midiInUnprepareHeader

The midiInUnprepareHeader function cleans up the preparation performed by the midiInPrepareHeader function. 

MMRESULT midiInUnprepareHeader(
  HMIDIIN hMidiIn,        
  LPMIDIHDR lpMidiInHdr,  
  UINT cbMidiInHdr        
);

Parameters

hMidiIn
Handle of the MIDI input device.
lpMidiInHdr
Address of a MIDIHDR structure identifying the buffer to be cleaned up.
cbMidiInHdr
Size of the MIDIHDR structure.

Return Values

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

Value Description
MIDIERR_STILLPLAYING The buffer pointed to by lpMidiInHdr is still in the queue.
MMSYSERR_INVALPARAM The specified pointer or structure is invalid.
MMSYSERR_INVALHANDLE The specified device handle is invalid.

Remarks

This function is complementary to midiInPrepareHeader. You must use this function before freeing the buffer. After passing a buffer to the device driver by using the midiInAddBuffer function, you must wait until the driver is finished with the buffer before using midiInUnprepareHeader. Unpreparing a buffer that has not been prepared has no effect, and the function returns MMSYSERR_NOERROR.

QuickInfo

  Windows NT: Requires version 3.1 or later.
  Windows: Requires Windows 95 or later.
  Windows CE: Unsupported.
  Header: Declared in mmsystem.h.
  Import Library: Use winmm.lib.

See Also

Musical Instrument Digital Interface (MIDI) Overview, MIDI Functions, midiInPrepareHeader, MIDIHDR, midiInAddBuffer