TuningFork.Envelope (TuningFork v0.1.11)

An attack-decay-sustain-release shape in seconds, sampled by time.

TuningFork.Envelope.new(attack: 0.01, decay: 0.2, sustain: 0.4, release: 0.3)

Summary

Types

t()

Functions

duration(env)

How long the envelope sounds, in seconds: attack, decay, hold and release together, or attack and decay alone when sustain is 0.0, since nothing is left to hold or release.

hit(decay)

A percussive envelope: a 2 ms attack, decay seconds of fall, and no sustain or release.

level(env, t)

The level at t seconds, from 0.0 to 1.0.

new(opts \\ [])

An envelope, with anything unset left at its default.

spanning(env, seconds)

The envelope with its decay set so the whole of it lasts seconds: the decay is seconds less the attack and, when there is a sustain level to release from, the release; any hold is dropped. The decay is never under 10 ms.

Types

t()

@type t() :: %TuningFork.Envelope{
  attack: float(),
  curve: float(),
  decay: float(),
  hold: float(),
  release: float(),
  sustain: float()
}

Functions

duration(env)

@spec duration(t()) :: float()

How long the envelope sounds, in seconds: attack, decay, hold and release together, or attack and decay alone when sustain is 0.0, since nothing is left to hold or release.

iex> TuningFork.Envelope.duration(TuningFork.Envelope.new(attack: 0.1, decay: 0.2, sustain: 0.5, hold: 1.0, release: 0.3))
1.6
iex> TuningFork.Envelope.duration(TuningFork.Envelope.new(attack: 0.1, decay: 0.4, sustain: 0.0, hold: 1.0, release: 0.3))
0.5

hit(decay)

@spec hit(float()) :: t()

A percussive envelope: a 2 ms attack, decay seconds of fall, and no sustain or release.

level(env, t)

@spec level(t(), float()) :: float()

The level at t seconds, from 0.0 to 1.0.

0.0 before the envelope starts and after it ends.

new(opts \\ [])

@spec new(keyword()) :: t()

An envelope, with anything unset left at its default.

Options

:attack — seconds from silence to full level, default 0.005
:decay — seconds from full level down to :sustain, default 0.05
:sustain — the level held after the decay, 0.0 to 1.0, default 0.0
:hold — seconds spent at :sustain, default 0.0
:release — seconds from :sustain back to silence, default 0.02
:curve — the exponent the decay falls by, default 2.0; 1.0 is a straight line

spanning(env, seconds)

@spec spanning(t(), number()) :: t()

The envelope with its decay set so the whole of it lasts seconds: the decay is seconds less the attack and, when there is a sustain level to release from, the release; any hold is dropped. The decay is never under 10 ms.

iex> TuningFork.Envelope.spanning(TuningFork.Envelope.new(attack: 0.1, sustain: 0.5, release: 0.2), 1.0).decay
0.7
iex> TuningFork.Envelope.spanning(TuningFork.Envelope.new(attack: 0.1, sustain: 0.0, release: 0.2), 1.0).decay
0.9
iex> TuningFork.Envelope.spanning(TuningFork.Envelope.new(attack: 0.1, sustain: 1.0, hold: 2.0, release: 0.2), 1.0) |> TuningFork.Envelope.duration()
1.0