The mixerMessage function sends a custom mixer driver message directly to a mixer driver.

DWORD mixerMessage(
  HMIXER    driverID,      
  UINT      uMsg,     
  DWORD_PTR dwParam1, 
  DWORD_PTR dwParam2  



Identifier of the mixer that receives the message. You must cast the device ID to the HMIXER handle type. If you supply a handle instead of a device ID, the function fails and returns the MMSYSERR_NOSUPPORT error code.


Custom mixer driver message to send to the mixer driver. This message must be above or equal to the MXDM_USER constant.


Parameter associated with the message being sent.


Parameter associated with the message being sent.

Return Values

Returns a value that is specific to the custom mixer driver message. Possible error values include the following.

Value Description
MMSYSERR_INVALHANDLE The specified device handle is invalid.
MMSYSERR_INVALPARAM The uMsg parameter specified in the MXDM_USER message is invalid.
MMSYSERR_NOSUPPORT The deviceID parameter must be a valid device ID.
MMSYSERR_NOTSUPPORTED The mixer device did not process the message.


User-defined messages must be sent only to a mixer driver that supports the messages. The application should verify that the mixer driver is the driver that supports the message by retrieving the mixer capabilities and checking the wMid, wPid, vDriverVersion, and szPname members of the MIXERCAPS structure.


  Windows NT/2000/XP: Included in Windows NT 3.1 and later.
  Windows 95/98/Me: Included in Windows 95 and later.
  Header: Declared in Mmsystem.h; include Windows.h.
  Library: Use Winmm.lib.

See Also

Audio Mixers, Audio Mixer Functions, mixerOpen, MIXERCAPS