“提前跳过15秒”的颤振音频处理

Question

我正在构建我的第一个Flutter应用，并且试图对音频进行精细控制。

我已经弄清楚了如何进行播放，暂停和停止功能，现在我想弄清楚如何跳过15秒或返回15秒，而我所做的一切都会破坏应用程序或不起作用

bool _isPlaying = false;
  bool _isPaused = false;
  FlutterSound _sound = FlutterSound();
  double _playPosition;
  Stream<PlayStatus> _playerSubscription;

  void initState() {
    super.initState();
    _sound = FlutterSound();
    _playPosition = 0;
  }

  void _stop() async {
    await _sound.stopPlayer();
    setState(() => _isPlaying = false);
  }

  void _play() async {
    await _sound.startPlayer(widget.snapshot.data["audio"]);
    _playerSubscription = _sound.onPlayerStateChanged
      ..listen((e) {
      if (e != null) {
        setState(() => _playPosition = e.currentPosition/ e.duration);
      }
    });
    setState(() => _isPlaying = true);
  }

  void _pause() async{
    await _sound.pausePlayer();
    setState(() {
      _isPaused = true;
      _isPlaying = false;
    });
  }

  void _resume() async{
    await _sound.resumePlayer();
    setState(() {
      _isPaused = false;
      _isPlaying = true;
    });
  }

  void fastForward() async{
    setState(() => _playPosition);
  }

  void rewind(){}

我希望使用这些功能在15秒之前跳过音频并在15秒之前返回