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