@codeplayer71/audio-recorder-core

Framework-independent and fully typed browser audio recording core based on the MediaRecorder API.

Installation

pnpm add @codeplayer71/audio-recorder-core

npm install @codeplayer71/audio-recorder-core

yarn add @codeplayer71/audio-recorder-core

Usage

import { createAudioRecorder } from '@codeplayer71/audio-recorder-core';

const recorder = createAudioRecorder({
  maxDurationMs: 120_000,
  maxFileSizeBytes: 10_000_000,
});

const unsubscribe = recorder.subscribe((snapshot) => {
  console.log(snapshot.state);
  console.log(snapshot.durationMs);
  console.log(snapshot.audioLevel);
  console.log(snapshot.recording);
  console.log(snapshot.error);
});

await recorder.start();

const recording = await recorder.stop();

console.log(recording.file);
console.log(recording.url);

unsubscribe();
recorder.destroy();

Live audio level

The recorder snapshot exposes a normalized live microphone level:

recorder.subscribe((snapshot) => {
  console.log(snapshot.audioLevel);
});

The value is always between:

0 <= audioLevel <= 1

The level is intended as lightweight visual feedback for microphone activity.

It is not a professional decibel measurement.

Behavior

The value is updated while the recorder is in the recording state.

It is reset to 0 when the recorder is:

• idle
• requesting microphone permission
• paused
• processing
• completed
• in an error state
• cancelled
• reset
• destroyed

Implementation details

Live audio level monitoring uses the Web Audio API internally.

The recorder reuses the same MediaStream that is already created for MediaRecorder.

No second microphone stream is requested.

Internally, the level is calculated from time-domain samples using an RMS-based measurement and simple smoothing.

The analyser is not connected to the audio output, so microphone monitoring does not produce speaker playback or feedback.

Failure behavior

Audio level monitoring is treated as an optional enhancement.

If the required Web Audio APIs are unavailable or AudioContext initialization fails:

• the audio recording continues normally
• audioLevel remains 0
• no fatal recorder error is generated solely because audio level monitoring failed

Resource cleanup

Audio level monitoring resources are cleaned up automatically.

This includes:

• AudioContext
• MediaStreamAudioSourceNode
• AnalyserNode
• requestAnimationFrame

Cleanup happens when monitoring stops, including on pause, stop, cancel, reset and destroy.

Documentation

Full documentation, framework integrations and examples are available in the main repository:

https://github.com/codeplayer71/jamit-audio-recorder

License

MIT