H.264/AVC is a new specification for digital video coding that aims at a deployment in a lot of multimedia applications, such as video conferencing, digital television broadcasting, and internet streaming. This is for instance reflected by the design goals of the standard, which are about the provision of an efficient compression
scheme and a network-friendly representation of the compressed data. Those requirements have resulted in a very flexible syntax and architecture that is fundamentally different from previous standards for video compression. In this paper, a detailed discussion will be provided on how to apply an extended version of the MPEG-21 Bitstream Syntax Description Language (MPEG-21 BSDL) to the Annex B syntax of the H.264/AVC specification. This XML based language will facilitate the high-level manipulation of an H.264/AVC bitstream in
order to take into account the constraints and requirements of a particular usage environment. Our performance measurements and optimizations show that it is possible to make use of MPEG-21 BSDL in the context of the current H.264/AVC standard with a feasible computational complexity when exploiting temporal scalability.
Video coding is used under the hood of a lot of multimedia applications, such as video conferencing, digital storage media, television broadcasting, and internet streaming. Recently, new standards-based and proprietary technologies have emerged. An interesting problem is how to evaluate these different video coding solutions in terms of delivered quality.
In this paper, a PSNR-based approach is applied in order to compare the coding potential of H.264/AVC AHM 2.0 with the compression efficiency of XviD 0.9.1, DivX 5.05, Windows Media Video 9, and MC-EZBC. Our results show that MPEG-4-based tools, and in particular H.264/AVC, can keep step with proprietary solutions. The rate-distortion performance of MC-EZBC, a wavelet-based video codec, looks very promising too.
The increasing diversity of the characteristics of the terminals and networks that are used to access multimedia content through the internet introduces new challenges for the distribution of multimedia data. Scalable video coding will be one of the elementary solutions in this domain. This type of coding allows to adapt an encoded
video sequence to the limitations of the network or the receiving device by means of very basic operations. Algorithms for creating fully scalable video streams, in which multiple types of scalability are offered at the same time, are becoming mature. On the other hand, research on applications that use such bitstreams is only recently
emerging. In this paper, we introduce a mathematical model for describing such bitstreams. In addition, we show how we can model applications that use scalable bitstreams by means of definitions that are built on top of this model. In particular, we chose to describe a multicast protocol that is targeted at scalable bitstreams. This way, we will demonstrate that it is possible to define an abstract model for scalable bitstreams, that can be used as a tool for reasoning about such bitstreams and related applications.
While the price of mobile devices is dropping quickly, the set of features and capabilities of these devices is advancing very dramatically. Because of this, new mobile multimedia applications are conceivable, also thanks to the availability of high speed mobile networks like UMTS and Wireless LAN. However, creating such applications is still difficult due to the huge diversity of features and capabilities of mobile devices. Software developers also have to take into account the rigorous limitation on processing capabilities, display possibilities, and the limited battery life of these devices. On top of that, the availability of the device resources fluctuates strongly during execution of an application, directly and violently influencing the user experience, whereas equivalent fluctuations on traditional desktop PC's are far less prominent. Using new technology like MPEG-4, -7 and -21 can help application developers to overcome these problems. We have created an MPEG-21-based Video-on-Demand application optimized for mobile devices that is aware of the usage environment (i.e., user preference, device capabilities, device conditions, network status, etc.) of the client and adapts the MPEG-4 videos to it. The application is compliant with the Universal Multimedia Access framework, supports Time-Dependent Metadata, and relies on both MPEG-4 and MPEG-21 technology.
A comprehensive approach to the access of archival collections necessitates the interplay of various types of metadata standards. Each of these standards fulfills its own part within the context of a 'metadata infrastructure'. Besides this, it should be noted that present-day digital libraries are often limited to the management of mainly textual and image-based material. Archival Information Systems dealing with various media types are still very rare. There is a need for a methodology to deal with time-dependant media within an archival context. The aim of our research is to investigate and implement a number of tools supporting the content management multimedia data within digital collections. A flexible and extendible framework is proposed, based on the emerging Metadata Encoding and Transmission Standard (METS). Firstly, we will focus on the description of archival collections according to the archival mandates of provenance for the benefit of an art-historical research in an archive-theoretically correct manner. Secondly, we will examine the description tools that represent the semantics and structure of multimedia data. In this respect, an extension of the present archival metadata framework has been proposed to time-based media content delivered via standards such as the MPEG-7 multimedia content description standard.
The number of terminals that have access to multimedia content by means of a network is rapidly increasing. More and more, the characteristics of different terminals are increasing in variety. In addition, their users can have different preferences. Therefore, the adaptation of multimedia content to a specific terminal and/or its user has become an important research issue. Such an adaptation is mainly based on two aspects: the description of the multimedia content and the description of the user environment. Both can be considered as metadata, and can be formatted in an XML language (e.g., MPEG-7 and CC/PP). However, it is not yet clear how we can realize a generic mapping mechanism between two such vocabularies. We feel that such a mechanism is necessary to accomplish a mature content adaptation framework. This paper describes how such a mechanism can be achieved. We attach requirements and preferences of the user environment to specific aspects of the description of multimedia content. Based on this information, we try to maximize the value of the adapted content, while making it appropriate for the terminal. We also take into account the extensibility of the existing vocabularies we focus on, because this means our mechanism will also be extensible.
The current explosive expansion of mobile communication systems will lead to an increased demand for multimedia applications. However, due to the large variety of mobile terminals (such as mobile phones, laptops .) and, because of this, a wide collection of different terminal possibilities and terminal characteristics, it is difficult to create a mobile multimedia application which can be used on mobile devices of different types. In this paper, we propose a mobile multimedia application that adapts its content to the possibilities of the mobile terminal and to the end-user preferences. Also the application takes changing device characteristics into account. To make this possible, a software framework is set up to enable negotiation between the mobile terminal and the content server. During the initial negotiation, the concept of the Universal Multimedia Access framework is used. Subsequent negotiations take place after changing terminal characteristics or end-user preferences, and this by means of time-dependent metadata. This newly created flexible and extendable framework makes it possible that multimedia applications interact with the content provider in order to deliver an optimal multimedia presentation for any arbitrary mobile terminal at any given time.