啥叫混音呢，其实很简单，如果两个人同时说话 ，他们俩发出的声波在空气中进行了波的叠加，这其实就是个混音。计算机的混音，其实是一个虚拟的混音操作，因为计算机其实是只有一个声源（现在的计算机通常有两声道甚至5声道的立体声，先忽略这些，我们先抽象，把计算机看作一个声源），通过在计算机内部进行运算，把两个波形进行叠加运算，然后由计算机唯一的音箱输出，这就是计算机混音技术。微软的API PlaySound是不支持混音的，调用一个PlaySound的时候，会终止上一个PlaySound调用所播放的声音（异步调用），如果要用PlaySound来实现混音效果，就需要自己写一个混音算法。幸运的是，该叠加算法不需要我们去写，微软的DirectX早已提供给我们了现成的算法，而且非常强大，参与叠加的每个声音分量甚至都能够有自己独立的空间坐标，这也就是3D音效了。我们不需要3d音效，只要能够多路混音就可以了，晚上找到一个开源的对DirectSound的封装，非常好用，现把代码公开如下：

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// DSBuffer.h : Definition of CDSBuffer class

//

#if !defined(AFX_DSBUFFER_H__7517D749_96E3_11D2_BBF3_9EB4940D843C__INCLUDED_)

#define AFX_DSBUFFER_H__7517D749_96E3_11D2_BBF3_9EB4940D843C__INCLUDED_

#if _MSC_VER > 1000

#pragma once

#endif // _MSC_VER > 1000

#include <mmsystem.h>

#include <dsound.h>

struct WaveHeader

{

BYTE RIFF[4]; // "RIFF"

DWORD dwSize; // Size of data to follow

BYTE WAVE[4]; // "WAVE"

BYTE fmt_[4]; // "fmt "

DWORD dw16; // 16

WORD wOne_0; // 1

WORD wChnls; // Number of Channels

DWORD dwSRate; // Sample Rate

DWORD BytesPerSec; // Sample Rate

WORD wBlkAlign; // 1

WORD BitsPerSample; // Sample size

BYTE DATA[4]; // "DATA"

DWORD dwDSize; // Number of Samples

};

class CDSBuffer : public CObject

{

// Attribute

protected:

LPDIRECTSOUNDBUFFER m_lpDSBuffer; // Sound buffer

LPDIRECTSOUND3DBUFFER m_lpDS3DBuffer; // 3D buffer

// Construction / Destruction

public:

CDSBuffer();

CDSBuffer(const char* FileName, LPDIRECTSOUND lpDS, DWORD dwFlags = DSBCAPS_CTRLDEFAULT);

~CDSBuffer();

// Methods

public:

BOOL PlaySound(DWORD dwFlags);

BOOL StopSound();

BOOL CreateSoundBuffer(LPDIRECTSOUND lpDS, DWORD dwFlags, DWORD dwBufSize, DWORD dwFreq, DWORD dwBitsPerSample, DWORD dwBlkAlign, BOOL bStereo);

BOOL ReadData(FILE* pFile, DWORD dwSize, DWORD dwPos);

BOOL IsValid();

LPDIRECTSOUNDBUFFER GetBuffer() { return m_lpDSBuffer;}

LPDIRECTSOUND3DBUFFER Get3DBuffer() { return m_lpDS3DBuffer;}

};

#endif // !defined(AFX_DSBUFFER_H__7517D749_96E3_11D2_BBF3_9EB4940D843C__INCLUDED_)

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///

// //

// DirectSound Mixer //

// //

// V1.0 by 1999 //

// //

// with core inputs from //

// Stack-Up //

// V1.0 1998 //

// //

// also //

// //

///

// DSBuffer.cpp : Implementation of CDSBuffer class

//

#include "stdafx.h"

#include "DSBuffer.h"

#ifdef _DEBUG

#define new DEBUG_NEW

#undef THIS_FILE

static char THIS_FILE[] = __FILE__;

#endif

/

// CDSBuffer

CDSBuffer::CDSBuffer()

{

// Reset the sound buffer

m_lpDSBuffer = NULL;

// Reset the 3D buffer

m_lpDS3DBuffer = NULL;

}

CDSBuffer::CDSBuffer(const char *FileName, LPDIRECTSOUND lpDS, DWORD dwFlags)

{

// Reset the sound buffer

m_lpDSBuffer = NULL;

// Reset the 3D buffer

m_lpDS3DBuffer = NULL;

// Open the wave file

FILE* pFile = fopen(FileName, "rb");

if(!pFile)

return;

// Read in the wave header

WaveHeader wavHdr;

if (fread(&wavHdr, sizeof(wavHdr), 1, pFile) != 1)

{

fclose(pFile);

return;

}

// Figure out the size of the data region

DWORD dwSize = wavHdr.dwDSize;

// Is this a stereo or mono file?

BOOL bStereo = wavHdr.wChnls > 1 ? true : false;

// Create the sound buffer for the wave file

if(CreateSoundBuffer(lpDS, dwFlags, dwSize, wavHdr.dwSRate, wavHdr.BitsPerSample, wavHdr.wBlkAlign, bStereo))

{

// Read the data for the wave file into the sound buffer

if (!ReadData(pFile, dwSize, sizeof(wavHdr)))

AfxMessageBox("Error - DS - Reading Data");

else if (dwFlags & DSBCAPS_CTRL3D)

{

// Get pointer to 3D buffer

if (S_OK != m_lpDSBuffer->QueryInterface(IID_IDirectSound3DBuffer, (void **)&m_lpDS3DBuffer))

AfxMessageBox("DirectSound3DBuffer not available");

}

}

fclose(pFile);

}

CDSBuffer::~CDSBuffer()

{

StopSound();

if(m_lpDSBuffer)

{

m_lpDSBuffer->Release();

}

if(m_lpDS3DBuffer)

{

m_lpDS3DBuffer->Release();

}

}

BOOL CDSBuffer::CreateSoundBuffer(LPDIRECTSOUND lpDS, DWORD dwFlags, DWORD dwBufSize, DWORD dwFreq, DWORD dwBitsPerSample, DWORD dwBlkAlign, BOOL bStereo)

{

PCMWAVEFORMAT pcmwf;

DSBUFFERDESC dsbdesc;

// Set up wave format structure.

memset( &pcmwf, 0, sizeof(PCMWAVEFORMAT) );

pcmwf.wf.wFormatTag = WAVE_FORMAT_PCM;

pcmwf.wf.nChannels = bStereo ? 2 : 1;

pcmwf.wf.nSamplesPerSec = dwFreq;

pcmwf.wf.nBlockAlign = (WORD)dwBlkAlign;

pcmwf.wf.nAvgBytesPerSec = pcmwf.wf.nSamplesPerSec * pcmwf.wf.nBlockAlign;

pcmwf.wBitsPerSample = (WORD)dwBitsPerSample;

// Set up DSBUFFERDESC structure.

memset(&dsbdesc, 0, sizeof(DSBUFFERDESC)); // Zero it out.

dsbdesc.dwSize = sizeof(DSBUFFERDESC);

dsbdesc.dwFlags = dwFlags;

dsbdesc.dwBufferBytes = dwBufSize;

dsbdesc.lpwfxFormat = (LPWAVEFORMATEX)&pcmwf;

if (DS_OK != lpDS->CreateSoundBuffer(&dsbdesc, &m_lpDSBuffer, NULL))

{

AfxMessageBox("Error - DS - CreateSoundBuffer");

return FALSE;

}

return TRUE;

}

BOOL CDSBuffer::ReadData(FILE* pFile, DWORD dwSize, DWORD dwPos)

{

// Seek to correct position in file (if necessary)

if (dwPos != 0xffffffff)

{

if (fseek(pFile, dwPos, SEEK_SET) != 0)

{

return FALSE;

}

}

// Lock data in buffer for writing

LPVOID pData1;

DWORD dwData1Size;

LPVOID pData2;

DWORD dwData2Size;

HRESULT rval;

rval = m_lpDSBuffer->Lock(0, dwSize, &pData1, &dwData1Size, &pData2, &dwData2Size, DSBLOCK_FROMWRITECURSOR);

if (rval != DS_OK)

{

return FALSE;

}

// Read in first chunk of data

if (dwData1Size > 0)

{

if (fread(pData1, dwData1Size, 1, pFile) != 1)

{

return FALSE;

}

}

// read in second chunk if necessary

if (dwData2Size > 0)

{

if (fread(pData2, dwData2Size, 1, pFile) != 1)

{

return FALSE;

}

}

// Unlock data in buffer

rval = m_lpDSBuffer->Unlock(pData1, dwData1Size, pData2, dwData2Size);

if (rval != DS_OK)

{

return FALSE;

}

return TRUE;

}

BOOL CDSBuffer::PlaySound(DWORD dwFlags)

{

if(m_lpDSBuffer) // Make sure we have a valid sound buffer

{

DWORD dwStatus;

if (DS_OK != m_lpDSBuffer->GetStatus(&dwStatus))

{

AfxMessageBox("Error - DS - GetStatus");

return FALSE;

}

if((dwStatus & DSBSTATUS_PLAYING) != DSBSTATUS_PLAYING)

{

if (DS_OK != m_lpDSBuffer->Play(0, 0, dwFlags)) // Play the sound

{

AfxMessageBox("Error - DS - Play");

return FALSE;

}

}

}

return TRUE;

}

BOOL CDSBuffer::StopSound()

{

if(m_lpDSBuffer) // Make sure we have a valid sound buffer

{

DWORD dwStatus;

if (DS_OK != m_lpDSBuffer->GetStatus(&dwStatus))

{

AfxMessageBox("Error - DS - GetStatus");

return FALSE;

}

if ((dwStatus & DSBSTATUS_PLAYING) == DSBSTATUS_PLAYING)

{

if (DS_OK != m_lpDSBuffer->Stop()) // Stop the sound

{

AfxMessageBox("Error - DS - Stop");

return FALSE;

}

}

}

return TRUE;

}

BOOL CDSBuffer::IsValid()

{

if (m_lpDSBuffer)

return TRUE;

else

return FALSE;

}

 

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-------------------------------------------------------------------------------------------------

// DSList.h : Definition of CDSList class

//

#if !defined(AFX_DSLIST_H__7517D749_96E3_11D2_BBF3_9EB4940D843C__INCLUDED_)

#define AFX_DSLIST_H__7517D749_96E3_11D2_BBF3_9EB4940D843C__INCLUDED_

#if _MSC_VER > 1000

#pragma once

#endif // _MSC_VER > 1000

#include "DSBuffer.h"

class CDSList : virtual protected CObList

{

// Attribute

private:

LPDIRECTSOUND m_lpDS; // DirectSound Object

// Construction / Destruction

public:

CDSList();

~CDSList();

// Methods

public:

BOOL Init();

BOOL StopAllBuffers();

BOOL AddNewBuffer(const char* FileName);

BOOL RemoveBuffer(int nBuffer);

BOOL PlayBuffer(int nBuffer, DWORD dwFlags);

BOOL StopBuffer(int nBuffer);

LPDIRECTSOUND GetDSObject() {return m_lpDS;}

};

#endif // !defined(AFX_DSLIST_H__7517D749_96E3_11D2_BBF3_9EB4940D843C__INCLUDED_)

-------------------------------------------------------------------------------------------------

-------------------------------------------------------------------------------------------------

///

// //

// DirectSound Mixer //

// //

// V1.0 by 1999 //

// //

// with core inputs from //

// Stack-Up //

// V1.0 1998 //

// //

// also //

// //

///

// DSList.cpp : Implementation of CDSList class

//

#include "stdafx.h"

#include "DSList.h"

#ifdef _DEBUG

#define new DEBUG_NEW

#undef THIS_FILE

static char THIS_FILE[] = __FILE__;

#endif

/

// CDSList

CDSList::CDSList()

{

// Reset the DirectSound pointer

m_lpDS = NULL;

}

CDSList::~CDSList()

{

// Stop all playing buffers

StopAllBuffers();

if(m_lpDS)

{

m_lpDS->Release();

}

}

BOOL CDSList::Init()

{

// Create DirectSound Object

if (DS_OK != DirectSoundCreate(NULL, &m_lpDS, NULL))

{

AfxMessageBox("Error - DS - Create/nAudio cannot be used");

return FALSE;

}

// Set Cooperative Level

if (DS_OK != m_lpDS->SetCooperativeLevel(*AfxGetMainWnd(), DSSCL_NORMAL))

{

AfxMessageBox("Error - DS - SetCooperativeLevel");

return FALSE;

}

return TRUE;

}

BOOL CDSList::AddNewBuffer(const char* FileName)

{

// Make sure that audio is initialized

if (!m_lpDS)

{

AfxMessageBox("Error - DS - Audio not initialized");

return FALSE;

}

// Try creating the new buffer

CDSBuffer* pNewBuffer = new CDSBuffer(FileName, m_lpDS);

// If succesfull add to playlist

if (pNewBuffer->IsValid())

{

AddTail(pNewBuffer);

return TRUE;

}

// Else forget it

else

{

delete(pNewBuffer);

return FALSE;

}

}

BOOL CDSList::RemoveBuffer(int nBuffer)

{

// Make sure that the buffer index is valid

if ((nBuffer < 0) || (nBuffer >= GetCount()))

{

AfxMessageBox("Error - DS - Invalid buffer selection index");

return FALSE;

}

// First stop the buffer

if (StopBuffer(nBuffer))

{

// Find the buffer

POSITION Pos = FindIndex(nBuffer);

// Remove it

RemoveAt(Pos);

return TRUE;

}

return FALSE;

}

BOOL CDSList::PlayBuffer(int nBuffer, DWORD dwFlags)

{

// Make sure that the buffer index is valid

if ((nBuffer < 0) || (nBuffer >= GetCount()))

{

AfxMessageBox("Error - DS - Invalid buffer selection index");

return FALSE;

}

// Find the buffer

POSITION Pos = FindIndex(nBuffer);

// Retrieve a pointer

CDSBuffer* DSBuffer = (CDSBuffer *)GetAt(Pos);

// Try playing it

return DSBuffer->PlaySound(dwFlags);

}

BOOL CDSList::StopBuffer(int nBuffer)

{

// Make sure that the buffer index is valid

if ((nBuffer < 0) || (nBuffer >= GetCount()))

{

AfxMessageBox("Error - DS - Invalid buffer selection index");

return FALSE;

}

// Find the buffer

POSITION Pos = FindIndex(nBuffer);

// Retrieve a pointer

CDSBuffer* DSBuffer = (CDSBuffer *)GetAt(Pos);

// Try stopping it

return DSBuffer->StopSound();

}

BOOL CDSList::StopAllBuffers()

{

for (POSITION Pos = GetHeadPosition(); Pos != NULL; )

{

CDSBuffer* DSBuffer = (CDSBuffer *)GetNext(Pos);

DSBuffer->StopSound();

}

return TRUE;

}

 

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代码使用方法：

1、首先把四个文件添加到工程中。

2、包含相应的头文件，在自己的代码中添加如下代码：

#include "DSList.h"

3、链接DirectSound的相关静态链接库

在自己的代码中加入如下静态链接代码：

//连接LIB库

#pragma comment (lib,"winmm.lib")

#pragma comment(lib,"dxguid.lib")

#pragma comment(lib,"dsound.lib")

4、在初始化代码中载入波形文件到缓冲区:

代码示例：

//初始化DirectSound混音器；

m_dslist.Init ();

m_dslist.AddNewBuffer(GetAppPath()+"//sound//one.wav");

m_dslist.AddNewBuffer(GetAppPath()+"//sound//two.wav");

m_dslist.AddNewBuffer(GetAppPath()+"//sound//three.wav");

5、在需要播放声音的时候调用：m_dslist.PlayBuffer(index,0);

index参数指的是添加缓冲区索引，最先添加的缓冲区索引为0，依此类推。

该函数是异步执行，自动与以前调用该函数所产生的尚未结束的声音混音输出。