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waveInUnprepareHeader function

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.

Syntax


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 value

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

Return codeDescription
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

Minimum supported client

Windows 2000 Professional [desktop apps only]

Minimum supported server

Windows 2000 Server [desktop apps only]

Header

Mmsystem.h (include Windows.h)

Library

Winmm.lib

DLL

Winmm.dll

See also

Waveform Audio
Waveform Functions

 

 

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