Introduction to Multimedia

SMDC Staff Training

6/9/06

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?

The Multi Part

Combine media elements with:

• Synchronization

• Navigation

• 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.

1 digit = bit (b) , 8 bits = Byte (B)(1 kB = 1024 Bytes)

Many systems to store: 0/1, On/Off, +/-, Up/Down

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███

████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████

████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████

Color Depth

• 8-bit grayscale: – I byte (8 bits) describe one pixel– Amount of grey from 0-255– 01001110 11000000 01011100

• 24-bit color:– 3 bytes describe one pixel– Red, Blue Green make up one pixel, blended like

light, not paint (Additive Color)– 01001110 11000000 01011100– Red (92,5C), Green (192,C0), Blue (92,5C)

Resolution

•Dots per Inch (DPI)

•Image Resolution (A x B)

Same Image Resolution, Different DPI

Resolution

•Dots per Inch (DPI)

•Image Resolution (A x B)

Same Image Resolution, Different DPI

Resolution

•Dots per Inch (DPI)

•Image Resolution (A x B)

Same DPI, Different Image Resolution

Resolution

•Dots per Inch (DPI)

•Image Resolution (A x B)

Same DPI, Different Image Resolution

Examples

• Flickr – http://www.flickr.com

• Creative Commons – http://www.creativecommons.org

Video

• Video is a series of still images – like a flip book

• Frames per Second (FPS), Frame Rate

• 24 FPS – Film

• 29.9 FPS – Video/TV

1 Frame Per Second

5 Frames Per Second

10 Frames Per Second

15 Frames Per Second

24 Frames Per Second

Examples

• Internet Archive – http://www.archive.org

• Video Podcast – iTunes: http://phobos.apple.com/WebObjects/MZStore.woa/wa/viewPodcast?id=152616201

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

Viewing Sound Waves

Audacity – free audio recording utility available @ http://audacity.sourceforge.net

•Launch Audacity

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

•Sampling Rate

•Sampling Bits

Sampling

-10

0

10

20

30

40

50

60

70

80

0 1:00 2:00 3:00 4:00

Sampling

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

Sampling

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

Sampling

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

Sampling

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

Interactive Multimedia

• UD Microscope: http://www.merlot.org/artifact/ArtifactDetail.po?oid=1010000000000146169

• Pipeline: http://pipeline.shsarts.com/

Compression

• This will be another day, but…

• Most audio-visual data files are huge

• Compression makes files smaller

• Lossless compression does so without changing the information

• Lossy compression throws information away to make files smaller

Compression Artifacts

Uncompressed tiff 319,808 bytes

Compression Artifacts

Compressed tiff 3,213 bytes

Compression Artifacts

100% Quality JPG 5,738 bytes

Compression Artifacts

50% Quality JPG 2,874 bytes

Compression Artifacts

25% Quality JPG 2,333 bytes

Compression Artifacts

1% Quality JPG 1,319 bytes

Video Compression Artifacts

Codec

• Compressor/Decompressor

• Coder/Decoder

• Tells computer what the binary 1’s and 0’s are

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• Pixel• Resolution• DPI

References and Attributions

• Iguana Photo (slides 9-12) ©2005 Aaron Logan, http://www.lightmatter.net used under Creative Commons Attribution 2.5 license

• “Pipeline” by Steven H. Silberg - http://pipeline.shsarts.com presented with permission of the artist

• Satellite dish footage from the Internet Archives Prelinger Collection, http://www.archive.org/details/1962-07-23_Kennedy_on_Telstar used under the Creative Commons Public Domain license

• Audio test files from Fred Nachbaur, http://www.dogstar.dantimax.dk/testwavs/

Free Software Used the produce these Materials

• XNview – Image editing:http://perso.orange.fr/pierre.g/xnview/enhome.html

• Audacity – audio recording/editing:http://audacity.sourceforge.net

• TMPGEnc – MPEG Editor/Converter:http://www.tmpgenc.net