本节编撰作者(鼓励有兴趣的同学自由撰写，总评成绩可适当加分)： * [[abcd@gmail.com|张三]] (3080100999)， 编写了... 浙江大学2008-2011版权所有，如需转载或引用，请与[[zhx@cad.zju.edu.cn | 作者联系]]。 What is Multimedia: –To distribute and present information coded as • Text, Graphics, animation, audio and video.. –By • Computer, TV, phone, etc. a number of key aspects of multimedia: –Multimedia involves “Many Media” • THE MEDIA DOMAIN –Multimedia involves Computers • THE SYSTEMS DOMAIN –Multimedia enhances the presentation and communication of information • THE APPLICATION DOMAIN -------------------------------------------------- Why do we need multimedia? 1.A computer database supports many basic data types: 2.Inadequate to hold documents such as letters, application forms or image (student photograph). 3.Need a document image processing system including: 4.Further enhancement to handle other types of information (voice)A short video clip Media types can be divided into two groups: Temporal media types: • audio, video, music, animation Non-temporal media typ • text, graphics, images --------------------------------------------------- Media Type: TextDifferent Representation ASCII ISO character sets Marked-up text Structured text Hypertext Media Type: Image Different Representation Color model Alpha channels Number of channels Channel depth Interlacing Indexing Pixel aspect ratio Compression Media Type: Graphics: Different Representation Geometric models Solid models Physically based models Empirical models Drawing models External format for models Media Type: Analog Video: Different Representation Frame rate Number of scan lines Aspect ratio Interlacing Hypertext Quality Component/Composite Media Type: Digital Video: Different Representation Sampling Sampling rate Sampling size and quantization Data rate Frame rate Compression Support for interactivity Scalability Media Type: Videos Media Type: Digital Audio Media Type: Audio Media Type: Music Different Representation Operational/Symbolic MIDI (Musical Instrument Digital Interface) Media Type: Animation Different Representation Cel models Scene-based models Event-based models Key frames Articulated objects and hierarchical models Scripting and procedural models Physically based and empirical models ----------------------------------------------------- Characteristics of MM Data -- challenges about managing MM data Huge Size Data Volume Similarity-based Search Quality of Service (QoS) Synchronization Content-Based Retrieval Temporal Aspects Media Representation ---------------------------------------------------- Characteristics of MM Data -- challenges about modeling MM data 1.High level content abstraction is natural to the way humans think 2.Effective modeling of MM data is critical 3.Low level representation of multimedia data, which encodes the physical reality, leads to the problem of huge amounts of data. 4.Another reason for introducing abstractions (providedby the user/system) is to allow the user to refer to the data in terms of abstractions which make up his modeof the application domain. ----------------------------------------------------- MMDBMS –a framework that manages different types of data potentially represented in a wide diversity of formats on a wide array of media sources Uniformly query data represented in different formats Query data represented in diverse media Retrieve media objects from a local storage devices in a smooth, jitter-free manner Provide audio visual presentation of a query result Deliver presentation to satisfy quality of service requirements ----------------------------------------------------------------------- Multimedia equation Multimedia = presentation + context presentation: sensory, aesthetic part （美学） context = convergence + information + architecture • convergence = data +platform + distribution • information = storage and retrieval • architecture = compression + components + connectivity