1.2 text, sound and images Flashcards
1
Q
unicode vs ASCII
A
- unicode allow greater range of characters and symbols
- unicode require more bits per character
2
Q
how does a computer represent text a text in binary
A
use character set
- collection of characters
- and corresponding binary codes that represent them
3
Q
describe data storage in ASCII
A
- 7bit
- use 1 byte to store value (MSB is 0)
4
Q
how does computer represent sound digitally
A
- sound wave sampled (convert from analogue to digital)
- sampled at regular time intervals where amplitude is measured
- cannot be measured precisely, so approx values stored
5
Q
how is sound recorded
A
- amplitude of sound wave first determined at set time intervals
- value converted to digital form
- each sample of sound wave encoded as series of binary digits
- series of readings gives approx representation of wave
6
Q
what is sample resolution
A
number of bits per sample
7
Q
effect of increasing sampling resolution
A
- increases accuracy of sampled sound (more detail stored about amplitude)
- increases memory usage of file (more bits used to store data)
8
Q
what is sampling rate
A
- number of sound samples taken per second
- measured in hertz (Hz)
9
Q
effect of increasing sample rate
A
- more accurate sound
- fewer estimations done between samples
10
Q
what is an image
A
- series of pixels that are converted to binary
- which is processed by a computer
11
Q
define character set
A
- all characters and symbols
- that can be represented by a computer system
- each chara/symbol assigned unique value
12
Q
what is colour depth
A
- number of bits representing each colour
13
Q
effect of increasing colour depth
A
- increases accuracy of colours
- increases file size
14
Q
what is image resolution
A
number of pixels that make up an image
15
Q
effect of increasing image resolution
A
- more detailed images
- increased memory use
