NAudio.MmException

Question

我正在试验如何使用Naudio播放mp3。我的简单应用程序有一个windows窗体和一个播放/暂停音乐的按钮。然而，这款应用有两个主要问题：

虽然它的目的是，如果音乐正在播放，并按下播放按钮，应用程序应该停止播放。相反，当按钮被重新按下时，应用程序会重新启动音乐，然后(有时)会抛出一个异常如果按钮被按下两三次(并且没有任何延迟)，应用程序会抛出一个NAudio.MmException (Message=InvalidParameter Can )谁能告诉我我的代码出了什么问题？下面是我的代码：

using System;
using System.Windows.Forms;
namespace NaudioTesting
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private NAudio.Wave.BlockAlignReductionStream stream = null;

        private NAudio.Wave.DirectSoundOut output = null;


        public void LoadFile(string filePath)
        {
            DisposeWave();

            if (filePath.EndsWith(".mp3"))
            {
                NAudio.Wave.WaveStream pcm =
                    NAudio.Wave.WaveFormatConversionStream.CreatePcmStream(new NAudio.Wave.Mp3FileReader(filePath));
                stream = new NAudio.Wave.BlockAlignReductionStream(pcm);
            }
            else if (filePath.EndsWith(".wav"))
            {
                NAudio.Wave.WaveStream pcm = new NAudio.Wave.WaveChannel32(new NAudio.Wave.WaveFileReader(filePath));
                stream = new NAudio.Wave.BlockAlignReductionStream(pcm);
            }
            else throw new InvalidOperationException("Not a correct audio file type.");

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

        private void playPauseButton_Click(object sender, EventArgs e)
        {
            string filePath = "GetLoud.mp3";
            LoadFile(filePath);
            if (output != null)
            {
                if (output.PlaybackState == NAudio.Wave.PlaybackState.Playing) output.Pause();
                else if (output.PlaybackState == NAudio.Wave.PlaybackState.Paused) output.Play();
            }
        }

        private void DisposeWave()
        {
            try
            {
                if (output != null)
                {
                    if (output.PlaybackState == NAudio.Wave.PlaybackState.Playing) output.Stop();
                    output.Dispose();
                    output = null;
                }
                if (stream != null)
                {
                    stream.Dispose();
                    stream = null;
                }
            }
            catch (NAudio.MmException)
            {
                throw;
            }
        }

        private void Form1_FormClosing(object sender, FormClosingEventArgs e)
        {
            DisposeWave();
        }
    }
}

Answer 1

查看DirectSoundOut源代码，Play和Pause的实现不支持恢复。也就是说，发生在你身上的事情正是它应该发生的。调用play将始终从流的开始处开始。您应该改用WaveOut。它支持通过再次调用Play来恢复，就像您在代码中所做的那样。

output = new NAudio.Wave.WaveOut();