mixerOpen

A version of this page is also available for

Windows Embedded CE 6.0 R3

4/8/2010

This function opens a specified mixer device and ensures that the device will not be removed until the application closes the handle.

Syntax

MMRESULT mixerOpen(
  LPHMIXER phmx, 
  UINT uMxId, 
  DWORD dwCallback, 
  DWORD dwInstance, 
  DWORD fdwOpen 
);

Parameters

• phmx
  Pointer to a variable that will receive a handle identifying the opened mixer device. Use this handle to identify the device when calling other audio mixer functions.

  This parameter cannot be NULL.

• uMxId
  Identifier of the mixer device to open. Use a valid device identifier or any HMIXEROBJ (see the mixerGetID function for a description of mixer object handles).

  A mapper for audio mixer devices does not currently exist, so a mixer device identifier of – 1 is not valid.

• dwCallback
  Handle to a window called when the state of an audio line and/or control associated with the device being opened is changed.

  Specify zero for this parameter if no callback mechanism is to be used.

• dwInstance
  User instance data passed to the callback function.

  This parameter is not used with window callback functions.

• fdwOpen
  Flags for opening the device.

  The following table shows the possible flags.

  Flag	Description
  CALLBACK_WINDOW	The dwCallback parameter is assumed to be a window handle.
  MIXER_OBJECTF_HMIXER	The uMxId parameter is a mixer device handle returned by the mixerOpen function. This flag is optional.
  MIXER_OBJECTF_MIXER	The uMxId parameter is a mixer device identifier in the range of zero to one less than the number of devices returned by the mixerGetNumDevs function. This flag is optional.
  MIXER_OBJECTF_HWAVEIN	The uMxId parameter is a waveform audio input handle returned by the waveInOpen function.
  MIXER_OBJECTF_HWAVEOUT	The uMxId parameter is a waveform audio output handle returned by the waveOutOpen function.
  MIXER_OBJECTF_WAVEIN	The uMxId parameter is the identifier of a waveform audio input device in the range of zero to one less than the number of devices returned by the waveInGetNumDevs function.
  MIXER_OBJECTF_WAVEOUT	The uMxId parameter is the identifier of a waveform-audio output device in the range of zero to one less than the number of devices returned by the waveOutGetNumDevs function.

  The following table shows flags are supported in other versions of Windows, but not in Windows Embedded CE.

  Flags not supported in Windows Embedded CE
  MIXER_OBJECTF_AUX
  MIXER_OBJECTF_HMIDIN
  MIXER_OBJECTF_HMIDIOUT
  MIXER_OBJECTF_MIDIIN
  MIXER_OBJECTF_MIDIOUT

Return Value

Returns MMSYSERR_NOERROR if successful or an error otherwise.

The following table shows the possible values.

Remarks

Use the mixerGetNumDevs function to determine the number of audio mixer devices present in the system.

The device identifier specified by uMxId varies from zero to one less than the number of devices present.

If a window is chosen to receive callback information, the MM_MIXM_LINE_CHANGE and MM_MIXM_CONTROL_CHANGE messages are sent to the window procedure function to indicate when an audio line or control state changes. For both messages, the wParam parameter is the handle of the mixer device.

The lParam parameter is the line identifier for MM_MIXM_LINE_CHANGE or the control identifier for MM_MIXM_CONTROL_CHANGE that changed state.

To query for audio mixer support or a media device, use the mixerGetID function.

Requirements

See Also

Reference

mixerGetID
mixerGetNumDevs
MM_MIXM_LINE_CHANGE
MM_MIXM_CONTROL_CHANGE
waveInOpen
waveOutOpen
waveInGetNumDevs
waveOutGetNumDevs
Hardware Audio Mixer Functions