1. Digital representation of information
Analog and Digital Communication/transmission
Digitization process (signal sampling, quantization, and encoding)
Number systems
Telecommunication signals and their representation
Analog to digital conversion of voice
Multimedia
FUNDAMENTAL PRINCIPLES
2. DIGITAL REPRESENTATION OF INFORMATION
Data can be name, number, colors in a photograph, notes in a musical composition, etc. Data
Representation refers to the form in which data is: Stored, Processed, and transmitted.
Devices such as smartphones, and computers store data in digital formats that can be handled
by electronic circuitry.
Digitization is the process of converting information into digital data that can be manipulated
by electronic devices. The 0s and 1s used to represent digital data are referred to as binary
digits. A bit is a 0 or 1 used in the digital representation of data.
A digital file is a collection of data that exits on a storage medium, such as a hard disk, CD,
DVD, or flash drive.
Numeric data consists of numbers that can be used in arithmetic operations. Digital devices
represent numeric data using the binary number system, also called base.
3. Data can be analog or digital. The term analog data refers to information that is continuous;
digital data refers to information that has discrete states. Analog data take on continuous values.
Digital data take on discrete values.
ANALOG AND DIGITAL
ANALOG AND DIGITAL SIGNALS
Signals can be analog or digital. Analog signals can have an infinite number of values in a
range. Digital signals can have only a limited number of values.
Figure 1: Comparison of analog and digital signals
4. PERIODIC ANALOG SIGNALS
In data communications, we commonly use periodic analog signals and nonperiodic digital
signals.
Periodic analog signals can be classified as simple or composite. A simple periodic analog
signal, a sine wave, cannot be decomposed into simpler signals. A composite periodic analog
signal is composed of multiple sine waves.
Figure 2: A sine wave
Figure 3: Two signals with the same phase and
frequency, but different amplitudes
5. FREQUENCYAND PERIOD
Frequency and period are the inverse of each other.
Figure 4: Two signals with the same amplitude and phase,
but different frequencies
Table 1: Units of period and frequency
Example: The period of a signal is 100 ms.
What is its frequency in kilohertz?
6. Frequency is the rate of change with respect to time. Change in a short span of time means
high frequency.
Change over a long span of time means low frequency.
If a signal does not change at all, its frequency is zero. If a signal changes instantaneously, its
frequency is infinite.
Phase describes the position of the waveform relative to time 0.
FREQUENCY
Figure 5: Three sine waves with the same amplitude and
frequency, but different phases
Example: A sine wave is offset 1/6 cycle with respect
to time 0. What is its phase in degrees and radians?
Solution
We know that 1 complete cycle is 360°. Therefore,
1/6 cycle is
7. THE TIME-DOMAIN AND FREQUENCY-DOMAIN PLOTS OF A
SINE WAVE
Figure 6: The time-domain and frequency-
domain plots of a sine wave
A complete sine wave in the time domain can be represented by one single spike in the
frequency domain.
The frequency domain
is more compact and
useful when we are
dealing with more than
one sine wave.
8. EXAMPLE
Figure 7 shows three sine waves, each with different amplitude and frequency. All can be
represented by three spikes in the frequency domain.
Figure 7: The time domain and frequency domain of three sine waves
9. SIGNALS AND COMMUNICATION
A single-frequency sine wave is not useful in data communications. We need to send a
composite signal, a signal made of many simple sine waves.
According to Fourier analysis, any composite signal is a combination of simple sine waves with
different frequencies, amplitudes, and phases.
COMPOSITE SIGNALS AND PERIODICITY
If the composite signal is periodic, the decomposition gives a series of signals with discrete
frequencies.
If the composite signal is nonperiodic, the decomposition gives a combination of sine waves
with continuous frequencies.
10. EXAMPLE
Figure 8 shows a periodic composite signal with frequency f. This type of signal is not typical
of those found in data communications. We can consider it to be three alarm systems, each with
a different frequency. The analysis of this signal can give us a good understanding of how to
decompose signals.
Figure 8: A composite periodic signal
Figure 9: Decomposition of a composite periodic
signal in the time and frequency domains
11. Figure 10 shows a nonperiodic composite signal. It can be the signal created by a microphone
or a telephone set when a word or two is pronounced. In this case, the composite signal cannot
be periodic, because that implies that we are repeating the same word or words with exactly the
same tone.
Figure 10: The time and frequency domains of a nonperiodic signal
TIME AND FREQUENCY DOMAINS OF A NON-PERIODIC SIGNAL
12. BANDWIDTH AND SIGNAL FREQUENCY
Figure 11: The bandwidth of periodic and nonperiodic composite signals
The bandwidth of a composite signal is the difference between the highest and the lowest
frequencies contained in that signal.
13. EXAMPLE
If a periodic signal is decomposed into five sine waves with frequencies of 100, 300, 500,
700, and 900Hz, what is its bandwidth? Draw the spectrum, assuming all components have a
maximum amplitude of 10V.
Solution: Let fh be the highest frequency, fl the lowest frequency, and B the bandwidth. Then
The spectrum has only five spikes, at 100, 300, 500, 700, and 900 Hz
Figure 12: The bandwidth for the Example
14. A periodic signal has a bandwidth of 20 Hz. The highest frequency is 60 Hz. What is the lowest
frequency? Draw the spectrum if the signal contains all frequencies of the same amplitude.
Solution: Let fh be the highest frequency, fl the lowest frequency, and B the bandwidth. Then
The spectrum contains all integer frequencies. We show this by a series of spikes.
Figure 13: The bandwidth for Example
EXAMPLE
15. A nonperiodic composite signal has a bandwidth of 200 kHz, with a middle frequency of 140
kHz and a peak amplitude of 20 V. The two extreme frequencies have an amplitude of 0. Draw
the frequency domain of the signal.
Solution: The lowest frequency must be at 40 kHz and the highest at 240 kHz.
Figure 14: The bandwidth for Example
EXAMPLE
16. PRINCIPLES OF DIGITIZATION
Digitization is achieved by recording or sampling the continuous sound wave at discrete points.
The more frequently one samples the closer one gets to capturing the continuity of the wave.
To store voice, audio, or video data on a computer, we must digitize it by converting it into a
stream of numbers. Three processes are involved: Sampling, Quantization, and Encoding.
The analog signal is sampled.
The sampled signal is
quantized.
The quantized values are
encoded as streams of bits.
Figure 15: Principles of Digitization
17. SAMPLING
By taking many measurements at uniform intervals, gives a series of numbers, the digital form.
This is called sampling. Digital samples capture the basic structure of analog data, but they can
be inaccurate due to limited precision.
Divide the horizontal axis
(time) into discrete pieces
The number of samples per second is called the
sampling rate (Eg. 34/s), and it is measured in Hz.
Telephone (sampling rate)=8 kHz (8,000 samples
per sec.)
VoIP (sampling rate )=16 kHz (16,000 samples
per sec.)
Audio CD or MP3 (sampling rate )=44 kHz
(44,000 samples per sec.)
Figure 16: Sampling
21. NUMBER SYSTEMS
Number systems are used in the digital world and the methods for converting them to and from
our everyday number system (decimal).
The four number systems are: Decimal -base (10), Binary-base (2), Octal -base (8), and
Hexadecimal-base (16)
22. BINARYTO DECIMALCONVERSION
Technique: Multiply each bit by 2n,
where n is the “weight” of the bit The
weight is the position of the bit,
starting from 0 on the right. Add the
results
Convert 101011 to decimal
Convert the following from base
two/binary to decimal
(1) 10101112
(2) 11012
(3)110010102
DECIMALTO BINARY CONVERSION
This method repeatedly divides a decimal number by 2
and records the quotient and remainder. The remainder
which will represent the binary equivalent of the decimal
number is written beginning at the least significant bit
(LSB) and each new digit is written to the most
significant bit (MSB) of the previous digit. Convert 13
from decimal to binary.
Convert the following from
Decimal to Binary.
6710
1210
12510
23. HEXADECIMAL SYSTEM
Hexadecimal digits, are base-16 numbers. It uses
decimal numbers, and then the first six Latin
letters: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F
Why Hexadecimal?
Four bits make one hexadecimal digit
1110 1011 0101
E B 5 => EB5 in hexadecimal
The octal numbering system is also known as the
base 8 system. It uses digits from 0 to 7. Groups of
three binary digits can be used to represent each
octal digit.
Why octal?
Ease of use and conversion
Three bits make one octal digit
111 010 110 101
7 2 6 5 => 7265 in octal
OCTAL SYSTEM
BINARY TO HEXADECIMAL
CONVERSION
Technique
Group bits in fours, starting on the
right
Convert to hexadecimal digits
Example: Convert
00101011101011012 to hexadecimal
Answer:
0010 1011 1010 1101
2 B A D
24. HEXADECIMALTO BINARY
Technique
Convert each hexadecimal digit to a
4-bit equivalent binary representation
Convert FAB416 to binary.
Answer:
F A B 4
1111 1010 1011 0100
FAB416=1111101010110100
BINARY TO OCTAL
Technique
Group bits in threes, starting on right
Convert to octal digits
25. OCTALTO BINARY
Technique
Convert each octal digit to a 3-bit
equivalent binary representation
OCTALTO DECIMAL
Technique:
Multiply each bit by 8n, where n is the
“weight” of the bit.
The weight is the position of the bit, starting
from 0 on the right. Add the results
1378 = 1 x 82 + 3 x 81 + 7 x 80
= 1 x 64 + 3 x 8 + 7 x 1
= 64 + 24 + 7
(137)8 = (95)10
26. DECIMAL TO OCTAL
The easiest way to convert a
decimal number to its octal
equivalent is to use the Division
Algorithm.
HEXADECIMAL TO DECIMAL
Technique:
Multiply each bit by 16n, where n is the
“weight” of the bit
The weight is the position of the bit,
starting from 0 on the right
Add the results
BAD = 11 x 162 + 10 x 161 + 13 x 160
= 11 x 256 + 10 x 16 + 13 x 1
= 2816 + 160 + 13
(BAD)16 = (2989)10
27. DECIMALTO HEXADECIMAL
Technique
Divide by 16
Keep track of the remainder
Convert 83010 to its hexadecimal equivalent
OCTALTO HEXADECIMAL
Technique:
Use binary as an intermediary
HEXADECIMALTO OCTAL
Technique:
Use binary as an intermediary
29. ADDITION OF CONTINUOUS TIME SIGNALS
We add the amplitudes of two or more signals at each instant of time to obtain their sum. Given
the diagram below, add the amplitudes of the continuous time signals of x1(t) and x2(t) at each
instant of time. Plot the resultant signal x3(t).
30. The first signal = x1(t)
The second signal = x2(t)
The resultant signal x3(t) = x1(t)+x2(t)
SOLUTION
32. We multiply the amplitudes of two or more signals at each instant of time to obtain their
product. Given the diagram below, multiply the amplitudes of x1(t) and x2(t) below at each
instant of time. Plot the resultant signal x3(t).
MULTPLICATION OF CONTINUOUS TIME SIGNALS
33. SOLUTION
The first signal = x1(t)
The second signal = x2(t)
The resultant signal x3(t) = x1(t)*x2(t)
35. WHY IS MULTIMEDIA USED?
What is the purpose of multimedia?
Why not simply read a long article about a subject of interest, but rather listen to an audio
podcast on the subject?
Why are presentations preferred at an academic seminar to reading out the long essay in full?
36. MULTIMEDIA
Multimedia is defined as the usage of multiple agents (text, audio, video, images) for
disseminating and presenting information to an audience
OR
It is any combination of text, art, sound, animation, and video delivered to you by computer or
other electronic or digitally manipulated means.
OR
It is the field concerned with the computer-controlled integration of text, graphics, drawings,
still and moving images (video), animation, audio, and any other media where every type of
information can be represented, stored, transmitted, and processed digitally.
OR
It can be described as the media that uses multiple forms of information content and
information processing (e.g. text, audio, graphics, animation, video, interactivity) to inform or
entertain the user.
OR
In simple terms, it refers to the use of electronic media to store and experience multimedia
content.
37. MULTIMEDIA
The basic elements of multimedia include text, video, audio, animation, and images/graphics.
Text: A book or other written or printed work or a human-readable sequence of characters and
the words they form that can be encoded into computer-readable formats.
Video: The recording, reproducing, or broadcasting of moving visual images
Audio: sound, especially when recorded or reproduced
Animation: Method in which pictures are manipulated to appear as moving images.
Images/Graphics: An image is an artifact that depicts visual perception, such as a photograph
or other two-dimensional picture that resembles a subject-usually a physical object and thus
provides a depiction of it.
Multimedia elements are typically put together into a project using authoring tools.
The people who weave multimedia into meaningful projects are called multimedia
developers.
When an end-user is allowed to control what and when the elements are delivered, it is called
interactive multimedia.
38. PURPOSE OF MULTIMEDIA
Multimedia serves three primary purposes, namely:
Storing and transferring information and media elements, such as video, audio, text,
animation, slide shows, and documentaries.
Interactivity for self-paced, user control, such as museum displays, bank ATMs, and other
types of multimedia kiosks.
Presenting information in the workplace and educational settings, such as online lectures,
teleconferencing, and digital whiteboards.
39. BENEFITS OF MULTIMEDIA
Addresses multiple learning styles: Provides an excellent way to convey content.
Uses a variety of media elements to reinforce one idea.
Enhances user enjoyment.
Improves retention.
Enables users to control the Web experience.
It is very user-friendly.
It doesn’t take much energy out of the user, in the sense that you can sit and watch the
presentation, you can read the text, and listen to the audio.
It is multi-sensorial. It uses a lot of the user’s senses while making use of multimedia, for
example, hearing, seeing, and talking.
It is integrated and interactive. All the different mediums are integrated through the digitization
process. Interactivity is heightened by the possibility of easy feedback.
Multimedia presentations are flexible. Being digital, this media can easily be changed to fit
different situations.
It can be used for a wide variety of audiences, ranging from one person to a whole group.
40. MULTIMEDIAAPPLICATIONS
A Multimedia Application is an application that uses multiple media sources, e.g. text, graphics,
images, sound/audio, animation, and/or video. Examples of Multimedia Applications include:
Interactive TV
Computer Games
Virtual reality
Digital video, editing, and production systems
Multimedia Database systems
41. GRAPHICS AND MULTIMEDIA SOFTWARE
Computer-aided
design (CAD) software
Desktop publishing
software
Paint/Image editing
software
Professional photo
editing software
Video and audio
editing software
Multimedia
authoring software
42. APPLICATIONS OF MULTIMEDIA
Applications in various areas include:
Advertisements
Art
Education
Entertainment
Engineering
Medicine
Mathematics
Business
Communication
Scientific research
43. DISADVANTAGES OF USING MULTIMEDIA
Large files like video and audio have an effect on the time it takes for your presentation to load.
Adding too much can mean that you have to use a larger computer to store the files.
Problems due to incompatible software, OS, and hardware.
Limited memory to run programs.
Limitations due to internet accessibility or browser incompatibility
Costly and time-consuming to produce, in some cases.
Complicated configuration for some authoring environments
Limitations with available technology.
44. STAGES OF MULTIMEDIA PROJECTS
Planning and costing
A project always begins with an idea. Identify how to make each part within the authoring
system.
Work up a short prototype or proof-of-concept, a simple, working example to demonstrate
whether or not the idea is feasible.
Designing and producing
Perform the activity in the planned tasks to create a finished product.
Testing
Test to make sure that it meets the objectives of the project works properly on the intended
delivery platforms and meets the needs of the client or end-user.
Delivering
Package and deliver the project to the end-user. Be prepared to follow up over time with
tweaks, repairs, and upgrades.
45. MULTIMEDIA PROJECTS: TEXT EDITING TOOLS
A word processor is usually the first software tool computer users learn.
Word processors such as Microsoft Word, OpenOffice, and WordPerfect are powerful
applications used in simple text media projects.
In many word processors, you can embed multimedia elements such as sounds, images, and
video.
MULTIMEDIA PROJECTS: PAINTING AND DRAWING TOOLS
Painting software, such as Photoshop, Fireworks, and Painter, is dedicated to producing
crafted bitmap images.
Drawing software, such as CorelDraw, FreeHand, Illustrator, Designer, and Canvas, is
dedicated to producing vector-based line art easily printed to paper at high resolution.
MULTIMEDIA PROJECTS: MODELING AND ANIMATION
Powerful modeling packages such as VectorWorks, AutoDesk’s Maya, Strata 3D, and Avid’s
SoftImage.
Many 3-D modeling applications include export facilities for creating and saving a moving
view or journey through a scene as a QuickTime or MPEG file.
46. MULTIMEDIA PROJECTS: IMAGE EDITING TOOLS
Image-editing applications are specialized and powerful tools for creating, enhancing, and
retouching existing bitmapped images.
They can be used to create images from scratch as well as images digitized from scanners, video
frame-grabbers, digital cameras, clip art files, or original artwork files created with a painting or
drawing package.
MULTIMEDIA PROJECTS: SOUND EDITING TOOLS
Tools for both digitized and MIDI sound allow users to see visual representations of music as
well as hear it.
Can cut, copy, paste, and edit segments of audio file with great precision even in real-time.
MULTIMEDIA PROJECTS: VIDEO TOOLS
Digital video movies are sequences of bitmapped graphic scenes (frames), rapidly played back.
To make movies from video, one needs special hardware to convert an analog video signal to
digital data.
Moviemaking tools such as Premiere, MS Movie Maker, Final Cut Pro, VideoShop, and
MediaStudio Pro let users edit and assemble video clips captured from a camera, tape, other
digitized movie segments, and scanned images
47. Authoring software provides an integrated environment for binding together the content and
functions of the project.
Authoring tools are used for designing interactivity and the user interface, presenting the project
on screen, and assembling diverse multimedia elements into a cohesive product.
With authoring software, you can make:
Video productions
Animations
Games
Interactive websites
Demo disks and guided tours
Presentations
Kiosk applications
Interactive training
Simulations, prototypes, and technical visualizations
AUTHORING TOOLS
48. ASSIGNMENT 1 (Submission Date: 31-05-2023)
1. Three processes are involved in digitization. State and explain each process.
2. An old-fashioned analog black-and-white TV screen is made up of pixels.
i. If we assume a resolution of 525 × 700, determine the pixels per screen.
ii. If we scan the screen 30 times per second, determine the pixels per second.
3. Convert the following from base two/binary to decimal
i. 10101112
ii. 11012
iii. 110010102
