8 some of the highly desirable features of a

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Unformatted text preview: o-end delays and packet losses. The timing relationships among the playback deadline Ts, the request time Tr, and the response time R are given by Tr = Ts - R and are depicted in Figure 19.17. The possible experienced end-to-end delays are contributed by (assuming that the presentation and server sites are different): 1. Request queuing delay and retrieval delay (i.e., seek, latency, and data transfer times) at server site. 2. Round-trip queuing delays, propagation delays, and transmission delays in network communication. 3. Queuing delay and processing delay at the presentation site. The time duration from when a user initiates a presentation request to when the presentation begins is called the set-up time. Figure 19.18 shows the set-up time in a presentation. The set-up time T must be long enough to compensate for the system delays and to achieve inter-media synchronization. The set-up time therefore is not necessarily equal to max {R !t R2, —, Rn} where Oh O2, —, On are the start objects and Ru R2, — Rn are their respective response times. T is largely dependent on the request time of the first request objects in the request ordering. For example, in Figure 19.18, T' is largely dependent on the request times of objects O1 and O2. The set-up time determines the earliest playback time of the corresponding scenario, which in turn determines the absolute playback deadlines of the subsequent objects. The earliest playback time is the earliest time a presentation can start after it is initiated, and it is also the actual playback deadline of the start objects. Combining the earliest playback time with the relative playback schedule gives the actual playback schedule. Points to Remember 1. Multimedia refers to the use of more than one of the following media for information presentation: • Text (alphanumeric characters) • Graphics (line drawings and images) • Animation (moving images) • Audio (sound) • Video (videographed real-life events) 2. A multimedia computer system is a computer...
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This document was uploaded on 04/07/2014.

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