Speed

Changes the clip's playback rate. Because the underlying audio engine resamples on rate change, this alters both tempo and pitch together, producing the classic chipmunk (faster) or slow-motion (slower) effect. The clip's scene-time duration shrinks or grows proportionally.

Usage

import { Sound, AudioFilters } from '@motion-script/core';

// Via AudioFilters builder — play at 1.5× speed
const clip = new Sound({ src: './beat.mp3', filters: AudioFilters.speed(1.5) });

// Via raw object
const clip = new Sound({ src: './beat.mp3', filters: [{ type: 'speed', value: 1.5 }] });

Props

Animating

Animate speed to simulate a tape machine winding up or winding down:

import { Sound, AudioFilters, tween, lerpNumber, easeOut } from '@motion-script/core';

const clip = new Sound({ src: './vinyl.mp3', filters: AudioFilters.speed(0.1) });
clip.start();

// Spin up from slow to normal
yield* tween(2, (t) => {
  clip.set({ filters: AudioFilters.speed(lerpNumber(0.1, 1, easeOut(t))) });
});

Notes

• Speed and pitch are coupled; there is no pitch-preservation mode. Use this filter for stylistic tape effects, not for tempo-matching.
• A value of 2 doubles speed and raises pitch by one octave. 0.5 halves speed and drops pitch by one octave.
• The clip's effective scene-time duration changes: a 10-second source at speed: 2 occupies 5 seconds on the timeline. Plan yield* clip.play() durations accordingly.
• value is fully animatable. Extremely low values (close to 0) can cause audio artifacts.