This function cleans up the preparation performed by waveOutPrepareHeader. The function must be called after the device driver is finished with a data block. You must call this function before freeing the data buffer.
At a Glance
| Header file: | Mmsystem.h |
| Windows CE versions: | 2.0 and later |
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 Values
One of the values described in the following table is returned.
| Value | Description |
| MMSYSERR_NOERROR | Success. |
| MMSYSERR_INVALHANDLE | Specified device handle is invalid. |
| MMSYSERR_NODRIVER | No device driver is present. |
| MMSYSERR_NOMEM | Unable to allocate or lock memory. |
| WAVERR_STILLPLAYING | 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.