flutter_recorder - Dart API docs

A low-level audio recorder plugin that uses miniaudio as the backend and supports all the platforms. It can detect silence and save to a WAV audio file. Audio wave and FFT data can be obtained in real-time as for the volume level.

Linux	Windows	Android	MacOS (under test)	iOS (under test)	web (WASM compatible)
💙	💙	💙	💙	💙	💙

Note: not yet available on pub.dev

🌟 Key Features:

🖥️ Cross-platform: Supports Linux, Windows, Android, MacOS, iOS, and web.
⚡ High performance: Built using the fast and efficient miniaudio C library with FFI.
🎙️ WAV Recording with Pause: Record in WAV format with pause functionality.
⚙️ Choose Data Type: samplerate, mono or stereo, audio format (s8, s16le, s24le, s32le or f32le).
🎛️ Device Flexibility: Choose your recording device.
📢 Stream audio data: Listen to PCM audio data stream.
🔇 Silence Detection: Automatically detects silence via callback or Stream.
📊 Customizable Silence Threshold: Define what’s considered “silence” for your recordings.
⏱️ Adjustable Pause Timing: Set how long silence lasts before pausing, and how soon to resume recording.
🔊 Real-time Audio Metrics: Access volume, audio wave, and FFT data in real-time.

A web example compiled in WASM.

🚀 Setup Permissions

After setting up permission for you Android, MacOS or iOS, in your app, you will need to ask for permission to use the microphonem maybe using permission_handler plugin. https://pub.dev/packages/permission_handler

Android

Add the permission in the AndroidManifest.xml.

<uses-permission android:name="android.permission.RECORD_AUDIO" />

MacOS, iOS

Add the permission in Runner/Info.plist.

<key>NSMicrophoneUsageDescription</key>
<string>Some message to describe why you need this permission</string>

Web

Add this in web/index.html under the <head> tag.

<script src="assets/packages/flutter_recorder/web/libflutter_recorder_plugin.js" defer></script>

🛠️ Usage Example

import 'package:permission_handler/permission_handler.dart';
[...]
/// If you are running on Android, MacOS or iOS, ask the permission to use the microphone:
if (defaultTargetPlatform == TargetPlatform.android ||
    defaultTargetPlatform == TargetPlatform.iOS ||
    defaultTargetPlatform == TargetPlatform.macOS) {
    Permission.microphone.request().isGranted.then((value) async {
    if (!value) {
        await [Permission.microphone].request();
    }
});

/// Initialize the capture device and start it:
try {
    Recorder.instance.init();
    Recorder.instance.start();
} on Exception catch (e) {
    debugPrint('init() error: $e\n');
}
/// On Web platform it is better to initialize and wait the user to give
/// mic permission. Then use `start()` when it's needed.

//Start recording:
Recorder.instance.startRecording(completeFilePath: 'audioCompleteFilenameWithPath.wav`);

/// Stop recording:
Recorder.instance.stopRecording();

Tip: Use Recorder.instance.listCaptureDevices() to see available devices and pass an optional deviceID to init(). Tip2: Use the format, sampleRate and channels with the init() method to define recorder parameters. Tip3: When recording with silence detection and want to record a little bit before the threshold db is reached, use the setSecondsOfAudioToWriteBefore() method.

🔇 Silence Detection Example

Want to skip the silence? Here’s how to configure it:

Recorder.instance.setSilenceDetection(
    enable: true,
    onSilenceChanged: (isSilent, decibel) {
        /// Here you can check if silence is changed.
        /// Or you can do the same thing with the Stream
        /// [Recorder.instance.silenceChangedEvents]
    },
);
/// the silence threshold in dB. A volume under this value is considered to be silence.
Recorder.instance.setSilenceThresholdDb(-27);
/// the value in seconds of silence after which silence is considered as such.
Recorder.instance.setSilenceDuration(0.5);
/// Set seconds of audio to write before starting recording again after silence.
Recorder.instance.setSecondsOfAudioToWriteBefore(0.0);

📊 Audio, FFT, and Volume Data

You can also access raw audio data and volume information like this:

/// Get the current volume in dB in the [-100, 0] range.
double volume = Recorder.instance.getVolumeDb();
/// Return a 256 float array containing wave data in the range [-1.0, 1.0] not clamped.
Float32List waveAudio = Recorder.instance.getWave();
/// Return a 256 float array containing FFT data in the range [-1.0, 1.0] not clamped.
Float32List fftAudio = Recorder.instance.getFft();

NOTE: this is only available when initializing the recorder with PCMFormat.f32le format.

📢 Audio data stream

/// Listen to audio data stream. The data is received in Uint8List.
Recorder.instance.uint8ListStream.listen((data) {
    /// the [data] is of type `AudioDataContainer` and, whatever format is passed to
    /// the `init()` method, it is available with [data.rawData] which is of `Uint8List`
    /// type. This is useful if we want to write into a file.
    /// It is possible to convert audio data to the desired format using one of the
    /// `data.to[*]List` methods. Be aware that the conversion is compute expensive and
    /// should be avoided if possible initializing the recorder with the format
    /// desired.
});

/// Start streaming:
Recorder.instance.startStreamingData();
/// Stop streaming:
Recorder.instance.stopStreamingData();