Three low complexity algorithms that allow spatial scalability in the context of video coding are presented in this paper. We discussed the feasibility of reusing motion and residual texture information of the base layer in the enhancement layer. The prediction errors that arise from the discussed filters and schemes are evaluated in terms of the Mean of Absolute Differences. For the interpolation of the decoded pictures from the base layer, the presented 6-tap and bicubic filters perform significantly better than the bilinear and nearest neighbor filters. In contrast, when reusing the motion vector field and the error pictures of the base layer, the bilinear filter performs best for the interpolation of residual texture information. In general, reusing the motion vector field and the error pictures of the base layer gives the lowest prediction errors. However, our tests showed that for some sequences that have regions with complex motion activity, interpolating the decoded picture of the base layer gives best result. This means that an encoder should compare all possible prediction schemes combined with all interpolation filters in order to achieve optimal prediction. Obviously this would not be possible for real-time content creation.
KEYWORDS: Scalable video coding, Receivers, Multimedia, Video, Signal to noise ratio, Internet, Video coding, Mathematical modeling, Data modeling, Surface plasmons
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.
KEYWORDS: Principal component analysis, Video, Video coding, Computer programming, Binary data, Statistical analysis, Data analysis, Chemical species, Profiling, Quantization
H.264/AVC is a video codec developed by the Joint Video Team (JVT); a cooperation between the ITU-T VCEG (Video Coding Experts Group) and ISO/IEC MPEG (Moving Picture Experts Group). This new video coding standard has some new features that allow to get significant improvements in coding efficiency. This improved coding efficiency leads to an overall more complex algorithm which has high demands regarding memory usage and processing power. Complexity, however, is an abstract concept and cannot be measured in a simple manner.
In this paper we present a method to obtain an accurate and more in-depth view on the internals of the JVT/AVC decoder. By decoding several bit streams having different encoding parameters, various program characteristics were measured. On these measurements, principal components analysis was performed to get a different view on these measurements. Our results show that the various encoding parameters have a clear impact on the low level behavior of the decoder. Moreover, our methodology allows us to give an explanation for the observed dissimilarities.
KEYWORDS: Video, Multimedia, Standards development, Mobile devices, Software development, Video coding, Web services, Network architectures, Local area networks
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.
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.
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 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.
Among some of the most popular multimedia formats available today
are: QuickTime, Shockwave, Advanced Streaming Format, RealVideo and {MPEG-4}. Since broadband Internet became widely available, these multimedia formats have strongly evolved and are extremely popular. This article analyzes these formats based on an existing reference model. This reference model is built on the state-of-the-art in three areas: temporal models, computer based descriptions and synchronization mechanisms. Out of these three areas a set of 10 criteria describing the reference model was created. In this paper we first shortly explain the reference model and it's ten criteria. Then each of the listed multimedia formats is mapped onto the reference model. Finally, a comparison based on the reference model is given. In the conclusions section we point out some of the strong and some of the weak points for the different multimedia formats based on the comparison.
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