void OnTrackBarTimerElapsed(object sender, ElapsedEventArgs e) { _trackBarValue = _audioPlayback.GetCurrentPosition(); RaisePropertyChanged("TrackBarValue"); TimeSpan current = TimeSpan.FromSeconds(_trackBarValue); TrackBarString = $"{current.ToString(@"hh\:mm\:ss")} / {_trackBarMaximumValue.ToString(@"hh\:mm\:ss")}"; }