Computer Science

Fundamentals of Data Representation

Binary = Base 2

Hexadecimal = Base 16

Denary = Base 10

Odd numbers in binary will always end with one and even numbers will always end with a zero 

Overflow errors are when you end up with more bits after an addition 

 Ascii is 7 bits – this is really important  

Hexadecimal is often used instead of binary because it is easier to read and interpret, and it also has fewer digits that can represent the same value 

Therefore it is less likely that a digit will be written down incorrectly 

A pixel is the smallest part of an image  

What is resolution? 

Number of pixels in width and height 

What is resolution? 

Number of pixels in width and height 

Colour depth is the amount of colours that can be used per pixel 

Analogue sound signals are continuous 

Digital signals are discreet 

Sound is digitized by repeatedly measuring and recording sound waves 

Convertors 

Sounds must be converted into a digital form in order to be stored and processed by a computer 

An ADC or DAC is used to process input and output 

Sample Resolution  

The amplitude used to record each measurement is known as the sample resolution 

More bits used per sample enables the height of a wave to be more accurately measured but increases in file size 

Sample Rate 

Sample rate is usually measured on Hertz 

1Hz = 1 sample per second 

The frequency or sample rate per second affects the level of detail in the digital representation 

The greater the frequency, the greater the accuracy and file size 

Calculating file sizes 

File size = sample rate x resolution x seconds 

6 samples per second x 4 resolution x 3 seconds 

72 bits / 8 = 9 bytes 

Digitized Sound Quality 

Recording quality improves: 

The more frequently we sample a sound  

The more accurately we record the wave height 

Sound Key Terms 

Rate = sampling rate 

Res= sample resolution 

Secs = number of second 

Sample Resolution is the number of bits per sample