Extracting pitch from the audio sample

main.dart

...
class _MyHomePageState extends State<MyHomePage> {
  final _audioRecorder = FlutterAudioCapture();
  final pitchDetectorDart = PitchDetector(44100, 2000);

  var note = "";
  var status = "Click on start";
  
  Future<void> _startCapture() async {
    await _audioRecorder.start(listener, onError,
        sampleRate: 44100, bufferSize: 3000);

    setState(() {
      note = "";
      status = "Play something";
    });
  }

  Future<void> _stopCapture() async {
    await _audioRecorder.stop();

    setState(() {
      note = "";
      status = "Click on start";
    });
  }

  void listener(dynamic obj) {
    //Gets the audio sample
    var buffer = Float64List.fromList(obj.cast<double>());
    final List<double> audioSample = buffer.toList();

    //Uses pitch_detector_dart library to detect a pitch from the audio sample
    final result = pitchDetectorDart.getPitch(audioSample);

    //If there is a pitch - evaluate it
    if (result.pitched) {
      //TODO
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body:
          Expanded(
              child: Row(
            children: [
              Expanded(
                  child: Center(
                      child: FloatingActionButton(
                          onPressed: _startCapture,
                          child: const Text("Start")))),
              Expanded(
                  child: Center(
                      child: FloatingActionButton(
                          onPressed: _stopCapture, child: const Text("Stop")))),
            ],
          ))
        ]),
      ),
    );
  }
}