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Computer Maths (Data Compression (When data is transmitted across the…
Computer Maths
Data Compression
When data is transmitted across the internet, the data goes across many links between routers. The connection into the internet is likely to be the lowest part of the route. One way to speed up this process is to compress the data and make them smaller. Smaller files take less time to transmit across a network.
Lossy compression : data encoding method is where file are compressed by removing detail.
Lossless compression : Files are compressed but NO data is lost. You can do this by "Zipping" the file
Run length encoding is a simple form of lossless data compression in which runs of data are stored using a thing called frequency pairs. For example the black and white image below in an uncompressed form would take up 64 bits, with 1 representing white and 0 representing black
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Binary arithmetic
In binary arithmetic, lay out the binary numbers the same way you would for denary. If the addition is 1+1, write a 0 and carry the 1. If the column is 1+1+1, write a 1 and carry the one
E.G. 100101
010110
111011
To add three numbers, add the first two numbers, then followed by the third.
Binary Shift
If a binary number is shifted left, it has the same effect as multiplying it by 2 for each shift to the left.
If a binary number is shifted to the right, it has the same effect of dividing the number by 2 for each shift.
Character Encoding
ASCII stands for America Standard Code Information Interchange. It is a code used to convert characters into numerical form for computer storage and transmission. Each of the 128 character used in the English language can be converted into a seven digit binary number
ASCII has now been integrated into unicode. Unicode is a wider coding convention for characters used in writing systems used throughout the world (Chinese, Hindi, Greek).
Image/Sound Size
To calculate the size of an image, you will use the following formula.
Size (bits) = Width image X Height of image X Colour Depth
Size (bytes) = ( Width image X Height of image X Colour Depth)/8
Size (kilobytes) = ((Width image X Height of image X Colour Depth)/8)/1000
To calculate the size of a sound file, use the following equation
Size = sample rate X sample resolution X number of seconds.