flutter_recorder 0.9.2

A low-level audio recorder plugin which uses miniaudio as backend. Detect silence and save to WAV audio file. Audio wave, FFT and volume level can be get in real-time.

example/lib/main.dart

import 'dart:io';

import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';

import 'package:flutter_recorder/flutter_recorder.dart';
import 'package:flutter_recorder_example/ui/bars.dart';
import 'package:open_filex/open_filex.dart';
import 'package:path_provider/path_provider.dart';
import 'package:permission_handler/permission_handler.dart';

/// Demostrate how to use flutter_recorder.
///
/// The silence detection and the visualizer works when using [PCMFormat.f32].
/// Writing audio stream to file is not implemented on Web.
void main() async {
  runApp(
    MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: Text('Flutter Recorder'),
        ),
        body: MyApp(),
      ),
    ),
  );
}

class MyApp extends StatefulWidget {
  const MyApp({super.key});

  @override
  State<MyApp> createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  Directory? savingDir;
  final format = PCMFormat.f32le;
  final sampleRate = 22050;
  final channels = RecorderChannels.mono;
  final _recorder = Recorder.instance;
  String? filePath;
  var thresholdDb = -20.0;
  var silenceDuration = 2.0;
  var secondsOfAudioToWriteBefore = 0.0;

  File? file;

  @override
  void initState() {
    super.initState();
    if (defaultTargetPlatform == TargetPlatform.android ||
        defaultTargetPlatform == TargetPlatform.iOS) {
      Permission.microphone.request().isGranted.then((value) async {
        if (!value) {
          await [Permission.microphone].request();
        }
      });
    }

    /// Listen to audio data stream. The data is received in Uint8List.
    _recorder.uint8ListStream.listen((data) {
      /// Write the PCM data to file. It can then be imported with the correct
      /// parameters with for example Audacity.
      /// Not testing on Web platform.
      if (!kIsWeb) {
        file?.writeAsBytesSync(
          // If you want a conversion, call one of the `to*List` methods.
          // data.toF32List(from: format).buffer.asUint8List(),
          data.rawData,
          mode: FileMode.writeOnlyAppend,
        );
      }
    });
  }

  @override
  Widget build(BuildContext context) {
    return Align(
      alignment: Alignment.topCenter,
      child: SingleChildScrollView(
        padding: const EdgeInsets.all(10),
        child: Column(
          children: [
            /// List capture devices, init, start, deinit
            Wrap(
              runSpacing: 6,
              spacing: 6,
              children: [
                OutlinedButton(
                  onPressed: () {
                    showDeviceListDialog();
                  },
                  child: const Text('listCaptureDevices'),
                ),
                OutlinedButton(
                  onPressed: () {
                    try {
                      _recorder.init(
                        format: format,
                        sampleRate: sampleRate,
                        channels: channels,
                      );
                    } on Exception catch (e) {
                      debugPrint('-------------- init() error: $e\n');
                    }
                  },
                  child: const Text('init'),
                ),
                OutlinedButton(
                  onPressed: () {
                    try {
                      _recorder.start();
                    } on Exception catch (e) {
                      debugPrint('-------------- start() error: $e\n');
                    }
                  },
                  child: const Text('start'),
                ),
                OutlinedButton(
                  onPressed: () {
                    _recorder.deinit();
                  },
                  child: const Text('deinit'),
                ),
              ],
            ),
            const SizedBox(height: 10),

            /// Recording
            Wrap(
              runSpacing: 6,
              spacing: 6,
              children: [
                ElevatedButton(
                  onPressed: () async {
                    try {
                      /// Asking for file path to store the audio file.
                      /// On web platform, it will be asked internally
                      /// from the browser.
                      if (!kIsWeb) {
                        final downloadsDir = await getDownloadsDirectory();
                        filePath = '${downloadsDir!.path}/flutter_recorder.wav';
                        _recorder.startRecording(completeFilePath: filePath!);
                      } else {
                        _recorder.startRecording();
                      }
                    } on Exception catch (e) {
                      debugPrint('-------------- startRecording() $e\n');
                    }
                  },
                  child: const Text('Start recording'),
                ),
                ElevatedButton(
                  onPressed: () {
                    _recorder.setPauseRecording(pause: true);
                  },
                  child: const Text('Pause recording'),
                ),
                ElevatedButton(
                  onPressed: () {
                    _recorder.setPauseRecording(pause: false);
                  },
                  child: const Text('UN-Pause recording'),
                ),
                ElevatedButton(
                  onPressed: () {
                    _recorder.stopRecording();
                    if (!kIsWeb) {
                      debugPrint('Audio recorded to "$filePath"');
                      showFileRecordedDialog(filePath!);
                    }
                  },
                  child: const Text('Stop recording'),
                ),
              ],
            ),
            const SizedBox(height: 10),

            /// Streaming
            Wrap(
              runSpacing: 6,
              spacing: 6,
              children: [
                CircularProgressIndicator(),
                OutlinedButton(
                  onPressed: () async {
                    _recorder.startStreamingData();

                    if (!kIsWeb) {
                      savingDir = await getDownloadsDirectory();
                      if (savingDir == null) {
                        debugPrint('Cannot get download directory!');
                        return;
                      }
                      savingDir =
                          Directory('${savingDir!.path}/flutter_recorder');
                      savingDir!.createSync();

                      file = File(
                          '${savingDir?.path}/fr_${sampleRate}_${format.name}_'
                          '${channels.count}.pcm');
                      try {
                        file?.deleteSync();
                      } catch (e) {
                        debugPrint('Error deleting file: $e');
                      }
                    }
                  },
                  child: const Text('start stream'),
                ),
                OutlinedButton(
                  onPressed: () {
                    _recorder.stopStreamingData();
                  },
                  child: const Text('stop stream'),
                ),
              ],
            ),
            const SizedBox(height: 10),

            /// The silence detection is available only with f32 format and
            /// the visualization is adapted only with that format.
            if (format == PCMFormat.f32le)
              Column(
                children: [
                  Column(
                    children: [
                      StreamBuilder(
                        stream: _recorder.silenceChangedEvents,
                        builder: (context, snapshot) {
                          return ColoredBox(
                            color: snapshot.hasData && snapshot.data!.isSilent
                                ? Colors.green
                                : Colors.red,
                            child: SizedBox(
                              width: 70,
                              height: 50,
                              child: Center(
                                child: Text(
                                    _recorder.getVolumeDb().toStringAsFixed(1)),
                              ),
                            ),
                          );
                        },
                      ),
                      const SizedBox(height: 10),
                      Wrap(
                        runSpacing: 6,
                        spacing: 6,
                        children: [
                          OutlinedButton(
                            onPressed: () {
                              _recorder.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]
                                  // debugPrint('SILENCE CHANGED: $isSilent, $decibel');
                                },
                              );
                              _recorder.setSilenceThresholdDb(-27);
                              _recorder.setSilenceDuration(0.5);
                              _recorder.setSecondsOfAudioToWriteBefore(0.0);
                              setState(() {
                                thresholdDb = -27;
                                silenceDuration = 0.5;
                                secondsOfAudioToWriteBefore = 0;
                              });
                            },
                            child: const Text(
                                'setSilenceDetection ON -27, 0.5, 0.0'),
                          ),
                          OutlinedButton(
                            onPressed: () {
                              _recorder.setSilenceDetection(enable: false);
                            },
                            child: const Text('setSilenceDetection OFF'),
                          ),
                        ],
                      ),
                      // Threshold dB slider
                      Row(
                        mainAxisSize: MainAxisSize.max,
                        children: [
                          Text(
                              'Threshold: ${thresholdDb.toStringAsFixed(1)}dB'),
                          Expanded(
                            child: Slider(
                              value: thresholdDb,
                              min: -100,
                              max: 0,
                              label: thresholdDb.toStringAsFixed(1),
                              onChanged: (value) {
                                _recorder.setSilenceThresholdDb(value);
                                setState(() {
                                  thresholdDb = value;
                                });
                              },
                            ),
                          ),
                        ],
                      ),

                      // Silence duration slider
                      Row(
                        mainAxisSize: MainAxisSize.max,
                        children: [
                          Text('Silence duration: '
                              '${silenceDuration.toStringAsFixed(1)}'),
                          Expanded(
                            child: Slider(
                              value: silenceDuration,
                              min: 0,
                              max: 10,
                              label: silenceDuration.toStringAsFixed(1),
                              onChanged: (value) {
                                _recorder.setSilenceDuration(value);
                                setState(() {
                                  silenceDuration = value;
                                });
                              },
                            ),
                          ),
                        ],
                      ),

                      // Silence duration slider
                      Row(
                        mainAxisSize: MainAxisSize.max,
                        children: [
                          Text('Write before: '
                              '${secondsOfAudioToWriteBefore.toStringAsFixed(1)}'),
                          Expanded(
                            child: Slider(
                              value: secondsOfAudioToWriteBefore,
                              min: 0,
                              max: 5,
                              label: silenceDuration.toStringAsFixed(1),
                              onChanged: (value) {
                                _recorder.setSecondsOfAudioToWriteBefore(value);
                                setState(() {
                                  secondsOfAudioToWriteBefore = value;
                                });
                              },
                            ),
                          ),
                        ],
                      ),
                    ],
                  ),
                  const Bars(),
                ],
              ),
          ],
        ),
      ),
    );
  }

  Future<void> showFileRecordedDialog(String filePath) async {
    return showDialog<void>(
      context: context,
      barrierDismissible: true,
      builder: (BuildContext context) {
        return AlertDialog(
          title: const Text('Recording saved!'),
          content: Text('Audio saved to:\n$filePath'),
          actions: <Widget>[
            TextButton(
              child: const Text('open'),
              onPressed: () async {
                OpenFilex.open(
                  filePath,
                  type: 'audio/wav',
                );
              },
            ),
            TextButton(
              child: const Text('close'),
              onPressed: () {
                Navigator.of(context).pop();
              },
            ),
          ],
        );
      },
    );
  }

  Future<void> showDeviceListDialog() async {
    final devices = _recorder.listCaptureDevices();
    String devicesString = devices.asMap().entries.map((entry) {
      return '${entry.value.id} ${entry.value.isDefault ? 'DEFAULT' : ''} - '
          ' ${entry.value.name}';
    }).join('\n\n');

    return showDialog<void>(
      context: context,
      barrierDismissible: true,
      builder: (BuildContext context) {
        return AlertDialog(
          title: const Text('Recording saved!'),
          content: Text(devicesString),
          actions: <Widget>[
            const Text(''),
            TextButton(
              child: const Text('close'),
              onPressed: () {
                Navigator.of(context).pop();
              },
            ),
          ],
        );
      },
    );
  }
}