1.2: MEMORY AND STORAGE 4.0

Question 1

what is metadata?

Answer 1

data about data

Question 2

why does a computer require meta data? (2)

Answer 2

• computer needs to know the size of the image in terms of height, width and colour depth in bits per pixel and format
• this allows the computer to recreate the image from binary.

Question 3

examples of metadata:

Answer 3

Height / width / resolution / dimensions of image​
Colour depth​
Resolution​
Details of hardware/software used​
Date / time created

Question 4

EQ: show how an input is represented in ASCII/Unicode (2)

Answer 4

• each character would be represented by one/two bytes by its binary ASCII/Unicode value
• written in the same order that the characters are entered in

Question 5

how must analogue sounds be recorded? and in what form?

Answer 5

analogue sounds must be digitally recorded in binary

Question 6

what is amplitude?

Answer 6

height of the sound wave

Question 7

Explain how sampling is used to store audio recordings: (2)

Answer 7

• an analogue-to-digital converter will measure the amplitude of the sound wave emitted and store it in binary/digital form.
• measurements are taken at regular time intervals

Question 8

what is sample rate?

Answer 8

number of samples recorded in any given period of time

Question 9

what is sample rate measured in?

Answer 9

Herts (Hz)

Question 10

what is bit depth?

Answer 10

number of bits used to record each sample

Question 11

what is the correlation between sample rate and sound quality?

Answer 11

The higher the sample rate, the closer the recorded signal is to the original.

Question 12

what is the correlation between bit depth and sound accuracy? and how does this affect file size?

Answer 12

• the higher the bit depth, the more accurately a sound can be recorded
• the larger the file size would be

Question 13

what is bit rate?

Answer 13

a measure of how much data is processed for each second of sound

Question 14

what is bit rate usually measured in?

Answer 14

kbps

Question 15

equation for calculating bit rate?

Answer 15

Sample rate × bit depth

Question 16

what is the correlation between bit rate and sound quality

Answer 16

the higher the bit rate, the better the quality of the recorded sound will be

Question 17

Advantages and Disadvantages of taking LESS samples: (2)

Answer 17

A-smaller file size as less data is stored

DA-sound will lose some quality and not be as accurate

Question 18

Advantages and Disadvantages of taking MORE samples: (2)

Answer 18

A-sound will be more accurate and have a better quality

DA- larger file size as more data is stored

Question 19

compare the use of ASCII and Unicode: (2)

Answer 19

• Unicode uses more bits(16), whereas ASCII uses less bits(8)
• Unicode can represent more character, whereas ASCII can represent fewer characters

Question 20

ADVANTAGES of LOSSY compression: (3)

Answer 20

Advantages​:

• file size is reduced so it is quicker to upload / download​
• takes up less storage space on hard drive// space on the web server
• uses less bandwidth /mobile data

Question 21

DISADVANTAGES of LOSSY compression: (3)

Answer 21

• quality of image is reduced because data is lost.
• reduction is permanent / not reversible.
• the decompressed file is not identical to the original

Question 22

ADVANTAGES of LOSSLESS compression: (3)

Answer 22

• file is compressed without the loss of data.
• No bits are lost after the image has been restored.
• crucial for files where missing data would result in a negative impact eg; missing text from source code