDMS. In this scheme, geographically dispersed receivers exchange(multicast) RTCP reports on their arrival and play out timing for RTP packets, and each one of them uses the collected reports from the other receivers belonging to the same logical group (or cluster) to adaptively adjust its local play out timing such that an overall synchronization status (within allowable limits) is maintained. Also, the strengths (interactivity, flexibility, scalability, and robustness) and weaknesses (traffic overhead, security) of a DCS for IDMS are discussed, in comparison with centralized approaches. Moreover, a simple technique to enhance the performance in terms of coherence when using the DCS for IDMS is proposed. Simulation results prove the effectiveness of the proposed control scheme and techniques to guarantee concurrently synchronized play outpoints for independent clusters of receivers.

Inter-Destination Media Synchronization (IDMS) is essential in the emerging media consumption paradigm, which is radically evolving from passive and isolated services towards dynamic and interactive group shared experiences. This paper concentrates on improving a standardized RTP/RTCP-based solution for IDMS. In particular, novel Early Event-Driven (EED) RTCP feedback reporting mechanisms are designed to overcome latency issues and to enable higher flexibility, dynamism and accuracy when using RTP/RTCP for IDMS. The faster reaction on dynamic situations (e.g., detection of asynchrony or channel change delays) and a finer granularity for synchronizing media-related events, while preserving the RTCP bandwidth bounds, are validated through simulation tests.

Many emerging multimedia applications enable independent groups (or clusters) of consumers to interact between them and share services within the context of simultaneous media content consumption. Owing to the semantic, spatial or temporal dependency among the involved media streams, concurrently synchronized playout points must be ensured so as not to spoil the user experience on such interaction. This paper presents the combination of an evolved Inter-Destination Multimedia Synchronization (IDMS) approach and a new designed Adaptive Media Playout (AMP) scheme that aims to smoothly adjust the playout timing of each one of the receivers in a specific cluster, if an asynchrony threshold between their playout states is exceeded. Simulation results prove the feasibility of such proposals, by employing several dynamic master selection policies, to maintain an overall synchronization status (within allowable limits) in each cluster, while minimizing the occurrence of long-term playout discontinuities (such as skips/pauses) which are subjectively more annoying to users than small variations in the media playout rate.

This paper presents an enhanced version of a proposed extension of the RTP/RTCP standard protocols to acquire Inter-Destination Multimedia Synchronization (IDMS) in one-way distributed applications. Several dynamic policies for selecting the master reference play out point to synchronize are introduced and their suitability is analyzed, for specific network conditions and application requirements, according to the impact of the play out adjustments (such as skips and/or pauses) on the overall quality and the buffer fullness variation. Simulation results prove the ability of our approach, for all the proposed master selection algorithms, to maintain the play out asynchrony between distributed receivers within acceptable limits, by dynamically adjusting their play out timing every time an allowed play out time discrepancy between their play out states is detected.

This paper presents an accurate simulation framework for video streaming evaluation. We have designed a full RTP/RTCP implementation for NS-2 and we propose to combine it with several multimedia tools to obtain an RTP-based tool-set that allows the measurement of network-level QoS and most common video quality metrics. As RTCP feedback reporting capabilities have been provided, researchers and practitioners could make us of this platform to assess novel source and receiver-based techniques for improving the QoS in multimedia streaming services.

Nowadays, many multimedia cluster-to-cluster applications exist, such as 3D tele-immersion (3DTI), computer-supported collaborative workspaces (CSCWs), distributed multimedia presentations (DMP).... All these applications have sophisticated data transport requirements due to the use of multiple, semantically related flows of information. A synchronization mechanism must be used to synchronize the playout of the streams, regardless of the number of receivers and the number of streams played on the receiver clusters. In this paper, we present a new solution for multimedia group synchronization in such applications. Rather than base the solution on the definition of a new synchronization protocol (as other authors do), we base it on small modifications or extensions to RTP/RTCP standard protocols already used in most multimedia applications. Due to this, the overload introduced by the approach is minimal. The suitability of the approach was evaluated in a real one-way cluster-to-cluster application, with satisfactory results.

Most of actual multimedia tools use RTP/RTCP for inter-stream synchronization, but not for group synchronization. In this paper we describe and evaluate a proposal of modification of RTCP packets to provide a sender-based method for synchronization of a group of receivers