Distributed multimedia systems




 

Another important trend is the requirement to support multimedia services in distributed systems. Multimedia support can usefully be defined as the ability to support a range of media types in an integrated manner. One can expect a distributed system to support the storage, transmission, and presentation of what is often referred to as discrete media types, such as pictures or text messages. A distributed multimedia system should be able to perform the same functions for continuous media types such as audio and video; that is, it should be able to store and locate audio or video files, to transmit them across the network (possibly in real time as the streams emerge from a video camera), to support the presentation of the media types to the user and optionally also to share the media types of a group of users.
The crucial characteristic of continuous media types is that they include a temporal dimension, and indeed, the integrity of the media type is fundamentally dependent on preserving real-time relationships between elements of a media type. For example, in a video presentation, it is necessary to preserve a given throughput in terms of frames per second and, for real-time streams, a given maximum delay or latency for the delivery of frames (this is one example of the quality of service.
The benefits of distributed multimedia computing are considerable in that a wide the range of new (multimedia) services and applications can be provided on the desktop, including access to live or pre-recorded television broadcasts, access to film libraries offering video-on-demand services, access to music libraries, the provision of audio and video conferencing facilities and integrated telephony features including IP telephony or related technologies such as Skype, a peer-to-peer alternative to IP telephony. Note that this technology is revolutionary for challenging manufacturers to rethink many
consumer devices. For example, what is the core home entertainment device of the future – the computer, the television, or the games console? 

Webcasting is an application of distributed multimedia technology. Webcasting is the ability to broadcast continuous media, typically audio or video, over the Internet. It is now commonplace for major sporting or music events to be broadcast in this way, often attracting large numbers of viewers (for example, the Live8 concert in 2005
attracted around 170,000 simultaneous users at its peak).
Distributed multimedia applications such as webcasting place considerable demands on the underlying distributed infrastructure in terms of: 

providing support for an (extensible) range of encoding and encryption formats, such as the MPEG series of standards (including, for example, the popular MP3 standard otherwise known as MPEG-1, Audio Layer 3) and HDTV;
providing a range of mechanisms to ensure that the desired quality of service can be met;
providing associated resource management strategies, including appropriate scheduling policies to support the desired quality of service;
providing adaptation strategies to deal with the inevitable situation in open systems where the quality of service cannot be met or sustained.

Topics You May Be Interested In
Difference Between Manual And Automated System - Manual System Vs Automated System Concurrency
Data And Fact Gathering Techniques- Interviews, Group Communication, Presentations, Site Visits Introduction
Feasibility Study And Its Importance Physical Models
Cost-benefit And Analysis -tools And Techniques Planning The Project-managing The Information Systems Project
Selected Application Domains And Associated Networked Applications Modern Methods For Determining System Requirements


Frequently Asked Questions

+
Ans: Technological advances in device miniaturization and wireless networking have led increasingly to the integration of small and portable computing devices into distributed systems. view more..
+
Ans: The Internet is also a very large distributed system. It enables users, wherever they are, to make use of services such as the World Wide Web, email and file transfer. (Indeed, the Web is sometimes incorrectly equated with the Internet.) view more..
+
Ans: the emergence of ubiquitous computing coupled with the desire to support user mobility in distributed systems view more..
+
Ans: The crucial characteristic of continuous media types is that they include a temporal dimension, and indeed, the integrity of the media type is fundamentally dependent on preserving real-time relationships between elements of a media type. view more..
+
Ans: hysical resources such as storage and processing can be made available to networked computers, removing the need to own such resources on their own. At one end of the spectrum, a user may opt for a remote storage facility for file storage requirements view more..
+
Ans: In practice, patterns of resource sharing vary widely in their scope and in how closely users work together. At one extreme, a search engine on the Web provides a facility to users throughout the world, users who need never come into contact with one another directly. At the other extreme, in computer-supported cooperative working (CSCW), a group of users who cooperate directly share resources such as documents in a small, closed group. view more..
+
Ans: Data types such as integers may be represented in different ways on different sorts of hardware – for example, there are two alternatives for the byte ordering of integers. These differences in representation must be dealt with if messages are to be exchanged between programs running on different hardware view more..
+
Ans: the publication of interfaces is only the starting point for adding and extending services in a distributed system. The challenge to designers is to tackle the complexity of distributed systems consisting of many components engineered by different people. view more..
+
Ans: a firewall can be used to form a barrier around an intranet, restricting the traffic that can enter and leave, this does not deal with ensuring the appropriate use of resources by users within an intranet, or with the appropriate use of resources in the Internet, that are not protected by firewalls. view more..
+
Ans: ly and efficiently at many different scales, ranging from a small intranet to the Internet. A system is described as scalable if it will remain effective when there is a significant increase in the number of resources and the number of users. The number of computers and servers in the Internet has increased dramatically. view more..
+
Ans: Failures in a distributed system are partial – that is, some components fail while others continue to function. Therefore the handling of failures is particularly difficult. The following techniques for dealing with failures are discussed throughout the book view more..
+
Ans: he process that manages a shared resource could take one client request at a time. But that approach limits throughput. Therefore services and applications generally allow multiple client requests to be processed concurrently. view more..
+
Ans: oncealment from the user and the application programmer of the separation of components in a distributed system, so that the system is perceived as a whole rather than as a collection of independent components view more..
+
Ans: Reliability and security issues are critical in the design of most computer systems. The performance aspect of quality of service was originally defined in terms of responsiveness and computational throughput, but it has been redefined in terms of ability to meet timeliness guarantees, as discussed in the following paragraphs view more..
+
Ans: The Web began life at the European centre for nuclear research (CERN), Switzerland, in 1989 as a vehicle for exchanging documents between a community of physicists connected by the Internet [Berners-Lee 1999]. A key feature of the Web is that it provides a hypertext structure among the documents that it stores, reflecting the users’ requirement to organize their knowledge. view more..
+
Ans: Resource sharing is the main motivating factor for constructing distributed systems. Resources such as printers, files, web pages or database records are managed by servers of the appropriate type. For example, web servers manage web pages and other web resources. Resources are accessed by clients – for example, the clients of web servers are generally called browsers. view more..
+
Ans: Physical models consider the types of computers and devices that constitute a system and their interconnectivity, without details of specific technologies. view more..
+
Ans: The discussion and examples of Chapter 1 suggest that distributed systems of different types share important underlying properties and give rise to common design problems. In this chapter we show how the properties and design issues of distributed systems can be captured and discussed through the use of descriptive models view more..



Recommended Posts:


Rating - 3/5
471 views

Advertisements