Question

我使用此代码为我的游戏播放MIDI文件，但我听不到扬声器发出的任何声音。你能帮我吗？这是一种紧急情况，请...... 我的扬声器已打开;）

[DllImport("winmm.dll", EntryPoint="mciSendStringA")]
private static extern long mciSendString(string lpstrCommand, string lpstrReturnString, long uReturnLength, long hwndCallback);
public static long PlayMidiFile(string MidiFile)
{
 long lRet = -1;

 if (File.Exists(MidiFile)) 
 {
  lRet = mciSendString("stop midi", "", 0, 0);
  lRet = mciSendString("close midi", "", 0, 0);
  lRet = mciSendString(("open sequencer!" 
   + (MidiFile + " alias midi")), "", 0, 0);
  lRet = mciSendString("play midi", "", 0, 0);
  return lRet;
 }

 else
 {
  //Error Message
  return lRet;
 }
}

Answer 1

我不确定你的winmm.dll的实现，但我有一个经过测试和运行的代码。

我从这个开源项目得到了源代码：Tea Timer。

代码的实现非常简单，如下所示。希望它有所帮助。

using System;
using System.Text;
using System.Runtime.InteropServices;
using System.IO;

namespace TeaTimer
{
    /// <summary>
    /// MCIPlayer is based off code by Slain.
    /// Found here: http://www.sadeveloper.net/Articles_View.aspx?articleID=212
    /// </summary>
    public class MCIPlayer
    {
        private static readonly string sAlias="TeaTimerAudio";

        [DllImport("winmm.dll")]
        private static extern long mciSendString(string strCommand,StringBuilder strReturn,int iReturnLength, IntPtr hwndCallback);
        [DllImport("Winmm.dll")]
        private static extern long PlaySound(byte[] data, IntPtr hMod, UInt32 dwFlags);

        public static void Play(string sFile)
        {
            _Open(sFile);
            _Play();
        }
        public static void Stop() 
        {
            _Close();
        }

        private static void _Open(string sFileName)
        {
            if(_Status()!="")
                _Close();

            string sCommand = "open \"" + sFileName + "\" alias "+sAlias;
            mciSendString(sCommand, null, 0, IntPtr.Zero);
        }

        private static void _Close()
        {
            string sCommand = "close "+sAlias;
            mciSendString(sCommand, null, 0, IntPtr.Zero);
        }

        private static void _Play()
        {
            string sCommand = "play "+sAlias;
            mciSendString(sCommand, null, 0, IntPtr.Zero);
        }

        private static string _Status()
        {
            StringBuilder sBuffer = new StringBuilder(128);
            mciSendString("status "+sAlias+" mode", sBuffer, sBuffer.Capacity, IntPtr.Zero);
            return sBuffer.ToString();
        }
    }
}

编辑：这是您播放和停止音乐文件的方式：

public static void playSound(string sFile) 
{
    //WavPlay.WavPlayer.Play(sFile);
    MCIPlayer.Play(sFile);
}
public static void stopSound() 
{
    //WavPlay.WavPlayer.StopPlay();
    MCIPlayer.Stop();
}

Answer 2

我曾经使用过这个定义......

[DllImport("winmm.dll", EntryPoint = "mciSendStringA")] 

public static extern void mciSendStringA(string lpstrCommand, string lpstrReturnString, long uReturnLength, long hwndCallback);

...在.Net 3.5但在.Net 4.0中给了我和不平衡的pinvoke异常！我通过使用它来修复它......

[DllImport("winmm.dll", EntryPoint = "mciSendStringA")]

public static extern void mciSendStringA(string lpstrCommand, string lpstrReturnString, int uReturnLength, IntPtr hwndCallback);

...并传递IntPtr.Zero作为最后一个参数。

唯一的区别是uReturnLength是int（而不是long）而hwndCallback是IntPtr（而不是{{1} }}）。

希望这会有所帮助......

在C＃.Net中播放MIDI文件时没有听到任何声音

2 个答案: