C#.NET No.25-4

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace NAudio_Project
{
    public partial class Form1 : Form
    {
        private NAudio.Wave.BlockAlignReductionStream stream = null; //
        private NAudio.Wave.DirectSoundOut output = null;

        public Form1()
        {
            InitializeComponent();
        }

        private void buttonOpen_Click(object sender, EventArgs e)
        {
            OpenFileDialog windowDialog = new OpenFileDialog();
            windowDialog.Filter = "Audio files (*.mp3;*.wav)|*.mp3;*.wav;";
            windowDialog.Title = "Open audio file";
            if (windowDialog.ShowDialog() == DialogResult.OK)
            {
                DisposeWave();//kita stop sound sebelumnya
                if (windowDialog.FileName.EndsWith(".mp3"))
                {
                    NAudio.Wave.WaveStream pcm = NAudio.Wave.WaveFormatConversionStream.CreatePcmStream(new NAudio.Wave.Mp3FileReader(windowDialog.FileName));
                    stream = new NAudio.Wave.BlockAlignReductionStream(pcm);
                }
                else if (windowDialog.FileName.EndsWith(".wav"))
                {
                    NAudio.Wave.WaveStream pcm = new NAudio.Wave.WaveChannel32(new NAudio.Wave.WaveFileReader(windowDialog.FileName));
                    stream = new NAudio.Wave.BlockAlignReductionStream(pcm);
                }
                else throw new InvalidOperationException("Not supported file");

                output = new NAudio.Wave.DirectSoundOut();
                output.Init(stream);
                output.Play();

                buttonPlayPause.Enabled = true;
                textBoxFilename.Text = windowDialog.FileName;
            }
        }

        private void buttonPlayPause_Click(object sender, EventArgs e)
        {
            if (output != null)
            {
                if (output.PlaybackState == NAudio.Wave.PlaybackState.Playing) output.Pause();
                else if (output.PlaybackState == NAudio.Wave.PlaybackState.Paused) output.Play();

            }

        }

        //kita buat method untuk men-stop sound sebelumnya
        private void DisposeWave()
        {
            if (output != null)
            {
                if (output.PlaybackState == NAudio.Wave.PlaybackState.Playing) output.Stop();
                output.Dispose();
                output = null;
            }

            if (stream != null)
            {
                stream.Dispose();
                stream = null;
            }
        }
    }
}