Chapter 1 Data representation: Unit 1.2: Text, Sound And Images Flashcards
What does ASCII stand for?
American Standard Code for Information Interchange
Define the ASCII code system
Set up in 1963 for use in communication systems and computer systems
Standard character set consists of 7-bit codes (0 to 127 in denary, 00 to 7F in hexadecimal)
What is the main disadvantage of the ASCII System?
Does not represent characters in non-Western languages.
What was the solution to the ASCII systems’s main disadvantage?
Create a coding system called Unicode.
Define the Unicode system
Can represent all languages of the world
Can use up to 4 bytes of data for one character
What were the 5 goals of the Unicode system?
Create a universal standard that covered all languages and all writing systems
Produce a more efficient coding system that ASCII
Adopt uniform encoding where each character is encoded as 16-bit or 32-bit code
Create unambiguous encoding where each 16-bit and 32-bit value always represents the same character
Reserve part of the code for private use to enable a user to assign codes for their own characters and symbols
How are sound waves converted into digital data that can be read by a computer?
A ADC (Analogue to Digital Converter) is used.
The sound waves are sampled at regular time intervals.
The amplitude of the sound cannot be measured precisely, so approximate values are stored.
How does increasing the number of possible values used to represent sound amplitude affect the accuracy of the sampled sound?
It increases the accuracy.
Define sampling resolution/bit depth
The number of bits per sample
Define sampling rate
The number of sound samples taken per second
How is sampling used to record a sound clip?
The amplitude of the sound wave is first determined at set time intervals
This gives an approximate representation of the sound wave
Each sample of the sound wave is then encoded as a series of binary digits.
What are the benefits of using a larger sampling resolution when recording sound?
Larger dynamic range
Better sound quality
Less sound distortion
What are the drawbacks of using a larger sampling resolution when recording sound?
Produces larger file size
Takes longer to transmit/download music files
Requires greater processing power
Define bitmap images
Images that are made up of pixels
Is 2 dimensional
Define image resolution
The number of pixels that make up an image
