Defining Objects for Multimedia Systems

DEFINING OBJECTS FOR MULTIMEDIA SYSTEMS

The basic data types of object using in multimedia include text, image, audio, holograms and full-motion video.

TEXT

It is the simplest of data types and requires the least amount of storage. Text is the base element of a relational database.

It is also the basic building of a document.

The major attributes of text include paragraph styling, character styling, font families and sizes, and relative location in a document

HYPERTEXT

It is an application of indexing text to provide a rapid search of specific text strings in one or more documents. It is an integral component of hypermedia documents. A hypermedia document is the basic complex object of which text is a sub object.

Sub-objects include images, sound and full motion video.

A hypermedia document always has text and has one or more other types of sub-objects

IMAGES

Image object is an object that is represented in graphics or encoded form. Image object is a subobject of the hypermedia document object. In this object, there is no direct relationship between successive representations in time.

The image object includes all data types that are not coded text. It do not have a temporal property associated with them.

Thc data types such as document images, facsimile systems, fractals, bitmaps, meta files, and still pictures or still video frames are grouped together.

Figure 3.6 describes a hierarchy of the object classes

Non-Visible: This type of images are not stored as images. But they are displayed as images. Example: Pressure gauges, and temperature gauges.

Abstract: Abstract images are computer-generated images based on some arithmetic calculations. They are really not images that ever existed as real-world objects. Example of these images is fractals.

AUDIO AND VOICE

Stored-Audio and Video objects contain compressed audio information. This can consist of music, speech, telephone conversation and voice commands. An Audio object needs to store information about thc sound clip.

Information here means length of the sound clip, its compression algorithm, playback characteristics, and any annotations associated with the original clip.

FULL MOTION AND LIVE VIDEO

Full motion video refers to pre-stored video clips. Live video refers to live and it must be processed while it is being captured by the camera. . From a storage perspective, we should have the information about the coding algorithm used for compression. It need decoding also.

From a processing perspective, video should be presented to user with smooth and there should not be any unexpected breaks.

Hence, video object and its associated audio object must be transferred over the network to the decompression unit. It should be then played at the fixed rate specified for it.

For successful playback of compressed video, there are number of technologies. They are database storage, network media and protocols, decompression engines and display engines.