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Introduction to Multimedia
Student Multimedia Design Center
06/06/06
Goals
• Understand how Multimedia is represented within a computer
• Become familiar with some core multimedia concepts and terms
• Be able to find Multimedia on the Internet
• Begin thinking of your own Multimedia project
What is Multimedia?
What is Media?
The Multi Part
Combine media elements with:
• Navigation
• Synchronization
• Interactivity
• Metadata
Multimedia
• Files– Contains one of more media elements and
metadata regarding how to decode and possibly decompress it.
– Singe accessible unit on a computer
• Frameworks– Pull together multiple files for presentation
and navigation– Points to other files rather than contains them
Digital Information
In a computer all digital information is stored in the same format – binary.
It’s how you encode and decode the binary that determines what the information is.
Two’s power number representation1 digit = bit
Many systems to store: 0/1, On/Off, +/-, Up/Down
All Digital Information is the Same
01000111011010011010010101001010100101010101001010101010010101010101010101010101010111101010111001010111010101011010010100100010011010011000
Black and White Pixels
01000111011010011010010101001010100101010101001010101010010101010101010101010101010111101010111001010111010101011010010100100010011010011000
█1███111█11█1██11█1██1█1█1██1█1█1██1█1█1█1█1██1█1█1█1█1██1█1█1█1█1█1█1█1█1█1█1█1█1█1111█1█1█111██1█1█111█1█1█1█11█1██1█1██1███1██11█1██11███
████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████
████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████
Black and White Pixels████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████
Black and White Pixels
Black and White Pixels
Resolution
•Dots per Inch (DPI)
•Image Resolution (A x B)
Same Number of Pixels, Different DPI
Binary
Usually work in set groups (8 bits = byte)
00100101 = (25*1)+(24*0)+(23*0)+(22*1)+(21*0)+(20*0)
=32+0+0+4+0+0
=36
Other Image Pixel Codings
• 8-bit grayscale: – I byte (8 bits) describe one pixel– Amount of grey from 0-255– 01001110 11000000 01011100
• 24-bit color:– 3 bytes: Red, Blue Green make up one pixel,
blended like light, not paint (Additive Color)– 01001110 11000000 01011100– Red (92), Green (192), Blue (92)
Hexidecimal
• Base-16 Number• 0-9 as in decimal• 6 new digits, A-F• A=10, B=11, C=12, D=13, E=14, F=15• Each Hex digit is 4 bits• 24-bit color often described as 6 hex
digits, 2 for each of R, G, B
=++010011101100000001011
100
ASCII
01000111011010011010010101001010100101010101001010101010010101010101010101010101010111101010111001010111010101011010010100100010011010011000
ASCII
01000111011010011010010101001010100101010101001010101010010101010101010101010101010111101010111001010111010101011010010100100010011010011000
32 5290
84 84
37 42
85 42
117 4657
85 82
77
85
42
85
72
24
ASCII
01000111011010011010010101001010100101010101001010101010010101010101010101010101010111101010111001010111010101011010010100100010011010011000
32 5290
84 84
37 42
85 42
117 4657
85 82
77
85
42
85
72
24
# 4Z
T T
% *
U *
u .9
U R
M
U
*
U
H
^T
So…
• The same 1’s and 0’ can either be:• A small part of a picture of UD:
• The text:– “#Z4TTU%**U*Uu9.URHM^T”
• An arbitrary number of other things
Depending on how it’s decoded
Digital Information
All digital information is stored in the same format – coded in binary.
It’s how you encode and decode the binary that determines what the information is.
In Multimedia a Coder/Decoder is known as a Codec
How Do You Get 1’s & 0’s?
• Many of our senses are analog
• Sight – light waves
• Touch – continuous motion
• Hearing – sound waves
• Think of a graph of something changing over time
How Do You Get 1’s & 0’s?
-10
0
10
20
30
40
50
60
70
80
0 1:00 2:00 3:00 4:00
How Do You Get 1’s & 0’s?
0
10
20
30
40
50
60
70
80
0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18
How Do You Get 1’s & 0’s?
02
70
4
60
0
10
20
30
40
50
60
70
80
0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18
0 2 70 4 60
00000000 00000010 00100110 00000100 00101000
Some Analog to Digital Terms
-5
-4
-3
-2
-1
0
1
2
3
4
5
0 0:05 0:10 0:15 0:20 0:25 0:30 0:35 0:40 0:45 0:50 0:55 1:00
•Amplitude
•Frequency (cycles/time)
•Sampling Rate
•Sampling BitsConsider and audio CD:
44,100 samples/second
16 bit samples
For 74 minutes (4440 seconds):
4440 sec x 2bytes/sample x 44100 samples/second =
391608000 bytes
x2 stereo channels = 783,216,000 bytes
How Do You Get 1’s & 0’s?
• Analog to Digital Conversion
• Digital to Analog Conversion
• What are some things that do this?
A/D D/A
Compression
• This will be another day, but…
• Most audio-visual data files are huge
• Compression makes them smaller
• Lossless compression does so without changing the information
• Lossless compression throws information away
Finding (Legal) Free Multimedia
• UD Library Multimedia Resourceshttp://128.175.83.12/eresources/multimedia/
• Library of Congresshttp://www.loc.gov/index.html
• Internet Archivehttp://www.archive.org
• Merlothttp://www.merlot.org
• Creative Commonshttp://creativecommons.org/
Key Terms
• Multimedia• Synchronization• Metadata• Digital• Binary• Encode• Decode• Analog
• Codec• Compression• ASCII• Pixel• Resolution• DPI