Taxonomy of Multimedia Objects

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Taxonomy of Multimedia Objects

• CHAPTER 2

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Type of media

• Discrete media
• Text
• Graphics (generated by computer)
• Still Image (captured from outside of computer)
• Continuous media
• Sound
• Video (captured from outside of computer)
• Animation (computer generated)

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The power of Meaning
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• Discrete media refers to text, still images or
  graphics which are composed of non-time-dependent
  fragments. Time is not part of the semantics of
  discrete media.
• Continuous media refers to information media,
  such as sound and motion video, the presentation
  of which requires a continuous play out as time
  passes or time-dependent fragments. Time is part
  of the semantics of continuous media.

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Text

• Printed text
• Scanned text
• Electronic text
• Hypertext (HTML ?)

I LOVE KUKTEM
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The power of hypertext.

• The words, sections and thoughts can be linked
  together.
• The user can navigate through text in a nonlinear
  way, quickly and intuitively.
• Can organize cross-linking of words to other
  media as well.

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Graphics

• Bitmaps
• Vector graphic
• Clip Art
• Digitized Pictures ? image
• Hyperpictures

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Images in Multimedia

• Images can be
• Drawings
• Paintings
• Photographs
• Sequences image?Video

Image Source http//www.toothpastefordinner.com/
111401/but-i-am-drawing.gif
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Sample of painting
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Sample of photograph
Image source http//www.malaysiaairlinesusa.com/
images/klia.jpg
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Colours and palettes in multimedia

• Colour is a frequency of a light wave within the
  narrow band of the electromagnetic spectrum to
  which the human eye responds.
• Different cultures associate certain colours with
  different meanings.
• The lowest common denominator for a multimedia
  display is a colour monitor that displays 8 bits
  of colour information per pixel in matrix of 640
  pixels across and 480 pixels down (640 x 480).

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Colours and palettes in multimedia

• for 256-color, 8-bit VGA systems, the computer
  uses a colour lookup table or palette to
  determine which 256 colours out of the million
  possible are available to you at any one time.
• Dithering is a process whereby the color value of
  each pixel is changed to the closest matching
  color value in the target palette, using a
  mathematical algorithm.

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The power of Sounds

• Sounds can closely touch our emotion or
  feeling.
• different intonations represent different
  messages even for the same sentences.
• Some feel-good music powerfully fills the heart,
  generating emotions of love etc.
• animation or video would not seems alive
  without sounds.

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Digital Audio

• Digitizing is a process converting a sound wave
  into numbers (binary system).
• Digitized sound is sampled sound. Every nth
  fraction of a second, a sample of sound is taken
  and stored as digital information in bits and
  bytes.
• The quality is depends on sampling rate or
  frequency in kilohertz (kHz).

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Sound in Multimedia

• Sound, also called audio, can be
• Voice-over or narration
• Sound effects
• Music

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Sound Object

• Waveform Audio
• MIDI
• Compact Disc (CD) Audio
• Audio CD
• CD Plus, CD Extra and Enhanced CD
• MP3
• Hyperaudio

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File Size Versus Quality

• Sampling at higher rates (44.1 kHz) more
  accurately captures the high frequency content of
  sound.
• Audio resolution ( 8- or 16-bit) determines the
  accuracy with which a sound can be digitized.
• Stereo recordings are more lifelike and realistic
  because human beings have two ears.

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Determine File Size

• File size (in bytes) abcd
• a sampling rate (44.1 kHz, 11 kHz etc)
• b duration or recording in seconds
• c bit resolution
• d channel (stereo 2, mono 1)

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Video in Multimedia

• Video can be
• Live
• Recorded

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Video in Multimedia

• Video requires the highest performance demand on
  computer compared to other media.
• Consider a high quality still image require as
  much as megabyte of storage memory. How about a
  video with 30 frames per second?
• To playback a very large file size of video
  requires fast data transfer devices such as RAID
  (Redundant Array of Independent Disks) which
  usually used by a server.
• Remember where the user will be using your
  multimedia product, PC?

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Video format

• Live video feeds
• Videotape (VHS)
• Videodisc (CAV CLV)
• Digital Video
• Digital Versatile Disc (DVD)
• Hypervideo

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Digital Video
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Animation in Multimedia

• Animation is a time-based graphics generated by
  computer program.
• 2D animation
• 3D animation

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Animation Techniques

• Frame Animation
• Vector Animation
• Computational Animation
• Morphing

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File Format

• There are two principal formats a file can have
• ASCII
• binary.

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Compression

• Data compression is making data use less space on
  a disk. When we compress data, we make it
  smaller. Some reasons why data are compressed
  are to make them download faster, to make them
  fit on floppy disks, and to make them easier to
  archive (keep).

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Lossy Compression

• A lossy data compression method is one where
  compressing a file and then decompressing it
  retrieves a file that may well be different to
  the original, but is "close enough" to be useful
  in some way. This type of compression is used
  frequently on the Internet and especially in
  streaming media and telephony applications. These
  methods are typically referred to as codecs in
  this context.

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Lossy File types

• JPEG
• Motion JPEG
• MPEG-1 Part 2
• MPEG-2 Part 2
• MPEG-4 Part 2
• DTS
• MP2
• MP3

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Lossless Compression

• Lossless data compression is a class of data
  compression algorithms that allows the original
  data to be reconstructed exactly from the
  compressed data

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Lossless File types

• RealPlayer - RealAudio Lossless
• PNG - Portable Network Graphics
• Lossless Transform Audio Compression (LTAC)

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Exercise

• What do you know about JPEG, GIF, SVG, SWF, PNG,
  TIFF, BMP and AVI.
• Printed books do not have hypertext ability.
  Compare the advantage and disadvantage of
  hypertext and traditional books.