iatt -- duration of attack phase
idec -- duration of decay
islev -- level for sustain phase
irel -- duration of release phase
idel -- period of zero before the envelope starts
The envelope is the range 0 to 1 and may need to be scaled further. The envelope may be described as:
Picture of an ADSR envelope.
The length of the sustain is calculated from the length of the note. This means adsr is not suitable for use with MIDI events. The opcode madsr uses the linsegr mechanism, and so can be used in MIDI applications.
madsr is new in Csound version 3.49.