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.binary It’s how you encode and decode the binary that determines what the information is. Two’s power number representation 1 digit = bit Many systems to store: 0/1, On/Off, +/-, Up/Down

All Digital Information is the Same

Black and White Pixels █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

Resolution Dots per Inch (DPI)Dots per Inch Image Resolution (A x B)Image Resolution Same Number of Pixels, Different DPI

Binary Usually work in set groups (8 bits = byte) = (25*1)+(24*0)+(23*0)+(22*1)+(21*0)+(20*0) = =36

Other Image Pixel Codings 8-bit grayscale: –I byte (8 bits) describe one pixel –Amount of grey from – bit color: –3 bytes: Red, Blue Green make up one pixel, blended like light, not paint (Additive Color)Additive Color – –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 =

ASCII

ASCII

ASCII # 4 Z TT %* U* u. 9 UR 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 CodecCodec

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?

Some Analog to Digital Terms Amplitude Frequency (cycles/time) Sampling Rate Sampling Bits Consider and audio CD: 44,100 samples/second 16 bit samples For 74 minutes (4440 seconds): 4440 sec x 2bytes/sample x samples/second = 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 smallerCompression Lossless compression does so without changing the informationLossless compression Lossless compression throws information awayLossless compression

Finding (Legal) Free Multimedia UD Library Multimedia Resources Library of Congress Internet Archive Merlot Creative Commons

Key Terms Multimedia Synchronization Metadata Digital Binary Encode Decode Analog Codec Compression ASCII Pixel Resolution DPI