28-09-2013, 01:15 PM
Introduction to Multimedia Systems
Multimedia Systems[.doc (Size: 600 KB / Downloads: 30)
What is Multimedia?
Before we go on, it is important to define multimedia. Let us define it from two perspectives:
1) In terms of what multimedia is all about?
It refers to the storage, transmission, representation, presentation and perception of different information types (data types) such as text, graphics, voice, audio and video where:
Storage- refers to the type of physical means to store data.
-Magnetic tape
-Hard disk
-Optical disk
-DVDs
-CD-ROMs, etc.
Presentation- refers to the type of physical means to reproduce information to the user. -Speakers
-Video windows, etc.
Representation- related to how information is described in an abstract form for use within an electronic system. E.g. to present text to the user, the text can be coded in raster graphics, primitive graphics, or simple ASCII characters. The same presentation, different representation.
General and working definition:
Multimedia is the field concerned with the computer controlled integration of text, graphics, drawings, still and moving images (video), animation, and any other media where every type of information can be represented, stored, transmitted, and processed digitally.
History of Multimedia Systems
Newspaper was perhaps the first mass communication medium, which used mostly text, graphics, and images.
In 1895, Gugliemo Marconi sent his first wireless radio transmission at Pontecchio, Italy. A few years later (in 1901), he detected radio waves beamed across the Atlantic. Initially invented for telegraph, radio is now a major medium for audio broadcasting. Television was the new media for the 20th century. It brings the video and has since changed the world of mass communications.
On computers, the following are some of the important events:
1945 -Vannevar Bush (1890-1974) wrote about Memex.
MEMEX stands for MEMory EXtension. A memex is a device in which an individual stores all his books, records, and communications, and which is mechanized so that it may be consulted with exceeding speed and flexibility. It is an enlarged intimate supplement to his memory.
Hypermedia/Multimedia
What is Hypertext and Hypermedia?
Hypertext is a text, which contains links to other texts. The term was invented by Ted Nelson around 1965. Hypertext is usually non-linear (as indicated below).
Hypermedia is not constrained to be text-based. It can include other media, e.g., graphics, images, and especially the continuous media -- sound and video. Apparently, Ted Nelson was also the first to use this term.
The World Wide Web (www) is the best example of hypermedia applications.
Desirable Features for a Multimedia System
Given the above challenges, the following features are desirable for a Multimedia System:
1. Very high processing speed processing power. Why? Because there are large data to be processed. Multimedia systems deals with large data and to process data in real time, the hardware should have high processing capacity.
2. It should support different file formats. Why? Because we deal with different data types (media types).
3. Efficient and High Input-output: input and output to the file subsystem needs to be efficient and fast. It has to allow for real-time recording as well as playback of data. e.g. Direct to Disk recording systems.
4. Special Operating System: to allow access to file system and process data efficiently and quickly. It has to support direct transfers to disk, real-time scheduling, fast interrupt processing, I/O streaming, etc.
5. Storage and Memory: large storage units and large memory are required. Large Caches are also required.
6. Network Support: Client-server systems common as distributed systems common.
7. Software Tools: User-friendly tools needed to handle media, design and develop applications, deliver media.