Parameter Automation

Use scheduled audio-parameter messages from any js node to automate audio parameters with sample-accurate timing.

These messages work with audio nodes that have an audio-parameter inlet, such as gain~, osc~, pan~, and delay~. Drag from an audio signal outlet to see eligible inlets turn blue.

Message Types

Set

Set a parameter value now or at a selected time.

// Set immediately
send({ type: 'set', value: 0.5 });

// Set at a specific time (absolute by default)
send({ type: 'set', value: 0.5, time: 1.0 });

// Set at a relative time (n seconds from now)
send({ type: 'set', value: 0.5, time: 0.5, timeMode: 'relative' });

The time field uses absolute time unless you set timeMode: 'relative'. Use it with clock scheduling for precise future changes. Pass { audio: true } for lookahead scheduling. Then pass the callback time argument directly:

// Schedule a parameter change on beat 0 with audio-precise timing
clock.onBeat(0, (time) => {
  send({ type: 'set', value: 440, time });
}, { audio: true });

// Schedule at a specific bar position
clock.schedule('4:0:0', (time) => {
  send({ type: 'set', value: 880, time });
}, { audio: true });

Trigger

Trigger an attack-decay-sustain envelope.

// Trigger immediately
send({
  type: 'trigger',
  values: { peak: 1, sustain: 0.7 },
  attack: 0.02,  // seconds
  decay: 0.1
});

// Trigger at a precise time (for beat-synced envelopes)
send({
  type: 'trigger',
  values: { peak: 1, sustain: 0.7 },
  attack: 0.02,
  decay: 0.1,
  time
});

If you omit values.start, it defaults to 0. The attack and decay fields accept a number or a config object. A number sets seconds with a linear curve. See the curve types section for custom curves.

Release

Trigger a release phase that ramps down from the current value.

// Release immediately
send({ type: 'release', release: 0.3, endValue: 0 });

// Release at a precise time
send({ type: 'release', release: 0.3, endValue: 0, time });

Like attack and decay, the release field accepts a duration or a config object.

Trigger and Release Example

Trigger on noteOn and release on noteOff:

recv((m) => {
  if (m.type === 'noteOn') {
    send({
      type: 'trigger',
      values: { peak: 1, sustain: 0.7 },
      attack: 0.02,
      decay: 0.1
    });
  } else if (m.type === 'noteOff') {
    send({ type: 'release', release: 0.3, endValue: 0 });
  }
});

The adsr object provides an inlet for each parameter in this pattern.

Curve Types

When you pass a number for attack, decay, or release, Patchies uses a linear curve. For a custom curve, pass an object with time and curve:

The full config object shape is { time, curve, timeConstant?, values? }:

// number shorthand — equivalent to { time: 0.02, curve: 'linear' }
attack: 0.02

// object form — specify a curve type
attack: { time: 0.1, curve: 'exponential' }

// targetAtTime — approaches the target asymptotically (never fully arrives)
// timeConstant controls speed: smaller = faster.
// Reaches ~63% of the way in one time constant.
// Defaults to time * 0.3 if omitted.
decay: { time: 0.3, curve: 'targetAtTime', timeConstant: 0.1 }

// valueCurve — custom shape from an array of values
attack: {
  time: 0.1,
  curve: 'valueCurve',
  values: [0, 0.05, 0.2, 0.5, 0.8, 0.95, 1.0]
}

// Full example: exponential decay with custom attack curve
send({
  type: 'trigger',
  values: { peak: 1, sustain: 0.7 },
  attack: {
    time: 0.1,
    curve: 'valueCurve',
    values: [0, 0.05, 0.2, 0.5, 0.8, 0.95, 1.0]
  },
  decay: { time: 0.2, curve: 'exponential' }
});

The values array defines the curve shape over the phase duration. Its values are absolute, not normalized. The first element is the start value. The last element is the end value. The array must contain at least two values.

Compatible Nodes

Any audio node with an AudioParam inlet accepts scheduled messages. Common targets include:

• gain~ — Automate volume.
• osc~ — Automate frequency and detune.
• pan~ — Automate stereo position.
• delay~ — Automate delay time.
• lowpass~ and highpass~ — Automate filter cutoff and Q.
• compressor~ — Automate threshold and ratio.

See Also

• Clock API — Schedule changes with clock.schedule.
• adsr — Send envelope messages.
• line~ — Generate signal-based control-value ramps.