BeatData

Info

BeatData contains the beat detection results from the current audio frame. It indicates whether a beat was detected, the estimated BPM (beats per minute), and the intensity of the detected beat. This is one of three analysis dimensions returned by AudioAnalysisResult.

Properties

Property	Type	Description
isBeat	boolean	true if a beat was detected in the current frame, false otherwise.
bpm	number	Estimated beats per minute. 0 when no rhythm is detected (e.g. silence or ambient audio).
intensity	number	Beat strength on a scale from 0.0 (weak) to 1.0 (strong).

Note

Beat detection uses onset detection algorithms on the audio stream. The bpm value stabilizes over time as the analyzer accumulates more beat intervals. Very short analysis periods may produce inaccurate BPM estimates.

Usage

BeatData is accessed via result.beat on an AudioAnalysisResult object. Use it for:

• Audio-reactive visual effects that pulse on beats
• BPM display for music applications
• Rhythm-based animations or game mechanics
• Detecting whether music is playing with a discernible rhythm

Tips

Combine isBeat with intensity to create weighted visual effects. A strong beat (intensity > 0.7) could trigger a large pulse, while a weak beat triggers a subtle one.

Example

TypeScript

import { getResult, BeatData } from '@eisland/windows-volume-analyzer';

const result = getResult();
const beat: BeatData = result.beat;

if (beat.isBeat) {
  // Trigger a visual pulse with intensity-based scaling
  const scale = 1 + beat.intensity * 0.5;
  console.log(`Beat! intensity=${beat.intensity.toFixed(2)}, scale=${scale.toFixed(2)}`);
}

// Display BPM when a rhythm is detected
if (beat.bpm > 0) {
  console.log(`BPM: ${beat.bpm.toFixed(1)}`);
} else {
  console.log('No rhythm detected');
}

JavaScript

const { getResult } = require('@eisland/windows-volume-analyzer');

const result = getResult();
const beat = result.beat;

if (beat.isBeat) {
  // Trigger a visual pulse with intensity-based scaling
  const scale = 1 + beat.intensity * 0.5;
  console.log(`Beat! intensity=${beat.intensity.toFixed(2)}, scale=${scale.toFixed(2)}`);
}

// Display BPM when a rhythm is detected
if (beat.bpm > 0) {
  console.log(`BPM: ${beat.bpm.toFixed(1)}`);
} else {
  console.log('No rhythm detected');
}

Notes

Note

isBeat is true only on the frame where the beat onset is detected. On subsequent frames it returns to false until the next beat. Use it as a trigger, not a continuous state.

Tips

The bpm value takes several seconds to stabilize. During the first few seconds of analysis, the reported BPM may fluctuate. Consider displaying BPM only after the analyzer has been running for at least 5 seconds.

Important

Beat detection accuracy depends on the audio content. Music with clear rhythmic patterns (pop, electronic, hip-hop) produces reliable results. Ambient, classical, or speech audio may yield bpm: 0 and isBeat: false consistently.

Danger Avoidance

Caution

Do not assume bpm is always accurate. The beat detection algorithm works best with steady rhythmic music. Irregular rhythms, tempo changes, or non-musical audio may produce misleading BPM values. Always treat bpm as an estimate.