Types of Data. Numbers Text Pictures Sound Video.
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Transcript of Types of Data. Numbers Text Pictures Sound Video.
Types of Data
Types of Data
Numbers Text Pictures Sound Video
Numbers
Computers use Binary Eg 10000110 in binary is
8 bits (a byte) can only hold numbers up to 255, so how do you hold bigger numbers?– Use more than one byte!
Sound
Sound can be drawn on a graph
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Digitizing Sound
Time is spit into units called the sampling rate
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As seen increasing the sampling rate makes the digitised data more accurate
Sampling Rate
As the sampling rate increases the quality of the digitised sound increases
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Converting to Digital
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1111111011011100
000000010010001101000101011001111000100110101011
Conversion Example
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1111111011011100
000000010010001101000101011001111000100110101011
Final Data
This little segment of music has the following code
1011,1101,1101,1100,1010,1000,0110,0011,0010,0001,0001,0011,0100,0110,0111,0110,0100
Without the commas 101111011101110010101000011000110010
00010001001101000110011101100100 This is just for a split second CD’s are sampled at 44KHz, ie 44000 times a
second!
Hardware
An Analogue to Digital converter is used to do this digitising.
To play back sound a sound card is needed– Converts the digital data back into an
analogue sound
Midi(Musical Instrument Digital Interface)
Electronic instruments use this standard to store data on notes.
Allows keyboard to communicate with Guitar!
Data stored includes– Pitch– Length– Dynamics– Type of sound– Very small file size (stores via ASCII)
Midi Examples
Midi
PC’s can work with Keyboards and other Midi instruments
Songs stored on disk then played through Keyboard etc
Editing the song then becomes extremely easy via the PC
Images
Two ways of creating an image on a PC
Bit-map Vector
Bit-map
Image made up of dots called pixels Each dot can have a colour assigned
to it The number of possible colours
depends upon the quality of the image Low quality = 2 colours ie black and
white High quality = over 4 billion colours
Example
Each pixel can be assigned either 0 for black or 1 for whiteThis graphic has the value
000111100010111111011101111011111011011111110011111111001111111011011111011110110101111110101110000111
All this for one 10 x 10 black and white picture
The Maths
10 x 10 pixels = 100 ones and zeros If you have a high quality image with lots of
colours you need 32 ones and zeros for each pixel!
10 x 10 x 32 = 320 ones and zeros This screen is 800 x 600 pixels! 800 x 600 x 32 = 15360000 ones and zeros
approx 15Mb of memory! (This is why graphics cards need lots of memory!)
Bit-maps
Used for photographs Jpeg, Giff, Tiff Easy to edit
– Brush / spray
Zoom / Resize problem!
Zoom / Resize Problems
Vectors
Sometimes called Object Orientated Drawing
Image made up of objects (shapes) Eg
– Lines– Rectangles– Circles
The shapes are mathematically stored in memory
Example
A rectangle can be stored with two points plus information about line type and fill.
(0,0)
(4,2)
Vectors
Very small memory overheads Device-independent Scalable
Any Questions