vstaudio — VST audio output.
vstaudio and vstaudiog are used for sending and receiving audio from a VST plugin.
vstaudio is used within an instrument definition that contains a vstmidiout or vstnote opcode. It outputs audio for only that one instrument. Any audio remaining in the plugin after the end of the note, for example a reverb tail, will be cut off and should be dealt with using a damping envelope.
vstaudiog (vstaudio global) is used in a separate instrument to process audio from any number of VST notes or MIDI events that share the same VST plugin instance (instance). The vstaudiog instrument must be numbered higher than all the instruments receiving notes or MIDI data, and the note controlling the vstplug instrument must have an indefinite duration, or at least a duration as long as the VST plugin is active.
instance - the number which identifies the plugin, to be passed to other vst4cs opcodes.