Georgios Gardikis

Shot boundary detection without threshold parameters

Automatic shot boundary detection is a field, where many techniques and methods have been proposed and have claimed to perform reliably, especially for abrupt scene cut detection. However, all the proposed methods share a common drawback: the necessity of a threshold value, which is used as a reference for detecting scene changes. The determination of the appropriate value or the dynamic reestimation of this threshold parameter remains the most challenging issue for the existing shot boundary detection algo- rithms. We introduce a novel method for shot boundary detection of discrete cosine transform (DCT)-based and low-bit-rate encoded clips, which exploits the perceptual blockiness effect detection on each frame without using any threshold parameter, therefore mini- mizing the processing demands required for algorithm

Quantifying TV white space capacity: quantifying tv white space capacity:

The so-called TV white spaces (TVWS) are locally underutilized portions of the terrestrial TV bands and occur as a by-product of the digital switchover taking place in most countries across the globe. Thanks to the very good characteristics of the TV bands in terrestrial radio communications, the exploitation of TVWS for local- or regional-area wireless license-exempt networking, under a carefully established regulatory framework, is a very attractive prospect. This article presents a generic methodology for determining the actual capacity of white spaces using a geolocation-based approach, that is, dynamic assignment of radio resources to TVWS networks according to their geographical location. This methodology is applied in a case study investigating a sample area in southeastern Europe and unveils a significant amount of access capacity that can be unleashed via TVWS exploitation.

Scalable Media Coding Enabling Content-Aware Networking

Increasingly popular multimedia services are expected to play a dominant role in the future of the Internet. In this context, it is essential that content-aware networking (CAN) architectures explicitly address the efficient delivery and processing of multimedia content. This article proposes the adoption of a content-aware approach into the network infrastructure, thus making it capable of identifying, processing, and manipulating media streams and objects in real time to maximize quality of service (QoS) and experience (QoE). Our proposal is built on the exploitation of scalable media coding technologies within such a content-aware networking environment. This discussion is based on four representative use cases for media delivery (unicast, multicast, peer-to-peer, and adaptive HTTP streaming) and reviews CAN challenges, specifically flow processing, caching/buffering, and QoS/QoE management.

Unidirectional lightweight encapsulation: performance evaluation and application perspectives

Multi Protocol Encapsulation (MPE) is today the dominant method for encapsulating IP data into the MPEG-2 Transport Stream so they can be conveyed over digital television platforms (DVB or ATSC). Unidirectional Lightweight Encapsulation (ULE) is a new alternative to MPE, providing simplicity, efficiency and configurability. This paper presents the principle and benefits of ULE, approaches the issues associated with its adoption and compares it against MPE through extensive performance measurements in a fully functional testbed under IPv4 and IPv6 load. It also proposes, implements and demonstrates the combination of MPEG-4/H.264, IPv6 and ULE as the most efficient and flexible protocol stack for next-generation transmission of digital video over Digital Television networks

Joint assessment of Network- and Perceived-QoS in video delivery networks

Given the increasing number of IP streaming video customers, service providers are seeking an efficient way to monitor in real time the offered quality of service, as perceived by each end user. Since real-time video quality assessment via image processing algorithms is quite bandwidth- and processing-power-demanding, a feasible alternative could be to monitor the Network-level Quality of Service (NQoS) and associate it with the Perceived QoS (PQoS). This article presents a network-agnostic framework for the joint assessment of N- and P-QoS, with the aim of correlating these two parameters for a specific network and service configuration. This framework/architecture is implemented with open source software tools and is being demonstrated in an actual WiMAX streaming video distribution platform.

Using DVB-S2 adaptive coding and modulation for the provision of satellite triple play services

The outstanding spectrum efficiency of DVBS2 along with its adaptability and configurability makes it a very promising technology for next-generation satellite communications. This article discusses the application of the adaptive coding and modulation feature of DVB-S2 in the provision of satellite triple play services over an interactive DVB-S2/DVB-RCS network in order to compensate for fluctuations in propagation conditions. A cross-layer resource management system is proposed in order to adapt the system to such fluctuations and improve its overall efficiency. Based on area-specific attenuation models, an efficiency study is presented, showing considerable capacity gains over static transmission schemes (DVB-S and DVB-S2 CCM).

Survey of cross-layer proposals for video streaming over Mobile Ad hoc Networks (MANETs)

Efforts to realize video streaming over Mobile Ad hoc Networks (MANETs) meet many challenges, which are addressed by different techniques. In the highly dynamic and unpredictable environment of MANETs, cross-layer mechanisms seem to be the most suitable for optimising video streaming. This paper presents a survey of 44 studied papers on the area, comparing tools, parameters and metrics used for their evaluation. It also indicatively describes in more detail some of these proposals.

Cross-layer monitoring in IPTV networks

In a time when media content, including user-generated, is flooding the Internet, and WebTV services are becoming more and more attractive and competitive, “fenced wall” IPTV operators need to come up with clear benefits, focusing on high content quality and guaranteed QoS/QoE. Quality guarantees can be achieved only via an end-to-end network and service management architecture, supported by an efficient monitoring system. This article discusses cross-layer IPTV service and network monitoring approaches, presenting overall aims and challenges, metrics to be monitored, and measurement strategies according to point of observation (in-network or client-side monitoring). Finally, it presents the monitoring system developed within the ALICANTE research project as an example of a complete end-to-end cross-layer monitoring framework for media services.

Satellite Media Broadcasting with Adaptive Coding and Modulation

Adaptive Coding and Modulation (ACM) is a feature incorporated into the DVB-S2 satellite specification, allowing real-time adaptation of transmission parameters according to the link conditions. Although ACM was originally designed for optimizing unicast services, this article discusses the expansion of its usage to broadcasting streams as well. For this purpose, a general cross-layer adaptation approach is proposed, along with its realization into a fully functional experimental network, and test results are presented. Finally, two case studies are analysed, assessing the gain derived by ACM in a real large-scale deployment, involving HD services provision to two different geographical areas.

Broadband multimedia on the move with DVB-H

DVB-H is the newly standardized extension to DVB-T, aiming at the provision of IP datacasting (IPDC) services to mobile terminals. This tutorial paper outlines the structure of an interactive DVB-H platform and presents in brief the technical advances of the new specification. It also discusses some interesting scenarios of interactive and non-interactive services which can be directly deployed with the use of the DVB-H technology either as a stand-alone broadcast network or as a complement to existing cellular (2G/3G/WLAN) infrastructures.