mixerGetLineInfo function (mmeapi.h)
The mixerGetLineInfo function retrieves information about a specific line of a mixer device.
Syntax
MMRESULT mixerGetLineInfo(
HMIXEROBJ hmxobj,
LPMIXERLINE 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 |
|---|---|
|
The audio line reference is invalid. |
|
The hmxobj parameter specifies an invalid device identifier. |
|
One or more flags are invalid. |
|
The hmxobj parameter specifies an invalid handle. |
|
One or more parameters are invalid. |
|
No mixer device is available for the object specified by hmxobj. |
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 |