data representation Flashcards
what is a character set
-list of characters recognized by a computer
-each represented by unique binary number
what is ASCII
-a 7 bit character set with 2^7 characters= 128
what is extended ASCII
-a 8 bit character set with 2^8 characters =256
what is unicode
-24 bit char set with 2^24 chars. = 16 mill +
what is metadata
additional info stored to define width, height, color depth & color palette
what is a sample size
no. of bits available for each sample
what is bit rate
-how its calculated
no. of bits used per second of audio
-sampling frequency x sample size
what is sampling intervals
gaps between each point where the analogue recording is sampled
when can lossy compression not be used:
-text and executable files
why do computers represent data in binary form
-computers consist of (transistors / logic circuits/ gates / switches)
-that only have two values: 1 or 0, on or off
describe how bitmap images are rep. in binary
-image made out of pixels
-each pixel given a binary code
-represents the color of that pixel, every unique color
describe what happens when the computer converts music into a file
- height of wave sampled at regular intervals
- turned into/stored as Binary
what is meant by a protocol
a division of network functionality
one advantage of using layers in network protocols
-self contained
so allows different developers to concentrate on one aspect of the network
-a layer can be taken out and edited w/o affecting other layers
promotes interoperability betw/ vendors and systems
how to reduce sound file size
- Reduce the sample rate (from 48KHz to a lower rate)…so fewer samples are taken per second
- Reduce the bit depth (from 24 bits to a lower bit depth) …so less data is used for each sample
- Use lossy compression … to remove data (that won’t be noticed)
what is sample rate
how often per second the sound wave is being sampled
what is bit depth
number of bits stored per sample
calculation for size of sound file
sample rate x bit depth x duration
what is sound file size:
total number of bits in a sounds
