Audio Streamer

Streaming of PCM audio from Android and iOS with a customizable sample rate.

Permissions

On Android add the audio recording permission to AndroidManifest.xml:

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

On iOS enable the following:

• Capabilities > Background Modes > Audio, AirPlay and Picture in Picture
• In the Runner Xcode project edit the Info.plist file. Add an entry for 'Privacy - Microphone Usage Description'

When editing the Info.plist file manually, the entries needed are:

<key>NSMicrophoneUsageDescription</key>
<string>YOUR DESCRIPTION</string>
<key>UIBackgroundModes</key>
<array>
  <string>audio</string>
</array>

• Edit the Podfile to include the permission for the microphone:

post_install do |installer|
  installer.pods_project.targets.each do |target|
    flutter_additional_ios_build_settings(target)

    target.build_configurations.each do |config|
      # for more infomation: https://github.com/BaseflowIT/flutter-permission-handler/blob/master/permission_handler/ios/Classes/PermissionHandlerEnums.h
      config.build_settings['GCC_PREPROCESSOR_DEFINITIONS'] ||= [
        '$(inherited)',
        'PERMISSION_MICROPHONE=1',]
    end
  end
end

Example

See the file example/lib/main.dart for a fully fledged example app using the plugin. Note that on iOS the sample rate will not necessarily change, as there is only the option to set a preferred one.

  AudioStreamer _streamer = AudioStreamer();
  bool _isRecording = false;
  List<double> _audio = [];

  void onAudio(List<double> buffer) {
    _audio.addAll(buffer);
    double secondsRecorded = _audio.length.toDouble() / _streamer.sampleRate.toDouble();
    print('$secondsRecorded seconds recorded.');
  }

  void start() async {
    try {
      //_streamer.start(onAudio, handleError, sampleRate: 16000); //uses custom sample rate
      _streamer.start(onAudio, handleError); //uses default sample rate of 44100 Hz
      setState(() {
        _isRecording = true;
      });
    } catch (error) {
      print(error);
    }
  }

  void stop() async {
    bool stopped = await _streamer.stop();
    setState(() {
      _isRecording = stopped;
    });
  }