【精品资料】多媒体同步.ppt

同步是一个与时间相关的概念。多媒体系统中的同步主要指各媒体对象间的时序关系，广义的多媒体同步包括媒体对象之间的内容、空间、时间关系。我们在此对时间相关或无关的媒体对象作区分。时间相关的媒体现为媒体流中，在媒体流中，各连续的单元之间存在时序关系的单元之间存在时序关系。如果时间相关的。 The word synchronization refers to time. Synchronization in multimedia systems refers to the temporal relations between media objects in the multimedia system. In a more general and widely used sense some authors use synchronization in multimedia as comprising content, spatial and temporal relations between media objects. We differentiate between time-dependent and time-independent media objects. A time-dependent media object is presented as a media stream. Temporal relations between consecutive units of the media stream exist. If the presentation durations of all units of a time-dependent media object are equal, it is called continuous media object. A video consists of a number of ordered frames; each of these frames has a fixed presentation duration. A time-independent media object is any kind of traditional media like text and images. The semantic of the respective content does not depend upon a presentation according to the time domain. 媒体对象间的同步包括时间相关和时间无关的媒体对象之间的同步，关于连续媒体对象同步的一个详细例子是：在电视中，视觉信息与听觉信息的同步。在多媒体系统中，必须为音频和运动图像提供相似的同步机制。关于时间相关媒体和时间无关媒体的同步关系的例子是幻灯片的放映，在幻灯片的放映时要与对其内容进行介绍或评价的音频同步。在多媒体系统中实现幻灯片的放映时，其图形显示必须与音频流中的适当单元进行同步。 Synchronizations between media objects comprises relations between time-dependent media objects and time-independent media objects. A daily example of synchronization between continuous media is the synchronization between the visual and acoustical information in television. In a multimedia system, the similar synchronization must be provided for audio and moving pictures. An example of temporal relations between time-dependent media and time-independent media is a slide show. The presentation of slides is synchronized with the commenting audio stream. To realize a slide show in a multimedia system., the presentation of graphics has to be synchronized with the appropriate units of an audio