> ## Documentation Index
> Fetch the complete documentation index at: https://hyperframes.heygen.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Automate a parameter over time

> Draw an envelope on a track's volume or an effect's knob, shape a selection, and know which parameters can move at all.

A static setting cannot say "quieter while the interview is on screen" or "fade
out over the last three seconds". An automation lane can: it is a set of points on
one parameter, and the value moves between them.

Lanes work on a track's own **volume** and on any supported effect parameter, and
a [group](/studio/audio-groups) has lanes of its own that apply to its whole bus.

## Show a track's lanes

Use the `∿` toggle on the track or group row. It shows a count when lanes already
exist, and it is independent of the row's expand caret — showing a group's members
does not open its lanes.

To start automating an effect parameter, automate it from the parameter's own
control in the rack. A parameter with a lane shows as **Automated**, and its
static control is disabled: the lane owns the value from then on.

## Draw and edit an envelope

Work directly on the lane:

* **Add a point** on the lane at the time you want it.
* **Drag a point** to move it in time or value.
* **Type an exact value** rather than dragging, when the number matters. A volume
  lane can go above unity — the ceiling is +12 dB, not 1.
* **Bend a segment** by dragging its curve, so the value holds and then moves late
  rather than travelling evenly.
* **Select a time range** to work on several points at once.

With a range selected, right-click it for the shape and cleanup menu:

| Item                        | Does                                                                                           |
| --------------------------- | ---------------------------------------------------------------------------------------------- |
| **Ramp up** / **Ramp down** | Replaces the selection with a single move in one direction                                     |
| **Swell**                   | Rises and returns                                                                              |
| **Dip**                     | Falls and returns — the shape most ducking wants                                               |
| **Simplify**                | Removes redundant points while keeping the shape. Needs at least three points in the selection |

A selection can also be **copied and pasted** onto another lane, and **retimed** by
stretching its edges — useful when narration moves and its ducking should move
with it.

## Two things that surprise people

**A track lane's times are relative to its clip.** A bed starting at 8 s has its
first point at composition time 8. Move the clip and its envelope moves with it.

**A group lane's times are composition time.** A group has no start of its own,
so its lanes are measured from the beginning of the video. If you are automating
a group bus, read the times as absolute.

**A lane holds its first value backwards** to the start of the clip, and its last
value forward to the end. So a bed that begins before the voice needs an explicit
"no cut" point at the start, or it begins already ducked. This is the single most
common automation mistake.

## Not every knob can move

A parameter can only be automated if the audio engine can schedule it directly.
Three kinds cannot:

| These                                            | Cannot be automated because                                                                   |
| ------------------------------------------------ | --------------------------------------------------------------------------------------------- |
| Compressor, limiter, gate, bitcrush, pitch shift | They are configured whole rather than knob-by-knob — **no parameter on any of them can move** |
| Saturation's type, threshold, and oversample     | They rebuild the distortion curve; only its output stage can move                             |
| Reverb's size and damping                        | They regenerate the room; its wet and dry levels can move                                     |

**A lane on one of those is silently inert** — it stores fine and never does
anything. Pitch shift is the one that catches people out, because a rising pitch
sounds like something a lane should do: it cannot, and the lane will not report
it. To make a compressor's behaviour change over time, automate a `gain` stage
*before* it instead: that changes how hard the compressor is driven, which
is most of what automating its threshold would have done.

To fade a whole preset in or out, automate the preset itself rather than its
parts — its nodes share no single parameter, so the preset as a unit is the only
handle that works.

The [effect registry](/reference/audio-effects#effect-registry) marks every
parameter that can move.

## What should happen

* The value moves between your points, in preview and in the render identically.
* A parameter with a lane reads **Automated** and its static control is disabled.
* A [carve](/studio/voiceover-carve) writes lanes of its own, and they are
  ordinary lanes: you can edit them afterwards like any others.

## Common problems

**The lane does nothing.** Either the parameter is one of those above, or the
effect it pointed at is gone. A lane whose effect was deleted is dropped silently
rather than reported.

**A newly added effect arrives already "Automated".** A lane left behind by a
deleted effect can be inherited by the next effect that takes the same internal
id. Remove the stale lane.

**The volume lane is ignored.** A `volume` lane and a timeline tween on the same
track's volume conflict; the lane wins. Pick one.

**The envelope is right but the level is wrong.** A tween's values are absolute
and replace a track's own gain rather than scaling it. Check whether the track
also carries a static level.

**The bed ducks before anyone speaks.** The first point is holding backwards. Add
a point at the clip's start.

## Related topics

* [Mix audio and apply effects](/studio/audio-effects)
* [Make music sit under narration](/studio/voiceover-carve)
* [Audio effects implementation](/reference/audio-effects#data-automation)


## Related topics

- [Mix audio and apply effects](/studio/audio-effects.md)
- [Group tracks, mute, and solo](/studio/audio-groups.md)
- [Audio effects implementation](/reference/audio-effects.md)