Presentation on theme: "Introduction MUMD-290 Multimedia Development. Concepts >> Practical Stuff Digital media studies rely on both conceptual and practical knowledge. Simply."— Presentation transcript:
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
Popular Programs Image/Photo Editing Adobe Photoshop Paint Shop Pro Aperture Drawing Adobe/Macromedia Fireworks Adobe Illustrator
Popular Programs Video Editing Apple iMovie Apple Final Cut Adobe Preimere Audio Editing Apple Garage Band Apple Logic Studio Adobe Audition Sony Sound Forge
KEY CONCEPTS Analog information versus digital data Converting analog to digital data: – sampling and – quantizing File size calculation File compression
KEY CONCEPTS Bits and bytes Base-10 versus base-2 Why study these?
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.
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.
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.
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.
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.
Analog Versus Digital Representations Pencil is between 7¼ and 7½ But as you zoom in, the precision is infinite.
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.
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)
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.
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
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 2 N colors 1 bits = 2 1 = 2 2 bits = 2 2 = 4 3 bits = 2 3 = 8 4 bits = 2 4 = 16 … 8 bits = 2 8 = 256
8 Bits = 1 Byte Aside from a bit (1 or 0), a byte is the base unit of measurement. Why? The answer is complicated…
Byte Prefixes Kilo K 2 10 = 1,024Mega M 2 20 = 1,048,576Giga G 2 30 = 1,073,741,824Tera T 2 40 = 1,099,511,627,776Peta P 2 50 = thousand trillionExa E 2 60 = million trillionZetta Z 2 70 = billion trillionYotta Y 2 80 = trillion trillion
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?
How many KB is 1500 bytes? 1500 bytes/1024 = 1.4648KB (NOT 1.5KB) How many bytes are in 4.7 Gigabytes?
How many bytes is 4.7 Gigabytes? 4.7 billion bytes = 4,700,000,000 bytes? Or 4.7 * 1,073,741,824 Gigabyte 2 30 = 5,046,586,572 bytes?
How many bytes is 4.7 Gigabytes? DVD makers label DVD-R’s as 4.7GB even though they contain exactly 4,700,372,992 bytes. Note that 4,700,372,992 bytes divided by a Gigabyte 2 30 is actually 4.3 GB 4,700,372,992 /1,073,741,824 = 4.3 GB
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 = 2 30 = 1,073,741,824 – Mebi = 2 20 – Kibi = 2 10 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.
What should I follow? Does a Kilobyte equal 1000 bytes or 1024 bytes? Does a Megabyte equal 1 million or 2 10 ? 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.
Binary Notation Math and CS Majors: Sorry, I know you know this… Everyone else: Sorry, I know this is not what you wanted to learn….
Digitizing Sound Time-based Sample many times per second For each sample, encode the volume, pitch, tone, etc. Channel- based For each sound/instrument, encode the time, duration, etc. In both cases, you need a device that can read the encoding and “recreate” the sound.
Digitizing video Sample analog video signal X times per second, convert each frame to digital image. Include Meta information, i.e., frame rate
Analog Digital Conversion No matter what your converting, two concepts are always important Sampling rate Quantization level
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
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
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.
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.
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!
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.
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.
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.
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.
Summary Digital really means “represented with only 0’s and 1’s.” – N bits can represent 2 N 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.
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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