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Multimedia technology – what we’ve learnt so far!

For the past few weeks the class has been studying the final topic of the course, multimedia technology. Here is a summary of what we’ve learnt so far.

Creating a multimedia solution/applications.

A multimedia application is the use of media types within the program. Multimedia applications are most of the time interactive. There are three types of multimedia applications:

  • A stand-alone application.
  • A web page.
  • A Presentation.
These applications are created using the same waterfall model used in the software development stage but are applied slightly differently. 
ANALYSIS:  Get specification/ aims of application
                   Who will use it
                   Where will it be shown/distributed.
                   Budget
DESIGN:      The program structure
                   How the HCI (human computer interface) works
                   How each screen will look (if there is multiple screens)
                   Which media elements will be used(video, audio and/or images)
IMPLEMENTATION: Create the application.
                               What software will be used to import/export/embed media elements.
                               What is the most appropriate authoring software.

TESTING: Make sure everything works as expected (multiple windows, links, videos/audio streaming etc)

DOCUMENTATION: Hardware requirements and where the user will find help with application.

EVALUATION: Evaluate robustness of application.

MAINTENANCE: Perform corrective, adaptive and perfective maintenance.

Fix bugs (corrective)  Add additional features/ make changes (perfective)  Improve application by external software/hardware (adaptive)

Bitmap Graphics

The two main devices used for capturing still graphic data are a scanner and a digital camera.

CCD(Charged Coupled Device): This is used to capture the light.

ADC(Analogue-Digital Converter): As light is an analogue signal, the ADC converts the light signal captured by the CCD into a digital signal.

There are 4 different file storage types:

  • Bitmap (.BMP)
  • Joint pictures expert group (.JPG/JPEG)
  • Graphic interchange format (.GIF)
  • Portable network graphics (PNG)
Features within Bitmap Graphics

GIF TRANSPARENCY: When a GIF is made transparent, the background of the GIF is made the same colour as the background of the document the user is placing it into. for example, a GIF that is made transparent and is placed on a blue background. The GIF’s background will become blue.
GIF ANIMATION: This allows a number of still pictures (frames) to be compressed together to create a moving picture (animation) 
RLE(Run Length Encoding): is a compression technique that runs of data. This means that sequences with the same value are stored as a single element, rather than the original run.
CLUT(Colour Look Up Table): This is a table of colours which is used to change a set of preset colours. they are found in graphic software packages. e.g. paint.
Calculating Bitmap graphic storage requirements
Firstly we must calculate the number of pixels in the image
Formula
number of pixels = image width x resolution x image height x resolution 
example: How many pixels are there in an image 5 inches by 6 inches and with 700 dpi(dots per inch)
number of pixels = 5 x 700 x 6 x 700
                         =14700000 pixels
Calculating File Size
to calculate the file size we must multiply the number of pixels by the colour depth. To get the answer into bytes, we must divide by 8. 
Formula
File size(in bytes) = total number of pixels x the colour depth of each pixel / 8
example: an image 5 inches by 6 inches with 700 dpi uses 16 bit colour depth. calculate the file size.
 
Number of pixels = 5 x 700 x 6 x 700
                         = 14700000 pixels 
File Size = 14700000 x 16 /8
              = 29400000 bytes 
                 29400000/1024 = 28710.9 KB
                 28710.9/ 1024 = 28.04 MB
 
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Posted by on March 17, 2012 in Computing

 

The Revision i did over the holidays…

Computing Christmas Revision Blog

The joys of Christmas revision.

 

During the Christmas holidays I was asked to do some computing revision, which I did as I do actually want to pass the subject. In total I revised about 6 and a half hours over the Christmas holidays.

What did I revise?

I mainly revised the software development section of the course because it has been a while since we touched on that. Within the section I revised each stage of the software development process (analysis, design, implementation, testing, documentation, evaluation and maintenance). I also used the flashcards on the wiki(the one day I had the opportunity to use internet as I have none due to building work. It was in no way helpful!) and I used notes which I took down in class. I revised the type of personnel used within the software development team and what each does.

I revised the computer systems topic too. The processor was the main thing I revised and also how to do most of the calculations required within these two topics. I studied the differences between RAM and ROM, the types of computers current trends and the key terms related. The Von Neumann Architecture was a great help in understanding the basic process of a computer.

 

 
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Posted by on January 9, 2012 in Computing

 

Computer Memory & Addressability

Computer memory and Addressability


 Computer Memory:

Computer memory consists of main memory (Primary memory) and backing storage (Secondary memory).

 

Each storage location within the main memory is a little chip. Each location holds one word.

 

A word is defined by the number of bits that the central processing unit can undertake in a single instruction. The length of the word is decided by the width of the data bus(which also determines how much data is stored in one memory location)because they are equal.

 

There are two types of memory: RAM – Random Access Memory

                                                ROM – Read Only Memory

 

Random Access Memory

 

When the computer is switched off, all the contents stored within RAM is wiped. This type of memory holds mainly data from input peripherals but it also holds data from applications which the computer is running.

 

There are two types of RAM, static and dynamic.

 

Static: With static RAM the contents of the memory will be retained until power is no longer supplied to the computer.

 

Dynamic: Dynamic RAM has to have a continuous signal to be supplied to the chip to re-write (refresh) its contents.

 

Read Only Memory

 

The contents of ROM are written to the chips when is it manufactured. When the computer is switched off all the data is retained. It also hold the bootstrap loader. This is part of the operating system.

 

There are three types of ROM:

 

PROM – Programmable Read Only Memory

Once it is programmed, it cannot be erased.

EPROM – Erasable Programmable Read Only Memory

Only the chip can be removed from the computer (like PROM) and the program will be erased and replaced by another using UV light

EEPROM – Electrically Erasable Programmable Read Only Memory

Like EPROM, but the program is erased and reprogrammed using electricity.

 

Temporary Storage-Cache Memory.


This is a small amount of memory built in next to the processor. Due to this, it is physically faster than RAM. It stores the next instruction to be read.

 

Write-through cache: The contents of the RAM are updated at the same time as the cache contents.

 

Write-back cache: The contents of the RAM are updated when the contents of the cache are cleared.

 

 

Addressability


Addressability is the way in which a computer identifies memory locations.

 

The width of the address bus determines how many memory locations can be addressed:

 

1 bit address bus = 2 memory locations

2 bit address bus = 4 memory locations

3 bit address bus = 8 memory locations

ETC ETC

8 bit address bus = 256 memory locations

16 bit address bus = 65536 memory locations

32 bit address bus = 4,294,967,296 memory locations

 

Calculating addressable memory

 

To work out the total addressable memory:

 

Number of storage locations (multiplied by) the Size of each memory location.

 

Example:

 

16 bit address bus & 8 bit data bus

2^16 bits x 8 bits = 65536 bits x 1 byte

                                    65536 x 1

                                    65536 bytes => 64kB 

 
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Posted by on December 7, 2011 in Computing

 

The Processor

This week in computing, our class learnt about the processor. Within the processor, there are the control unit, ALU, MAR, MDR and Registers.

Von Neumann Architecture.


Inside the Processor

ALU: This is the arithmetic and logic unit. This part of the processor carries out all the arithmetic calculations and logical operations (AND, OR, NOT) the computer is asked to do.

Control Unit: This part of the processor controls the fetching and executing of instructions. It keeps everything synchronised and manages the reading and writing to and from the main memory. #

General purpose registers: These are very fast temporary storage locations on the processor.

MAR: The Memory Address Register is the register which holds the unique storage location of what piece of information is needed from the main memory

MDR: The Memory Data Register is the register which the information from the main memory is retrieved and also where it is sent back to the main memory if it is re-written or slightly changed.

Buses: These are physical wires which connect each part of the processor together.

The Control Bus

Each wire on the control bus has its own separate function. There are five:

Read Line: This informs the memory that data has been sent to the processor from a particular memory location.

Write Line: It informs the memory that data is to be written to a specific memory location.

Interrupt: A message which is received from a peripheral device causes the processor to stop doing the current task and deal with the message from the peripheral. Current data is stored into a temporary storage location on the processor called the stack. The processor then deals with the interrupt and once the task has done, it retrieves the data from the stack and carries on with the task.

Clock: This line keeps everything synchronised. It generates a steady pulse which keeps the flow of information constant.

Reset: This line clears all the internal processor registers and switches the computer back to its original switched on state.


 
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Posted by on November 29, 2011 in Computing

 

bitmapped graphics

Pictures which are viewed on digital devices are made up of pixels(picture elements). A pixel is the smallest unit of picture which can be controlled.Pixels are normally arranged in a two-dimensional grid and are often represented by dots or squares. To represent a black and white image, it will be stored in 2 bits, 1 being black and 0 being white. Although what would happen if the picture was in colour? It would be stored using more bits per pixel.

The resolution determines the quality of the image. So the smaller the pixels the greater the resolution.

There are two types of graphic, bitmapped and vector.

Bitmapped Graphics.
Bitmapped graphics are stored in a two dimensional grid (array) using binary to represent the colours of the pixels. Each pixel is represented by the same number of bits.

For black and white, each pixel is represented by one bit. Black = 1 and white = 1.

For colour, each pixel will be represented by the amount of bits required. For example, if there are four colours (black, white, red and green), each pixel would be represented as 2 bits.

00 = Black

01 = White

10 =  Red

11 = Green

Vector Graphics

Vector graphics  are objects such as geometrical shapes which are stored as mathematical equations which contain attributes of how they are to be drawn.

The computer will automatically save the new attributes if the object if :

-it is moved around the screen

-it is resized

– the fill pattern is changed

-the line thickness is changed

When using vector graphics, it is not possible to change the colour if the object or delete part of the object.

 

 
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Posted by on November 7, 2011 in Computing

 

Representing Real Numbers

In representing real numbers, computers are programmed to use Floating Point Representation. In floating point represnetation, the real number is stored as two seperate pieces of data, called the mantissa and exponent.

The mantissa holds the complete number without the point.

The exponent holds the amount of places the point needs to be moved to the left hand side to keep the original number.

Example:

What is the mantissa and exponent of 011010.01?

The mantissa would be: 01101001

The exponent would be: 6 (0110) as the decimal point needs to be moved 6 places until it gets to the far left-hand side.

=> 01101001 x2^0110

although it is not necessary to store the base 2 or the”x” sign as they will always be involved.

Accuracy in real numbers.

If the mantissa is onlt storing 8 bits for the whole number and the number is nore than 8 then some of the numbers after the point will have to be discarded, therefore the accuracy of the number will be decreased

Example:

Ifthe binary number is: 0110100.1001

it will have to be reduced to 0110100.1 as the mantissa can only hold 8 bits, decreasing the accuracy.

Range.

Increasing the range of the mantissa and exponent allows the number to have more accuracy and a larger range of numbers which it could be.

Representing Negative Numbers.

There are two ways to represent negative numbers. a theoretical way is called signed bit represtentation. This is when the computer would take the leftmost bit of the number and assign a positive or negative sign but this is not used as there is two values for zero. So two’s compliment represetation is used.

When using twos compliment, all the zeros in the binary number must be changed to a one and all the ones must be changed to a zero. Then a one is added on.

Example.

What is negative 5?

firstly what is 5 in binary? 0101-> 1010

1010

  +1

= 1011 -> negative 5

 
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Posted by on November 5, 2011 in Computing

 

Binary- Whait is it and why do computers use it?

In everyday life, we use 10 decimal numbers to represent numerical data,
BUT
Computers cant do that. The lowest base number system we can use is 2 so instead, computers use this to represent numbers. This is the binary system. As computers use voltages, there is not a specific voltage for each number in the decimal system because voltages change constantly. Therefore it is measured as a two state system, either on or off. Computers also use the binary system to keep things simple, such as calculations. If we used the decimal system, 100 rules would have have to be wired into the computer, whereas in the binary system there would only be 4 rules for calculations. Finally the last main reason why computers are two state systems and use binary is that the magnetic and optical storage devices used are suited best to two state systems.

How to convert (decimal -> binary)

In the decimal system the number 34567 could be represented as

10^4       10^3       10^2       10^1    10^0

3            4            5            6         7

In binary the number 11001 could be written as:

2^4         2^3         2^2         2^1         2^0

1            1            0            0            1

OR

16           8              4              2              1

1             1              0              0              1

To convert binary numbers to decimal (1 byte):

The term bit is short for binary digit.

so 8 bits make up 1 byte.

The byte is 10010111

128         64           32           16           8              4              2              1

1              0            0              1           0              1              1              1

To work this out, you multiply the numbers which are a 1 by 1 and add them together to give you the decimal number

= (128×1) + (16×1) + (4×1) + (2×1) +(1×1)

= 128 + 16 + 4 + 2 + 1

= 151

How to convert (decimal -> binary)

Convert the number 98 into binary:

To do this, does the number go into 128? no. so this becomes a 0.

Does it go into 64? yes, so this becomes a 1.

Does the remaining 34 go into 32? Yes so this is also a 1

Does the remaining 2 go in 16, 8,  4, or 1? No so these are all 0’s.

Does the remaining 2 go into 2? Yes, so this is a 1.

128       64       32       16       8       4       2       1

0          1          1         0        0       0       1       0

98 in binary = 01100010

The largest number we can make with 1 byte is 255. so if we wanted to make a number which is larger, we’d just add another byte on.

Units of Measurement:

1 byte (8 bits) – used to store binary numbers.

1 Kilobyte (1024 bytes) – A very very short story

1 Megabyte (1024 Kilobytes) – 1 minute of MP3 compressed music.

1 Gigabyte (1024 Megabytes) – A DVD-R can hold about 4.7 GB.

1 Terabyte (1024 Gigabytes) – becoming more common as the standard size of hard drive on a computer.

 
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Posted by on October 29, 2011 in Computing