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Introduction

Introduction. MUMD-290 Multimedia Development. Concepts >> Practical Stuff. Digital media studies rely on both conceptual and practical knowledge. Simply learning a particular version of a particular program restricts your creativity Instead, focus on the concepts

jaquelyn-albert
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Introduction

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  1. Introduction MUMD-290 Multimedia Development

  2. Concepts >> Practical Stuff • Digital media studies rely on both conceptual and practical knowledge. • Simply learning a particular version of a particular program restricts your creativity • Instead, focus on the concepts • New programs are constantly being developed

  3. Popular Programs Image/Photo Editing • Adobe Photoshop • Paint Shop Pro • Aperture Drawing • Adobe/Macromedia Fireworks • Adobe Illustrator

  4. Popular Programs Video Editing • Apple iMovie • Apple Final Cut • Adobe Preimere Audio Editing • Apple Garage Band • Apple Logic Studio • Adobe Audition • Sony Sound Forge

  5. KEY CONCEPTS • Analog information versus digital data • Converting analog to digital data: • sampling and • quantizing • File size calculation • File compression

  6. KEY CONCEPTS • Bits and bytes • Base-10 versus base-2 Why study these?

  7. File size and prefixes • Digital files—image, sound, and especially video files—can be very large. • Prefixes (such as kilo, mega, and giga) should mean something to you.

  8. Bits • By learning binary notation and decimal to binary conversion, you will see how digital multimedia can be stored and handled on a computer as bits.

  9. Bit depth • Understanding binary systems helps you comprehend the connection between bit depth or color depth of an image and the number of colors; for example, • 8-bit refers to 256 colors and • 24-bit refers to millions of colors.

  10. Bit rate • In working with digital video, you will often encounter the term bit rate. • The bit rate of a video affects the smoothness of its playback. • Understanding bits helps you understand how you can calculate your video’s average bit rate to predict its playback.

  11. hexadecimal • In Web graphic creation, hexadecimal notation is used to designate color • For example, #FF0000 represents red. • conversion of decimal to binary notations helps you learn how the hexadecimal notation of a color is obtained.

  12. Analog Versus Digital Representations • Pencil is between 7¼ and 7½ • But as you zoom in, the precision is infinite.

  13. Analog Versus Digital Analog is continuous • infinite number of divisions exist between two points • Real numbers • 1/3 = 1.33333333….forever Digital is Discrete • Finite number of divisions exist between two points • Integer numbers • 1, 2, 3, 4, …., • Only 9 divisions exist between 0 and 10.

  14. Digital Data • Digital images, video, or audio are ALL represented using binary numbers • Digital  Binary (1,0) • CD, DVD – Laser Etch (1) or no etch (0) • Hard drive – Magnetized (1) or not (0)

  15. Analog vs. Digital Old fashioned records… • Etching device is mechanical and analog • Etch depth is continuous • Infinite depths are possible Music CDs • Laser etching device is digital • Etch or no etch • There is NO half etch, quarter etch, etc.

  16. Analog vs. Digital • Mixing paint is an analog way to make colors • You can add an infinitesimal amount of paint to achieve infinite colors. • Digitally, you have to encode colors using binary numbers • 00 – Black • 01 – Red • 10 – Blue • 11 – Pink

  17. Binary Numbers  Colors 3 bits can encode 8 colors • 000 Black • 001 Red • 010 Blue • 011 Green • 100 Purple • 101 Yellow • 110 Pink • 111 White • In general N bits can encode 2N colors • 1 bits = 21 = 2 • 2 bits = 22 = 4 • 3 bits = 23 = 8 • 4 bits = 24 = 16 • … • 8 bits = 28 = 256

  18. 8 Bits = 1 Byte • Aside from a bit (1 or 0), a byte is the base unit of measurement. • Why? • The answer is complicated…

  19. Byte Prefixes

  20. DOES A KILO EQUAL 1000 OR 1024? • Although in science one kilo equals 1000 (e.g., one kilogram equals 1000 grams), • a kilobyte (KB) is 1024 bytes, • a megabyte (MB) is 1,048,576 bytes • Nerd test: How many KB is 1500 bytes?

  21. How many KB is 1500 bytes? • 1500 bytes/1024 = 1.4648KB (NOT 1.5KB) • How many bytes are in 4.7 Gigabytes?

  22. How many bytes is 4.7 Gigabytes? • 4.7 billion bytes= 4,700,000,000 bytes?Or • 4.7 * 1,073,741,824  Gigabyte 230= 5,046,586,572 bytes?

  23. How many bytes is 4.7 Gigabytes?

  24. How can they do that? • How can Sony label a DVD with 4.7 GB when it really only stores 4.3 GB? • Answer: In 1998 the International Electrotechnical Commission (IEC) approved new prefixes (see the book). • Gibi = 230 = 1,073,741,824 • Mebi = 220 • Kibi = 210 • So, sony thinks its OK to interpret Giga as a billion • Microsoft, Apple, and other stick to the base-2 intepretation of Kilo, Mega, Giga, etc.

  25. What should I follow? • Does a Kilobyte equal 1000 bytes or 1024 bytes? • Does a Megabyte equal 1 million or 210? • The new prefixes are meant to make it crystal clear if you are not measuring digital storage, i.e., • A kilogram is 1000 grams • A kibigram is 1024 grams • If you are talking about Bytes, the base-2 interpretation is still the practical standard. • Sony is just misleading people.

  26. Binary Notation

  27. Base 10 Base 10 Base 10 Base 10 Base 10 • 3872 • 3 × 103 + 8 × 102 + 7 × 101 + 2 × 100 = • 3 × 1000 + 8 × 100 + 7 × 10 + 2 × 1 = • 3000 + 800 + 70 + 2 = • 3872

  28. Base 2 • 1101 • 1 × 23 + 1 × 22 + 0 × 21 + 1 × 20 = • 1 × 8 + 1 × 4 + 0 × 2 + 1 × 1 = • 8 + 4 + 0 + 1 = • 13 (in decimal notation) Base 2 Base 2 Base 2 Base 2

  29. Convert 19 to binary • Division of Number Remainder • 19/2 = 9 1 • 9/2 = 4 1 • 4/2 = 2 0 • 2/2 = 1 0 • 1/2 = 0 1 • Answer 11001

  30. Simple but Ground-breaking • Every base-10 number can be represented using binary notation.

  31. Nerd Clock - BCD clockbinary coded decimal

  32. Digital Progression • Text • Numbers and math • Images • Sound • Video • What’s next (smell?) • Francis Bacon 1605 • Claude Shannon 1937 • 1957 • 1970’s • 1990’s

  33. Digitizing Text - ASCII Codes

  34. Digitizing Images

  35. Digitizing Sound

  36. Digitizing video

  37. Analog  DigitalConversion

  38. Sampling Rate • How often do you measure? • How often do you capture the signal? • Example: • In Video  Frames per second • Determines motion realism and smoothness

  39. Quantizing • When you sample, how precise is your measurement. • How detailed is your sample. • Example: • In Images  Bit Depth of each pixel • Determines the number of colors in the image • True color  8-bit  black & white

  40. Limits of Digital Representations • Our eyes and ears naturally perceive the world in analog. • In Digital images, audio, and video, humans can notice • Low sampling – Choppy video, distorted sound • Low quantization level – Unrealistic color, dull sound • Digital representations can never be exactly the same as the natural/analog equivalents • This would require infinite bits.

  41. Goal: Indistinguishable • By sampling enough data and by measuring it very precisely (quantization), you can… • Create digital media that is indistinguishable from the analog equivalent • Human eye can NOT distinguish an image with 16 million colors from one that has 4 billion colors • Similarly can NOT tell 120 FPS video from 600 FPS.

  42. Data/File Sizes • To store quality digital media requires • High sample rate • 44,000 times per second for CD quality audio • Deep bit-depth • 24-bit for true color images • Lots of data • File sizes can be enormous!

  43. File Size – First Road block • In the 1970’s, 80’s, and 90’s, the concepts and technology existed to support digital media. • Initially the files where too big to fit on “portable” storage devices. • Compact Disks (CDs) brought digital music to the masses. • But, CD’s still didn’t have the capacity to bring digital video to the masses.

  44. Bandwidth – Second Road block • Today: DVD, Blu-ray and Flash Memory provide adequate storage and portability for digital video. • But, the Internet/WWW is still not suitable for disseminating (sharing) high quality digital video. • However, this is already changing.

  45. Compression • File compression techniques helped overcome serious problems caused by limitations on portable storage and network bandwidth. • The compression in MP3 digital audio files brought a single song from 200MB to 5MB, • which single-handedly led to the birth of digital music piracy.

  46. Nature of Compression Lossy • Loss of quality • Reduce bit-depth • Reduce sampling rate Lossless • No loss of quality • Via clever tricks • Exploits patterns and repetition in the binary data.

  47. Summary • Digital really means “represented with only 0’s and 1’s.” • N bits can represent 2N different things… • Those things could be • Colors • Volume levels • Etc. • Representing images, audio, and video digitally requires lots of bits  big files • Digital media compression is still very important when transmitting over the Internet.

  48. What the book doesn’t say • Digital media can be easier • To edit • To combine (Multimedia) • To interact with • Digital media does NOT • Degrade in quality (etches wear down) • But it’s much easier to lose/erase.

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