Authoring and Multimedia Data

Data Sources Data Types Data Compression Techniques Data Security

Data Sources Data can be collected from many sources, such as books, people, Internet, magazines, television, radio. When we are using a source of data it is important to acknowledge that source and check the source for copyright. If we do acknowledge then we are plagarising someone else’s work and it is illegal to copy other people’s material without permission. If we are conducting a survey, interview or questionnaire, then it is vital that we have permission of the person before we publish any data about them.

CASE STUDY Art Plagiarism – read the following article on the website and answer the questions tion/case10.htmlhttp:// tion/case10.html How to avoid plagiarism – click on the Macromedia Flash version. enter/modules/plagiarism/start.htmlhttp:// enter/modules/plagiarism/start.html

Data Types Computers are great tools that can store, retrieve and manipulate information. Before this can be data we must collect, organise and analyse the data so that it can be transformed into information. Data falls into five main categories:  Text  Audio  Images  Hypertext  Animation and Video

Common Data Types TypeDescriptionUse TextA meaningful string of characters – letters, numbers, symbols or punctuation Fonts, Menus, Animated Text, Links AudioDigital Sound consisting of waves the represent change in air pressure Illustration and demonstration of concepts Speech and music ImagesDigitised pictures – graphicsLine drawings, photographs, scanned diagrams, icons, graphs etc HypertextText that acts as a link to another document or place. Link documents, images, etc Animation and Video The illusion of movement achieved by displaying a series of static images, called frames in a rapid sequence. Web pages, presentations, movies etc

Data Compression Techniques Graphics, audio and video files tend to very large which can be a problem for storage devices and transmission times. Two important methods are used to reduce the file size. They are:  Compression  streaming

Compression Compression reduces the physical size of large files using techniques to remove or summarise redundant or repetitious data. There are various methods of compressing files depending on the type of media. Most files can be reduced by 5 and 95 percent.

Methods of Data Compression TechniqueDescriptionUseCompression LosslessRepetitive patterns are coded into a summary and data retrieved is the same as data stored Most text files where it is vital that no data is lost, e.g. database files File may be reduced to 30% or more of original size LossyData discarded during compression e.g. shades of colour in a graphic or soft sounds in a sound file; some data is irretrievable lost Sound, images, and video files where lost data can be masked by other data File may be reduced to 5% of original size

Streaming Streaming is the process that allows video or audio frames to be loaded and played before later frames are loaded. As the frames are loaded, some are being played, others are being discarded from memory and still others are being loaded into RAM It appears that the whole movie is loaded, but only a few frames are retained in RAM Streaming depends on getting the steam of frames to move at the right rate (frames per second)

Data Security