Transcript Intermediate 2 Multimedia Technology

Computing
Intermediate 2
Multimedia Technology
1
The 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.
2
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.
3
The 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.
4
The 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.
5
The 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.
6
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.
7
Methodologies used to view
multimedia applications
 Displaying multimedia applications in a
browser.
 Displaying multimedia applications using a
file player or viewer.
8
Methodologies used to view
multimedia applications
Multimedia application as an executable file
9
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
10
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.
11
Bit-mapped Graphic Data
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.
12
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.
13
Bit-mapped Graphic Data
 JPEG format suitable
for storing
photographs
and paintings.
14
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.
15
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.
16
Bit-mapped Graphic Data
Main features of image editing programs






Decrease resolution
Alter colour depth
Crop
Alter brightness and contrast
Insert graphic
Re-size.
17
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.
18
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.
19
Digitised Sound Data
Hardware for capturing sound
 Microphone
 Sound cards: to sample, store and process
audio data.
20
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
21
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.
22
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.
23
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.
24
Digitised Sound Data
Editing sound file features:




Volume
Effects
Echo
Reverse
25
Digitised Sound Data
Sound cards and playback:
Sound cards needed to change the digital
audio data into analogue signals to control
output from speakers.
26
Video Data
Hardware for
capturing images
 Digital video camera
 Web cam
27
Video Data
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.
28
Video Data
Compressing video data
 MPEG-2
Lossy compression: cuts out unnecessary
parts of a video clip
29
Video Data
Compressing video data
Using MP3 compression:
 Reduces file sizes
 With no noticeable loss of
video quality.
30
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’.
31
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.
32
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.
33
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.
34
Vector Graphics Data
Common attributes of vector
graphic objects:



Position
Shape
Size
35
Vector Graphics Data
Common attributes of vector
graphic objects:




Rotation
Line
Layer
Fill
36
Vector Graphics Data
Attributes of a 3D image:





Shape
Position
Size
Rotation
Texture
37
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
38
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.
39
Synthesised Sound Data
Musical Instrument Digital Interface:
MIDI
Common attributes of notes stored as
MIDI data:
 Instrument: defines which
instrument is playing
 Pitch: defines the height of the note
 Volume: determines the amplitude
 Duration: determines the length of
40
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.
41
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.
42
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.
43
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.
44
Implications of Multimedia
Technologies
 Immersive VR
 Output: Using speakers, stereo screens,
headsets
 Input: sensors in gloves, headsets and
suits
45