Data Representation

• Computers require any data to be converted into binary before it can be processed by the computer.
• Different number systems exist such as denary, binary, and hexadecimal.
• Hexadecimal is used in computer science for uses such as aiding programmers and representing MAC addresses.
• Binary numbers can be added using four rules. If this creates a greater result than 255 for 8-bit binary numbers, an overflow error occurs.
• Logical binary shifts can be performed on binary numbers. These can shift left or shift right and can be done multiple times. This changes the binary number and can affect the accuracy of the binary number.
• Text is converted into binary using a character set such as ASCII or Unicode.
• Images are converted to binary by taking each pixel and providing it with a colour code that is converted to a binary value. The larger the resolution and colour depth of an image, the greater amount of data that will need to be stored in the image file. This also increases the quality of the image.
• Sound is converted into binary by sampling the sound at a set time interval. The value of each sound sample is converted to binary. The greater the sample rate, and resolution of the sound, the greater the amount of data that will need to be stored in the sound file. This also increases the accuracy of the recording.
• Data is measured in different units such as bits, bytes, and mebibytes.
• Data can be compressed, using lossy or lossless compression, to reduce the size of a file. This means it will take up less storage space and it can be quicker to transmit the file.
• Negative binary numbers are represented using two’s complement. First you invert all the values in the binary number (1s to 0s and reverse), then you add 1 to the result.
• Binary addition rules are: 0+0=0, 1+0=1, 1+1=10, 1+1+1=11.
• Denary is base-10. Binary is base-2. Hexadecimal is base-16.
• Calculating the size of an image file: width of image x height of image x colour depth of image x number of images in file
• Calculating the size of a sound file: sample rate x sample resolution x length of soundtrack
• Perceptual music shaping is a process that is used in lossy compression that removes sounds that are not normally heard by the human ear.
• Run length encoding (RLE) is an algorithm that groups together repeating patterns and indexes them. Used with lossless compression.