Abstract: This paper addresses the efficient adaptation of encrypted scalable video content (H.264/SVC). RTP-based in-network adaptation schemes on a media aware network element (MANE) in an IPTV and VoD scenario are considered. Two basic alternatives to implement encryption and adaptation of H.264/SVC content are investigated: (i) full, format-independent encryption making use of Secure RTP (SRTP); (ii) SVC-specific encryption that leaves the metadata relevant for adaptation (NAL unit headers) unencrypted. The SRTP-based scheme (i) is straightforward to deploy, but requires the MANE to be in the security context of the delivery, i.e., to be a trusted node. For adaptation, the content needs to be decrypted, scaled, and re-encrypted. The SVC-specific approach (ii) enables both full and selective encryption, e.g., of the base layer only. SVC-specific encryption is based on own previous work, which is substantially extended and detailed in this paper. The adaptation MANE can now be an untrusted node; adaptation becomes a low-complexity process, avoiding full decryption and re-encryption of the content. This paper presents the first experimental comparison of these two approaches and evaluates whether multimedia-specific encryption can lead to performance and application benefits. Potential security threats and security properties of the two approaches in the IPTV and VoD scenario are elementarily analyzed. In terms of runtime performance on the MANE our SVC-specific encryption scheme significantly outperforms the SRTP-based approach. SVC-specific encryption is also superior in terms of induced end-to-end delays. The performance can even be improved by selective application of the SVC-specific encryption scheme. The results indicate that efficient adaptation of SVC-encrypted content on low-end, untrusted network devices is feasible.

Abstract: In this paper, an interoperable framework for the delivery of scalable media resources, e.g., in the standardized Scalable Video Coding (SVC) format, is presented. The framework provides support for Video on Demand (VoD) as well as multicast streaming and performs an efficient, generic, and interoperable adaptation of the streamed content based on MPEG-21 Digital Item Adaptation (DIA). The server as well as the clients of the streaming framework implement the MPEG Extensible Middleware (MXM) and utilize the MPEG Query Format (MPQF) for querying the available media resources. The framework has been fully integrated into the VLC media player. The architecture for both, VoD and multicast is presented in detail. Finally, a comparison in terms of performance of the generic MPEG-21 metadata-based adaptation approach to an SVC-specific adaptation approach is provided.

Abstract: The streaming of multimedia content over Peer-to-Peer (P2P) networks is nowadays a well appreciated concept, as it helps distributing content to a great number of users and additionally reduces the server costs for providing the content. As the users of P2P networks often have different bandwidth connections and terminals, the same content is usually provided in different qualities. Although such a provision of the same content in different qualities helps to satisfy all users, it makes the sharing process less efficient. Users that are interested in the content in a specific quality can only exchange pieces with those users that are interested in the same content and the same quality. Thus, layered video coding, which provides different qualities within one bitstream, is especially well suited for P2P distribution. If the layered content is provided once in the best quality, all peers interested in this content can at least exchange the base layer, plus the enhancement layers they are interested in with those peers that have them available.

Abstract: In this thesis I give an overview of current research done in the fields of video abstraction, video browsing and interactive video retrieval. In these research fields, which are summarized under the term video exploration, new concepts and solutions are developed that should help the users to get more control over video content again. Furthermore, I am going to introduce "FVET", the Flexible Video Exploration Toolkit. This is a platform that has been developed in the scope of this thesis, to be able to experiment with different approaches of video exploration. As it can be extend with plug-ins, it is very flexible regarding future developments. For this purpose an own plug-in architecture has been implemented that addresses especially the needs of video exploration applications.

Abstract: This paper presents an image retrieval suite called img(Rummager) which brings into effect a number of new as well as state of the art descriptors. The application can execute an image search based on a query image, either from XML-based index files, or directly from a folder containing image files, extracting the comparison features in real time. In addition the img(Rummager) application can execute a hybrid search of images from the application server, combining keyword information and visual similarity. Also img(Rummager) supports easy retrieval evaluation based on the normalized modified retrieval rank (NMRR) and average precision (AP).

Abstract: Compact Composite Descriptors (CCD) are global image features capturing both, color and texture characteristics, at the same time in a very compact representation. In this paper we propose a combination of two recently introduced CCDs (CEDD and FCTH) into a Joint Composite Descriptor (JCD). We further present a method for descriptor selection to approach the best ANMRR that would result from CEDD and FCTH. With our approach the most appropriate descriptor in terms of maximization of information content can be found on a per image basis without knowledge of the data set as a whole. Experiments conducted on three known benchmarking image databases demonstrate the effectiveness of the proposed technique.

Abstract: One possibility to provide mobile multimedia in domestic multimedia systems is the use of Universal Plug and Play Audio Visual (UPnP-AV) devices. In a standard UPnP-AV scenario, multimedia content provided by a Media Server device is streamed to Media Renderer devices by the initiation of a Control Point. However, there is no provisioning of context-aware multimedia content customization. This paper presents an enhancement of standard UPnP-AV services for home multimedia environments regarding context awareness. It comes up with context profile definitions, shows how this context information can be queried from the Media Renderers, and illustrates how a Control Point can use this information to tailor a media stream from the Media Server to one or more Media Renderers. Moreover, since a standard Control Point implementation only queries one Media Server at a time, there is no global view on the content of all Media Servers in the UPnP-AV network. This paper also presents an approach of multimedia content integration on the Media Server side that provides fast search for content on the network. Finally, a number of performance measurements show the overhead costs of our enhancements to UPnP-AV in order to achieve the benefits.

Abstract: End-to-end support for Quality of Service (QoS) has been broadly discussed in the literature. Many technologies have been proposed, each focusing on specific aspects for providing QoS guarantees to the end user. However, the integrated management of the end-to-end chain preserving QoS in heterogeneous environments is still a significant issue and insufficiently addressed to date. In this paper we propose an integrated management supervisor that takes into account the requirements from all stakeholders along the multimedia content delivery chain and provides an end-to-end management solution enabling QoS to the end user. This architecture and the subsystems that can be distributed along the end-to-end chain are detailed in this paper.

Abstract: The MPEG-21 standard forms a comprehensive multimedia framework covering the entire multimedia distribution chain. In particular, it provides a flexible approach to represent, process, and transact complex multimedia objects which are referred to as Digital Items (DIs). DIs can be quite generic, independent of the application domain, and can encompass a diversity of media resources and metadata. This flexibility has an impact on the level of interoperability between systems and applications, since not all the functionality needs to be implemented. Furthermore, additional semantic rules may be implemented through the processing of the Digital Item which is possibly driven by proprietary metadata. This jeopardizes interoperability and consequently raises barriers to the successful achievement of augmented and transparent use of multimedia resources. In this context, we have investigated and evaluated the interoperability at the semantic level of Digital Items throughout the automated production, delivery and consumption of complex multimedia resources in heterogeneous environments. This paper describes the studies conducted, the experiments performed, and the conclusions reached towards that goal.

Abstract: Multimedia adaptation decision-taking is referred to as the process of finding the optimal parameter settings for (multiple, possibly in series connected) multimedia content adaptation engines given the properties, characteristics, and capabilities of the content and the context in which it will be processed.

Abstract: We plan to setup a VoD service built on an innovative multimedia server architecture which enables dynamic adaptation to the changing circumstances. The adaptation happens by replicating the server components and the stored videos based on real-time host and network monitoring and resource constraint analysis. In addition, the terminal capabilities and client preferences are considered. The paper focuses on the challenge of the optimal placement of storage components and the videos in the network. We compare three implemented optimisation algorithms (so called simple, incremental and complex incremental); the latter one can be calibrated against different preferences. We examine the effect of changing weights of the algorithm onto the recommendation.

Abstract: On the web, search engines represent a primary instrument through which users exercise their intent. Understanding the specific goals users express in search queries could improve our theoretical knowledge about strategies for search goal formulation and search behavior, and could equip search engine providers with better descriptions of users’ information needs. However, the degree to which goals are explicitly expressed in search queries can be suspected to exhibit considerable variety, which poses a series of challenges for researchers and search engine providers. This paper introduces a novel perspective on analyzing user goals in search query logs by proposing to study different degrees of intentional explicitness. To explore the implications of this perspective, we studied two different degrees of explicitness of user goals in the AOL search query log containing more than 20 million queries. Our results suggest that different degrees of intentional explicitness represent an orthogonal dimension to existing search query categories and that understanding these different degrees is essential for effective search. The overall contribution of this paper is the elaboration of a set of theoretical arguments and empirical evidence that makes a strong case for further studies of different degrees of intentional explicitness in search query logs.

Abstract: On the web, search engines represent a primary instrument through which users exercise their intent. Understanding the specific goals users express in search queries could improve our theoretical knowledge about strategies for search goal formulation and search behavior, and could equip search engine providers with better descriptions of users’ information needs. However, the degree to which goals are explicitly expressed in search queries can be suspected to exhibit considerable variety, which poses a series of challenges for researchers and search engine providers. This paper introduces a novel perspective on analyzing user goals in search query logs by proposing to study different degrees of intentional explicitness. To explore the implications of this perspective, we studied two different degrees of explicitness of user goals in the AOL search query log containing more than 20 million queries. Our results suggest that different degrees of intentional explicitness represent an orthogonal dimension to existing search query categories and that understanding these different degrees is essential for effective search. The overall contribution of this paper is the elaboration of a set of theoretical arguments and empirical evidence that makes a strong case for further studies of different degrees of intentional explicitness in search query logs.

Abstract: One of the future visions of multimedia networking is the provision of multimedia content at a variety of quality and price levels. Of the many approaches to this issue, one of the most predominant techniques is the concept of Perceived Quality of Service (PQoS), which extends the traditional engineering-based QoS concept to the perceptual satisfaction that the user receives from the reception of multimedia content. In this context, PQoS monitoring is becoming crucial to media service providers (SPs) for providing not only quantified PQoS-based services, but also service assurance based on multimedia content adaptation across heterogeneous networks. This work proposes a novel cross-layer monitoring architecture that utilizes a new Network QoS (NQoS) to PQoS mapping framework at the application level. The resulting QoS monitoring should allow the content delivery system to take sophisticated actions for real time media content adaptation, and aims to provide perceived service performance verification with respect to the QoS guarantees that have been specified in contractual agreements between providers and end-users. A subsequent performance evaluation of the proposed model conducted using a real test-bed environment demonstrates both the accuracy and feasibility of the network level measurements, the NQoS to PQoS mapping and the overall feasibility of the proposed end-to-end monitoring solution.

Abstract: We present a video content browsing tool which is supposed to be used for two purposes: (1) efficiently searching a certain scene within a long video sequence and (2) quickly identifying videos out of interest. Instead of a complex user interface with many features we rather use a simple but flexible player-like interface which can, however, support the user on taking advantage of his/her knowledge about the content semantics. The content analysis is based on some simple features which can be extracted from compressed data of H264/AVC and, thus, allow very fast analysis. An early user study has shown encouraging results.