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)
