What is multimediacgscomputing.weebly.com/uploads/1/6/9/9/16994998/... · Intermediate 2 Computing...

Intermediate 2 Computing Multimedia Technology

- 1 -

What is multimedia?

A multimedia application might be defined as an interactive piece of

software communicating to the user using several media, for example text,

images (photographs, illustrations), audio (music, sounds), video and

animation.


- 2 -

The development process for a multimedia project

The process of developing a multimedia project follows the same seven

stages of development as any software development.

1. Analysis

2. Design

3. Implementation

4. Testing

5. Documentation

6. Evaluation

7. Maintenance

Analysis

Analysis turns a vague idea into an exact description of what the multimedia

project is expected to do, the specification

Design

Design produces a detailed plan which defines what the different parts of

the project are and how they are linked together. The design will contain

important details about the content of the project.

Storyboarding is a technique that is used to describe the layout of the

multimedia elements of each screen and how they are linked together, the

text used, the number and type of graphics and the need for sound files and

video clips.


- 3 -

Implementation

The design of the multimedia application can be turned into a working

project using a variety of different types of software combining graphics,

video clips, text files and sound files

Testing

A series of practical tests that check that all the multimedia elements

function correctly, the video clips run, the sound files play and the links

between the screens operate correctly

Documentation

Documentation usually consists of two documents:

A user guide containing advice and help on how to use the finished

project

A technical guide is produced containing information about the

specification of the computer system, operating system and software

required to run the project. I t will also contain instructions on how to

install and maintain the software

Evaluation

Evaluation takes place to ensure that the multimedia application meets the

user’s requirements. Evaluation is carried out by the client or user

Maintenance

Fixing previously undetected errors

Adapting to changes in hardware and/or software

Adding new features


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Implementing a multimedia project

There are different types of multimedia projects, for example, web pages,

an interactive CD-Rom or a multimedia presentation and although different

types of software will be used to create the different types of multimedia

project the development process for the multimedia project will always

remain the same

Types of software used

Authoring packages

Multimedia authoring software is a program that allows the multimedia

application, such as an interactive CD-ROM, to be created by dragging and

dropping the multimedia elements onto the page, although scripting

authoring software, when you write code, is also available

A screen from an authoring package

An interactive CD-ROM


- 5 -

Presentation software Presentation software allows the creation of a multimedia slide show with

links between the slides. Presentation software packages a relatively easy to

use and presentations can be produced without any great expertise but

often presentations produced can be similar as there are a limited number of

templates and producers do not adhere to sound presentation rules.

Presentation software

Viewing the multimedia projects

Both types of software, authoring packages and presentation software will

allow the running of the created files without the need for the application to

be present on the user’s computer. A stand alone executable file is created

which can be run itself for authoring packages, distributed with the CD/DVD

multimedia application. Particular executable files will be needed for

different operating system

Free stand alone file players or media players are used to run presentation software files. This means that the person running the file can view the

multimedia creation but cannot edit it

Examples of media players


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Text editors

Text editors can be used to produce multimedia web pages. Text editors are

used to enter HTML code (Hypertext Markup Language), this requires

programming expertise in HTML and can be very time consuming but using

HTML can produce original and innovative results

An example of the HTML used to produce a web page

How the web page looks when viewed using a browser


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WYSIWYG editor A WYSIWYG editor allows web pages to be created without the need to

know HTML. WYSIWYG means what you see is what you get. You create the

web page by dragging and dropping the elements, titles, graphics, tables etc

onto the page. A preview feature will allow you to see how exactly it would

look in a browser. Using a WYSIWYG editor to create a web page is quicker

than producing it using HTML, as you don’t have to learn HTML but pages

created by different people can look quite similar as there are a limited

amount of styles available

A WYSIWYG editor

Web browser

Web browsers are needed to display web pages and to allow the user to

navigate between web pages. A web browser can also be used like a text

editor to produce multimedia web pages using HTML. Common web browsers

are Internet Explorer and Mozilla Firefox


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Questions on software

1 List the seven stages, in the correct order, for developing a

multimedia application or project

2

2 At what stage of the development of a multimedia project is a

storyboard produced?

1

3 List three elements that may be contained on a typical storyboard 3

4 What happens at the evaluation stage? 2

5 There are two types of software used to create multimedia

applications. Which type would be best for creating a multimedia

application which required the user to be actively involved with the

content?

1

6 Why would it be better for you to create a website using a

WYSIWYG editor than using a text editor?

2

7 What type of software is needed to display web pages? 1

8 When is a file player needed? 1

9 Name three modifications that can be carried out at the maintenance

stage of the development process

3

10 What type of file is created at the end of the software development

process when using an authoring package?

1

Total 17


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Bit-mapped graphics

Bit-mapped graphics are graphics that are stored as a grid of pixels. Pixels

are the tiny dots that make up an image. A bitmap corresponds bit-for-bit

with an image displayed on a screen.

Capturing bit-mapped graphics Several hardware devices can be used to capture bit-mapped graphics. The

two most common are:

Digital cameras

Scanners

Digital cameras use an array of CCDs

(Charged Couple Devices) which are

electronic light sensors used to capture

the light emitted by an image and turn it

into a voltage that can be stored as

digital data. Each CCD captures the data

for one pixel

Scanners use a line of CCDs on a moveable scan head that pass over an image

converting the light reflected off the document into an analogue signal which

is then converted to digital data and stored.


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Storage of graphics In a black and white graphic each pixel is represented as either a 1 or a 0,

black=1 and white=0.

Storing colour graphics requires many more bits. A black and white graphic 3

inches by 3 inches with a resolution of 600 pixels per inch requires 396 KB

of storage, the same graphic with 256 colours would require 3.09MB and a

photograph using True Colour with 16,777,216 colours would need 9.27MB.

As more colours are used the file size increases and storing these large files

becomes a problem. To help solve this storage problem a technique known as

compression was developed. Compression reduces the size of the file

Images captured using digital cameras will be

stored on memory cards. Typical memory card

sizes can range from 128MB to 8GB

Unwanted images can be deleted

Memory cards can be removed from the camera

an inserted into a printer or computer

Scanned graphics will be stored on the computer system attached to the

scanner

The scanned

graphic will be

stored on the

computers hard

drive


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Factors affecting the quality and file size of graphics

Compressing graphics Uncompressed graphics, can have very large file sizes, take up lots of

storage space and take longer to transmit across networks. Compressing the

graphic makes the file size smaller. There are two types of compression:

Lossless

Lossy

Lossless compression reduces the file size without any loss of detail or

quality. Lossy compression reduces the file size at the expense of detail and

quality.

How does lossless compression work? Lossless compression creates a code from the original and stores the code.

When you want to view the picture or read the message the original is

rebuilt from the code. The coded version will be smaller in file size than the

original but bigger than a lossy compressed file. As there is a need to rebuild

the file there is a time delay between opening the file and actually seeing

the picture

How does Lossy compression work? Lossy compression removes some of the data, keeping only what is necessary

to convey the message. You could apply text compression when you are text

messaging by removing the vowels.

Cn y rd ths mssg?

Lossy compression is applied to graphics by removing parts of the picture

that are not deemed significant, small details that the human would not pick

out anyway. Lossy compression applied to sound (mp3) removes sound out

with your hearing range and when compression is applied to video (MPEG)

this involves storing only certain frames

File formats and compression A bitmap is an uncompressed file format where a binary code is stored for

the colour of each pixel. This type of file will take up the largest amount of

storage space.


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GIF (Graphics Interchange Format) is a bit map file format which uses

lossless compression to reduce the file size. This is done by using a code to

store patterns of bits that are repeated throughout the graphic file and

therefore do not have to store the actual pixels more than once. GIF is

based on an 8 bit colour code giving a maximum of 28 therefore GIF files

store a maximum of 256 colours. A maximum of 256 colours means that GIF

is an unsuitable format for representing photographs as there are not

enough colours to be life like. GIFs are used to represent charts, cartoons

and drawings

JPEG (Joint Photographic Expert Group) is a bit map file format that uses

lossy compression. This makes the graphic file smaller by cutting out parts

of the graphic that won’t be noticed by the human eye. JPEG is a common

format for storing digital photographs. Depending on the image or the

amount of compression used the loss of detail can range from not noticeable

to seriously reducing the quality of the image. JPEG is not suitable for

storing cartoons or drawings because the data that is lost notably reduces

the quality of the image

Summary of compression

The higher the level of compression, the smaller the file size

The smaller the file size, the more data is lost

The more data is lost the poorer the graphic quality is

Factors affecting the quality and file size of graphics

Resolution

The term resolution is a measure of the size of the pixels in the image. High

resolution graphics, like a photograph (JPEG), have a large number of small

pixels.

JPEG GIF


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Low resolution graphics (GIF) have a small number of large pixels. High

resolution graphics have better quality than low resolution but require more

storage. Resolution is usually measured in dpi (dots per inch), were each dot

is represented by a pixel and each pixel stored using binary.

Increasing the resolution of an image increases the amount of pixels and

increases the storage space required. Reducing the resolution decreases the

amount of storage space required but lowers the quality of the image

Colour depth

Colour depth is the number of bits used to store the colour of each pixel.

The more bits used the more colours can be represented and the more

storage space is needed to store the graphic. Or the higher the colour depth

then the higher the number of colours that can be represented, the better

the quality of an image

The GIF file format has a colour depth of 8 bits (1 byte), which gives

a maximum 256 colours

The JPEG file format has a colour depth of 24 bits (3 bytes) which

allows for over 16 million colours (16,777,216), this often referred to

as True Colour

Summary of factors affecting the quality and file size of graphics Bit –mapped graphics have high storage requirements

Compression reduces the file size

Lossless compression reduces the file size without loss of quality

Lossy compression reduces file size more than lossless

Reducing the resolution, reducing the colour depth and using lossy

compression all contribute to reducing the file size but at the expense

of the quality of an image


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Changing the colour depth

A comparison of storage requirements of the same graphic using three different graphic types Example 1 - Black and white

A black and white graphic 6 inches by 6 inches (6*6) with a dpi of 300 will

require storage of 396KB

With a black and white graphic 1 bit is required to store each pixel

(6*300)*(6*300) * 1 (1 bit per pixel)

3240000/8 (divide by 8 to get the number of bytes)

405000/1024 (divide by 1024 to get the number of KB)

395.5 (round up to nearest whole KB)

396KB

396KB of storage is needed

Example 2 - GIF

A GIF graphic 6 inches by 6 inches (6*6) with a dpi of 300 will require

storage of 3.09MB

With a GIF graphic which can produce 256 colours 8 bits or 1 byte is needed

to store each pixel

(6*300)*(6*300) *8 (8 bits per pixel)



3164.0625/1024 (divide by 1024 to get the number of MB)

3.09MB

3.09MB of storage is needed


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Example 3 - JPEG (True Colour)

A JPEG graphic 6 inches by 6 inches (6*6) with a dpi of 300 will require

storage of 9.269MB

A JPEG graphic which can represent 16,777,216 colours and needs 24 bits

(3 bytes) to store each pixel. This level of colour depth is often referred to

as True Colour

(6*300)*(6*300)*24 (24 bits per pixel)




9.27MB

9.27MB of storage is needed

Summary

A graphic 6 inches by 6 inches (6*6) with a dpi of 300 changing the colour

depth

B/W graphic 396 KB

GIF 3.09MB

JPEG 9.27MB

Increasing the resolution

A graphic 6 inches by 6 inches (6*6) with a dpi of 600

Example 4 - Black and white

(6*600)*(6*600) *1 (1 bit per pixel)




1.54MB


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Example 5 – GIF

(6*600)*(6*600) *8 (8 bits per pixel)




12.36MB

Example 6 – JPEG (True Colour)

(6*600)*(6*600) *24 (24 bits per pixel)




37.08MB

Summary

A graphic 6 inches by 6 inches (6*6) with a dpi of 600

B/W graphic 1.54MB

GIF 12.36MB

JPEG 37.08MB

How changes in colour depth affect the storage size of a graphic

How changes in dpi affect the storage size of a graphic

Graphic Colour depth File format Size of file

6*6 at 300dpi 1 bit Bitmap (B&W) 396KB

6*6 at 300dpi 8 bit GIF 3.09MB

6*6 at 300dpi 24 bit JPEG 9.27MB

Graphic Black and white GIF JPEG

6*6 at 300dpi 396KB 3.09MB 9.27MB

6*6 at 600dpi 1.54MB 12.36MB 37.08MB


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Questions on bitmapped graphics

1 Explain how a digital camera captures an image? 2

2 How does a scanner capture an image 2

3 What does a digital camera use for backing storage 1

4 In a bit map black and white file how is each pixel represented 1

5 What is the purpose of compression 1

6 JPEG uses lossy compression. Explain what is meant by the term

“lossy compression”.

1

7 State the difference in colour depth between a JPEG file and a GIF

file.

2

8 What type of compression does GIF use? 1

9 You can use a WYSIWYG web page creator when creating the web

pages. Suggest one other type of software you could use to create

the web pages.

1

10 When would the following pieces of software be used, a) a file player,

b) a stand alone executable file

2

11 What is meant by “colour depth”? 1

12 What is meant by “resolution”? 1

13 What is the effect of changing the colour depth of a graphic from 8

bits to 24 bits?

2

14 State two effects of increasing the resolution of a graphic 2

Total 20


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Hardware required to display graphics Graphics card

A graphics card is a circuit board attached to the

motherboard of the computer and has input and

output ports to allow peripheral hardware such as

monitors to be attached. A graphics card has

its own memory (RAM) and processor to store

and process the graphics data relieving the pressure on the computer’s CPU

and memory. Graphic cards are needed because processing graphics,

animations and video clips in a multimedia requires substantial processing

power and lots of RAM.

Monitors

Large screens with a high resolution are required to produce the high quality

images needed for editing bit-mapped graphics and CAD (Computer Aided

Design).

CRT (Cathode Ray Tube)

CRT monitors are large and heavy

Medium to high resolution

Can display very high quality images

Use for CAD and art work

The higher the screen resolution, the more pixels on the screen, the clearer

the image, the more memory (RAM) is needed to store them and the more

processing power needed to manipulate them

The resolution of different standards of monitors

Mode Resolution

SVGA 800*600

SXGA 1280*1024

UXGA 1600*1200


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LCD (Liquid Crystal Display)

Use transistors and a thin film of liquid crystals

to control light passing through the screen

Light weight

Compact

Need little power (so can be run on batteries)

Often found on palmtop and laptop computers

Screens not very bright

Can cause eye strain if used for long periods of

time

Not good for use in high resolution dependent activities such as CAD

TFT (Thin Film Transfer)

A type of LCD but using many more

transistors

The use of lots of transistors

produces a high quality display

TFTs used to display animations and

3D graphics

Much clearer than ordinary LCDs

More expensive than ordinary LCD

Less power consumption than CRTs

Less space need than CRTs

Although flat screens have replaced CRTs as the most popular type of

monitor in most homes and offices CRT monitors are still popular in the

printing and broadcasting industries as well as in the professional video,

photography, and graphics fields due to their better representation of

colour detail


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Questions on hardware to display graphics

1 Describe the purpose of a graphics card 2

2 What do the letters CRT mean? 1

3 Why would a UXGA monitor require more memory than a SVGA

monitor?

1

4 What do the letters LCD mean? 1

5 Give one advantage a LCD monitor has over a CRT monitor 1

6 Give one advantage a CRT monitor has over a LCD monitor 1

7 What do the letters TFT mean? 1

8 Give one advantage a TFT monitor has over a LCD monitor 1

9 Other than less space needed give one advantage a TFT monitor has

over a CRT monitor

1

10 Give one advantage a CRT monitor has over a TFT monitor 1

11 Give two reasons why LCD monitors are used on palmtops and laptops 2

12 Which type of monitor would need the most RAM to operate? Give a

reason.

2

Total 15


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Paint programs and bit map editing software Paint programs let you make let you make changes to bit map images. Two

common tools are:

Fill Tool which allows you to choose colour from a chart and then pour

it into the graphic

Paintbrush Tool which allows you to apply colour in a more controlled

way to particular parts of the graphic

Image editing software IES can be used to edit a graphic loaded in from a digital camera or from a

scanner. IES can be used to:

Alter the resolution, decreasing the resolution reduces the quality of

the image and any hardcopy produced, since there are fewer pixels

but the file size will be reduced

Alter colour depth, increasing the colour depth increases both quality

of the graphic and the file size

Crop, select parts of a graphic and cut out what is not needed

Alter brightness and contrast, to lighten up shady areas and improve

the overall appearance of the image

Re-size or scale, to adjust the width and/or height of a graphic

Use special effects, image editing packages have a whole range of

special effects which can be used to enhance a graphic

Vector Graphics Vector graphics is another way of representing graphical data. VG store an

image as a list of layered objects with each object being described by its

attributes. Unlike a bitmapped graphic which is made up of small squares of

coloured (pixels) each object in VG is described mathematically as a list of

attributes. These attributes fully describe the type of object, its position

on the screen, its size and the colour/pattern of its outline (line), its middle

(fill), its degree of rotation and which layer it is on.

Example of attributes of objects in a vector graphic

Object Attributes Line start x, start y, end x, end y, line colour, line thickness, layer etc

Circle centre x, centre y, radius, line colour, line thickness, fill colour, layer etc

Rectangle start x, start y, length, breadth, line colour, line thickness, fill colour, layer etc


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The original graphic comprising of three

objects, a line, a circle and a rectangle, with

default attribute settings

The graphic with changes to attribute

settings

The objects are individual elements of the

graphic and can be moved independently of

each other


graphic and can be resized independently of

each other


graphic and can be layered independently of

each other

Figure 1 original

Figure 2 attribute changes

Figure 3 moving objects

Figure 4 resizing objects

Figure 5 layering objects


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File size and complexity of an image As more objects are added to the picture the amount of object descriptions

increase and therefore file gets longer. When a vector graphic file is loaded

the object attributes are read by the application package and the objects

drawn on the screen layer by layer. The more complex the image (the more

layers or objects its has) the greater the file size

3D objects in vector graphics It is possible to draw three dimensional

objects. All the application has to do is

recognise the type of object and to interpret the

list of attribute correctly. The attibutes will be the

same as flat (2D) objects but with a few extra ones. 3D objects

will also have attibutes for:

angle of rotation, the x, y and z axis need to be defined

surface texture, the surface appearance of the 3D object

shadow, the position and intensity of the light source

A comparison of Vector and Bitmapped Graphics

Vector Graphics Bitmapped Graphics resolution independent- always crisp and

smooth when rescaled

resolution dependent- can become blocky

when rescaled

small file sizes large file sizes

difficult to create realistic images images very realistic-photos

objects edited as a whole entity, objects

cannot be cropped

each individual pixel can be edited and

therefore cropped

each object can be individually dupilcated,

moved, scaled or manipulted easily as it is on

its own layer

flat bed of pixels, painting on top of an

image destroys whats underneath

Objects can be group together to form a

whole or ungrouped to be individual objects

always grouped as default can never be

ungrouped


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Common file formats for Vector Graphics Many vector graphic application packages store the graphic in their own

format but there are some industry standards which allow different

packages to read files created by other applications

SVG- scalable vector graphics

scalable without loss of quality therefore used on smartphones to CRT

monitors

Any browser can recognise graphics in SVG format, so suitable for

use on WWW

SVG are smaller than equivalent bitmap image, quicker to transmit,

smaller to store

VRML- (virtual reality markup language) virtual

reality modelling

WRL- world description language

Each of these allows a 3D world

to be defined as a group of

objects, each described

mathematically by its attributes.

All the advatages of vector

graphics apply, plus the ability to do 3D modelling

VRML (vermal) is used widely in smartphones and the web

Virtual reality Virtual reality can be described as the ultimate multimedia experience when

the user is immersed in the world of the computer and can journey through,

and interact with, a computer that generates a 3D multimedia world

VR is used to:

For training e.g. pilots

Creating and inspecting and testing a 3D CAD model

Simulating scientific processes

Forecasting e.g. weather

Gaming


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VR hardware Data gloves fitted with sensors so

movement of the hand can be sensed by the

computer

Data suits with

sensors so movement

of the body can be

sensed by the

computer

VR headset will allow the computer to sense were the user is looking

and create the scene they should be seeing

Video output can be achieved by using split

screen technology, multiple projectors or

headsets equipped with miniature stereo

monitors

Audio output can be achieved by sets of

surround speakers either embedded in a

headset or placed around a VR room

Sensors used in virtual reality:

Magnetic

Ultrasonic tracking systems

Optical position sensors


- 26 -

Questions on Bitmapped software and Vector Graphics

Total 24

1 Name two common tools of bitmap paint programs and explain what

each would be used for

2

2 List two things you could do to a photograph with image editing

software

2

3 What would happen to the quality of the hardcopy if you increased

the colour depth?

1

4 How is a graphic stored in a vector graphic application 1

5 Look at figure 1 on page 22 and identify the three objects 3

6 Look at figure 1 on page 22 and compare it with figure 2, what

changes to the objects attributes have taken place

5

7 Why would a vector graphic package not be used to remove “red eye”

from a photograph?

2

8 3D graphics have all the attributes of 2D graphics plus more beside,

name two attributes that have to be defined for 3D graphics but not

2D graphics

2

9 What is virtual reality? 1

10 Name two things virtual reality is used for 2

11 Data gloves and data suits are worn in virtual reality to provide

information to the computer what does the computer use to get the

information?

1

12 What piece of VR hardware is both an input device and an output

device?

1

13 What are SVG, VRML WRL? 1


- 27 -

Video data Video data is a sequence of pictures, called frames, which are shown in

sequence to simulate a moving image. Each picture in a video is a bitmap

image

Hardware required

Digital video camera- DVC is used to capture high quality video

Webcams are used to capture video which is of less quality than that

captured by DVC

Graphics or video card is required to input and output video data. The

graphics card is also used to compress and decompress video data

Storage of video data

Video data files can be very large and so it is usually stored in compressed

file formats however there are uncompressed formats as well.

Standard file formats for video are:

AVI- Audio Video Interleave, this is used by the Windows based

operating system and is an uncompressed format

MPEG- Motion Pictures Experts Group, is a compressed format using a

form of lossy compression used to reduce the file size.

MPEG explained

MPEG stores only some of the frames in the clip. These key frames are

stored normally. The format then stores the differences between the

individual frames. Storing the changes takes up less space than storing whole

frames. Each key frame is stored as a JPEG graphic

Key Frame

Changes Key Frame

Changes Changes Changes

A graphics/video card has its own memory (RAM)

and processor to store and process the video data

relieving the pressure on the computer’s CPU and

memory. Graphic/video cards are needed because

processing video clips in a multimedia requires

substantial processing power and lots of RAM.

Key Frame


- 28 -

File size and file quality

Factors that affect the file size and quality are:

Length of clip

The length of clip, measured in seconds, means the longer the video lasts the

bigger the file size

Frames per second (fps)

Also known as the frame rate, reducing the amount of frames will reduce the

size of the file. Each frame is one picture, one JPEG. If the frame rate is

set to low the movement will appear jerky. UK TV and professional video

capture at 25fps, cinema at 24fps and web cams are usually set between 8

and 16 fps. There is no point capturing above 25fps because the eye does not

notice, a frame rate of less than 15fps and the picture will appear jerky. A

video stored at 25fps will require 21/2 times more storage space than one

stored at 10fps

Colour depth

Reducing the amount of colours in each frame reduces the storage

requirements for that frame and the whole video if is repeated throughout.

This is the same as any bitmapped image, with a number of bits or bytes

required to store each pixel. 8 bit colour, 8 bits required to store each pixel,

gives 256 possible colours, 24 bit, 24 bits required to store each pixel,

colour gives over 16 million colours and 32 bit colour gives 4 billion colours.

Reducing the colour depth below 24 bit colour would result in a noticeable

depreciation of picture quality

Resolution

The resolution of the image, measured in dots per inch (dpi) effects the size

and quality of each frame and therefore the size and quality of the over the

whole clip. The higher the resolution the better quality, the lower the

resolution the poorer the quality. The most common resolution for video is

768*576, that is the number of pixels per frame. A video with a resolution

of 640*480 will be 4 times as large as a video with resolution 320*240


- 29 -

Calculating the file size of video

The file size is calculated by first finding the size of a single frame, using

the resolution and colour depth. This is then multiplied by the frame rate

and the numbers of seconds in the clip

File size for a typical 20 minute video would be 37.08 Gigabytes, with

resolution 768*576, colour depth 24 bits, frame rate 25 fps, length 20*60

(R*CD) * (fps*L)

A single frame

768*576 = 442368 *24 = 10616832/8 = 1327104 (bytes)

1327104/1024 = 1296/1024 = 1.265625 MB

Frame rate and length

1.265625 *25= 31.640625 *20*60 = 37968.75/1024 = 37.08 Gigabytes


- 30 -

Video editing software

This software allows various means of editing video, including changing the

sequence of clips, adding transition effects between clips, adding a

soundtrack, importing or exporting clips and cropping.

Features of video editing software

Cropping, to trim or cut out part of

the video

Import clips into your film or export

clips to use in another film

Sequence clips by rearranging the

order the clips are seen according

to a chosen timeline

Transitions, jump, fade or dissolve

between clips

Adding a soundtrack, importing

sound

Adding visual (titles) or sound

effects

The “timeline” area of Windows Movie Maker


- 31 -

Questions on video data (1)

Total 13

1 What name is given to a single bitmap image in a video? 1

2 What piece of hardware is used to compress and decompress video

data?

1

3 Video data can be stored compressed or uncompressed, name a file

format for each

2

4 Explain how MPEG works 3

5 What does the colour depth of a video refer to? 1

6 How many bits would be needed to represent each pixel so that

16,777,216 colours could be displayed

1

7 Explain the term frame per second 1

8 What is the standard fps for video and TV 1

9 What effect would it have on the video if a frame rate was below 15

fps?

1

10 What is the resolution measured in?

11 What is the standard resolution for video? 1


- 32 -

Questions on video data continued

Total 12

12 Copy and complete the table 6

13 Calculate the file size for a 10 minute video with resolution 768*576,

colour depth 24 bits, frame rate 25 fps

3

14 What is cropping? 1

15 List two things you can add in to a video clip 2


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Digitised Sound Data An important component of any multimedia application is the inclusion of

sound data. This might be a clip downloaded from the internet, copied for a

CD or it could be captured live. It might be spoken instructions for the user,

a commentary running over the action or just some music or sound effects to

make an application more interesting

Sound editing software

Hardware required for sound data

To capture voice commentary or live music you need a microphone and a

sound card and for output you need speakers

Sound card

Sound cards contain processors and memory chips. They are installed in your

computer and they take over some of the processing of sound data, relieving

the main processor. They can do a variety of things including:

Recording audio directly to hard disk

Playback of digitised sound

Sound synthesis

Interfacing with midi instruments


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The sound card captures the sound as a wave.

It then samples the wave as a series of

numbers. These numbers are then converted

to digital values and processed by the

processor. The sound card plays a vital role in

the playback of audio, along with speakers

Audio Formats

Uncompressed sound data files tend to be very large so it is usually stored in

compressed file formats. Here are three common file formats

RAW – uncompressed audio file format

WAV – compressed file format using lossless compression

MP3 – compressed file format which uses lossy compression

Factors affecting file size and sound quality

Lossless compression can reduce the file size without affecting the quality

of the sound but the file size will be much larger than lossy compression and

may not be much less than the RAW format

Lossy compression reduces the file size but at the expense of quality. Think

of the difference between CD quality audio and a MP3 track. However lossy

compression attempts to minimise the loss in quality by removing sounds that


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are inaudible to the human ear and also removes quieter sounds that are

drowned out by other parts of the recording. The more compression the

smaller the files size but the poorer the quality, the less compression the

greater the file size

Sampling depth/resolution is the numbers of bits or bytes used to store a

single sample. The greater the sample depth the more detailed the digital

picture of the original sound will be, the greater the file size. WAV files are

sampled using a bit depth of 8 or 16 bits

Sampling frequency is how often the sound is sampled per second. Sampling

frequency is measured in hertz. Sampling frequencies of 22 KHz (22,000

samples per second) and 44 KHz are common, CD audio samples at 44 KHz.

The more often you sample the better the quality but the greater the file

size. Set the sample rate too low and you can miss the variations in the sound

and a bit like a low frame rate in video the playback is jerky

Sound time, is measured in seconds, the greater the length of soundtrack

the larger the file size

Summary table- Factors affecting file size and sound quality

Factor Sound quality File size lossy compression the more compression the

poorer the sound quality

the more compression the

smaller the file size

sampling depth the greater the sampling

depth the better the sound

quality

the greater the sampling

depth the bigger the file

size

sampling frequency the greater the sampling

frequency the better the

sound quality

the greater the sampling

frequency the bigger the file

size

sound time no effect the longer the soundtrack

the bigger the file


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Sound editing software

The main features of sound editing software are:

Decrease sampling frequency – this reduces the quality of the sound

since there are fewer sample taken per second, but the file size is

smaller

Decrease sampling depth - this reduces the quality of the sound by

decreasing the number of bits used to store each sample, but the file

size is smaller

Crop – shortens the length of a track by cutting parts of it away

Volume – the loudness of parts of the track or individual instruments

can be adjusted

Reverse – playing or recording parts of the track backwards

Special effects – echo, reverberation, normalise, noise removal and

fade in/out


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Synthesised sound data Instead of capturing sound you can get the computer to produce its own.

Producing sound this way is called synthesising. A common format for storing

synthesised sound is MIDI

Musical Instrument Digital Interface

In MIDI each note is stored as a list of attributes (like vector graphic

images). Some common attributes of notes stored as MIDI data are:

Instrument – type of instrument, violin, guitar, piano etc

Pitch – the pitch of the note, that is, the frequency of the sound, how

high or low the note is

Volume - the volume of the note

Duration - the length of the note, how many seconds it carries on for

Tempo – how fast the notes are played

These attributes describe all that is needed to play any tune on any

instrument. The MIDI interface allows the creation and editing of tunes, any

note can be altered to achieve the user’s requirements


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MIDI Software/hardware

MIDI keyboards, or other instruments, are used

to create sound data in MIDI format. However

you don’t even need actual instruments, as there

are software packages that allow you to create

and edit MIDI files directly from your

computer

MIDI software

The advantages of MIDI are;

Music can be produced at the computer with an easy to use interface

no instruments required

Individual instruments and notes can be easily edited.

MIDI format has much smaller file size than digitised sound data as it

is the attributes of the sound that is stored not every sound sample.

The MIDI format is a common standard which allows the musical data

to be passed between devices made by different manufactures of

musical instruments and a computer

The disadvantages of a MIDI are;

Synthesised sound, poor representation of human voice and other

naturally occurring non uniform sounds

Limited realism, sound can be “electronic” sounding

Sound quality, dependent on quality of soundcard


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Questions on sound data

1 Give three examples of sound data used in multimedia 3

2 Other than a sound card name two pieces of hardware needed for sound data

2

3 Sound cards contain two types of chips, what is the purpose of the chips on a

sound card?

2

4 Sound can be captured using a microphone, describe what a soundcard does to the

sound wave that is captured

2

5 Match these three audio formats WAV, MP3 and RAW with the terms,

uncompressed, lossy compression and lossless compression

3

6 What affect would continually increasing the compression on an audio file have?

2

7 What affect on the quality of the sound and the file size if you decreased the

sampling depth from 16 bits to 8 bits

2

8 What would happen to the files size and the quality of the sound if you increased

the sampling frequency from 44 KHz to 66 KHz?

2

continued on next page


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9 Copy and complete the table below

5

10 Explain the following features found in sound editing software:

a) crop

b) Volume

c) Reverse

d) Special effects

4

11 How is synthesised sound data produced? 1

12 What is the common format for storing synthesised sound data? 1

13 Each note in synthesised is stored as a list of attributes, name three common

attributes and explain what each does

6

14 Explain the similarity between the storage of synthesised sound data and the way

vector graphics are stored?

1

15 Name a common piece of hardware used to create sound data in MIDI format 1

16 What else, other than hardware can be used to create MIDI files? 1

17 List three advantages of MIDI 3


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18 What is MIDI particularly poor at reproducing? 1

19 List these audio formats in terms of size, with the smallest first: MIDI, RAW,

MP3 and WAV

2

20 List four processes that a soundcard carries out 4

Total 48


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Implications of multimedia technology

Converging technologies

In recent years we have seen the increasing spread of hardware devices

that combine tow or more functions. Converging technologies means two or

more technologies being combined, some examples are smart phones, Pocket

PCs, digital television and tablet computers.

Apples iPad, a tablet computer.

Smartphone

A smartphone is a mobile phone offering

advanced capabilities, often with PC-like

functionality (PC-mobile handset

convergence). There is no industry

standard definition of a smartphone. For

some, a smartphone is a phone that runs

complete operating system software

providing a standardised interface and

platform for application developers. For

others, a smartphone is simply a phone

with advanced features like e-mail, Internet and e-book reader capabilities,

and/or a built-in full keyboard or external USB keyboard and VGA

connector. In other words, it is a miniature computer that has phone

capability.


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Features of a smart phone;

All the features of a mobile phone, including WIFI or Bluetooth

Specialised operating system allowing applications with limited editing

functions

A multimedia device which can handle text, graphics, audio (MP3),

games and video

Has browser software to access web pages and send email

Digital camera to capture images which can be exchange with other

phone users or uploaded via the internet

Connects with laptops and desktops

Pocket PC

It is a hardware specification for a handheld-

sized computer that runs the Microsoft

'Windows Mobile Classic' operating system and

shares a lot of characteristics with a PDA

(Personal Digital Assistant). It may have the

capability to run an alternative operating system

like NetBSD, Linux, Android or others. It has some of the capabilities of

modern desktop PCs. The Pocket PC is a handheld device that enables users

to store and retrieve e-mail, contacts, appointments and tasks, play

multimedia files, games, exchange text messages with Windows Live

Messenger (formerly known as MSN Messenger), browse the Web, and more

Features of a pocket PC;

Most commonly found with Windows Pocket PC operating system,

although can work with other OS

Compact versions of popular desktop applications such as Word , Excel

and Internet Explorer

Handwriting recognition and/or voice recognition

Touch screen

MP3 playback

Voice recording

E-book reader

Wireless internet connection

USB ports to connect to other devices

Synchronise linking to desktop and laptops


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Digital television, DTV

DTV is an interactive multimedia device. Digital television is the sending and

receiving of moving images and sound by discrete (digital) signals, in contrast

to the analogue signals used by analogue TV.

Standard television, SDTV, is broadcast at 768x576 which is 442368 pixels

at 25 fps whereas high definition television, HDTV, is broadcast at

1920x1080 which is 2,073,600 pixels at 25fps; this means that HDTV has

approximately five times more pixels per frame. HDTV is digitally broadcast

using video compression.

Features of a DTV; BBC Digital

Is capable of display high quality

audio, video, animation and text

Enables users to interact with the

broadcast

Can link up to your computer or

home network

Can be accessed over the internet

Using the internet to access DTV


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Questions on converging technologies

1 What is meant by the term “converging technologies”? 1

2 A “tablet computer” is a type of converging technology, list two

others

1

3 Some present day mobile phones could be described as “smart

phones”, because they have extra features. List four extra features

2

4 What benefits does a operating system provide to a “smart phone” 1

5 Name three features a Pocket PC has that a smart phone does not? 3

6 List two benefits that DTV give to is users compared to standard

television

2

7 Why is HDTV digitally broadcast using video compression? 1

Total 11

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