Loudness Audio Worklet Processor

A real-time loudness meter for Web Audio API based on the ITU-R BS.1770-5 standard, implemented as an AudioWorkletProcessor.

Installation

Download pre-built file loudness.worklet.js

Usage

Basic Example

1. Register the processor in your audio context:

   audioContext.audioWorklet.addModule('loudness.worklet.js').then(() => {
     const loudnessNode = new AudioWorkletNode(audioContext, 'loudness-processor');
     audioSource.connect(loudnessNode).connect(audioContext.destination);
   
     loudnessNode.port.onmessage = (event) => {
       console.log('Loudness Data:', event.data);
     };
   });

2. The processor outputs the following via the port:

   {
     "currentFrame": 2048,
     "currentTime": 3.42,
     "currentMetrics": [
       {
         "momentaryLoudness": -18.2,
         "shortTermLoudness": -17.5,
         "integratedLoudness": -20.0,
         "loudnessRange": 6.2,
         "maximumTruePeakLevel": -0.8
       }
     ]
   }

Acknowledgments

This project is a learning experiment aimed at exploring audio signal processing and ITU-R BS.1770 loudness measurement standards. I am not an expert in audio engineering or signal processing, and this project was developed as a way to better understand the concepts of audio loudness and implementation techniques. Thanks to the ITU-R BS.1770 standards for providing the theoretical basis for loudness measurement.

License

This project is licensed under the MIT License.