1 Introduction

Internet Protocol Television (IPTV) is capable of delivering a rich set of ancillary services along with high quality TV content through Internet Protocol (IP) networks. Commercial IPTV usually is distributed over a form or another of Virtual Private Network or VPN to ensure end-to-end quality of the delivery. The use of IP networking implies that media located in different sources can be distributed over any IP network to reach a large number of consumers and be rendered over an increasingly diverse set of end devices. Moreover, media content may be re-assembled at the end points to satisfy different consumer needs using locally executed software and personalization engines. This increased level of connectivity and convergence has fostered the development of new platforms that makes possible to aggregate information and entertainment, meeting individual user requirements.

IPTV technology also provides attractive business model for telecommunication service providers and creates new challenges in research along the television value chain. Furthermore, it is also appealing to service and application providers, who can offer personalized content and widgets, individually customized to individual’s TV programs or localized to a specific region or community. For example, one main revenue source in the IPTV industry is expected to be recommendation systems in conjunction with top existing social media providers.

Television as a monolithic distribution medium is undergoing a radical transformation: from unidirectional broadcasting to Internet-connected. New challenges are emerging: how to deliver a world of content to “any device, anytime, anywhere” and innovative new means of interacting with content and other viewers such as Social TV? As a result, IPTV technology will evolve rapidly from its original concept of “me-too” TV over IP to encompass services usually associated with the web, gaming and social networking and change the way we access information and entertainment in the near future.

2 Summary of selected papers for this special issue

The first paper, by Avramova et al., studies the performance of scalable video coding for VBR TV channels transport with multiple device resolutions and required video quality. The work characterizes the fluctuations of the bit rate associated with one TV channel. The authors explore the conditions under which different transport schemes will be efficient. They compare a simulcast and a scalable video coding (SVC) transport scheme in several realistic use-cases with different encoding modes.

The second paper, by Montpetit, Klym and Mirlacher, presents a vision of IPTV in the next future combining social and mobile aspects. New innovative approaches offer a number of value-added services for operators, and content producers as well as for emerging social networking operators. For example, social networking sites could become “virtual operators” and offer personalized TV services on top of social connectivity. The article addresses the architecture, the value chain and the technical and business challenges associated with connected mobile and social TV. To put the architecture into a context, the authors also present a use case of the distributed community Digital Video Recorder (DVR) as an implementation of this vision.

The third paper, by Stockhammer, Heiles and Lüken, addresses the high bandwidth demands of IPTV. The authors explore Content Download Services (CDSs) as an alternative for operators’ current distribution models. The main contribution of the paper is in the development of selected use cases with CDS architecture and technology as well as their mapping to operators’ business models.

In the fourth paper, Cruz et al., describe the development, implementation and evaluation of a SIP based IPTV architecture with a new dynamic QoS adaptation method and signaling structure. Prototype implementations are described as well as the results of field tests carried out across different fixed and mobile access networks, for each of the signaling methods presented.

Finally, the fifth paper, by Palau et al. proposes an architecture for Wireless IPTV, making traditional IPTV and related services available in heterogeneous networks. They propose an alternative CDN-based architecture to distribute contents to different access networks, creating a triple screen distribution platform. The paper is focused on the wireless components of the system. They analyze their architecture and its performance, based on video coding, and the efficiency obtained by the judicious placement of the streaming servers.

3 Final thoughts

We believe that the aforementioned five papers cover some major challenges in IPTV technologies and provide a valuable reference for further research on multimedia networking. The targeted audience of the special issue is not limited solely to the research community, but encompasses designers, field engineers, operators, business analysts and software and content developers who can benefit from the findings reported in this special issue. Based on the variety of topics and on the quality of the articles, we infer that IPTV is a lively and robust research area. We hope that the readers will be interested by the research presented here and motivated to apply it to their specific area of activities and research.

4 Reviewers

Konstantinos Chorianopoulos, Ionian University, Greece

Cristian Hesselman, Novay, Netherlands

Rodrigo Laiola Guimaraes, CWI, Netherlands

Marianna Obrist, University of Salzburg, Austria

Robert Seeliger, Fraunhofer Institute, FOKUS, Germany

Alberto Gil Solla, University of Vigo, Spain

Ishan Vaishnavi, CWI, Netherlands

Stefan Arbanowski, FOKUS' Media Interoperability Lab, Germany

Hassnaa Moustafa, France Telecom Research (Orange Labs), France