waveOutUnprepareHeader function

The waveOutUnprepareHeader function cleans up the preparation performed by the waveOutPrepareHeader function. This function must be called after the device driver is finished with a data block. You must call this function before freeing the buffer.

Syntax

MMRESULT waveOutUnprepareHeader(
  HWAVEOUT  hwo,
  LPWAVEHDR pwh,
  UINT      cbwh
);

Parameters

hwo

Handle to the waveform-audio output device.

pwh

Pointer to a WAVEHDR structure identifying the data block 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 code 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 data block pointed to by the pwh parameter is still in the queue.

Remarks

This function complements waveOutPrepareHeader. You must call this function before freeing the buffer. After passing a buffer to the device driver with the waveOutWrite function, you must wait until the driver is finished with the buffer before calling waveOutUnprepareHeader.

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]
Target Platform Windows
Header mmeapi.h (include Windows.h)
Library Winmm.lib
DLL Winmm.dll

See Also

Waveform Audio

Waveform Functions