midiOutUnprepareHeader function
The midiOutUnprepareHeader function cleans up the preparation performed by the midiOutPrepareHeader function.
Syntax
MMRESULT midiOutUnprepareHeader(
HMIDIOUT hmo,
LPMIDIHDR lpMidiOutHdr,
UINT cbMidiOutHdr
);
Parameters
hmo
Handle to the MIDI output device. This parameter can also be the handle of a MIDI stream cast to HMIDIOUT.lpMidiOutHdr
Pointer to a MIDIHDR structure identifying the buffer to be cleaned up.cbMidiOutHdr
Size, in bytes, of the MIDIHDR structure.
Return value
Returns MMSYSERR_NOERROR if successful or an error otherwise. Possible error values include the following.
| Return code | Description |
|---|---|
| MIDIERR_STILLPLAYING | The buffer pointed to by lpMidiOutHdr is still in the queue. |
| MMSYSERR_INVALHANDLE | The specified device handle is invalid. |
| MMSYSERR_INVALPARAM | The specified pointer or structure is invalid. |
Remarks
This function is complementary to the midiOutPrepareHeader function. You must call midiOutUnprepareHeader before freeing the buffer. After passing a buffer to the device driver with the midiOutLongMsg function, you must wait until the device driver is finished with the buffer before calling midiOutUnprepareHeader.
Unpreparing a buffer that has not been prepared has no effect, and the function returns MMSYSERR_NOERROR.
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 |