Publications of Wolfgang Effelsberg

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Konferenz Beitrag

Buch

Forschungs Papier

  • Stefan Fischer, Bernd Hofmann und Wolfgang Effelsberg. , Technical Reports. 1994 Efficient Configuration of Protocol Software for Multiprocessors Mannheim, . 94-006
    Efficient implementation of communication software is of crucial importance for high-speed networks. One way to improve the runtime performance of protocol implementations in the network nodes is the use of parallelism. Formal description techniques like Estelle improve the specification process in many respects and allow for semiautomatic code generation. Therefore, they are now widely accepted. We present a code generator for Estelle that compiles and automatically configures protocol software for a multiprocessor. Software modules are distributed over the available processors and executed concurrently. We report performance results on a KSR1 with 28 available processors under the OSF/1 operating system.
  • Ralf Keller und Wolfgang Effelsberg. , Manuskripte / Reihe Informatik. 1994 Effiziente Verarbeitung von multimedialen Datenströmen in Window-Systemen Mannheim, . 94-14
    Fensterorientierte Oberflaechen haben sich auf Workstations aller Leistungsklassen durchgesetzt. Deshalb liegt es nahe, Multimedia-Anwendungen in solche Oberflaechen zu integrieren. Dieser Artikel gibt zunaechst eine Uebersicht ueber die verschiedenen technischen Moeglichkeiten zur Integration von Multimedia-Datenstroemen in ein Fenstersystem; die Vor- und Nachteile der einzelnen Ansaetze werden gegenuebergestellt. Waehrend Loesungen mit Hardware-Unterstuetzung im allgemeinen schneller sind, sind reine Software-Implementierungen flexibler und portabler. Als ein Beispiel fuer eine Software-Loesung werden Architektur, Implementierung und Leistungsanalyse eines netzwerkfaehigen Filmsystems fuer das X-Window-System ausfuehrlich diskutiert. Es zeigt sich, dass die Uebertragung und Darstellung von digitalen Filmen auf modernen Workstations in Hochgeschwindigkeitsnetzen ohne spezielle Hardware in Realzeit moeglich ist. Außerdem werden neue Ansaetze zur Gestaltung der Mensch-Maschine-Schnittstelle mit multimedialen Komponenten vorgestellt.
  • Ralf Keller, Wolfgang Effelsberg und Bernd Lamparter. , Technical Reports. 1994 XMovie: Architecture and Implementation of a Distributed Movie System Mannheim, . 94-012
    We describe a system for storing, transmitting and presenting digital movies in a computer network. The hardware used in the system is standard hardware, as found in typical workstations today; no special hardware is required. The movies are shown in windows of the X window system. This allows full integration with the classical components of computer applications such as text, color graphics, menus and icons. The XMovie system has several innovative features: First, it contains a new algorithm for the gradual adaptation of the color lookup table during the presentation of the movie to ensure optimal color quality on low-end workstations. Second, it is a multi-standard system supporting the compression techniques MPEG, H.261, Motion JPEG, and a newly developed extension to the well known Color Cell Compression method. Third, we introduce AdFEC, a new adaptable forward error correction method for our movie transmission protocol.
  • Ralf Keller, Stefan Fischer und Wolfgang Effelsberg. , Technical Reports. 1994 Implementing Movie Control, Access and Management - from a Formal Description to a Working Multimedia System Mannheim, . 94-005
    In this paper we describe the tool-supported specification and implementation of a multimedia communication protocol on parallel hardware. MCAM is an application layer protocol for movie control, access and management. We specify the full MCAM protocol together with ISO presentation and session layers in Estelle. Using a code generator, we derive parallel C++ code from the specification. The code is compiled and executed on a multiprocessor system under OSF/1 and on UNIX workstations. Measurements show the performance speedup gained by several different configurations of parallel units. We also report on experiences with our methodology.
  • Bernd Lamparter und Wolfgang Effelsberg. , Manuskripte / Reihe Informatik. 1994 eXtended Color Cell Compression -- A Runtime-efficient Compression Scheme for Software Video Mannheim, . 94-15
    Multimedia applications require a compression and decompression scheme for digital video. The standardized and widely used techniques JPEG and MPEG provide very good compression ratios, but are computationally quite complex and demanding. We propose to use an extension to the much simpler Color Cell Compression scheme as an alternative. Our extension includes the use of variable block sizes, the reuse of color index values from previously encoded blocks, and Huffman encoding of the stream of blocks. We present experimental results showing that our scheme provides much better runtime performance than MPEG, at the cost of a slightly inferior compression ratio. It is thus especially suited for software videos in high-speed networks.
  • Thomas Meyer-Boudnik und Wolfgang Effelsberg. , . 1994 MHEG: An Interchange Format for Interactive Multimedia Presentations , .
    This paper surveys the upcoming MHEG standard, as under development by the Multimedia Hypermedia Experts Group of ISO. It's scope is to define a system-independent encoding of the structure information which can be used for storing, exchanging, and executing of multimedia presentations in final form. We use a running example to describe the building blocks of an MHEG encoded presentation. To contribute our experience using MHEG in a networked multimedia kiosk environment, we present a complete MHEG run-time environment.

Buch Kapitel

[2018] [2017] [2016] [2015] [2014] [2013] [2012] [2011] [2010] [2009] [2008] [2007] [2006] [2005] [2004] [2003] [2002] [2001] [2000] [1999] [1998] [1997] [1996] [1995] 1994 [1993] [1992] [1991] [1990] [1988] [1987] [1986] [1985] [1984] [1983] [1981] [1980] [1979]