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					                                               MULTIMEDIA

Introduction
What is Multimedia?
Multimedia consists of two words.
According to the Oxford Dictionary:
      Multi: many; more than one
      Media: main means of mass communication regarded collectively

By combining those two words multi & media we can get a definition of the term „Multimedia‟ to
mean the combination of more than one medium of communication in one application or interface.

Another definition is:
      “Digital Multimedia is any combination of two or more media, represented in a digital form,
      sufficiently well integrated to be presented via a single interface, or manipulated by a single
      computer program.”
      Digital Multimedia, Nigel Chapman and Jenny Chapman, Wiley, 2000.




Text
Introduction
Text is a powerful tool that can be used as a language to convey information or as a graphic or
visual medium. These can include examples such as the font style or the style in which the font is
displayed.




 This is an example of text being used to represent language, i.e. express information.




 The Glamorgan University Logo is an example of text being used as a graphic element.




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Terminology
Here is a closer look at some of the more commonly used attributes for defining the look of a font.

Typeface Family This would be the name of the general look of the font. =e.g. Arial
Typeface: This would be the more specific look of the font to include the style. = e.g. Arial italics
(Although sometimes „typeface‟ is used instead of the „typeface family‟ term.)
Font This is the comprehensive description of the collection of characters. This description would
include the typeface the style and the size - e.g. Arial italics 12-point

Style = e.g.: italics, bold, underline
Size: The size of the font is measured in points. The standard default size is 12-point.



Sans Serif & Serif
Sans Serif is a font style that includes only the lines necessary to make up a character.
Serif is a font style that includes additional decorative lines that enhance the style of the font.

Example:


       ABC ABC
           Sans           Serif

A typical sans serif is „Times New Roman‟ and a typical sans is „Arial‟.



Images
Bitmap Graphics (or Raster Graphics)

Bitmaps are images that consist of individual pixels on a grid. Each pixel stores information about
its colour. When resizing an image quality can be easily lost.
Bitmaps are use for photo-realistic images and for drawings that require fine detail.

An example of a program that works with Bitmap Graphics is Adobe Photoshop.

Examples of bitmap file types:
 GIF – Graphic Interchange Format
 JPEG – Joint Photographic Expert Group (Bitmap Compression)
 PSD – Photoshop document – Allows to save image with layers
 BMP – Windows Bitmap
 PICT – Apple file format

GIFs and JPEGs are the most commonly used type of web graphic.




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GIF (Graphic Interchange Format)


GIFs can only use up to 256 colours. Therefore
they are more useful for images with fewer
colours and are not as good for photos. GIFs can
be transparent, interlaced (the image starts to
appear before the whole image has been loaded)
or animated (multiple images are combined into
one file).




JPEG (Joint Photographic Expert Group)


The compression method used in JPEGs does
not reduce the amount of colours used (millions
of colours can be used). JPEGs are useful for
photographic images or very detailed
illustrations, especially those with gradations of
colours.




Vector Graphics

Vector Graphics are images that are mathematically expressed in angles, coordinates, and distances.
Vector Graphic is especially useful when creating images with lots of shapes. But they can not be
used directly for the web. Instead, they have to be converted into a pixel-based image such as GIF
or JPEG. One of the Vector Graphic‟s advantages is that it does not loose quality when it is scaled
down.

Example of programs that work with Vector Graphics:
      Adobe Illustrator
      Corel Draw
      Macromedia Freehand


Audio




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Digital Sound
Digital sound is made up of a large number of discrete samples which approximate the original
analogue sound, and which require large amounts of storage space.

Digital representations have a number of advantages over analogue:

          ease of manipulation and editing
          ease and accuracy of replication
          single storage medium
          ease of compression



Audio Use in Multimedia

Audio could be used as:
 Background sound: Music or sound effects can be used to convey a specific atmosphere.
 Narration: Something is happening on the screen and a voice describes it.
 Testimonial: i.e. when an individual recommends a specific product or service.
 Music: When the sound is used for its own purpose and not as a background.

A Useful Tip:
If audio is used as background sound it is important to give an option to switch it off.


Animation

According to www.webopedia.com animation is “a simulation of movement created by displaying a
series of pictures, or frames.”

Animation distinguishes itself from video by having each frame individually created whereas a
video automatically records a certain amount of frames per second.

Animations can be created in programs such as Marcromedia Fireworks where they are saved as an
animated GIF file or Marcromedia Flash where it is saved as a SWF file.


Video


What is a Video
A video is similar to an animation but the frames are recorded rather than individually created and
therefore they tend to hold more frames per second than an animation. This can take a large amount
of storage space making videos harder to work with on the web.

Types of Videos
 Analogue Video
 Digital Video
           o QuickTime
           o Audio Video Interleaved (AVI)
           o Fractal Movie (VideoBox)

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           o Motion Picture Expert Group (MPEG)


Video on the Web
 Video can tell a story
 Entertain an audience
 Explain a complex process

Videos can enhance the experience for the web user, but due to their high bandwidth demand tend
to be compressed or displayed in miniaturised form i.e. small window.

An example of a good use of video on the web is the apple trailer website. See link below.
http://www.apple.com/trailers/


Terminology
Frame size = Number of pixels per frame (The more pixels the better the quality but the larger the
file size)

Frame rate = Number of frames per second.
      On a computer a rate of at least 12-15 frames per second is needed to not get a flickering
      effect. Because of that it takes a lot of storage and therefore requires compression.

Colour depth = Number of bits to represent colours



Interactivity

Interactivity is an attempt of incorporating users into the decision of how a particular process will
flow, i.e. how much control does a user have over the given experience.

It is important to design a multimedia application in a way that the user always feels in control,
making actions predictable and reversible, with a clear indication of the progress made. This tends
to give the user a sense of satisfaction with a feeling of progress and achievement.



Compression
Data Compression
Multimedia on the web would not be possible without data compression.

   Compression works like this:
       Multimedia content of web page is digitised and stored in file.
       Multimedia content in file is compressed using appropriate software i.e. a codec.
       Compressed file linked or embedded in web page.
       User downloads web page including the compressed multimedia content
       User‟s browser decompresses the multimedia content and transmits it through the PC.
       User sees or hears the decompressed item.



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   The greater the compression the faster it will travel over the web; however the lower the quality.



Compression Techniques

Removing repetition:
The codec finds identical pixels and rather than recording each pixel, just makes of note of how
many they were. This is a form lossless compression.

Averaging:
Where pixels are very similar the codec records one average pixel rather than each individual pixel.

Range reduction:
Rather than delivering the full original range compression takes place by choosing an average range
that will represent the original. This is often used for compressing sound.

Selectivity:
By being selective a codec can compress file sizes with hardly any perceptive loss. The codec
achieves this by having innate knowledge of what humans actually notice and removing the things
we don't. Typical examples are lowering the frame rate, removing low background noise.

Frame-difference compression (or 'Inter-frame compression'):
This form of compression records compares video frame by frame and records all the unchanging
pixels (such as the background) only once. Only the frame differences are recorded in the form of a
list of which pixels change.




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Quiz

Q 1: The term Multi means?
A: Using images as maps E.g.: Multimap.com
B: A rare spice like Ginger, Psyllium, or Saffron.
C: Many; more than one.
D: Something bigger or greater than oneself.

Q 2: The term Media means?
A: Propaganda spread by the newspapers.
B: A method of communicating to collectives.
C: A recordable device like a CD.
D: Psychic or supernatural vision.

Q 3: The term Sans Serif means?
A: A commonly used Text editor.
B: A font that strip away all but its necessities.
C: Fonts based on ancient Roman times.
D: The term used to describe the font. I.e.: the fonts Size, Colour, and Style.

Q 4: The term Serif means?
A: The name of an image file-type.
B: A type of compression codec.
C: The local police force in old western towns.
D: A font style that includes additional decorative lines.

Q 5: The term JPEG means?
A: Joint Pixels Expressed Graphically
B: Joint Photographic Expert Group
C: An analogue to digital conversion system.
D: A Corel Draw file-type.

Q 6: Images that are mathematically expressed in angles, coordinates, and distances are
known as?
A: PICT
B: Animations
C: Vector Graphics
D: Background Images

Q 7: Analogue sound is better for?
A: Manipulation and editing.
B: Accuracy of replication.
C: Easy compression.
D: Quality.

Q 8: Animation files are commonly stored as?
A: GIF or SWF files
B: AVI or PSD files
C: PICT or JPEG files
D: BMP or MPEG files


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Q 9: The main problem with incorporating videos in websites is?
A: They are very complex to incorporate.
B: They require a high bandwidth.
C: They don‟t tell the whole story.
D: They detract from the main point of the website.

Q 10: The most important elements of interactivity in a website are?
A: Directing the user‟s progress and having an attractive display of links.
B: Insuring the users gets back to where they started and know where they are.
C: Giving user control, having predictable links and options to go back.
D: Giving users more than one possible rout to take and having a satisfying background display.



Answers:

Q 1: C
Q 2: B
Q 3: B
Q 4: D
Q 5: B
Q 6: C
Q 7: D
Q 8: A
Q 9: B
Q 10: C



Resources

Web Multimedia Tutorial
http://www.w3schools.com/media/default.asp

Web Graphics Tutorial
http://www.htmlgoodies.com/tutorials/web_graphics/index.php

Dictionary and search engine for computer and internet technology definitions
http://www.webopedia.com/

The web developer's resource
http://webmonkey.wired.com/webmonkey/

IBM Ease of Use Guidelines
http://www-3.ibm.com/ibm/easy/eou_ext.nsf/publish/567PV




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