轉載自:http://www.cnblogs.com/rainbowzc/archive/2006/08/07/2422323.html
AEC回聲抑制算法，這個比較難，目前可以使用directsound進行處理，不過只能在xp下使用，別的系統不支持！
目前gips對本算法有出色的實現，skype就是使用的該引擎！
要想自己實現，恐怕很困難！
AEC 模塊是 Microsoft DirectSound 底層結構的一部分。該組件包括下列特性和限制：
AEC只在不超過 25×15×9 英尺的小房間才會有效；
AEC只對單聲道有效，當輸出是多個通道的立體聲的時候，只有一個通道能夠具有回波抵消的效果；
AEC不能抵消來自其它聲音源的聲音，比如背景中收音機放出來的歌曲；
IDirectSoundFullDuplex8* DirectSoundFD;//
IDirectSoundCaptureBuffer8* DirectSoundCaptureBuf8;//捕捉緩沖區接口指針
IDirectSoundBuffer8* DirectSoundBuf8;//回放緩沖區接口指針
IDirectSoundBuffer8* pIUnkown;//回放緩沖區接口指針
extern "C" const GUID IID_IDirectSoundBuffer8 = {0x6825a449, 0x7524, 0x4d82,{ 0x92, 0x0f, 0x50, 0xe3, 0x6a, 0xb3, 0xab, 0x1e}};
extern "C" const GUID GUID_DSCFX_MS_NS = {0x11c5c73b, 0x66e9, 0x4ba1, {0xa0, 0xba, 0xe8, 0x14, 0xc6, 0xee, 0xd9, 0x2d}};
extern "C" const GUID GUID_DSCFX_CLASS_NS = {0xe07f903f, 0x62fd, 0x4e60, {0x8c, 0xdd, 0xde, 0xa7, 0x23, 0x66, 0x65, 0xb5}};
extern "C" const GUID GUID_DSCFX_MS_AEC = {0xcdebb919, 0x379a, 0x488a, {0x87, 0x65, 0xf5, 0x3c, 0xfd, 0x36, 0xde, 0x40}};
extern "C" const GUID GUID_DSCFX_CLASS_AEC = {0xBF963D80L, 0xC559, 0x11D0, {0x8A, 0x2B, 0x00, 0xA0, 0xC9, 0x25, 0x5A, 0xC1}};
extern "C" const GUID DAlgorithm ={0x00000000, 0x0000, 0x0000, {0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}};
//1.創建及初始化DirectSound
WAVEFORMATEX WaveDataFormat={WAVE_FORMAT_PCM, 1,8000,16000,2,16, 0};
//回放緩沖區。render buffer
DSBUFFERDESC desc;
memset(&desc, 0, sizeof(desc));
desc.dwSize = sizeof(desc);
desc.dwFlags = DSBCAPS_CTRLFX | DSBCAPS_GLOBALFOCUS;
desc.dwBufferBytes = 2000 * NUM_REC_NOTIFICATIONS;//待定
desc.dwReserved = 0;
desc.lpwfxFormat = &WaveDataFormat;
//捕捉緩沖區AEC和NS效果。
DSCEFFECTDESC efft[2];
memset(efft, 0, sizeof(efft));
//AEC效果
efft[0].dwSize = sizeof(efft[0]);
efft[0].dwFlags = DSCFX_LOCSOFTWARE;
efft[0].guidDSCFXClass = GUID_DSCFX_CLASS_AEC;
efft[0].guidDSCFXInstance = GUID_DSCFX_MS_AEC;
//NS效果
efft[1].dwSize = sizeof(efft[1]);
efft[1].dwFlags = DSCFX_LOCSOFTWARE;
efft[1].guidDSCFXClass = GUID_DSCFX_CLASS_NS;
efft[1].guidDSCFXInstance = GUID_DSCFX_MS_NS;
//捕捉緩沖區。capture buffer
DSCBUFFERDESC cdesc;
memset(&cdesc, 0, sizeof(cdesc));
cdesc.dwSize = sizeof(cdesc);
cdesc.dwFlags = DSCBCAPS_CTRLFX;
cdesc.dwBufferBytes = 2000 * NUM_REC_NOTIFICATIONS;//待定
cdesc.lpwfxFormat = &WaveDataFormat;
cdesc.dwFXCount = 2;
cdesc.lpDSCFXDesc = efft;
HWND win = AfxGetApp()->m_pMainWnd->m_hWnd;
hr = DirectSoundFullDuplexCreate8(0, 0,&cdesc, &desc,win,
DSSCL_PRIORITY,&DirectSoundFD, &DirectSoundCaptureBuf8,&DirectSoundBuf8, 0);
DXTRACE_ERR( TEXT("DirectSoundFullDuplexCreate8"), hr );
//成功創建DirectSoundFD，DirectSoundCaptureBuf8，DirectSoundBuf8，均不為零。
if(!FAILED(hr))
DirectSoundFD->QueryInterface(IID_IDirectSoundBuffer8, (void**)pIUnkown);
//發現上面的pIUnkown=0，查詢失敗，為什么？
AfxMessageBox("失敗");