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