Flutter Audio Playback & Recording in Mobile Apps

Introduction

Flutter’s cross-platform capabilities extend seamlessly into audio features, letting developers integrate playback and recording into mobile apps. This tutorial explores how to set up dependencies, request permissions, play audio files or streams, record user input, and optimize performance. By the end, you’ll have a solid foundation for audio-centric Flutter mobile development.

Setting Up Dependencies

To work with audio in Flutter, two popular packages are just_audio for playback and record for recording. Add these to your pubspec.yaml under dependencies:

dependencies:
  flutter:
    sdk: flutter
  just_audio: ^0.9.26
  record

Run flutter pub get to fetch the packages. just_audio provides a high-level API to load and play audio from assets, files, or URLs. record offers an easy interface to capture microphone input and save it as WAV or AAC.

Requesting Permissions

Mobile platforms require runtime permissions for microphone and storage. Use permission_handler or the built-in record methods to prompt users.

For Android, add to AndroidManifest.xml:

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

In Dart, before recording, check and request:

import 'package:record/record.dart';

Future<bool> ensureMicPermission() async {
  final record = Record();
  if (await record.hasPermission()) return true;
  return await record.requestPermission();
}

This snippet verifies or requests microphone access, returning true if granted.

Implementing Audio Playback

just_audio features a simple AudioPlayer class. Initialize, load, and control playback:

import 'package:just_audio/just_audio.dart';

final player = AudioPlayer();

Future<void> playUrl(String url) async {
  await player.setUrl(url); // Load from network
  player.play();
}

Use setAsset for bundled files or setFilePath for local storage. Control volume, seek, and loop via player.setVolume, player.seek, and player.setLoopMode. Listen to player.playerStateStream for UI updates:

player.playerStateStream.listen((state) {
  // update play/pause button
});

Implementing Audio Recording

With permissions granted, start and stop recordings easily:

import 'package:record/record.dart';

final recorder = Record();

Future<String?> startRecording() async {
  await recorder.start(
    path: '/storage/emulated/0/Download/temp.wav',
    encoder: AudioEncoder.wav,
    bitRate: 128000,
  );
  return recorder.recordingPath;
}

Future<void> stopRecording() async {
  await recorder.stop();
}

The recordingPath is available after start. You can then play the file with just_audio or upload it. Monitor sound levels via recorder.onStateChanged and recorder.getAmplitude for UI metering.

Optimizing Performance

Handling audio efficiently is crucial for mobile. Follow these best practices:

• Dispose of players and recorders: call player.dispose() and recorder.dispose() in dispose() to free native resources.

• Use lower bit rates or AAC encoder for smaller file sizes and faster uploads.

• Preload short sounds (UI feedback) with AudioPlayer.setAsset at app start to reduce latency.

• Offload heavy processing (e.g., audio analysis) to isolates to keep the UI thread responsive.

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Conclusion

Integrating audio playback and recording in Flutter involves selecting robust packages, requesting platform permissions, and implementing clear APIs for play and record. By following best practices—disposing resources, optimizing bit rates, and managing threads—your mobile app can deliver high-quality audio experiences. Experiment with advanced features like background playback, audio focus, and waveform visualization to take your app to the next level.