Analog and Digital Representation
CSCI N35100
Andy Harris
Indiana University / Purdue University - Indianapolis
What is multimedia?
- Not just more than one media
- Something new
- Something digital
- Something interactive
What's new media?
- It’s not just old media
- Interactive
- adaptive
It's not technology
- Many kinds of hardware
- Lots of software tools
- Tools change quickly
N351 Multimedia Programming
- What does this mean?
- Two, or green.
The point of digital multimedia
- The world is analog
- computers are digital
- digital representation is mainly very poor
- -but it has a few interesting advantages
Computers can’t do multimedia!
- They seem to handle music videos, images, games, text
- Ultimately, though, the computer can’t handle any of these things
- All that works inside a computer is millions of little light switches
An analog thermometer
- Analog representation of data
- The world is analog
- Infinite resolution
- Infinite variety
- Infinite room for error
- Great precision, limited accuracy
Digital representation
- divides data into discrete chunks
- finite resolution
- less precision
- built-in error correction
- More accuracy
Getting to better precision
- An analog audio signal:
- Smooth and continuous
- Impossibly complex
Adding time slices
- Slice into small time segments
- Each is same distance apart
Quantizing the data
- Draw a horizontal line representing each slice
- Pick average, top, middle, first point
Adding numeric values
- Assign a numeric value to each slice
- Use some approximation technique
Comparing analog to digital
- Digital is worse than analog - but -
Improving the quality
- Make more time slices
- Make them closer together
- Infinitely large number of slices infinitely close together...
- is the original curve.
- We've just invented the Reimann sum in calculus
What's so great about digital?
- Accuracy is built-in
- We can get whatever level of precision we want
- Digital media is easier to transfer and store than analog
- It can be manipulated mathematically
