Introduction - Scalable Continuous Media Streaming Systems - page 3

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Introduction

Rapid advances in computing and the Internet have spawnedmany new services and applica-
tions. Among them, applications such as the WorldWide Web (WWW) have achieved great
success and transformed many facets of the society. With the continuous improvements in
network bandwidth, computing power, and storage capacity, existing network services are
evolving from the delivery of texts and graphics towards sophisticated multimedia contents
combing high-quality audio and video.
Delivery of audio and video, however, poses far greater challenges than data applications
such as the WWW. Moreover, unlike web pages, multimedia contents often occupy signifi-
cantly more space for storage, and bandwidth for retrieval and delivery. Coupled with the
demand for serving thousands or even tens of thousands of concurrent users, the challenge
of designing scalable, reliable, and yet cost-effective multimedia systems has been an area
of intense research in the past decade.
In this introductory chapter we will first study the properties of multimedia data and
explain the key challenges in building high-performance yet cost-effective systems for
multimedia content delivery. The rest of the chapters in Part I will introduce the funda-
mental concepts in media compression, storage, retrieval, scheduling, fault tolerance, and
streaming.

1.1 Elements of a Multimedia System
In this topic our focus is on systems for delivering multimedia data over a communication
network such as the Internet or broadband residential networks. This system approach is
desirable as it takes into account the interaction between various system components to achieve
the stringent performance required in multimedia data presentation.
Figure 1.1 shows a generic client-server model for end-to-end multimedia data delivery.
At the source we have encoded/compressed media data stored in storage devices such as
hard disks. Through media server software these media data are then retrieved according to
user requests from the disk to the main memory for transmission over the network. A media
application/transport protocol is used to deliver the media data to the client hosts, where the