Distributed multimedia systems

Multimedia systems will allow professionals worldwide to collaborate more effectively and to travel substantially less. But for multimedia systems to be effective, a good systems infrastructure is essential. In particular, support is needed for global and consistent sharing of information, for long-distance, high-bandwidth multimedia interpersonal communication, greatly enhanced reliability and availability, and security. These systems will also need to be easily usable by lay computer users. \ud In this paper we explore the operating system support that these multimedia systems must have in order to do the job properly

Reconfigurable Mobile Multimedia Systems

This paper discusses reconfigurability issues in lowpower hand-held multimedia systems, with particular emphasis on energy conservation. We claim that a radical new approach has to be taken in order to fulfill the requirements - in terms of processing power and energy consumption - of future mobile applications. A reconfigurable systems-architecture in combination with a QoS driven operating system is introduced that can deal with the inherent dynamics of a mobile system. We present the preliminary results of studies we have done on reconfiguration in hand-held mobile computers: by having reconfigurable media streams, by using reconfigurable processing modules and by migrating functions

Analysis of a Multimedia Stream using Stochastic Process Algebra

It is now well recognised that the next generation of distributed systems will be distributed multimedia systems. Central to multimedia systems is quality of service, which defines the non-functional requirements on the system. In this paper we investigate how stochastic process algebra can be used in order to determine the quality of service properties of distributed multimedia systems. We use a simple multimedia stream as our basic example. We describe it in the Stochastic Process Algebra PEPA and then we analyse whether the stream satisfies a set of quality of service parameters: throughput, end-to-end latency, jitter and error rates

Online Reinforcement Learning for Dynamic Multimedia Systems

In our previous work, we proposed a systematic cross-layer framework for dynamic multimedia systems, which allows each layer to make autonomous and foresighted decisions that maximize the system's long-term performance, while meeting the application's real-time delay constraints. The proposed solution solved the cross-layer optimization offline, under the assumption that the multimedia system's probabilistic dynamics were known a priori. In practice, however, these dynamics are unknown a priori and therefore must be learned online. In this paper, we address this problem by allowing the multimedia system layers to learn, through repeated interactions with each other, to autonomously optimize the system's long-term performance at run-time. We propose two reinforcement learning algorithms for optimizing the system under different design constraints: the first algorithm solves the cross-layer optimization in a centralized manner, and the second solves it in a decentralized manner. We analyze both algorithms in terms of their required computation, memory, and inter-layer communication overheads. After noting that the proposed reinforcement learning algorithms learn too slowly, we introduce a complementary accelerated learning algorithm that exploits partial knowledge about the system's dynamics in order to dramatically improve the system's performance. In our experiments, we demonstrate that decentralized learning can perform as well as centralized learning, while enabling the layers to act autonomously. Additionally, we show that existing application-independent reinforcement learning algorithms, and existing myopic learning algorithms deployed in multimedia systems, perform significantly worse than our proposed application-aware and foresighted learning methods.Comment: 35 pages, 11 figures, 10 table

Quality of service in distributed multimedia systems

The Unix operating system made a vital contribution to information technology by introducing the notion of composing complicated applications out of simple ones by means of pipes and shell scripts. One day, this will also be possible with multimedia applications. Before this can happen, however, operating systems must support multimedia in as general a way as Unix now supports ordinary applications. Particularly, attention must be paid to allowing the operating-system service to degrade gracefully under heavy loads.\ud This paper presents the Quality-of-Service architecture of the Huygens project. This architecture provides the mechanisms that allow applications to adapt the level of their service to the resources the operating system can make available

Systems for the Nineties - Distributed Multimedia Systems

We live at the dawn of the information age. The capabilities of computers to store and look up information are only just beginning to be exploited. As little as ten years ago, practically all the information stored in computers was entered and retrieved in the form of text. Today, we are just starting to use other means of communicating information between people and machines -- computers can now scan images, they can record sound, they can produce synthesized speech, and they can show two- and three-dimensional images of spatial data. The realization that we are still at the beginning of the information age comes when we notice the vast difference between the way in which people interact with each other and the way in which people can interact with (or through) machines. When people communicate, they tend to use speech, gestures, touch, even smell; they draw pictures on the white board, they use text, pictures, photos, graphs, sometimes even video presentations. nterpersonal communication is truly multimedia communication in that it makes use of all our senses

Distributed multimedia systems

A distributed multimedia system (DMS) is an integrated communication, computing, and information system that enables the processing, management, delivery, and presentation of synchronized multimedia information with quality-of-service guarantees. Multimedia information may include discrete media data, such as text, data, and images, and continuous media data, such as video and audio. Such a system enhances human communications by exploiting both visual and aural senses and provides the ultimate flexibility in work and entertainment, allowing one to collaborate with remote participants, view movies on demand, access on-line digital libraries from the desktop, and so forth. In this paper, we present a technical survey of a DMS. We give an overview of distributed multimedia systems, examine the fundamental concept of digital media, identify the applications, and survey the important enabling technologies.published_or_final_versio

Multicast using PIM-SM in Broadband Satellite Multimedia Systems

The approach currently being taken by ETSI (BSM) to standardisation for Multicast PIM-SM protocols is described. This paper describes methods, architectures and adaptations to support IP-multicast services efficiently across IP-based broadband multimedia satellite systems. This work has recently begun and the final objective is to arrive at a consensus for a standard on this subject

Octopus - an energy-efficient architecture for wireless multimedia systems

Multimedia computing and mobile computing are two trends that will lead to a new application domain in the near future. However, the technological challenges to establishing this paradigm of computing are non-trivial. Personal mobile computing offers a vision of the future with a much richer and more exciting set of architecture research challenges than extrapolations of the current desktop architectures. In particular, these devices will have limited battery resources, will handle diverse data types, and will operate in environments that are insecure, dynamic and which vary significantly in time and location. The approach we made to achieve such a system is to use autonomous, adaptable modules, interconnected by a switch rather than by a bus, and to offload as much as work as possible from the CPU to programmable modules that is placed in the data streams. A reconfigurable internal communication network switch called Octopus exploits locality of reference and eliminates wasteful data copies

Avoiding DAD for Improving Real-Time Communication in MIPv6 Environments

Joint International Workshops on Interactive Distributed Multimedia Systems and Protocols for Multimedia Systems, IDMS/PROMS 2002 Coimbra, Portugal, November 26–29, 2002 ProceedingsCurrent specification of address configuration mandates the execution of the Duplicate Address Detection (DAD) mechanism to prevent address duplication. However, a proper support for real time multimedia applications in mobile IPv6 nodes is undermined by the disruption imposed by DAD. In order to overcome this limitation, the usage of randomly generated IPv6 Interface Identifiers without previously performing DAD is proposed, based on the statistic uniqueness of the addresses generated through this method. The address duplication risk is quantified through the calculation of the probability of an Interface Identifier collision among the nodes sharing a link. The calculated probability is deemed to be negligible compared to other causes of communication failure, such as network outages.This research was supported by the LONG (Laboratories Over Next Generation Networks) project IST-1999-20393 and Moby Dick (Mobility and Differentiated Services in a Future IP Network) project IST-2000-25394