Computing
Intermediate 2
Multimedia Technology
The Development Process and
Multimedia Applications
The Software Development Process and
Multimedia Applications
• Analysis: The main purpose of this stage is
to be absolutely clear about what the
multimedia project is supposed to do.
The Development Process and
Multimedia Applications
• Design: Producing a detailed plan which
defines what the different parts of the
project are and how they are linked
together.
The Development Process and
Multimedia Applications
The Software Development Process and
Multimedia Applications
• Implementation: This is the point at which
the multimedia authoring, or web-page
authoring, package is used to turn the
design into a working project.
The Development Process and
Multimedia Applications
The Software Development Process and
Multimedia Applications
• Testing: A series of practical tests are
carried out to check that the multimedia
project functions properly.
• Documentation: User Guide and Technical
Guide.
The Development Process and
Multimedia Applications
The Software Development Process and
Multimedia Applications
• Evaluation: Checks that the finished
application meets the user’s requirements.
Includes an assessment of the HCI design.
• Maintenance: Fixing bugs and adapting the
design to suit client needs and the demands
of new technology.
Methodologies used in creation
of multimedia applications
• Text editor: Creating simple web pages
using HTML.
• WYSIWIG editors: Previewing applications
under development to check that what you
see is what you get.
• Multimedia authoring packages, e.g.
Mediator Pro.
• Presentation software, e.g. PowerPoint.
Methodologies used to view
multimedia applications
• Displaying multimedia applications in a
browser.
• Displaying multimedia applications using a
file player or viewer.
Methodologies used to view
multimedia applications
Multimedia application as an executable file
Bit-mapped Graphic Data
• Capturing still images
using a digital camera
• Using a CCD to capture
light coming in through a
lens
• CCD charged coupled
device: uses sensors to
capture light
• Capturing images using a
scanner: also uses CCD
Bit-mapped Graphic Data
• Storing graphics as a bit map: each pixel in the
image is represented by a binary number.
• Uncompressed bit-map format: a file which holds
a binary number for each pixel in an image.
• Large file size: main limitation of bit-map format.
• Need for compression: to relieve demands on
storage and transmission times.
Bit-mapped Graphic Data
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Compression using GIF format
Lossless compression: GIF format compresses
graphic data without losing any information about
the image. It compresses by encoding repeated
patterns of data.
Limited number of colours: limited to 28, 256
colours.
Transparency: colours set as transparent let the
background colours and patterns show through.
Used for storing cartoons, and line drawings.
Bit-mapped Graphic Data
JPEG
• Uses lossy compression: parts of the
graphic are cut out, e.g. shades of colour.
At low rates of compression this is not
noticeable.
Bit-mapped Graphic Data
JPEG
• JPEG format suitable
for storing
photographs
and paintings.
Bit-mapped Graphic Data
Trading quality for file size
• Resolution: increasing resolution increases the
number of pixels, can improve the quality of a
graphic but increases the file size.
• Colour depth: increasing colour depth increases
the number of colours or shades of grey, can
improve the quality of a graphic but increases the
file size.
• Lossy compression: reduces file size and,
providing the rate of compression is not too high,
does not affect the quality of the graphic.
Bit-mapped Graphic Data
Simple bit-map editing and creation
software
Painting programs
Fill tool: a feature for pouring colour into a
graphic.
Paintbrush tool: for more precise
application of colour.
Bit-mapped Graphic Data
Main features of image editing programs
• Decrease resolution
• Alter colour depth
• Crop
• Alter brightness and contrast
• Insert graphic
• Re-size.
Bit-mapped Graphic Data
Hardware for displaying 2D
graphics
• CRT monitor: bulky, heavy, run
on mains power, cost less than
equivalent TFT screens.
• LCD and TFT screens: flat, light,
need less power, more expensive
than CRT.
Bit-mapped Graphic Data
Hardware for displaying graphic data
• Need for graphics cards to store and process
graphic data, relieving the main processor
of the task.
Digitised Sound Data
Hardware for capturing sound
• Microphone
• Sound cards: to sample, store and process
audio data.
Digitised Sound Data
Uncompressed sound data
• RAW: Uncompressed samples of sound
waves
0101010101010101 1111111101010101
0011001100101011 1100101000110001
• RIFF: Resource Interchange File Format
• WAV: Microsoft's format for sound files,
part of RIFF
Digitised Sound Data
• Lossy compression: reduces file sizes by
cutting out some of the data.
• MP3: uses lossy compression without
noticeable loss of sound quality.
Digitised Sound Data
Balancing file size and sound quality
• Sampling depth: increased sound depth =
greater range of values = better sound
quality and greater file size.
• Sampling frequency: The higher the
sampling frequency, the better the sound
quality, the greater the file size.
• Sound time: affects file size but not quality.
Digitised Sound Data
Simple sound editing software
• Reducing sample frequency, e.g. from 44.1
KHz to 22.05 KHz, reduces file size and
audio quality.
• Reducing sample depth, e.g. from 16 bits to
8 bits per sample, reduces file size and
audio quality.
Digitised Sound Data
Editing sound file features:
Volume
Effects
Echo
Reverse
Digitised Sound Data
Sound cards and playback:
Sound cards needed to change the digital
audio data into analogue signals to control
output from speakers.
Video Data
Hardware for capturing images
• Digital video camera
• Web cam
Video Data
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Storing video data
Uncompressed format
Uncompressed video data = Large file sizes
1 second of uncompressed wide-screen
video can take up 53 Megabytes of storage
AVI: Audio Visual Interleave, an
uncompressed format.
Video Data
Compressing video data
• MPEG-2
Lossy compression: cuts out unnecessary
parts of a video clip
Video Data
Compressing video data
Using MP3 compression:
• Reduces file sizes
• With no noticeable loss of video
quality.
Video Data
Video quality and file size
• Colour depth: increasing colour depth improves
quality and file sizes.
• Resolution: increasing resolution improves quality
and increases file sizes.
• Frame rate: measured in frames per second, fps.
30fps is the rate for a video clip. Increasing frame
rate increases file size. Lower frame rates reduce
file size but make video clip ‘jerky’.
Video Data
Video quality and file size
• Video time: increasing or reducing the time of a
video is the obvious way to affect the file size.
Quality of the display of the clip is not affected.
• Lossy compression: Using MP3 compression
reduces file sizes without affecting quality.
Video Data
Video editing software features and
applications used with single video clips
• Cropping: cutting unwanted data from the
beginning and end of a clip.
• Add effects, titles, sound tracks.
• The need for graphics cards to process and
output video data.
Vector Graphics Data
Basic features of vector graphics
• They are scalable: resolution independent.
• In a vector graphic individual objects can be
edited.
• Graphics can be assembled by placing
objects in layers.
Vector Graphics Data
Common attributes of vector graphic
objects
Position
Shape
Size
Vector Graphics Data
Common attributes of vector graphic objects
Rotation
Line
Layer
Fill
Vector Graphics Data
Attributes of a 3D image
Shape
Position
Size
Rotation
Texture
Vector Graphics Data
Standard formats for vector graphics
Scalable Vector Graphics (SVG) format
Scalable: resolution independent
Vector: represents objects by defining a
series of attributes
Vector Graphics Data
Standard formats for vector graphics
Virtual Reality Markup Language
A standard language used to model and
animate geometric shapes
Used to define 3D environments for the
WWW.
Synthesised Sound Data
Musical Instrument Digital Interface:
MIDI
Common attributes of notes stored as MIDI
data:
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Instrument: defines which instrument is playing
Pitch: defines the height of the note
Volume: determines the amplitude
Duration: determines the length of the note.
Synthesised Sound Data
Common attributes of notes stored as MIDI
data
Duration: determines the length of the note.
Tempo: the speed at which a piece of music is
played.
Implications: Multimedia
Technologies
Converging contemporary technologies
• Smartphone: merging technologies of a
mobile phone and a laptop.
• Pocket PC: merging technologies of a
laptop, mobile phone and desktop
operating system and application
software.
Implications of Multimedia
Technologies
Contemporary technologies
• Digital television: an interactive multimedia
device which, because of the digital nature
of its signals, is easily integrated into your
digital computer and home networks.
Implications of Multimedia
Technologies
Contemporary technologies
Virtual reality
The ultimate multimedia experience where the
user is immersed in the world of the
computer and can journey through, and
interact with, a computer generated 3dimensional multimedia world.
Implications of Multimedia
Technologies
• Immersive VR
• Output :Using speakers, stereo screens,
headsets
• Input: sensors in gloves, headsets and suits