Modeling distributed multimedia synchronization with DSPN

Multimedia computing has become an important study area in recent years. Multimedia synchronization mechanism is a key issue of the distributed multimedia system. The research of multimedia synchronization technology will greatly promote the popularity and applications of the distributed multimedia systems. In this paper, on the basis of the four layers reference model of multimedia synchronization, a synchronization frame of distributed multimedia system in practical application is presented, and some key contents such as the buffer and its control time are discussed. The frame does not require high network bandwidth and QOS parameters and can obtain good effect in the TCP/IP network environment which is currently widespread used.

The multimedia synchronization is used to coordinate the timing of each multimedia object in the multimedia system. After studying different multimedia synchronization systems that have been published, an Interactive Synchronization multimedia based on Petri Nets model (ISPN) is proposed in this paper. The system is capable of describing the dynamic timing actions of multimedia objects vividly as well as controlling them interactively to maintain the system level synchronization balance.

A synchronization problem, which always arises when sound, video, motion pictures and other media are brought together and integrated into a computer system, is one of the most important issues in multimedia communications and applications. In a time-sharing and multi-process environment such as the UNIX operating system, the traditional synchronization mechanism results in two fatal defects, namely, audio discontinuity and out of synchronization between the audio and video signals. A novel media synchronization model in a multi-process environment is proposed. Based on this model, a continuous media playback module was implemented and served as the key component of the two multimedia systems developed in the Communication and Multimedia Laboratory of National Taiwan University. One is the multimedia authoring system which provides interactive VCR-like operations and audio/video editing facilities. The other is a prototype of the VOD (video on demand) system which provides video browsing facility. Both systems show that the performance of the proposed synchronization model is quite satisfactory. >

Object Composition Petri Nets, Priority Petri Nets, Dynamic OCPN, and Enhanced P-Nets have extended the original Petri Net to achieve the modeling of media synchronization and asynchronous user interactions during multimedia playback. The dynamic Petri Net (DPN) has been conceptualized to tackle existing problems in these two areas of modeling distributed multimedia systems. DPN features dynamic modeling elements which allows iteration and hence is able to reduce graph sizes of synchronous playback models while allowing greater details to be shown. DPN also introduces asynchronous event handling techniques that are powerful and effective. DPN was used in the design and modeling of a multimedia orchestration tool which is a typical representation of an application that works in a distributed multimedia system.

This paper contributes toward exception handling and fault-tolerance in multimedia presentation. Our study is based on the well-known four phases in fault-tolerant computing: fault detection, damage assessment, error recovery, and continued service. We define a fault in multimedia synchronization and a simple fault detection mechanism. Using the concept of a partner set of a media stream, we assess the damage caused to media presentation due to a fault. From the point of error recovery and reducing synchronization failures, we introduce the ideas of a k-cycle virtual fault. A k-cycle virtual fault suggests the possibility of a failure in the future after k presentation cycles. Detection of a possible presentation failure in the future gives lead time to take corrective measures to avoid the failure. In order to handle exception conditions during a synchronization failure, we define pinned and sliding semantics of media presentation. These two semantics allow us to define different levels of quality of presentation during a failure. Finally, we present the detailed design of a fault-tolerant presentation architecture and prove its properties. We discuss how the ideas of virtual fault and damage assessment can be used in generating useful information for the underlying data transfer protocol so that synchronization failures can be reduced.

Multimedia synchronization is a significant requirement for distributed multimedia applications. In this paper, a multimedia dynamic timed synchronization model based on Petri nets is presented (MDTSPN), which can describe the temporal synchronization accurately, and has stronger interactive ability. The backtracking algorithm is introduced to ensure the whole synchronization under the users' interactive control, and describe the dynamic behaviors of multimedia.

In this paper, we propose a new PBMSM (Petri-net and Buffer for Multimedia Synchronization Model) for the synchronization specification. It can address QoS requirements for jitter that represents the time difference in the media by using Petri-net and variance buffer to express multiple media with respect to multimedia synchronization. Simulation results show the proposed PBMSM improved QoS such as a high playout rate and a low loss rate. Therefore, PBMSM is the appropriate model for multimedia systems that require QoS guarantees.

WWW is used increasingly for dealing with large amounts of multimedia data. Unfortunately early WWW concepts are not particularly supportive of such kinds of applications. The simple link paradigm of ordinary WWW does not handle links in arbitrary document types, or multiple views of the same document space and does not support automatic link maintenance. Nor is the link concept powerful enough to handle complex structural requirements in distributed databases. The author defines the scope of multimedia. They then discuss features needed in a distributed multimedia system and why some of them are difficult to implement in ordinary WWW systems. They finally show that WWW systems that generalise the link concept and introduce additional structuring mechanisms to handle the problems discussed can be and have indeed been developed: they explain some of the relevant points using as an example the most prominent such system, Hyperwave.

In this paper, we firstly analyze all kinds of resource allocation schemes in distributed multimedia system, including QoS manager, SRT, GARA, and propose a novel distributed multimedia service grid architecture & multimedia service grid. Based on grid architecture, this paper introduces a novel resource allocation scheme & grid-based on-demand queuing, GOD queuing. We propose the function architecture of the scheme, and describe the main function of each component. Furthermore, this paper emphasizes on the resource usage monitoring and adapting mechanism of VOD multimedia service grid based on GOD queuing scheme, illustrating the characteristic of GOD queuing scheme in resource allocation. At last, we illustrate the prospective research direction on the combination of distributed multimedia system and grid technology

In previous years, various real-time scheduling techniques have been proposed to improve the performance of a distributed multimedia system. However, not much work has been done on how a client player can play multiple videos concurrently. In this paper, we have designed a distributed multimedia system where a client player can play different videos at the same time. We introduce two mechanisms: priority assignment mechanism and feedback capture video mechanism for the system. The issues on how to implement the mechanisms in Windows NT are discussed. Experiments are conducted to investigate the performance of the proposed mechanism in Windows NT to study the most optimum configuration factors. We also define the monitoring factor and priority group mapping difference and study how they affect the overall system performance. From the results, we find that the mechanisms can effectively improve the system performance in terms of percentage of displayed frames.

Multimedia distance education is the teaching mode based on computer and network, so that we can accomplish the tasks of teaching in different places or at different times. The distributed multimedia distance education system is low cost, and it can effectively overcome the limitations of time and space, and is being morewidely used. Multimedia distance education system needs to solve the key problem of how to transfer the audio and video to the destination by internet technology effectively. The multimedia distance education system needs to transmit audio and video in real time, so the transmission delay must be reduced in order to ensure the teaching and interaction between teachers and students. In this paper, we design a more advanced and efficient remote teaching system based on the node management of a distributed system. Firstly, we take the distributed multimedia technology as the key technology and an important means to facilitate the transmission of streaming media data. Then, we put forward the method of configuration management and state management in the media server cluster. Secondly, on the basis of the previous method, we put forward a method of load balancing management based on RTCP control message. Based on the design in this paper, we realize the orderly and efficient management of the media server cluster in a distributed system. Finally, we simulate the performance test of the node management in the media server cluster to validate the advantages of the node management. This design can effectively reduce the transmission delay of streaming media data.

There have been research works on supporting QoS (Quality of Service) in a distributed multimedia systems. These researches can be categorized as following; system platform, real-time operating system, transport protocol, communication architecture. In distributed multimedia environment, QoS must be guaranteed in end systems, but much less progress has been made in addressing this problem. As the processing power of end systems increases, most of the bottleneck occurs in communication protocol, especially transport protocol. To meet an end-to-end QoS, overall QoS architectures must be integrated. In this paper, we propose a new QoS architecture and control mechanisms (group control, and flow control) to guarantee an end-to-end QoS for distributed multimedia services. We also verify proposed architecture by applying them to a multimedia conferencing system in LAN.

The amount of streaming multimedia data delivered to mobile devices is growing at a high rate. Research shows that a large number of daily commuters stream audio and video to their mobile devices during their travels. This makes urban rail environments a suitable platform for delivering entertainment, information and advertisement multimedia using novel delivery techniques. In order to do so, the system presented in this paper utilizes the unused bandwidth of a Communications-Based Train Control link to transmit multimedia to urban trains. Once on the train, multimedia is distributed to passenger devices using Wi-Fi Peer-to-Peer (P2P) technology. Such a multimedia distribution system can be deployed incrementally, as it can function concurrently with Wi-Fi connections already available in a number of trains. This paper presents the results obtained by emulating multimedia streaming in an urban rail use-case. Namely, it evaluates the received streaming multimedia quality parameters when new users arrive or existing users are replaced during the train stops.

This paper presents an approach for the specifications of the configurable distributed systems, which is based on the computational model with information transport ports. Features of the approach are demonstrated with the help of a reference example. Fragments of the system architects' language are presented which illustrate the flexibility of the approach and its wide areas of application. Examples of specifications for ATM and distributed multimedia systems are shown.

A window-assisted video partitioning strategy for partitioning and caching video streams in distributed multimedia systems