指定声卡输出固定频率的声音

[Gabriel2005]

电脑装有两个声卡，通过waveOutOpen指定其中一个声卡后，如何让其输出固定频率（如1000Hz)的声音，

老大追的急，没时间去找了，哪位能帮忙给出源代码，或者是相关链接，谢谢先！

[Gabriel2005]

刚找到一个，还不知道能不能用
http://www.codeproject.com/cpp/Frequency_Generator.asp

[Gabriel2005]

问题已解决

[mynamelj]

那就结帖!

[Gabriel2005]

#include <math.h>
#include <time.h>
#include <mmsystem.h>
#include "Generator.h"

#define DllExport extern "C" __declspec( dllexport )

BOOL APIENTRY DllMain( HANDLE hModule,
DWORD ul_reason_for_call,
LPVOID lpReserved
)
{
return TRUE;
}


UINT CloseDevice(void)
{
delete [] buf;
mmres=waveOutReset(ghwo);
if(mmres != MMSYSERR_NOERROR)
return 1; //"Cant close device.";
mmres=waveOutClose(ghwo);
if(mmres != MMSYSERR_NOERROR)
return 1; //"Cant close device.";
return 0;
}


UINT PrepareDevice(UINT uDeviceID)
{
pwfx=new WAVEFORMATEX;
pwfx->wFormatTag=WAVE_FORMAT_PCM;
pwfx->nChannels=1;
pwfx->nSamplesPerSec=SPS;
pwfx->nAvgBytesPerSec=SPS;
pwfx->nBlockAlign=1;
pwfx->wBitsPerSample=8;
mmres=waveOutOpen(&ghwo,uDeviceID,pwfx,dwCallback,dwCallbackInstance,fdwOpen);
delete pwfx;
if(mmres != MMSYSERR_NOERROR)
{
return 1; //"Cant open device.";
}
buf=new char[SPS];
if(buf == NULL)
{
CloseDevice();
return 2; //"Cant allocate memory.";
}
pwh.lpData=buf;
pwh.dwBufferLength=SPS;
pwh.dwFlags=WHDR_BEGINLOOP;
pwh.dwLoops=1;
mmres = waveOutPrepareHeader(ghwo,&pwh,sizeof(pwh));
pwh.dwFlags=WHDR_BEGINLOOP|WHDR_ENDLOOP|WHDR_PREPARED;
pwh.dwLoops=0xFFFFFFFF; // Number of loops == about 136 years:)
if(mmres != MMSYSERR_NOERROR)
{
CloseDevice();
return 3; //"Device prepare error.";
}
return NULL;
}


//---------------------------------------------------------------------------

void FillBuf(int freq,char amp,float phase)
{
float x=(float)(freq*2*3.1416/SPS);
for(int cnt=0;cnt<SPS;cnt++)
buf[cnt]=(char)(cos(phase+cnt*x)*amp+127);
}
//---------------------------------------------------------------------------

UINT GenFreq(void)
{
waveOutReset(ghwo);
if(mmres != MMSYSERR_NOERROR)
return 1; //"Cant reset device.";
mmres=waveOutWrite(ghwo,&pwh,sizeof(WAVEHDR));
if(mmres != MMSYSERR_NOERROR)
return 2; //"Cant write data to device.";
return 0;
}
//---------------------------------------------------------------------------

UINT StopGen(void)
{
mmres=waveOutReset(ghwo);
if(mmres != MMSYSERR_NOERROR)
return 1; //"Cant stop device.";
return 0;
}

DllExport UINT __stdcall StartAudio(int AudioDuration,UINT DevID,int freq,char amp,float phase)
{
PrepareDevice(DevID);
FillBuf(freq,amp,phase);
time(&lngStartTime);
time(&lngCurrentTime);

while(lngCurrentTime-lngStartTime<AudioDuration)
{
GenFreq();
time(&lngCurrentTime);
}

StopGen();
CloseDevice();

return 0;
}