What types of compression are there?
There are two main types of compression that can be used. One form is lossless compression, and the other form is lossy compression. Lossless compression manages to keep all the information that was originally recorded, but squeezes it into a smaller space. When at the other end, the squeezed version is expanded back into it’s original form, and is exactly the same as the original recording. Lossy compression uses various techniques to analyse the signal, and work out which bits you won’t notice go missing. This throwing away of bits helps keep the information small, and can be used to help a lossless compression to it’s job better. The most popular lossy compression techniques use a model of the human hearing to work out which parts can be thrown out. Lossy compression is often based on psychoacoustic compression. Lossy Compression Techniques Temporal masking Temporal masking is an effect of the way that humans hear. If you play a single note at one frequency, it takes time before the
