A playback schedule is the set of playback deadlines

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Unformatted text preview: e subwoofer. Since the subwoofer has only limited frequency response (about 100 Hz), it is sometimes referred to as the ".1" channel. MPEG-2 audio is backward compatible to MPEG-1 audio because it uses the same coding methods and syntax as that of MPEG-1 audio for the two main channels (left and right). However, MPEG-2 audio uses new coding methods and syntax for the surround channels. MULTIMEDIA SYNCHRONIZATION Often multimedia presentation involves simultaneous presentation of two or more types of media. For example, a movie involves simultaneous presentation of video and audio. Similarly, a French movie with English subtitles involves simultaneous presentation of video, audio and text. In such cases, multimedia synchronization is required to ensure the desired temporal ordering among a set of multimedia objects in a multimedia presentation. One such example is lip synchronization, which refers to the requirement that the voice should match the movement of the lips of the speaker. Another example is subtitle synchronization, which refers to the requirement, that the timing of the displayed text (subtitle) should match with the timing of the video (scene) and the voice (spoken words) of the speaker that correspond to the subtitles. Multimedia synchronization can be divided into two levels - temporal specification and temporal synchronization. They are described below. Temporal Specification Temporal specification is used to model the temporal relationships among the set of related abstract multimedia objects of a presentation scenario, where an abstract object denotes a logical unit of media data such as a video object or a text object. The two commonly used approaches for temporal specification are graphicalbased and language-based. These are described below. Graphical-based Approach In this approach, the temporal relationships among the multimedia objects of a presentation scenario is represented in the form of a graph, such as an X-Y graph with X-coordinate representing time and Y-coordina...
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This document was uploaded on 04/07/2014.

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