You create a capture buffer by calling the IDirectSoundCapture::CreateCaptureBuffer method of the DirectSoundCapture object.

One of the parameters to the method is a DSCBUFFERDESC structure that describes the characteristics of the desired buffer. The last member of this structure is a WAVEFORMATEX structure, which must be initialized with the details of the desired wave format. For more information on this structure, see Sound Data.

Note that if your application is using DirectSound as well as DirectSoundCapture, capture buffer creation can fail when the format of the capture buffer is not the same as that of the primary buffer. The reason is that some cards have only a single clock and cannot support capture and playback at two different frequencies.

The following example sets up a capture buffer that will hold 1 second of data:

/* In this example it is assumed that pDSC is a valid pointer to
   a DirectSoundCapture object. */
 
DSCBUFFERDESC              dscbd;
LPDIRECTSOUNDCAPTUREBUFFER pDSCB;
WAVEFORMATEX               wfx =
    {WAVE_FORMAT_PCM, 2, 44100, 176400, 4, 16, 0};
    // wFormatTag, nChannels, nSamplesPerSec, mAvgBytesPerSec,
    // nBlockAlign, wBitsPerSample, cbSize
dscbd.dwSize = sizeof(DSCBUFFERDESC);
dscbd.dwFlags = 0;
dscbd.dwBufferBytes = wfx.nAvgBytesPerSec;
dscbd.dwReserved = 0;
dscbd.lpwfxFormat = &wfx;
 
pDSCB = NULL;
 
HRESULT hr = pDSC->CreateCaptureBuffer(&dscbd, 
        &pDSCB, NULL);
 

You create a capture buffer by calling the DirectSoundCapture.CreateCaptureBuffer method of the DirectSoundCapture object.

One of the parameters to the method is a DSCBUFFERDESC type that describes the characteristics of the desired buffer. The fxFormat member is a WAVEFORMATEX type, which must be initialized with the details of the desired wave format. For more information on this structure, see Sound Data.

Note that if your application is using DirectSound as well as DirectSoundCapture, capture buffer creation can fail when the format of the capture buffer is not the same as that of the primary buffer. The reason is that some cards have only a single clock and cannot support capture and playback at two different frequencies.

The following example sets up a capture buffer that will hold 1 second of data:

' In this example it is assumed that DSC is a valid 
' DirectSoundCapture object
 
Dim dscbd As DSCBUFFERDESC
Dim DSCB As DIRECTSOUNDCAPTUREBUFFER
Dim waveFormat As WAVEFORMATEX
 
' Set up the wave format
waveFormat.nSize = LenB(WAVEFORMATEX)
    waveFormat.nFormatTag = WAVE_FORMAT_PCM
    waveFormat.nChannels = 2
    waveFormat.lSamplesPerSec = 22050
    waveFormat.nBitsPerSample = 16
    waveFormat.nBlockAlign = waveFormat.nBitsPerSample / 8 * WaveFormat.nChannels
    waveFormat.lAvgBytesPerSec = waveFormat.lSamplesPerSec * waveFormat.nBlockAlign
 
' Set up the DSCBUFFERDESC
dscbd.lFlags = DSCBCAPS_DEFAULT
dscbd.lBufferBytes = waveFormat.nAvgBytesPerSec
dscbd.fxFormat = waveFormat
 
' Now were ready to create the capture buffer
DSCB = DSC.CreateCaptureBuffer (dscbd)