Virtual Studio Technology (VST) is a protocol for integrating software audio synthesizer and effect plugins with audio host applications such as editors and hard-disk recording systems. VST and similar technologies use Digital Signal Processing to simulate traditional recording studio hardware with software. Thousands of plugins exist, both commercial and freeware, and VST is supported by a large number of audio applications.
VST plugins are generally run within a Digital Audio Workstation, providing the host application with additional functionality. Most VST plugins can be classified as either instruments (VSTi) or effects, although other categories exist. VST plugins generally provide a custom GUI, displaying controls similar to the physical switches and knobs on audio hardware. Some (often older) plugins rely on the host application for their UI.
VST instruments generate audio. They require notes to be sent via MIDI in order to do so. They are generally either virtual synthesizers or samplers. VST instruments include software emulations of well-known hardware instruments, emulating the look of the original equipment and its sonic characteristics. This enables VSTi users to use virtual versions of instruments that may be otherwise difficult to obtain.
VST effects, such as reverb and phaser effects, process audio signals, such as a recorded input or the output from a software synthesizer. Other monitoring effects provide visual feedback of the signal without processing the audio.
VST MIDI effects process MIDI messages prior to routing the MIDI data to other VST instruments or hardware devices; for example, to transpose or create arpeggios.
MIDI messages can often also be used to control parameters of both instrument and effect plugins. Most host applications allow the audio output from one VST to be routed to the audio input of another VST (known as chaining). For example, output of a VST synthesizer can be sent to a VST reverb effect for further processing.
The preceeding takes material from the following article:
Wikipedia contributors, "Virtual Studio Technology," Wikipedia, The Free Encyclopedia (accessed December 24, 2008).