Abstract: This paper presents a cross-layer model—formulated using interoperable description formats—for the adaptation of scalable H.264/MPEG-4 AVC (i.e., SVC) content in a video streaming system operating on aWireless LANaccess network without QoS mechanisms.SVCcontent adaptation on the server takes place on the application layer using an adaptation process compliant with the MPEG-21 Digital Item Adaptation (DIA) standard, based on input comprised of MPEG-21 DIA descriptions of content and usage environment parameters. The latter descriptions integrate information from different layers, e.g., device characteristics and packet loss rate, in an attempt to increase the interoperability of this cross-layer model, thus making it applicable to other models. For the sake of deriving model parameters, performance measurements from two wireless access point models were taken in account. Throughout the investigation it emerged that the behavior of the system strongly depends on the access point. Therefore, we investigated the use of end-to-end-based rate control algorithms for steering the content adaptation. Simulations of rate adaptation algorithms were subsequently performed, leading to the conclusion that a TFRC-based adaptation technique (TCP-Friendly Rate Control) performs quite well in adapting to limited bandwidth and varying network conditions. In the paper we demonstrate howTFRC-based content adaptation can be realized using MPEG-21 tools.

Abstract: Recent advances in video coding technology like the scalable extension of the MPEG-4 AVC/H.264 video coding standard pave the way for computationally cheap adaptation of video content. In this paper we present our work on a lightweight RTSP/RTP proxy that enables in-network stream processing. Based on an off-the-shelf wireless router that runs a Linux-based firmware we demonstrate that the video adaptation can be performed on-the-fly directly on a network device. The paper covers design and implementation details of the proxy as well as a discussion about the actual adaptation of the SVC stream. Based on experimental evaluations we show that our approach can handle a reasonable number of concurrent sessions for a typical home deployment scenario. Furthermore, the paper covers possible applications in which adaptation on the network device can be beneficial.

Abstract: The multimedia community is pursuing, among others, the vision of Universal Multimedia Access (UMA). UMA denotes the concept that any multimedia content should be available anywhere, anytime, on any device, tailored to the user's needs and preferences, accessible for the user in a transparent and convenient way. Key to achieving this vision is to realize collaborative adaptive behavior of the involved distributed multi-media system components (server, media-aware net-work elements like proxies or gateways, and clients), based on intense metadata exchange and multimedia content negotiation, adaptation, or personalization. This paper outlines the key challenges and the state of the art in achieving such adaptive behavior. The major challenges have been tackled recently and many of the building blocks of UMA have become or are becoming available from standardization groups, which are instrumental in this area to ensure interop-erable use of the media and metadata items. However, making use of these standards in practical multimedia systems raises additional issues, both of conceptual nature and in terms of implementation. Based on years of contributions to ISO/IEC MPEG standardization efforts and of research work into adaptive multimedia systems, we will give an overview of these challenges, discuss the state of the art, and introduce an emerging principled solution for format-independent multimedia content adaptation.

Abstract: In this paper, an interoperable streaming framework for the adaptation and streaming of scalable multimedia content is presented. The streaming framework’s architecture for Video on Demand (VoD) as well as multicast streaming is presented. The VoD test-bed allows each client to set up a separate streaming session and receive the bitstreams in a quality tailored to the clients requirements, while the multicast test-bed provides a layered scalable multicast to all clients and every client needs to decide which layers to subscribe to. After the description of the architectures, a comparison in terms of performance of the MPEG-21 DIA metadata-based adaptation approach to an SVC-specific adaptation approach is presented. Furthermore, optimizations for both adaptation approaches are presented and the performance improvements due to the optimizations are discussed.

Abstract: This paper presents an interoperable framework for the streaming of scalable multimedia content such as Scalable Video Coding (SVC). In particular, the framework’s architecture for both, Video on Demand (VoD) and multicast streaming, is presented. The architecture includes a detailed description of the adaptation engine – conforming to MPEG-21 Digital Item Adaptation – as well as the integration of the adaptation engine into VideoLAN’s VLC media player, which provides the streaming server and client for the framework. Following the description of the architecture, a comparison in terms of performance of the generic MPEG-21 DIA-based adaptation approach, which is utilized by the described demo, versus an SVC-specific adaptation approach is presented and possible further improvements for both approaches are investigated.

Abstract: In this paper we present an interoperable multimedia delivery framework for scalable video coding based on MPEG-21 Digital Item Adaptation (DIA). In can be used to transmit scalable video contents within heterogeneous usage environments where the properties of the usage environment (e.g., terminal/network capabilities) may change dynamically during the streaming session. The usage environment is signaled by interoperable description formats provided by the DIA standard. Additionally, the adaptation itself is done by exploiting the standard's generic adaptation approach, i.e., independent of the actual coding format. Thus, the overall framework is also applicable for other scalable coding formats.

Abstract: This paper provides a performance analysis of adaptation approaches designed for scalable media resources. In particular, we investigate the streaming of media resources compliant to the Scalable Video Coding (SVC) extensions of Advanced Video Coding (AVC)within heterogeneous environments, i.e., terminals and networks with different capabilities. Therefore, we have developed a test-bed in order to analyze two different approaches for the adaptation of scalable media resources, namely a generic approach that is applicable independently of the actual scalable coding format used and a specific approach especially built for SVC.The results show that if adaptation is required the generic approach clearly outperforms the approach specifically built for SVC

Abstract: Current trends in smart homes suggest that several multimedia services will soon converge towards common standards and platforms. However this rapid evolution gives rise to several issues related to the management of a large number of multimedia streams in the home communication infrastructure. An issue of particular relevance is how a context acquisition system can be used to support the management of such a large number of streams with respect to the Quality of Service (QoS), to their adaptation to the available bandwidth or to the capacity of the involved devices, and to their migration and adaptation driven by the users' needs that are implicitly or explicitly notified to the system. Under this scenario this paper describes the experience of the INTERMEDIA project in the exploitation of context information to support QoS, migration, and adaptation of multimedia streams.

Abstract: Due to the increasing heterogeneity in the current multimedia landscape, the delivery of multimedia content has become an important issue today. This heterogeneity is not only reflected by a plethora of different usage environments, but also by the presence of multiple (scalable) coding formats. Therefore, format-independent adaptation engines have to be used within a multimedia delivery platform, which are able to adapt the multimedia content according to a certain usage environment, independent of the underlying coding format of the content. By relying on automatically created textual descriptions of the highlevel syntax of binary media resources, a format-independent adaptation engine can be build. MPEG-21 generic Bitstream Syntax Schema (gBS Schema) is a tool that is part of the MPEG-21 Multimedia Framework. It enables the use of generic Bitstream Syntax Descriptions (gBSDs), i.e., textual descriptions in XML, to steer the adaptation of a binary media resource, using format-independent adaptation logic. In this paper, we address the design and performance evaluation of a multimedia delivery platform that relies on gBS Schema-driven adaptation engines. This platform is called MuMiVA; it is a fully integrated, extensible platform for multimedia delivery in heterogeneous usage environments, using streaming technologies. To demonstrate the flexibility of our multimedia delivery platform, we discuss the functioning of two different applications (i.e., exploitation of temporal scalability and shot selection) applied to two different coding formats (i.e., MPEG-4 Visual and H.264/AVC). Keywords— Content adaptation, Content delivery, MPEG-21 gBS Schema, XML transformations.

Abstract: MPEG-21 Digital Item Adaptation (DIA) allows for a media codec agnostic multimedia adaptation approach which enables the implementation of generic adaptation engines. However, DIA is optimized for static, server-based adaptation. In this paper we introduce novel mechanisms to extend the DIA approach towards dynamic and distributed scenarios. This facilitates the placement of generic adaptation nodes which perform media codec agnostic and dynamic adaptation anywhere along the content delivery path. To validate our work we implemented such an adaptation node and evaluate its performance.

Abstract: Today’s increasing variety of media data results in a great diversity of XMLbased metadata, which describes the media data on semantic or syntactic levels, in order to make it more accessible to the user. This metadata can be of considerable size, which leads to problems in streaming scenarios. Other than media data, XML metadata has no concept of “samples”, thus inhibiting streamed (and timed) processing, which is natural for media data. In order to address the challenges and requirements resulting from this situation, the concept of streaming instructions is introduced. In particular, streaming instructions address the problem of fragmenting metadata, associating media segments and metadata fragments, and streaming and processing them in a synchronized manner. This is achieved by enriching the metadata with additional attributes to describe media and XML properties. Alternatively, a style sheet approach provides the opportunity to dynamically set such streaming properties without actually modifying the XML description.

Abstract: Enabling transparent and augmented use of multimedia content across a wide range of networks and devices is still a challenging task within the multimedia research community. Within multimedia frameworks, content adaptation is the core concept to overcome this issue. Most media adaptation engines targeting Universal Multimedia Access (UMA) scale the content w.r.t. terminal capabilities and network resource constraints and do not sufficiently consider user preferences. This paper focuses on a hybrid recommender technique for configuring a cross-modal utility model that guides adaptation of multimedia content. This approach additionally considers the user environment as well as demographic user data which leads to a personalized and increased multimedia experience. Based on a related adaptation decision technique we show how it is possible to offer a personalized adaptation for the individual user. We present a detailed evaluation of the approach based on results earned by subjective tests.

Abstract: Content adaptation is an important issue of multimedia frameworks in order to achieve universal multimedia access (UMA), i.e., to enable consumption of multimedia content independently of the given resource limitations, terminal capabilities, and user preferences. The digital item adaptation (DIA) standard, one of the core specifications of the MPEG-21 framework, supports content adaptation considering a wide range of networks, devices, and user preferences. Most adaptive multimedia frameworks targeting the UMA vision do not consider utility aspects in their adaptation decisions. This paper focuses on a generic semantic-based audio–visual utility model for DIA that aims to enhance the multimedia experience for the user. Our proposed model is able to take the semantics and the perceptual features of the content as well as the users' specific utility aspects into account. Based on a detailed analysis of these constraints, we will show how the model reacts on individual input data. For choosing the best adaptation decision considering resource limitations on client and server sides as well as network characteristics, we evaluate four algorithms for performing this adaptation decision taking task. We will discuss results according to some use case scenarios.

Abstract: Providing transparent and augmented use of multimedia content across a wide range of networks and devices is still a challenging task within the multimedia research community. Multimedia adaptation was figured out as a core concept to overcome this issue. Most multimedia adaptation engines for providing Universal Multimedia Access (UMA) scale the content under consideration of terminal capabilities and resource constraints but do not really consider individual user preferences. This paper introduces an adaptive multimedia framework which offers the user a personalized content variation for satisfying his/her individual utility preferences.

Abstract: Currently, much research aims at coping with the shortcomings in multimedia consumption that may exist in a user's current context, e.g., due to the absence of appropriate devices at many locations, a lack of capabilities of mobile devices, restricted access to content, or non-personalized user interfaces. Recently, solutions to specific problems have been emerging, e.g., wireless access to multimedia repositories over standardized interfaces; however, due to usability restrictions the user has to spend much effort to or is even incapable of fulfilling his/her demands. The vision of user-centric multimedia places the user in the center of multimedia services to support his/her multimedia consumption intelligently, dealing with the aforementioned issues while minimizing required work. Essential features of such a vision are comprehensive context awareness, personalized user interfaces, and multimedia content adaptation. These aspects are addressed in this paper as major challenges toward a user-centric multimedia framework.

Abstract: This paper introduces aWeb-based guidance system which supports optimized presentations of sights or exhibited objects on different types of available stationary and mobile consumer devices, possibly running different operating systems. This is accomplished by adapting both the objects’ content, as well as their presentation to the current usage context. Content thereby may be encoded in different presentation formats like video, audio, image, and marked-up text. The usage context embraces a set of properties describing the current usage environment of the guide. This includes, for example, the consumer device’s capabilities, its current location, and the user’s preferences. Both, the content adaptation and presentation services are based on standardWeb technologies for increased interoperability. Finally, the guidance system is augmented with a Web-based content management and a statistics module, which enable for remote content administration and usage evaluations, respectively.

Abstract: The adaptation of multimedia resources is a common method to enable the transport and consumption of audio-visual content in constrained environments. An important aspect in this field is adaptation decision-taking, which aims to find adaptation parameters that maximize the quality for the consumer while considering the constraints of the networks and terminals involved. In this paper we focus on improving the adaptation of audio-visual content by maximizing the perceived quality. This can be realized by using a multimedia quality model and content-related metadata. We present an approach to derive this content-related metadata from subjective tests and use it for adaptation decision-taking within the MPEG-21 multimedia framework.

Abstract: The MPEG-21 standard defines a framework for the interoperable delivery and consumption of multimedia content. Within this framework the adaptation of content plays a vital role in order to support a variety of terminals and to overcome the limitations of the heterogeneous access networks. In most cases the multimedia content can be adapted by applying different adaptation operations that result in certain characteristics of the content. Therefore, an instance within the framework has to decide which adaptation operations have to be performed to achieve a satisfactory result. This process is known as adaptation decision-taking and makes extensive use of metadata describing the possible adaptation operations, the usage environment of the consumer, and constraints concerning the adaptation. Based on this metadata a mathematical optimization problem can be formulated and its solution yields the optimal parameters for the adaptation operations. However, the metadata is represented in XML resulting in a verbose and inefficient encoding. In this paper, an architecture for an Adaptation Decision-Taking Engine (ADTE) is introduced. The ADTE operates both on XML metadata and on metadata encoded with MPEG's Binary Format for Metadata (BiM) enabling an efficient metadata processing by separating the problem extraction from the actual optimization step. Furthermore, several optimization algorithms which are suitable for scalable multimedia formats are reviewed and extended where it was appropriate

Abstract: Universal Plug and Play (UPnP) is a widely accepted standard for automatically detecting devices and services in a local area network as well as for describing and controlling them. In order to deal with multimedia devices and especially content, in 2002 the UPnP-AV standard definition was released. It defines device and service descriptions for Media Servers and Renderers. Thereby, the Media Server’s Content Directory Service allows an easy management and the exchange of metadata about the provided media data. Media content became browsable by semantic meta information about it. There are still two major drawbacks of UPnP-AV, which make its usage in real world multimedia communication scenarios very difficult. First, searching for similar content on distributed Media Servers with a huge number of media files is not economically possible. Second, the media content must be consumed by Renderers as provided by the Servers, independently of their terminal capabilities and network connections. In order to deal with these two drawbacks, this work proposes a novel approach of metadata integration and media transcoding in UPnP networks. First, the Media Server is extended by a Control Point which offers discovery of other Media Servers and fetches metadata from their Content Directories. Furthermore, it integrates the gathered information in its own Content Directory. Control Points are then able to query this Integrating Media Server for a desired content, and get a network-complete search result. Second, terminal and network capabilities of the Render-ers are taken into account in order to transcode and transmit the content in a suitable way for the consuming device. These two approaches of metadata integration and media data adaptation enable searchable logical views on tailored multimedia content in UPnP-AV networks.

Abstract: An adaptive multimedia proxy is presented which provides (1) caching, (2) filtering, and (3) media gateway functionalities. The proxy can perform media adaptation on its own, either relying on layered coding or using transcoding mainly in the decompressed domain. A cost model is presented which incorporates user requirements, terminal capabilities, and video variations in one formula. Based on this model, the proxy acts as a general broker of different user requirements and of different video variations. This is a first step towards What You Need is What YouGet (WYNIWYG) video services, which deliver videos to users in exactly the quality they need and are willing to pay for. The MPEG-7 and MPEG-21 standards enable this in an interoperable way. A detailed evaluation based on a series of simulation runs is provided.

Abstract: Access devices of all shapes and forms that can connect to different networks and be used for a myriad of applications are becoming an integral part of our everyday lives. For better or worse, these devices keep us connect at all times to our families, friends, and the office. They allow us to share our experiences and emotions, conduct business, or just say hello. With multimedia, the form of communication is much more powerful. However, we face this serious problem of heterogeneity in our terminals, in our networks and in the people that ultimately consume and interact with the information being presented to them. This chapter describes work developed within the MPEG standardization committee to help alleviate some of the burdens confronting us in connecting a wide range of multimedia content with different terminals, networks and users. Specifically, Part 7 of MPEG-21, Digital Item Adaptation (DIA) [MP21-7], is covered in this chapter.