Multimedia catalogue multimedia brochures and

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Unformatted text preview: thout leaving the comfort of their homes, and interact with the programs via VCR-like functions, such as fastforward and rewind. In essence, it implements a virtual video-rental shop from which customers can borrow and view the videos of their choice at their own convenient time. The rental shop being virtual provides 24 hours service. Interactive TV is implemented by using a Video-on-Demand (VoD) system and the facilities offered are often referred to as movie-on-demand, news-on-demand, sports-on-demand, education-on-demand, etc. depending on which ones of these are supported by the system. The main components of a VoD system are as follows (see Figure 19.8): 1. Video server. A video server consists of massive storage and media controllers. It stores a large number of digitized videos and serves simultaneous video requests to the same or different videos on demand. The storage media usually consist of magnetic disks, optical disks, and magnetic tape and are usually organized hierarchically for cost effectiveness. Under this configuration, popular videos are stored in the disks. Less popular ones are stored in tape devices with terabyte capacity and retrieved as necessary to the disk drive for processing. The basic functions supported by video servers include request handling, random access, and user interactions. 2. Transport network. The transport network delivers video programs from the video server to the customers. The network must have a very high data rate and satisfy the real-time delivery constraints of video traffic. 3. Set-top box. A set-top box along with the television monitor and the infrared controller (i.e., remote control), serves as the bridge between the subscribers and the system. With on-screen images and cursor-like devices, viewers are connected to the video server and can browse the video selections and interact with the services via VCR-like functions. The major functions of the set-top box include receiving the incoming video streams; demodulating, demultiplexing, and decoding the si...
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This document was uploaded on 04/07/2014.

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