Pedro Debevere

Multimedia information seeking through search and hyperlinking

Searching for relevant webpages and following hyperlinks to related content is a widely accepted and effective approach to information seeking on the textual web. Existing work on multimedia information retrieval has focused on search for individual relevant items or on content linking without specific attention to search results. We describe our research exploring integrated multimodal search and hyperlinking for multimedia data. Our investigation is based on the MediaEval 2012 Search and Hyperlinking task. This includes a known-item search task using the Blip10000 internet video collection, where automatically created hyperlinks link each relevant item to related items within the collection. The search test queries and link assessment for this task was generated using the Amazon Mechanical Turk crowdsourcing platform. Our investigation examines a range of alternative methods which seek to address the challenges of search and hyperlinking using multimodal approaches. The results of our experiments are used to propose a research agenda for developing effective techniques for search and hyperlinking of multimedia content.

Semantic patient information aggregation and medicinal decision support

Although the health care sector has already been subjected to a major computerization effort, this effort is often limited to the implementation of standalone systems which do not communicate with each other. Interoperability problems limit health care applications from achieving their full potential. In this paper, we propose the use of Semantic Web technologies to solve interoperability problems between data providers. Through the development of unifying health care ontologies, data from multiple health care providers can be aggregated, which can then be used as input for a decision support system. This way, more data is taken into account than a single health care provider possesses in his local setting. The feasibility of our approach is demonstrated by the creation of an end-to-end proof of concept, focusing on Belgian health care providers and medicinal decision support.

Real-time error concealing bitstream adaptation methods for SVC in IPTV systems

The current heterogeneity in networks and devices demands for a high degree of flexibility in IPTV systems for digital television. A scalable video coding scheme (in this paper we focus on H.264/AVC’s scalable video coding extension SVC) accommodates this flexibility from the coding point of view. Because the IP-based network delivery chain in IPTV systems may suffer from packet loss (having a severe impact on the visual quality) it is necessary to provide means for error concealment. In this paper we propose a novel method that performs adaptation on impaired SVC bitstreams so that the resulting adapted bitstream is compliant to the SVC specification and that the reconstruction result at the decoder is equivalent compared to the approach where the error concealment is implemented in the decoder itself. The adapted bitstreams have a significantly higher visual quality while our approach does not require any modification to existing SVC-compliant decoders. The results of several experiments show that the proposed method is extremely fast (over 900 frames/s) and that it introduces a negligible overhead in terms of bit rate (ca. 0.02%).

Enabling semantic search in a news production environment

News production is characterized by a complex and dynamic workflow, in which it is important to produce and broadcast reliable news as fast as possible. In this process, the efficient retrieval of previously broadcasted news items is important, both for gathering background information and for reuse of footage in new reports. This paper discusses how the quality of descriptive metadata of news items can be optimized, by collecting data generated during news production. Starting from a description of the news production process of the Flemish public service broadcaster in Belgium (VRT), information systems containing valuable metadata are identified. Subsequently, we present a data model that uniformly represents the available information generated during news production. This data model is then implemented using Semantic Web technologies. Further, we describe how other valuable data sets, present in the SemanticWeb, are connected to the data model, enabling semantic search operations.

Format-Independent Media Delivery, Applied to RTP, MP4, and Ogg

The current multimedia landscape is characterized by a significant heterogeneity in terms of coding and delivery formats, usage environments, and user preferences. This paper introduces a transparent multimedia content adaptation and delivery approach, i.e., model-driven content adaptation and delivery. It is based on a model that takes into account the structural metadata, semantic metadata, and scalability information of media bitstreams. Further, a format-independent multimedia packaging method is proposed based on this model for media bitstreams and MPEG-B BSDL. Thus, multimedia packaging is obtained by encapsulating the selected and adapted structural metadata within a specific delivery format. This packaging process is implemented using XML transformation filters and MPEG-B BSDL. To illustrate this format-independent packaging technique, we apply it to three packaging formats: RTP, MP4, and Ogg.

Next generation assisting clinical applications by using semantic-aware electronic health records

The health care sector is no longer imaginable without electronic health records. However, since the original idea of electronic health records was focused on data storage and not on data processing, a lot of current implementations do not take full advantage of the opportunities provided by computerization. This paper introduces the Patient Summary Ontology for the representation of electronic health records and demonstrates the possibility to create next generation assisting clinical applications based on these semantic-aware electronic health records. Also, an architecture to interoperate with electronic health records formatted using other standards is presented.

On the performance of scalable video coding for VBR TV channels transport in multiple resolutions and qualities

Video broadcast operators target a variety of receiving devices of different resolutions and processing capabilities. In such a heterogeneous TV network, the transport resource consumption is likely to increase. In this paper we estimate the required transport capacity for a broadcast TV network taking into account parameters as currently proposed in standardization bodies. We target constant video quality, hence the TV channel has variable bit rate (VBR). We consider a multicast-based transport system where only the required versions of a TV channel are transported; this leads to fluctuation of the consumed transport capacity over time. The main focus in this paper is on the comparison of a simulcast and a scalable video coding (SVC) transport scheme in several realistic examples with different encoding modes, including spatial and/or quality scalability. To estimate the required transport capacity for simulcast and SVC, we use a comprehensive toolkit based on a Gaussian approximation of the capacity demand. In order to obtain realistic input values for our calculation tools, we characterize the fluctuations of the bit rate associated with a TV channel by encoding a representative set of video clips. Based on the considered realistic examples, we explore under what conditions either the simulcast or the SVC transport scheme is more efficient.

Optimizing IPTV video delivery using SVC spatial scalability

This paper focuses on two typical constraints present in current video delivery platforms such as IPTV: accommodating the diversity of consumer end-devices and coping with various bandwidth constraints of the deployed network access technologies. We propose the use of the Scalable Video Coding (SVC) extension of H.264/AVC to cope with these two constraints: three different techniques to combine SD and HD versions of a video sequence in one SVC stream are presented and we assess how quality scalability compares to spatial scalability in producing video streams that can be tailored to various bandwidth constraints. The results show that the three proposed techniques for combining SD and HD perform equally good and that, under certain conditions, spatial scalability outperforms quality scalability to cope with various bandwidth constraints.