Working with Envelopes

Envelopes are used to control property values with a predefined shape. An envelope has an ADSR shape:

Property	Description
Attack Time	Defines the time taken for initial run-up of level from nil to peak, beginning when the key is first pressed (in seconds).
Attack Curve	Adjusts the Attack Curve from its linear default slope (50%), to either an exponential-style of envelope (0%) where the rate of change starts slow and then increases or logarithmic (100%) where the rate of change starts fast, then decreases.
Decay Time	Defines the time taken for the subsequent run down from the attack level to the designated sustain level. (in seconds)
Sustain Level	Defines the level during the main sequence of the sound's duration, until the key is released. (in percentage of the range)
Release Time	Defines the time taken for the level to decay from the sustain level to zero after the key is released. (in seconds)
Scope	Define how envelope instances are created: Voice: An envelope instance is created for every sound/object playback. Note/Event: An envelope instance is created for every playing instance, or note when used in MIDI context.
Trigger On	The actions/MIDI Events that may Trigger the envelope (i.e. enter the attack phase). Play: either a play action or a MIDI note event. Note-Off: only a MIDI note-off event
Auto Release	Determines if the envelope requires an action/MIDI Event to exit the sustain phase and enter the release phase. If set, the envelope exits the sustain phase after Sustain Time. If not set, the envelope requires an Event to exit the sustain phase.
Sustain Time	Defines the time which the envelope will remain in the sustain phase before entering the release phase (in seconds). This value is valid only if Auto Release is set.
Stop playback after release	If set, the playback of the associated sound is terminated once the release phase is complete.

Envelopes can either be used in the context of MIDI or in the context of a normal playback.

When used in the context of MIDI, the envelope is configured for a sound to be played either on note-on or note-off. In the case of a sound to be played on note-on:

The envelope is configured to trigger on note-on (Trigger On parameter).
The envelope sustains until the first occurrence of:
- reception of a Release Envelope event,
- reception of a MIDI note-off event,
- max duration of sustain phase (Auto Release is set).

In the case of a sound to be played on note-off:

The envelope is configured to trigger on note-off (Trigger On parameter).
The envelope sustains until the first occurrence of:
- reception of a Release Envelope event,
- max duration of sustain phase (Auto Release is set).

When used in the general context of a play sound:

The envelope is configured to trigger on a play action (Trigger On parameter).
The envelope sustains until the first occurrence of:
- reception of a Release Envelope event,
- max duration of sustain phase (Auto Release is set).

	Caution
	A modulator's processing time depends on its RTPC usage. For most properties, a modulator is evaluated once per audio frame. However, for the property voice volume, the associated modulator is evaluated at every frame. Use modulators selectively as they can consume a significant amount of a platform's memory and CPU.

	Note
	The RTPC cursors for Modulators, both LFO and Envelope, do not tell you their specific values at any point in time since they are determined by the modulator's internal properties.

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