einundzwanzig-verein/videos/.opencode/skills/remotion-best-practices/rules/timing.md

---
name: timing
description: Interpolation curves in Remotion - linear, easing, spring animations
metadata:
  tags: spring, bounce, easing, interpolation
---

A simple linear interpolation is done using the `interpolate` function.

```ts title="Going from 0 to 1 over 100 frames"
import {interpolate} from 'remotion';

const opacity = interpolate(frame, [0, 100], [0, 1]);
```

By default, the values are not clamped, so the value can go outside the range [0, 1].  
Here is how they can be clamped:

```ts title="Going from 0 to 1 over 100 frames with extrapolation"
const opacity = interpolate(frame, [0, 100], [0, 1], {
  extrapolateRight: 'clamp',
  extrapolateLeft: 'clamp',
});
```

## Spring animations

Spring animations have a more natural motion.  
They go from 0 to 1 over time.

```ts title="Spring animation from 0 to 1 over 100 frames"
import {spring, useCurrentFrame, useVideoConfig} from 'remotion';

const frame = useCurrentFrame();
const {fps} = useVideoConfig();

const scale = spring({
  frame,
  fps,
});
```

### Physical properties

The default configuration is: `mass: 1, damping: 10, stiffness: 100`.  
This leads to the animation having a bit of bounce before it settles.

The config can be overwritten like this:

```ts
const scale = spring({
  frame,
  fps,
  config: {damping: 200},
});
```

The recommended configuration for a natural motion without a bounce is: `{ damping: 200 }`.

Here are some common configurations:

```tsx
const smooth = {damping: 200}; // Smooth, no bounce (subtle reveals)
const snappy = {damping: 20, stiffness: 200}; // Snappy, minimal bounce (UI elements)
const bouncy = {damping: 8}; // Bouncy entrance (playful animations)
const heavy = {damping: 15, stiffness: 80, mass: 2}; // Heavy, slow, small bounce
```

### Delay

The animation starts immediately by default.  
Use the `delay` parameter to delay the animation by a number of frames.

```tsx
const entrance = spring({
  frame: frame - ENTRANCE_DELAY,
  fps,
  delay: 20,
});
```

### Duration

A `spring()` has a natural duration based on the physical properties.  
To stretch the animation to a specific duration, use the `durationInFrames` parameter.

```tsx
const spring = spring({
  frame,
  fps,
  durationInFrames: 40,
});
```

### Combining spring() with interpolate()

Map spring output (0-1) to custom ranges:

```tsx
const springProgress = spring({
  frame,
  fps,
});

// Map to rotation
const rotation = interpolate(springProgress, [0, 1], [0, 360]);

<div style={{rotate: rotation + 'deg'}} />;
```

### Adding springs

Springs return just numbers, so math can be performed:

```tsx
const frame = useCurrentFrame();
const {fps, durationInFrames} = useVideoConfig();

const inAnimation = spring({
  frame,
  fps,
});
const outAnimation = spring({
  frame,
  fps,
  durationInFrames: 1 * fps,
  delay: durationInFrames - 1 * fps,
});

const scale = inAnimation - outAnimation;
```

## Easing

Easing can be added to the `interpolate` function:

```ts
import {interpolate, Easing} from 'remotion';

const value1 = interpolate(frame, [0, 100], [0, 1], {
  easing: Easing.inOut(Easing.quad),
  extrapolateLeft: 'clamp',
  extrapolateRight: 'clamp',
});
```

The default easing is `Easing.linear`.  
There are various other convexities:

- `Easing.in` for starting slow and accelerating
- `Easing.out` for starting fast and slowing down
- `Easing.inOut`

and curves (sorted from most linear to most curved):

- `Easing.quad`
- `Easing.sin`
- `Easing.exp`
- `Easing.circle`

Convexities and curves need be combined for an easing function:

```ts
const value1 = interpolate(frame, [0, 100], [0, 1], {
  easing: Easing.inOut(Easing.quad),
  extrapolateLeft: 'clamp',
  extrapolateRight: 'clamp',
});
```

Cubic bezier curves are also supported:

```ts
const value1 = interpolate(frame, [0, 100], [0, 1], {
  easing: Easing.bezier(0.8, 0.22, 0.96, 0.65),
  extrapolateLeft: 'clamp',
  extrapolateRight: 'clamp',
});
```