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mixerGetLineInfoA function (mmeapi.h)

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The mixerGetLineInfo function retrieves information about a specific line of a mixer device.

Syntax

MMRESULT mixerGetLineInfoA(
  HMIXEROBJ    hmxobj,
  LPMIXERLINEA pmxl,
  DWORD        fdwInfo
);

Parameters

hmxobj

Handle to the mixer device object that controls the specific audio line.

pmxl

Pointer to a MIXERLINE structure. This structure is filled with information about the audio line for the mixer device. The cbStruct member must always be initialized to be the size, in bytes, of the MIXERLINE structure.

fdwInfo

Flags for retrieving information about an audio line. The following values are defined.

Value Meaning
MIXER_GETLINEINFOF_COMPONENTTYPE The pmxl parameter will receive information about the first audio line of the type specified in the dwComponentType member of the MIXERLINE structure. This flag is used to retrieve information about an audio line of a specific component type. Remaining structure members except cbStruct require no further initialization.
MIXER_GETLINEINFOF_DESTINATION The pmxl parameter will receive information about the destination audio line specified by the dwDestination member of the MIXERLINE structure. This index ranges from zero to one less than the value in the cDestinations member of the MIXERCAPS structure. All remaining structure members except cbStruct require no further initialization.
MIXER_GETLINEINFOF_LINEID The pmxl parameter will receive information about the audio line specified by the dwLineID member of the MIXERLINE structure. This is usually used to retrieve updated information about the state of an audio line. All remaining structure members except cbStruct require no further initialization.
MIXER_GETLINEINFOF_SOURCE The pmxl parameter will receive information about the source audio line specified by the dwDestination and dwSource members of the MIXERLINE structure. The index specified by dwDestination ranges from zero to one less than the value in the cDestinations member of the MIXERCAPS structure. The index specified by dwSource ranges from zero to one less than the value in the cConnections member of the MIXERLINE structure returned for the audio line stored in the dwDestination member. All remaining structure members except cbStruct require no further initialization.
MIXER_GETLINEINFOF_TARGETTYPE The pmxl parameter will receive information about the audio line that is for the dwType member of the Target structure, which is a member of the MIXERLINE structure. This flag is used to retrieve information about an audio line that handles the target type (for example, MIXERLINE_TARGETTYPE_WAVEOUT). The application must initialize the dwType, wMid, wPid, vDriverVersion and szPname members of the MIXERLINE structure before calling mixerGetLineInfo. All of these values can be retrieved from the device capabilities structures for all media devices. Remaining structure members except cbStruct require no further initialization.
Note  In the ANSI version of this function (mixerGetLineInfoA), you cannot use the ANSI string returned from mixerGetLineInfo or waveOutGetDevCaps for the value of the psPname string when calling mixerGetLineInfo with the MIXER_GETLINEINFOF_TARGETTYPE flag. The reason is that an internal conversion to and from Unicode is performed, which might result in loss of data.
 
MIXER_OBJECTF_AUX The hmxobj parameter is an auxiliary device identifier in the range of zero to one less than the number of devices returned by the auxGetNumDevs function.
MIXER_OBJECTF_HMIDIIN The hmxobj parameter is the handle of a MIDI input device. This handle must have been returned by the midiInOpen function.
MIXER_OBJECTF_HMIDIOUT The hmxobj parameter is the handle of a MIDI output device. This handle must have been returned by the midiOutOpen function.
MIXER_OBJECTF_HMIXER The hmxobj parameter is a mixer device handle returned by the mixerOpen function. This flag is optional.
MIXER_OBJECTF_HWAVEIN The hmxobj parameter is a waveform-audio input handle returned by the waveInOpen function.
MIXER_OBJECTF_HWAVEOUT The hmxobj parameter is a waveform-audio output handle returned by the waveOutOpen function.
MIXER_OBJECTF_MIDIIN The hmxobj parameter is the identifier of a MIDI input device. This identifier must be in the range of zero to one less than the number of devices returned by the midiInGetNumDevs function.
MIXER_OBJECTF_MIDIOUT The hmxobj parameter is the identifier of a MIDI output device. This identifier must be in the range of zero to one less than the number of devices returned by the midiOutGetNumDevs function.
MIXER_OBJECTF_MIXER The hmxobj 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_WAVEIN The hmxobj 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 hmxobj 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.

Return value

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

Return code Description
MIXERR_INVALLINE
 The audio line reference is invalid.
MMSYSERR_BADDEVICEID
 The hmxobj parameter specifies an invalid device identifier.
MMSYSERR_INVALFLAG
 One or more flags are invalid.
MMSYSERR_INVALHANDLE
 The hmxobj parameter specifies an invalid handle.
MMSYSERR_INVALPARAM
 One or more parameters are invalid.
MMSYSERR_NODRIVER
 No mixer device is available for the object specified by hmxobj.

Remarks

Note

The mmeapi.h header defines mixerGetLineInfo as an alias that automatically selects the ANSI or Unicode version of this function based on the definition of the UNICODE preprocessor constant. Mixing usage of the encoding-neutral alias with code that is not encoding-neutral can lead to mismatches that result in compilation or runtime errors. For more information, see Conventions for Function Prototypes.

Requirements

Requirement Value
Minimum supported client Windows 2000 Professional [desktop apps only]
Minimum supported server Windows 2000 Server [desktop apps only]
Target Platform Windows
Header mmeapi.h (include Windows.h)
Library Winmm.lib
DLL Winmm.dll

See also

Audio Mixer Functions

Audio Mixers