API Reference

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API Reference / analyzeFullBuffer

Function: analyzeFullBuffer()

function analyzeFullBuffer(originalBuffer, options?): Promise<Tempo[]>;

Defined in: core/analyzer.ts:460

Analyzes a complete audio buffer to detect the BPM (tempo) synchronously.

This function performs offline analysis of an entire audio file to detect its tempo. It's ideal for analyzing pre-recorded audio files where you have the complete audio data available.

Parameters

Parameter	Type	Description
originalBuffer	AudioBuffer	The AudioBuffer containing the complete audio to analyze
options?	BiquadFilterOptions	Optional filter configuration to customize bass detection

Returns

Promise<Tempo[]>

A promise that resolves to an array of tempo candidates sorted by confidence

Examples

Analyze an uploaded audio file

const audioContext = new AudioContext();

// Load audio file
const response = await fetch('song.mp3');
const arrayBuffer = await response.arrayBuffer();
const audioBuffer = await audioContext.decodeAudioData(arrayBuffer);

// Analyze BPM
const tempos = await analyzeFullBuffer(audioBuffer);

console.log('Detected BPM:', tempos[0].tempo);
console.log('Confidence:', tempos[0].count);
console.log('Top 5 candidates:', tempos);

With custom filter settings

const audioBuffer = await audioContext.decodeAudioData(arrayBuffer);

const tempos = await analyzeFullBuffer(audioBuffer, {
  frequencyValue: 150,  // Focus on bass frequencies
  qualityValue: 1       // Filter steepness
});

// Get the most likely BPM
const mostLikelyBPM = tempos[0].tempo;

Analyze from file input

const fileInput = document.querySelector('input[type="file"]');

fileInput.addEventListener('change', async (e) => {
  const file = e.target.files[0];
  const arrayBuffer = await file.arrayBuffer();
  const audioBuffer = await audioContext.decodeAudioData(arrayBuffer);

  const tempos = await analyzeFullBuffer(audioBuffer);

  if (tempos.length > 0) {
    console.log(`Detected BPM: ${tempos[0].tempo} with ${tempos[0].count} matching intervals`);
  }
});

Remarks

• This is a synchronous/offline analysis method (analyzes complete audio at once)
• For real-time streaming audio, use createRealtimeBpmAnalyzer instead
• The function returns multiple candidates sorted by confidence (count)
• Analysis applies a lowpass filter to isolate bass frequencies for better beat detection
• BPM values are normalized to the 90-180 range (doubles/halves if outside this range)
• Higher count values indicate more confidence in the detected tempo

See

• createRealtimeBpmAnalyzer for real-time streaming audio analysis
• getBiquadFilter for the lowpass filter used internally
• Tempo for the structure of returned tempo candidates
• BiquadFilterOptions for filter configuration options