Data storage and compression

What the syllabus asks of you

• Understand how data storage is measured • Including: – bit – nibble – byte – kibibyte (KiB) – mebibyte (MiB) – gibibyte (GiB) – tebibyte (TiB) – pebibyte (PiB) – exbibyte (EiB) • The amount of the previous denomination present in the data storage size, e.g.: – 8 bits in a byte – 1024 mebibytes in a gibibyte
• Calculate the file size of an image file and a • Answers must be given in the units specified sound file, using information given in the question. Calculations must use the measurement of 1024 and not 1000 • Information given may include: – image resolution and colour depth – sound sample rate, resolution and length of track
• Understand the purpose of and need for data • Compression exists to reduce the size of the file compression • What the impact of this is, e.g.: – less bandwidth required – less storage space required – shorter transmission time Candidates should be able to: Notes and guidance
• Understand how files are compressed using • Lossy compression reduces the file size by lossy and lossless compression methods permanently removing data, e.g. reducing resolution or colour depth, reducing sample rate or resolution • Lossless compression reduces the file size without permanent loss of data, e.g. run length encoding (RLE)