Christian Timmerer

Dynamic adaptive streaming over HTTP dataset

The delivery of audio-visual content over the Hypertext Transfer Protocol (HTTP) got lot of attention in recent years and with dynamic adaptive streaming over HTTP (DASH) a standard is now available. Many papers cover this topic and present their research results, but unfortunately all of them use their own private dataset which -- in most cases -- is not publicly available. Hence, it is difficult to compare, e.g., adaptation algorithms in an objective way due to the lack of a common dataset which shall be used as basis for such experiments. In this paper, we present our DASH dataset including our DASHEncoder, an open source DASH content generation tool. We also provide basic evaluations of the different segment lengths, the influence of HTTP server settings, and, in this context, we show some of the advantages as well as problems of shorter segment lengths.

Digital item adaptation: overview of standardization and research activities

MPEG-21 Digital Item Adaptation (DIA) has recently been finalized as part of the MPEG-21 Multimedia Framework. DIA specifies metadata for assisting the adaptation of Digital Items according to constraints on the storage, transmission and consumption, thereby enabling various types of quality of service management. This paper provides an overview of DIA, describes its use in multimedia applications, and reports on some of the ongoing activities in MPEG on extending DIA for use in rights governed environments.

Challenges of QoE management for cloud applications

Cloud computing is currently gaining enormous momentum due to a number of promised benefits: ease of use in terms of deployment, administration, and maintenance, along with high scalability and flexibility to create new services. However, as more personal and business applications migrate to the cloud, service quality will become an important differentiator between providers. In particular, quality of experience as perceived by users has the potential to become the guiding paradigm for managing quality in the cloud. In this article, we discuss technical challenges emerging from shifting services to the cloud, as well as how this shift impacts QoE and QoE management. Thereby, a particular focus is on multimedia cloud applications. Together with a novel QoE-based classification scheme of cloud applications, these challenges drive the research agenda on QoE management for cloud applications.

A VLC media player plugin enabling dynamic adaptive streaming over HTTP

This paper describes the implementation of a VLC media player plugin enabling Dynamic Adaptive Streaming over HTTP (DASH). DASH is an emerging ISO/IEC MPEG and 3GPP standard for HTTP streaming. It aims to standardize formats enabling segmented progressive download by exploiting existing Internet infrastructure as such. Our implementation of these formats as described in this paper is based on the well-known VLC. Hence, it is fully integrated into the VLC structure and has been also submitted to the VLC development team for consideration in future releases of VLC. Therefore, it is licensed under the GNU Lesser General Public License (LGPL). The plugin provides a very flexible structure that could be easily extended with respect to different adaptation logics or profiles of the DASH standard. As a consequence, the plugin enables the integration of a variety of adaptation logics and comparison thereof, making it attractive for the research community.

Bitstream syntax description: a tool for multimedia resource adaptation within MPEG-21

Abstract In this paper, a generic method is described to allow the adaptation of different multimedia resources by a single, media resource-agnostic processor. This method is based on an XML description of the media resources bitstream syntax, which can be transformed to reflect the desired adaptation and then be used to generate an adapted version of the bitstream. Based on this concept, two complementary technologies, BSDL 2 and gBS Schema, are presented. The two technologies provide solutions for parsing a bitstream to generate its XML description, for the generic structuring and marking of this description, and the generation of an adapted bitstream using its transformed description. The two technologies can be used as stand-alone tools; however, a joint approach has been developed in order to harmonise the two solutions and exploit their strengths. This paper is focusing on the gBS Schema and the joint BSDL/gBS Schema harmonised approach.

Bitstream syntax description-based adaptation in streaming and constrained environments

The seamless access to rich multimedia content on any device and over any network, usually known as Universal Multimedia Access, requires interoperable description tools and adaptation techniques to be developed. To address the latter issue, MPEG-21 Digital Item Adaptation (DIA) introduces the Bitstream Syntax Description (BSD) framework, which provides tools for adapting multimedia content in a generic (i.e., coding format independent) way. The basic idea is to use the eXtensible Markup Language (XML) to describe the high-level structure of a binary media bitstream, to transform its description [e.g., by means of eXtensible Stylesheet Language Transformations (XSLT)], and to construct the adapted media bitstream from the transformed description. This paper presents how this basic BSD framework, initially developed for nonstreamed content and suffering from inherent limitations and high memory consumption of XML-related technologies such as XSLT, can be advanced and efficiently implemented in a streaming environment and on resource-constrained devices. Two different attempts to solve the inherent problems are described. The first approach proposes an architecture based on the streamed processing of Simple Application Programming Interface for XML (SAX) events and adopts Streaming Transformations for XML (STX) as an alternative to XSLT, whereas the second approach breaks a BSD up into well-formed fragments called process units that can be processed individually by a standard XSLT processor. The current status of our work, as well as directions for future research, are given.

A knowledge-based framework for multimedia adaptation

AbstractPersonalized delivery of multimedia content over the Internet opens new business perspectives for future multimedia applications and thus plays an important role in the ongoing MPEG-7 and MPEG-21 multimedia standardization efforts. Based on these standards, next-generation multimedia services will be able to automatically prepare the digital content before delivery according to the clients device capabilities, the network conditions, or even the users content preferences. However, these services will have to deal with a variety of different end user devices, media formats, as well as with additional metadata when adapting the original media resources. In parallel, an increasing number of commercial or open-source media transformation tools will be available, capable of exploiting such descriptive metadata or dealing with new media formats; thus it is not realistic that a single tool will support all possible transformations.In this paper, we present a novel, fully knowledge-based approach for building such multimedia adaptation services, addressing the above mentioned issues of openness, extensibility, and concordance with existing and upcoming standards. In our approach, the original media is transformed in multiple adaptation steps performed by an extensible set of external tools, where the construction of adequate adaptation sequences is solved in an Artificial Intelligence planning process. The interoperability issue is addressed by exploiting standardized Semantic Web Services technology. This technology allows us to express tool capabilities and execution semantics in a declarative and well-defined form. In this context, existing multimedia standards serve as a shared domain ontology.The presented approach was implemented and successfully evaluated in an official ISO/IEC MPEG (Moving Picture Experts Group) Core Experiment and is currently under further evaluation by the standardization body.

Mulsemedia: State of the Art, Perspectives, and Challenges

Mulsemedia—multiple sensorial media—captures a wide variety of research efforts and applications. This article presents a historic perspective on mulsemedia work and reviews current developments in the area. These take place across the traditional multimedia spectrum—from virtual reality applications to computer games—as well as efforts in the arts, gastronomy, and therapy, to mention a few. We also describe standardization efforts, via the MPEG-V standard, and identify future developments and exciting challenges the community needs to overcome.

Dynamic adaptive streaming over CCN: A caching and overhead analysis

In this paper, we present our implementation and evaluation of Dynamic Adaptive Streaming over Content centric networking (DASC) which implements MPEG Dynamic Adaptive Streaming over HTTP (DASH) utilizing a Content Centric Networking (CCN) naming scheme to identify content segments in a CCN network. In particular, video segments formatted according to MPEG-DASH are available in different quality levels but instead of HTTP, CCN is used for referencing and delivery. Based on the conditions of the network, the DASC client issues interests for segments achieving the best throughput. Due to segment caching within the network, subsequent requests for the same content can be served quicker. As a result, the quality of the video a user receives progressively improves, effectively overcoming bottlenecks in the network. We present two sets of experiments to evaluate the performance of DASC showing that throughput indeed improves. However, the generated overhead is relatively large and the adaptation strategy used for DASH that assumes an end-to-end connection could be revised for the hop-by-hop architecture of CCN.

Improving the Quality of multimedia Experience through sensory effects

In previous and related work sensory effects are presented as a tool for increasing the user experience of multimedia presentations by stimulating also other senses than vision or audition. In this paper we primarily investigated the relationship of the Quality of Experience (QoE) due to various video bit-rates of multimedia contents annotated with sensory effects (e.g., wind, vibration, light). Therefore, we defined a subjective quality assessment methodology based on standardized methods. The paper describes the test environment, its setup, and conditions in detail. Furthermore, we experimented with a novel voting device that allows for continuous voting feedback during a sequence in addition to the overall quality voting at the end of each sequence. The results obtained from the subjective quality assessment are presented and discussed thoroughly. In anticipation of the results we can report an improvement of the quality of the multimedia experience thanks to the sensory effects.