Data Compression

Data compression is a method of reducing the file size for conserving drive space or easier transfer. Data compression comes in three forms:

• Archival
• A lossless method of packing a file into a smaller space.
• The file will need to be unpacked before using.
• Also useful for collecting multiple files into one package for transfer.
• Examples include zip, rar, tar, gz.
• Lossless
• A method of reducing the size of a file by removing statistical redundancies.
• When the file is decompressed, the result should be identical to the original.
• The file is decompressed by the decoder in real-time for consumption.
• Examples include flac, alac.
• Lossy
• A method of reducing the size of a file by removing irrelevant information.
• The information is gone forever.
• Irrelevancy of information is determined by the codec used.
• The codec determines irrelevant information based on psychovisual or psychoacoustic models.
• Benefits include reduced disk space and bandwidth use.
• Examples include jpeg, mp3.