1. Introduction to Interactive Media 03: The Nature of Digital Media

2. Introduction to Interactive Media WHY DO WE NEED TO UNDERSTAND THE NATURE OF DIGITAL MEDIA?

3. Introduction to Interactive Media Digital is our Medium All of the materials we work with as interactive media creators must be digital.

4. Introduction to Interactive Media SO WHAT DOES IT MEAN TO BE DIGITAL?

5. Introduction to Interactive Media Digital is not Analog Analog data is continuous Digital data consists of separate, discreet pieces.

6. Introduction to Interactive Media An analog /digital analogy Hour glass to tell time. Wind mill motion.

7. Introduction to Interactive Media Anything Digital is Made of Bits A bit is a 0 or a 1. –1 = on, 0 = off All digital files are ultimately comprised of 0s and 1s.

8. Introduction to Interactive Media HOW DO WE CONVEY COMPLEX INFORMATION USING ZEROS AND ONES?

9. Introduction to Interactive Media Bits and Bytes Putting bits together allows you to encode more complex data. E.g. if we use 2 bits, we can represent 4 different possible things. –00, 01, 10, 11

10. Introduction to Interactive Media Building Digital Codes Number of distinct bit combinations that can be produced is given by the formula 2 n. – n = number of bits used in the code. Adding a bit to the string of bits, doubles the number of possibilities you can represent. 2 1 2 2 3 2 4 2 5 2 6 2 7 2 8 2 items4 items8 items16 items Complete the table to identify the number of distinct items represented by 2 5, 2 6, 2 7, and 2 8.

11. Introduction to Interactive Media Common Codes ASCII-8, an 8 bit code. –256 characters in English language. Letter A = 0100 0001 Number 5 = 0011 0101 24-bit color. –Displays the full range a human eye can perceive. 16-bit sound. –Plays the full decibel range the human ear can perceive.

12. Introduction to Interactive Media 8 Bits = 1 Byte File sizes are often referred to in Bytes, Kilobytes (1000 bytes) and Megabytes ( 1 million bytes). File size indicates number of bits in the file. How many bits are in a 40KB file?

13. Introduction to Interactive Media SO… IF EVERY FILE IS JUST ZEROS AND ONES, HOW DOES YOUR COMPUTER KNOW WHAT TO DO WITH IT?

14. Introduction to Interactive Media Digital Files A container for binary codes. File formats define how instructions and data are encoded in the file. Without a specific file format, a binary code has no meaning.

15. Introduction to Interactive Media All About Files File size –Measured in units of bytes. 1 byte = 8 bits Kilo (1,000) Bytes, Mega (1 million) Bytes, (1 billion) Giga Bytes. File extensions –Series of letters to designate the file format..fla,.exe,.rtf,.jpg Help the OS find the right program to launch the file. File compatibility –Ability to use the file in a different platform of hardware and software.

16. Introduction to Interactive Media Different File Types Program files –Contain executable instructions. Data files –Can hold text, images, sounds, video, animation.

17. Introduction to Interactive Media Data File Compatibility Cross-platform compatible files. –Open and use on any computer hardware and software configuration, e.g..JPG,.TXT Files that are native or specialized to the application that created the data file. –Require source application to open the file. E.g. PhotoShop files.PSD

18. Introduction to Interactive Media File Maintenance Preserve original and derivative files Effective file maintenance involves: – Identification - create descriptive file names – Categorization - group related files – Preservation - back-up Why is file maintenance so important in this field?

19. Introduction to Interactive Media HOW DO WE CONVERT ANALOG INFORMATION INTO DIGITAL FILES.

20. Introduction to Interactive Media Digitization To be able to manipulate images, sound, video it must be in a digital format. Analog -> Video Conversion = Sampling Always involves making a compromise.

21. Introduction to Interactive Media Examples of Analog -> Digital Digital camera Scanner Recording audio on computer or with digital audio recorder Digitizing video or shooting video on a digital video camera

22. Introduction to Interactive Media Sampling = How much to capture? Sampling analyzes a small portion of the analog source and converts it to digital code.

23. Introduction to Interactive Media Sample Quality Factors that influence sample quality –Sample Resolution. Number of bits used to represent digital sample. –More bits = more precision. –Sample Rate. Number of samples taken in a given unit of time (sounds) or space (images). –More samples taken - more info within a given space

24. Introduction to Interactive Media How Sample Resolution Affects Quality ImageSound 8 bits / sample 24 bits / sample16 bits / sample Which image uses fewer bits to describe the color sample? Which image and sound sample will have better quality?

25. Introduction to Interactive Media How Sample Rate Affects Quality ImageSound 72 pixels / inch11 kHz 300 pixels / inch44 kHz Which image has higher spatial resolution? 50ppi300ppi

26. Introduction to Interactive Media IF CONVERSION TO A DIGITAL FORM REQUIRES A COMPROMISE – WHAT ARE THE PROS?

27. Introduction to Interactive Media Pros of Being Digital Reproduction without generation decay. Editing and re-editing is much easier than with analog media. Integration of media using cut, copy, paste is more efficient. Distribution over Internet - nearly everyone can be reached by anyone else.

28. Introduction to Interactive Media HOW DO WE DELIVER ALL THESE BITS AND BYTES OVER THE INTERNET?

29. Introduction to Interactive Media File Compression Process of re-encoding digital data to reduce file size. Codec: a program to compress a file into a smaller size and decompress it into a usable form. Improvements in compression techniques have facilitated the advancement of sharing, displaying images, video and audio over the Internet

30. Introduction to Interactive Media Lossy vs. Lossless Compression Lossy –Number of bits is reduced and some data is lost. –Lossy strategies include MP3 and JPEG compression. Lossless –Efficient encoding reduces file size without loss of original data. –Lossless strategies include TIF

31. Introduction to Interactive Media Lossy or Lossless Compression? 1. Photograph of sailboat on ocean. 2. Journal article explaining nanotechnology. 3. 1812 Overture by New York Philharmonic Orchestra. 4. Database of student names and addresses. 5. Video of hot air balloon flying over a cornfield.

32. Introduction to Interactive Media NOT ALL DIGITAL FILES ARE STORED IN THE SAME WAY.

33. Introduction to Interactive Media Digital Encoding of Media Description-based encoding –A detailed representation of the discrete elements that comprise the media. Command-based encoding –A set of instructions the computer follows to produce the digital media.

34. Introduction to Interactive Media Digital Coding Compared Description (All Audio except MIDI, PhotoShop files) Command (Flash, Illustrator, MIDI) Advantages Represent natural scenes and sounds. File sizes are small. Supports detailed editing.Scaled without distortion. Limitations Large file sizes.Not appropriate for detailed photographs and natural sounds. Lose quality if enlarged.Requires knowledge of music and vector image creation.

35. Introduction to Interactive Media Command vs. Description Let students do green circle exercise. Introduction to Interactive Media