audio_monitor

A Flutter desktop plugin for live audio input monitoring on desktop platforms.

audio_monitor lets a Flutter app select an input device and monitor that signal through an output path in real time.

Example flow:

Microphone / Line In / Audio Interface Input -> Headphones / Speakers / Output Device

audio_monitor macOS example UI

Official documentation

The full documentation website for this repository is available at:

domingomg.github.io/audio_monitor

Use the documentation site for:

installation and platform setup
macOS permissions and requirements
API reference
architecture notes
release notes and roadmap
screenshots and usage guidance

Key capabilities

Input device enumeration
Output device enumeration
Live desktop input monitoring
Monitor mute and unmute without tearing down the session
Dedicated monitor playback volume
Current monitoring state from Flutter

Important scope

This plugin is intentionally focused on live monitoring and routing.

It does not record audio
It does not persist audio buffers
It does not generate FFT data
It does not generate waveforms
It does not provide RMS or peak metering
It does not replace system_audio_meter

Platform support

Platform	Status	Notes
macOS	Supported	Current backend targets `selected input -> system default output`
Windows	Planned	Intended to align with native listen-to-device behavior
Linux	Not supported yet	Deferred for a future release

Installation

Add the dependency:

dependencies:
  audio_monitor:
    path: ../audio_monitor

Then run:

flutter pub get

Quick start

import 'package:audio_monitor/audio_monitor.dart';

final monitor = AudioMonitor();

final inputs = await monitor.getInputDevices();
final outputs = await monitor.getOutputDevices();

await monitor.setVolume(0.5);

await monitor.start(
  inputDeviceId: inputs.first.id,
  outputDeviceId: outputs.first.id,
);

await monitor.mute();
await monitor.unmute();

final active = await monitor.isMonitoring();
final state = await monitor.getState();

await monitor.stop();

setVolume() can also be called before start(), so the monitoring session begins with the desired playback level.

Public API

`AudioMonitorDevice`

id
name
isDefault
type

`AudioMonitorState`

isMonitoring
isMuted
volume
inputDeviceId
outputDeviceId

Errors

Native failures are surfaced as AudioMonitorException with one of these codes:

deviceNotFound
permissionDenied
monitoringAlreadyActive
monitoringNotActive
platformNotSupported
nativeAudioError

macOS host app requirements

If your Flutter app uses this plugin on macOS, review the full setup guide in the official docs. At minimum, host applications must declare the microphone privacy key, and sandboxed apps also need the correct audio-input entitlement.

Documentation:

Limitations

The current macOS backend routes monitoring to the current system default output.
Near-zero latency is not physically possible; end-to-end latency still depends on hardware and buffer sizes.
Windows and Linux are not implemented in this release.

Repository

GitHub repository