多媒体通信网络英文课件Chapter6 Synchronization.ppt

MMCN-Chapter6 Chapter 6 Synchronization Prof. Guohui Li Doctor. Zhihui Xiong Department of Management Science and Engineering National University of Defense Technology Spring 2010 From user’s perspective, Multimedia means that information can be represented through audio and /or video, in addition to text, image, graphics and animation. Chapter 6 6.1 Introduction 6.2 Basic synchronization issues 6.3 Intra- and inter-synchronization 6.4 Live and synthetic synchronization The reference: Ralf Steinmets. Multimedia: computing, communications and applications. Prentice Hall, 1995. 6.1 Introduction 1. Basic concept The word synchronization refers to time 6.1 Introduction synchronization in multimedia systems refers to the temporal relations between media objects in the multimedia system. 6.1 Introduction Synchronization between media objects comprises time relations between time-dependent media objects and time-independent media objects. e.g., video and audio in TV e.g., audio and slides in a presentation. 6.1 Introduction 2. Synchronization level Why? Since synchronization is addressed and supported by many system components, including the operating system, communication system, database, documents and even often applications. Hence, synchronization must be considered at several levels in a multimedia system. 6.1 Introduction 2. Synchronization level Including: 1) operating system and communication level; 2) application level. Operating system and communication level handle single media streams with the objective to avoid jitter at the presentation. e.g., users will be annoyed if an audio presentation is interrupted by pauses. 6.1 Introduction 2. Synchronization level Application level synchronization of multiple media streams：objective is to maintain the temporal relations between various streams. e.g. lip synchronization (对口型) synchronization between time-dependent and time-independent media together with the handling of user inte