waveInUnprepareHeader

The waveInUnprepareHeader function cleans up the preparation performed by the waveInPrepareHeader function. This function must be called after the device driver fills a buffer and returns it to the application. You must call this function before freeing the buffer.

MMRESULT waveInUnprepareHeader(
  HWAVEIN hwi,    
  LPWAVEHDR pwh,  
  UINT cbwh       
);

Parameters

hwi

Handle to the waveform-audio input device.

pwh

Pointer to a WAVEHDR structure identifying the buffer to be cleaned up.

cbwh

Size, in bytes, of the WAVEHDR structure.

Return Values

Returns MMSYSERR_NOERROR if successful or an error otherwise. Possible error values include the following.

Value Description
MMSYSERR_INVALHANDLE Specified device handle is invalid.
MMSYSERR_NODRIVER No device driver is present.
MMSYSERR_NOMEM Unable to allocate or lock memory.
WAVERR_STILLPLAYING The buffer pointed to by the pwh parameter is still in the queue.

Remarks

This function complements the waveInPrepareHeader function.

You must call this function before freeing the buffer. After passing a buffer to the device driver with the waveInAddBuffer function, you must wait until the driver is finished with the buffer before calling waveInUnprepareHeader. Unpreparing a buffer that has not been prepared has no effect, and the function returns zero.

Requirements

  Windows NT/2000/XP: Included in Windows NT 3.1 and later.
  Windows 95/98/Me: Included in Windows 95 and later.
  Header: Declared in Mmsystem.h; include Windows.h.
  Library: Use Winmm.lib.

See Also

Waveform Audio, Waveform Functions, waveInPrepareHeader, WAVEHDR, waveInAddBuffer

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