Wave Driver介绍-3（Wave API waveOutSetVolume）

1.1 定义及简要说明

函数waveOutSetVolume可以用来调整系统的音量，其定义如下：

MMRESULT WINAPI waveOutSetVolume(HWAVEOUT hwo, DWORD dwVolume);

         其中，第一个参数HWAVEOUT hwo可以传入两种值，第一种是wave-out设备ID号，此时函数调整的是设备音量，第二种是Stream句柄，调整的是所指向的Stream的音量。

         今天为这个地方晕乎乎了半天，最后还是写了点测试程序才搞懂，有关这个函数的具体使用方法及操作细节请看下面的验证过程。

注：

         下面的代码实际上是一个应用程序中部分代码，有关该应用程序的源码可以从我的资源中下载，主界面如下：

1.2 给函数传入wave-out设备ID的验证

         下面的代码实现了对设备音量进行调整的功能，对应上图中的Loud和Soft按键的功能。其中函数void CWaveAPI_TestDlg::OnBnClickedButton1()实现了将设备音量（0～0xffff ffff）增加0x1000的功能，也即Loud按钮的功能，而按钮Soft的功能由函数void CWaveAPI_TestDlg::OnBnClickedButton2()实现，每次点击该按钮设备音量将减少0x1000。

详细如下：

static DWORD g_dwWaveOutGain = 0;   void CWaveAPI_TestDlg::OnBnClickedButton1() {      // TODO: Add your control notification handler code here      DWORD dwDeviceID = 0;      DWORD deDeviceGain = 0;        for (dwDeviceID = 0; dwDeviceID < waveOutGetNumDevs(); dwDeviceID++)  {            NKDbgPrintfW(L"Device #%d/r/n", dwDeviceID);            waveOutSetVolume((HWAVEOUT)dwDeviceID, g_dwWaveOutGain);          waveOutGetVolume((HWAVEOUT)dwDeviceID, &deDeviceGain);            NKDbgPrintfW(L"/r/n         dst 0x%8x, read 0x%8x/r/n", g_dwWaveOutGain, deDeviceGain);            if (g_dwWaveOutGain <= (0xffffffff - 0x1000))               g_dwWaveOutGain+=0x1000;          else               g_dwWaveOutGain = 0xffffffff;      } }   void CWaveAPI_TestDlg::OnBnClickedButton2() {      // TODO: Add your control notification handler code here          DWORD dwDeviceID = 0;      DWORD deDeviceGain = 0;        for (dwDeviceID = 0; dwDeviceID < waveOutGetNumDevs(); dwDeviceID++)  {            NKDbgPrintfW(L"Device #%d/r/n", dwDeviceID);            waveOutSetVolume((HWAVEOUT)dwDeviceID, g_dwWaveOutGain);          waveOutGetVolume((HWAVEOUT)dwDeviceID, &deDeviceGain);            NKDbgPrintfW(L"/r/n         dst 0x%8x, read 0x%8x/r/n", g_dwWaveOutGain, deDeviceGain);            if (g_dwWaveOutGain >= 0x1000)               g_dwWaveOutGain-=0x1000;          else               g_dwWaveOutGain = 0;      } }

1.3 给函数传入Stream句柄的验证

         下面的代码中包括下面三个函数：

int StringFormatToWaveFormatEx( WAVEFORMATEX *wfx, const TCHAR* szWaveFormat ); ULONG SineWave( void* pBuffer, ULONG ulNumBytes, WAVEFORMATEX *pwfx, double dFrequency ); void PlayBackSound(bool bLoud);

         其中第一个函数StringFormatToWaveFormatEx实现了格式转换的功能。我们一般都习惯上使用形如“WAVE_FORMAT_1M08”的标记来表示wave in/out的格式，该函数完成在形如“WAVE_FORMAT_1M08”的标志和结构体WAVEFORMATEX之间进行等价转换的功能。

/* defines for dwFormat field of WAVEINCAPS and WAVEOUTCAPS */ #define WAVE_INVALIDFORMAT     0x00000000       /* invalid format */ #define WAVE_FORMAT_1M08       0x00000001       /* 11.025 kHz, Mono,   8-bit  */ #define WAVE_FORMAT_1S08       0x00000002       /* 11.025 kHz, Stereo, 8-bit  */ #define WAVE_FORMAT_1M16       0x00000004       /* 11.025 kHz, Mono,   16-bit */ #define WAVE_FORMAT_1S16       0x00000008       /* 11.025 kHz, Stereo, 16-bit */ #define WAVE_FORMAT_2M08       0x00000010       /* 22.05  kHz, Mono,   8-bit  */ #define WAVE_FORMAT_2S08       0x00000020       /* 22.05  kHz, Stereo, 8-bit  */ #define WAVE_FORMAT_2M16       0x00000040       /* 22.05  kHz, Mono,   16-bit */ #define WAVE_FORMAT_2S16       0x00000080       /* 22.05  kHz, Stereo, 16-bit */ #define WAVE_FORMAT_4M08       0x00000100       /* 44.1   kHz, Mono,   8-bit  */ #define WAVE_FORMAT_4S08       0x00000200       /* 44.1   kHz, Stereo, 8-bit  */ #define WAVE_FORMAT_4M16       0x00000400       /* 44.1   kHz, Mono,   16-bit */ #define WAVE_FORMAT_4S16       0x00000800       /* 44.1   kHz, Stereo, 16-bit */

typedef struct {     WORD        wFormatTag;         // format type     WORD        nChannels;          // number of channels (i.e. mono, stereo...)     DWORD       nSamplesPerSec;     // sample rate     DWORD       nAvgBytesPerSec;    // for buffer estimation     WORD        nBlockAlign;        // block size of data     WORD        wBitsPerSample;     // number of bits per sample of mono data     WORD        cbSize;             // the count in bytes of the size of                                     // extra information (after cbSize) } WAVEFORMATEX, *PWAVEFORMATEX, *LPWAVEFORMATEX;

         接下来说第二个函数SineWave，它完成根据调用者传入的参数构建正选波数据到pBuffer的功能，可以省却我们解析wav文件的烦恼。

         第三个函数PlayBackSound是今天的主角，它完成了创建Stream，并使用Stream播放音频的同时调整音量的功能。

         详细的代码如下：

// 转换数据 int StringFormatToWaveFormatEx( WAVEFORMATEX *wfx, const TCHAR* szWaveFormat ) {      int iRet;      DWORD tr=true;      TCHAR channels,bits1,bits2;        ZeroMemory(wfx,sizeof(*wfx));          iRet = _stscanf ( szWaveFormat, TEXT("WAVE_FORMAT_%i%c%c%c"), &wfx->nSamplesPerSec, &channels, &bits1, &bits2 );      if( iRet != 4 )      {          NKDbgPrintfW( ( TEXT( "ERROR:  %s not recognized/n" ), (LPWSTR)szWaveFormat ) );          NKDbgPrintfW(TEXT("Possible Cause:  Supplied format not in the form of WAVE_FORMAT%%i%%c%%c%%c/n"));          tr = false;          goto Error;      }        wfx->wFormatTag = WAVE_FORMAT_PCM;      switch( channels )      {      case 'M':      case 'm':          wfx->nChannels=1;          break;        default:          wfx->nChannels=2;      }        switch( wfx->nSamplesPerSec )      {      case 1:      case 2:      case 4:          wfx->nSamplesPerSec=11025*wfx->nSamplesPerSec;      }        wfx->wBitsPerSample=(bits1-TEXT('0'))*10+(bits2-TEXT('0'));      wfx->nBlockAlign=wfx->nChannels*wfx->wBitsPerSample/8;      wfx->nAvgBytesPerSec=wfx->nSamplesPerSec*wfx->nBlockAlign;   Error:      return tr; }

// 产生正选波数据 ULONG SineWave( void* pBuffer, ULONG ulNumBytes, WAVEFORMATEX *pwfx, double dFrequency ) {      double dPhase = 0.0;      double dAmplitude = 1.0;      char *pClear, *pClearEnd;      const double TWOPI = 2* 3.1415926535897931;        pClearEnd = (char*)pBuffer + ulNumBytes;      pClear = pClearEnd - ulNumBytes % 4;      while( pClear<pClearEnd )      {          *pClear = 0;          pClear++;      }        int nsamples = ulNumBytes / pwfx->nBlockAlign;      int i, m_t0 = 0;      int m_dSampleRate = pwfx->nSamplesPerSec;      double dMultiplier, dOffset, dSample;        if( pwfx->wBitsPerSample == 8 )      {          unsigned char * pSamples = (unsigned char *) pBuffer;          dMultiplier = 127.0;          dOffset = 128.0;          if( pwfx->nChannels == 1 )          {               for (i = 0; i < nsamples; i ++ )               {                    double t = ((double) (i+m_t0)) / m_dSampleRate;                    dSample = dAmplitude * sin( t*dFrequency* TWOPI + dPhase );                    pSamples[i] = (unsigned char) (dSample * dMultiplier + dOffset);               }          }          else          {               for (i = 0; i < nsamples; i ++)               {                    double t = ((double) (i+m_t0)) / m_dSampleRate;                    dSample = dAmplitude * sin (t*dFrequency* TWOPI + dPhase);                    pSamples[2*i] = (unsigned char) (dSample * dMultiplier + dOffset);                    pSamples[2*i+1] = pSamples[2*i]; // replicate across both channels               }          }      }      else      {          short * pSamples = (short *) pBuffer;          const double dMultiplier2 = 32767.0;          const double dOffset2 = 0.0;          if( pwfx->nChannels == 1 )          {               for (i = 0; i < nsamples; i += 1)               {                    double t = ((double) (i+m_t0)) / m_dSampleRate;                    dSample = dAmplitude * sin (t*dFrequency* TWOPI + dPhase);                    pSamples[i] = (short) (dSample * dMultiplier2 + dOffset2);               }          }          else          {               for (i = 0; i < nsamples; i ++)               {                    double t = ((double) (i+m_t0)) / m_dSampleRate;                    dSample = dAmplitude * sin( t*dFrequency* TWOPI + dPhase );                    pSamples[2*i] = (short) (dSample * dMultiplier2 + dOffset2);                    pSamples[2*i+1] = pSamples[2*i]; // replicate across both channels               }          }      }      m_t0 += i;      return ulNumBytes; }

/* 功能： 播放正选波声音文件 参数： bLoud：调整播放声音增益 true：   增大 false：  减小 返回值： 无 */ void PlayBackSound(bool bLoud) {      // TODO: Add your control notification handler code here      HWAVEOUT       hwo = NULL;      WAVEFORMATEX  wfx;      MMRESULT hr;      static HANDLE hEvent;      WAVEHDR wh;      char *data = NULL;      DWORD dwSeconds = 1;      double dFrequency = 440.0;      DWORD dwExpectedPlaytime, dwTime = 0;      DWORD dwSleepInterval            = 50;    //50 milliseconds        // ***********************************************************************      // 1. 初始化相关资源      // ***********************************************************************      // 初始化WAVEFORMATEX变量wfx      if (!StringFormatToWaveFormatEx(&wfx,TEXT("WAVE_FORMAT_2M16")))  {          NKDbgPrintfW(L"Convert Audio Format Failed!/r/n");          return ;      }        // 输出格式信息      NKDbgPrintfW(L"************************************/r/n");      NKDbgPrintfW(L"wfx.wBitsPerSample %d/r/n", wfx.wBitsPerSample);      NKDbgPrintfW(L"wfx.nChannels %d/r/n", wfx.nChannels);      NKDbgPrintfW(L"wfx.nSamplesPerSec %d/r/n", wfx.nSamplesPerSec);      NKDbgPrintfW(L"************************************/r/n");        hEvent = CreateEvent( NULL, FALSE, FALSE, NULL );        // 打开wave out设备      hr = waveOutOpen(&hwo, 0, &wfx, NULL,(DWORD)hEvent, CALLBACK_NULL);      if(hr != MMSYSERR_NOERROR)      {          NKDbgPrintfW(L"waveOutOpen failed! Error number 0x%x/r/n", hr);          return ;      }        // 分配buffer      data = new char[dwSeconds * wfx.nAvgBytesPerSec];      if (!data)    {          NKDbgPrintfW(L"Out of memeory/r/n");          return ;      }        ZeroMemory(data, dwSeconds * wfx.nAvgBytesPerSec);        // 初始化wh（WAVEHDR）      ZeroMemory(&wh, sizeof(WAVEHDR));      wh.lpData = data;      wh.dwBufferLength = dwSeconds * wfx.nAvgBytesPerSec;      wh.dwLoops = 1;      wh.dwFlags = WHDR_BEGINLOOP | WHDR_ENDLOOP;      dwExpectedPlaytime = wh.dwBufferLength * 1000 / wfx.nAvgBytesPerSec;        // 创造声波      SineWave(wh.lpData, wh.dwBufferLength, &wfx,dFrequency );        // ***********************************************************************      // 2. 开始播放声音操作      // ***********************************************************************      // 调整Stream音量       DWORD deDeviceGain = 0;        waveOutSetVolume((HWAVEOUT)hwo, g_dwWaveOutGain);      waveOutGetVolume((HWAVEOUT)hwo, &deDeviceGain);        NKDbgPrintfW(L"Volume of device 0 successfully set to 0x%8x, previous 0x%8x/r/n", g_dwWaveOutGain, deDeviceGain);        if (bLoud)    {          if (g_dwWaveOutGain <= (0xffffffff - 0x1000))               g_dwWaveOutGain+=0x1000;          else               g_dwWaveOutGain = 0xffffffff;      }else    {          if (g_dwWaveOutGain >= 0x1000)               g_dwWaveOutGain-=0x1000;          else               g_dwWaveOutGain = 0;      }        // 准备buffer      hr = waveOutPrepareHeader(hwo, &wh, sizeof(WAVEHDR));      if(hr != MMSYSERR_NOERROR)      {          NKDbgPrintfW(L"waveOutPrepareHeader failed! Error number 0x%x/r/n", hr);          return ;      }        // 写入buffer      hr = waveOutWrite(hwo, &wh, sizeof(WAVEHDR));        while( (!(wh.dwFlags&WHDR_DONE)) && ( dwTime<dwExpectedPlaytime+1000) )      {          Sleep( dwSleepInterval );           dwTime += dwSleepInterval;      }        // ***********************************************************************      // 3. 销毁所有资源      // ***********************************************************************      NKDbgPrintfW(L"Destroy all the resource/r/n");      waveOutReset(hwo);      if(hr != MMSYSERR_NOERROR)  {          NKDbgPrintfW(L"waveOutUnprepareHeader failed! Error number 0x%x/r/n", hr);          return ;      }        hr = waveOutUnprepareHeader(hwo,&wh,sizeof(WAVEHDR) );      if(hr != MMSYSERR_NOERROR)  {          NKDbgPrintfW(L"waveOutUnprepareHeader failed! Error number 0x%x/r/n", hr);          return ;      }        waveOutClose(hwo);      if(hr != MMSYSERR_NOERROR)  {          NKDbgPrintfW(L"waveOutUnprepareHeader failed! Error number 0x%x/r/n", hr);          return ;      }        if (data)          delete []data;        if( hEvent)          CloseHandle(hEvent); }

         前面提到，应用程序中有四个按钮，左边的两个按钮已经讲过，右边的两个按钮“Loud Stream”和“Soft Stream”的实现就是通过调用上面的函数PlayBackSound完成，这部分代码如下：

void CWaveAPI_TestDlg::OnBnClickedButton3() {      PlayBackSound(true); }   void CWaveAPI_TestDlg::OnBnClickedButton4() {      // TODO: Add your control notification handler code here          PlayBackSound(false); }