Nat 4/5 - Software Design and Development – Low Level Operations - 1 National 4/5 – Computing...

Nat 4/5 - Software Design and Development – Low Level Operations - 1

National 4/5 – Computing ScienceInformation Systems Design and

Development

Media Types


Media Types – National 4

Computers use data of many different data types. Examples of data types are:-

• Numbers• Text• Graphic• Audio• Photographic• Video• Animation

You will already be familiar with audio data files (eg MP3) and video data files (eg MP4, AVI), or even photographic data files (eg JPG) just from using your Smartphone! For data to be able to be freely shared between computers it must be saved in a standard file format. MP3, MP4 and JPG file formats are some examples of standard file formats.



Multimedia consists of text, graphics, sound, video and animation which is used to create a presentation/web page. Presentations created in packages such as Powerpoint are made up of lots of different presentation elements. Presentation elements are in multimedia format ie text, graphic, audio video, and animation. These elements are brought together to create a multimedia presentation – just like the ones you created in lower school. When these types of data are incorporated into web pages or presentations it makes the presentation more interesting to the user and is more likely to catch the reader’s attention.

Nat 4 - Tasks 1 and 2



Presentations are viewed as slides in the order they were created eg Slide 1 > Slide 2 > Slide 3 etc.

However, it is possible to view slides in any order if Hyperlinks are used to move from one slide to any other slide. Hyperlinks can be links to:

A page in the current document A web page A file




Hyperlinks can therefore be used to view slides in a presentation in a different order eg

Nat 4 - Tasks 1-4

By clicking on the hyperlinks (underlined) you can go directly to the slide you want.If you put a home link on the individual pages it can take you back to the home page.



Standard File Formats Files should be stored in a standard file format so

that a file can be imported into most software packages, irrespective of the manufacturer of the package.

This means that it is much easier to share data between users using different computer hardware and software.

Packages such as word processors, presentation, spreadsheet, database and web authoring packages can all import different file types that they have been programmed to support.

It is always best to save files as a standard file format if you are intending sending the file to someone else, to allow data to be freely shared between different systems.



Let’s look at some of the different standard file formats that we need to get to know:



Standard File Formats for Text TXT – Text File format contains only ASCII characters

and no formatting information (this means all fonts, styles and sizes are lost when data is saved in this format).

RTF - Rich Text Format – a complex format that retains the formatting information (font, size, colour, graphics). This means your nicely formatted document can be read by different software packages, eg transferred from one Word Processor to another.




Standard File Formats for Audio WAV - Waveform Audio File Format stores an audio

bit-stream for PCs in an uncompressed format. This format is a Microsoft/IBM format and is used for most Windows applications that support sound.

MP3 - The MP3 format compresses sound data without losing sound quality and so these files are smaller but just as sharp as their CD counterparts. Their smaller size means that they’re ideal for transferring across the internet.

Nat 5 – Task 7



Standard File Formats for Graphic JPEG - This is a compressed graphic format where

similar colours and minor changes are removed. Joint Photographic Expert Group images are mainly used for saving high quality photos for use on the web. The greater compression used when the file is saved, the more information is lost and so the lower the quality of the photograph, but the file size is smaller.

This format can use an infinite number of colours and so can be the highest quality.

Files created with a digital camera or scanner can be saved in this format.

JPG uses lossy compression



Standard File Formats for Graphic BMP - This is a bitmapped image file which is not

compressed and therefore takes a large amount of storage space. BMP are for pixel based images, eg Windows wallpaper

BMP files do not scale well. BMP files are usually 16-bit, 24-bit or 32-bit (ie 65,536; 16,777,216; or 4,294,967,296 colours)

Files which are scanned or taken by a digital camera have a ‘native file format’ that is BMP, they are files of pixel data – these are compressed to JPG etc on saving. The native file format is the original file before it is compressed by the digital camera/saved to ad different file format when the scanned image is saved.



Standard File Formats for Graphic GIF - This is a compressed graphic format. Graphics

Interchange Format is mainly used for saving icons and other small graphic files and uses 2-256 colours, so it’s not ideal for photographic images to be saved this way.

Note: There is also a type of GIF that shows movement, an animated GIF. It combines several images into one file, and works by cycling through the images in the file. This file type is often used on the internet as it is supported by most of the main web browser programs and is quite a bit smaller than its rivals. This format can use up to 256 colours. GIF uses lossless compression

PNG - This is a lossless compression format that uses 48-bit colour and can produce files 10-30% smaller than GIF format. Nat 5 - Tasks 8, 9 and

10



Standard File Formats for Video AVI - This is the standard for Microsoft’s Video of

Windows and uses file compression to reduce file size.

MPEG - This is a compressed video file format. The mpeg format is a higher quality, compressed format than AVI. Compression is achieved by only storing what changes between each frame, and not the entire frame. It uses a type of lossy compression.



Standard File Formats for Spreadsheets XLS - This is the default file extension for MS Excel

spreadsheet files up to 2003. CSV - This stands for Comma Separated Value file.

It stores tabular ASCII text data as a field value followed by a comma. This allows text/number data to be read into the fields in a database, cells in a spreadsheet or into a word processor where it can be formatted using the tab key. Eg to store pupil names and classes it could look something like this: John,Smith,3.2Ann,Grant,3.9The commas are used to separate the data into fields/records, or cell/rows.

XML - XML is an Extensible Markup Language file type designed to transport and store data independent of both hardware and software. (HTML is used to format and display the data).Nat 5 - Tasks 11a and

11b



Standard File Formats for Documents PDF - Portable Document Format is a file format

used to represent documents in a manner independent of application software, hardware and OS. The file type holds a complete description of a fixed-layout document including text, fonts, graphics and other information needed to display it. PDF reader (Adobe Reader) is free of charge and allows you to read PDF files.



Factors Affecting File Size and Quality - Graphic

Resolution - This is the total number of pixels in the height and width of an image.

The more pixels the better the quality the image as the pixels are smaller and can store more detail. However, this will increase the file size.

Teletext graphics are very low resolution (images tend to be jagged/blocky), while computer monitors are high resolution (pixels small with lots of detail).



Factors Affecting File Size and Quality - Graphic

Colour Depth/Bit Depth – This is the number of colours that can be stored per pixel. In a graphic with 8-bit colour each pixel can have 256 different colours but 8 bits must be stored for every pixel on screen. If the colour depth is increased to 16 bits then 16-bits must be stored for every pixel to determine its colour, but it can then display 65,536 different colours. Bits Per Pixel Calculation Number of

Colours1 21 22 22 43 24 88 28 256n 21



Factors Affecting File Size and Quality - Audio

Sampling Rate - The sample rate is the number of times per second a sound is stored. The more times per second the sound is stored the closer to the original the sound is, therefore the higher the quality of the sound. This is turn leads to a larger file size. A sample rate of 44.1 kHz will produce a much bigger file size than a sample rate of 22 kHz.



Compression Compression reduces the size of a file and is

really important when transferring files on the internet, or when storing data on an external device such as a small pen drive. Keeping file sizes small means that data can be transferred quicker, ie it downloads the file faster. However, compressing a file can affect its quality.

Lossy Compression - Losses some of the original data by removing data the eye will not miss eg shading in a blue sky.

Lossless Compressions - This does not lose the original data.

Nat 5 – Task 12

Nat 4/5 - Software Design and Development – Low Level Operations - 1 National 4/5 – Computing...

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