MIXERLINEA structure (mmeapi.h)

Article
09/01/2022

The MIXERLINE structure describes the state and metrics of an audio line.

Syntax

typedef struct tagMIXERLINEA {
  DWORD     cbStruct;
  DWORD     dwDestination;
  DWORD     dwSource;
  DWORD     dwLineID;
  DWORD     fdwLine;
  DWORD_PTR dwUser;
  DWORD     dwComponentType;
  DWORD     cChannels;
  DWORD     cConnections;
  DWORD     cControls;
  CHAR      szShortName[MIXER_SHORT_NAME_CHARS];
  CHAR      szName[MIXER_LONG_NAME_CHARS];
  struct {
    DWORD     dwType;
    DWORD     dwDeviceID;
    WORD      wMid;
    WORD      wPid;
    MMVERSION vDriverVersion;
    CHAR      szPname[MAXPNAMELEN];
  } Target;
} MIXERLINEA, *PMIXERLINEA, *LPMIXERLINEA;

Members

cbStruct

Size, in bytes, of the MIXERLINE structure. This member must be initialized before calling the mixerGetLineInfo function. The size specified in this member must be large enough to contain the MIXERLINE structure. When mixerGetLineInfo returns, this member contains the actual size of the information returned. The returned information will not exceed the requested size.

dwDestination

Destination line index. This member ranges from zero to one less than the value specified in the cDestinations member of the MIXERCAPS structure retrieved by the mixerGetDevCaps function. When the mixerGetLineInfo function is called with the MIXER_GETLINEINFOF_DESTINATION flag, properties for the destination line are returned. (The dwSource member must be set to zero in this case.) When called with the MIXER_GETLINEINFOF_SOURCE flag, the properties for the source given by the dwSource member that is associated with the dwDestination member are returned.

dwSource

Index for the audio source line associated with the dwDestination member. That is, this member specifies the nth audio source line associated with the specified audio destination line. This member is not used for destination lines and must be set to zero when MIXER_GETLINEINFOF_DESTINATION is specified in the mixerGetLineInfo function. When the MIXER_GETLINEINFOF_SOURCE flag is specified, this member ranges from zero to one less than the value specified in the cConnections member for the audio destination line given in the dwDestination member.

dwLineID

An identifier defined by the mixer device that uniquely refers to the audio line described by the MIXERLINE structure. This identifier is unique for each mixer device and can be in any format. An application should use this identifier only as an abstract handle.

fdwLine

Status and support flags for the audio line. This member is always returned to the application and requires no initialization.

Name	Description
MIXERLINE_LINEF_ACTIVE	Audio line is active. An active line indicates that a signal is probably passing through the line.
MIXERLINE_LINEF_DISCONNECTED	Audio line is disconnected. A disconnected line's associated controls can still be modified, but the changes have no effect until the line is connected.
MIXERLINE_LINEF_SOURCE	Audio line is an audio source line associated with a single audio destination line. If this flag is not set, this line is an audio destination line associated with zero or more audio source lines.

If an application is not using a waveform-audio output device, the audio line associated with that device would not be active (that is, the MIXERLINE_LINEF_ACTIVE flag would not be set).

If the waveform-audio output device is opened, then the audio line is considered active and the MIXERLINE_LINEF_ACTIVE flag will be set.

A paused or starved waveform-audio output device is still considered active. In other words, if the waveform-audio output device is opened by an application regardless of whether data is being played, the associated audio line is considered active.

If a line cannot be strictly defined as active, the mixer device will always set the MIXERLINE_LINEF_ACTIVE flag.

dwUser

Instance data defined by the audio device for the line. This member is intended for custom mixer applications designed specifically for the mixer device returning this information. Other applications should ignore this data.

dwComponentType

Component type for this audio line. An application can use this information to display tailored graphics or to search for a particular component. If an application does not use component types, this member should be ignored. This member can be one of the following values:

Name	Description
MIXERLINE_COMPONENTTYPE_DST_DIGITAL	Audio line is a digital destination (for example, digital input to a DAT or CD audio device).
MIXERLINE_COMPONENTTYPE_DST_HEADPHONES	Audio line is an adjustable (gain and/or attenuation) destination intended to drive headphones. Most audio cards use the same audio destination line for speakers and headphones, in which case the mixer device simply uses the MIXERLINE_COMPONENTTYPE_DST_SPEAKERS type.
MIXERLINE_COMPONENTTYPE_DST_LINE	Audio line is a line level destination (for example, line level input from a CD audio device) that will be the final recording source for the analog-to-digital converter (ADC). Because most audio cards for personal computers provide some sort of gain for the recording audio source line, the mixer device will use the MIXERLINE_COMPONENTTYPE_DST_WAVEIN type.
MIXERLINE_COMPONENTTYPE_DST_MONITOR	Audio line is a destination used for a monitor.
MIXERLINE_COMPONENTTYPE_DST_SPEAKERS	Audio line is an adjustable (gain and/or attenuation) destination intended to drive speakers. This is the typical component type for the audio output of audio cards for personal computers.
MIXERLINE_COMPONENTTYPE_DST_TELEPHONE	Audio line is a destination that will be routed to a telephone line.
MIXERLINE_COMPONENTTYPE_DST_UNDEFINED	Audio line is a destination that cannot be defined by one of the standard component types. A mixer device is required to use this component type for line component types that have not been defined by Microsoft Corporation.
MIXERLINE_COMPONENTTYPE_DST_VOICEIN	Audio line is a destination that will be the final recording source for voice input. This component type is exactly like MIXERLINE_COMPONENTTYPE_DST_WAVEIN but is intended specifically for settings used during voice recording/recognition. Support for this line is optional for a mixer device. Many mixer devices provide only MIXERLINE_COMPONENTTYPE_DST_WAVEIN.
MIXERLINE_COMPONENTTYPE_DST_WAVEIN	Audio line is a destination that will be the final recording source for the waveform-audio input (ADC). This line typically provides some sort of gain or attenuation. This is the typical component type for the recording line of most audio cards for personal computers.
MIXERLINE_COMPONENTTYPE_SRC_ANALOG	Audio line is an analog source (for example, analog output from a video-cassette tape).
MIXERLINE_COMPONENTTYPE_SRC_AUXILIARY	Audio line is a source originating from the auxiliary audio line. This line type is intended as a source with gain or attenuation that can be routed to the MIXERLINE_COMPONENTTYPE_DST_SPEAKERS destination and/or recorded from the MIXERLINE_COMPONENTTYPE_DST_WAVEIN destination.
MIXERLINE_COMPONENTTYPE_SRC_COMPACTDISC	Audio line is a source originating from the output of an internal audio CD. This component type is provided for audio cards that provide an audio source line intended to be connected to an audio CD (or CD-ROM playing an audio CD).
MIXERLINE_COMPONENTTYPE_SRC_DIGITAL	Audio line is a digital source (for example, digital output from a DAT or audio CD).
MIXERLINE_COMPONENTTYPE_SRC_LINE	Audio line is a line-level source (for example, line-level input from an external stereo) that can be used as an optional recording source. Because most audio cards for personal computers provide some sort of gain for the recording source line, the mixer device will use the MIXERLINE_COMPONENTTYPE_SRC_AUXILIARY type.
MIXERLINE_COMPONENTTYPE_SRC_MICROPHONE	Audio line is a microphone recording source. Most audio cards for personal computers provide at least two types of recording sources: an auxiliary audio line and microphone input. A microphone audio line typically provides some sort of gain. Audio cards that use a single input for use with a microphone or auxiliary audio line should use the MIXERLINE_COMPONENTTYPE_SRC_MICROPHONE component type.
MIXERLINE_COMPONENTTYPE_SRC_PCSPEAKER	Audio line is a source originating from personal computer speaker. Several audio cards for personal computers provide the ability to mix what would typically be played on the internal speaker with the output of an audio card. Some audio cards support the ability to use this output as a recording source.
MIXERLINE_COMPONENTTYPE_SRC_SYNTHESIZER	Audio line is a source originating from the output of an internal synthesizer. Most audio cards for personal computers provide some sort of MIDI synthesizer.
MIXERLINE_COMPONENTTYPE_SRC_TELEPHONE	Audio line is a source originating from an incoming telephone line.
MIXERLINE_COMPONENTTYPE_SRC_UNDEFINED	Audio line is a source that cannot be defined by one of the standard component types. A mixer device is required to use this component type for line component types that have not been defined by Microsoft Corporation.
MIXERLINE_COMPONENTTYPE_SRC_WAVEOUT	Audio line is a source originating from the waveform-audio output digital-to-analog converter (DAC). Most audio cards for personal computers provide this component type as a source to the MIXERLINE_COMPONENTTYPE_DST_SPEAKERS destination. Some cards also allow this source to be routed to the MIXERLINE_COMPONENTTYPE_DST_WAVEIN destination.

cChannels

Maximum number of separate channels that can be manipulated independently for the audio line. The minimum value for this field is 1 because a line must have at least one channel.

Most modern audio cards for personal computers are stereo devices; for them, the value of this member is 2.

Channel 1 is assumed to be the left channel; channel 2 is assumed to be the right channel.

A multichannel line might have one or more uniform controls (controls that affect all channels of a line uniformly) associated with it.

cConnections

Number of connections that are associated with the audio line. This member is used only for audio destination lines and specifies the number of audio source lines that are associated with it. This member is always zero for source lines and for destination lines that do not have any audio source lines associated with them.

cControls

Number of controls associated with the audio line. This value can be zero. If no controls are associated with the line, the line is likely to be a source that might be selected in a MIXERCONTROL_CONTROLTYPE_MUX or MIXERCONTROL_CONTROLTYPE_MIXER but allows no manipulation of the signal.

szShortName[MIXER_SHORT_NAME_CHARS]

Short string that describes the audio mixer line specified in the dwLineID member. This description should be appropriate as a concise label for the line.

szName[MIXER_LONG_NAME_CHARS]

String that describes the audio mixer line specified in the dwLineID member. This description should be appropriate as a complete description for the line.

Target

Target media information.

Target.dwType

Target media device type associated with the audio line described in the MIXERLINE structure. An application must ignore target information for media device types it does not use. The following values are defined:

Name	Description
MIXERLINE_TARGETTYPE_AUX	The audio line described by the MIXERLINE structure is strictly bound to the auxiliary device detailed in the remaining members of the Target structure member of the MIXERLINE structure.
MIXERLINE_TARGETTYPE_MIDIIN	The audio line described by the MIXERLINE structure is strictly bound to the MIDI input device detailed in the remaining members of the Target structure member of the MIXERLINE structure.
MIXERLINE_TARGETTYPE_MIDIOUT	The audio line described by the MIXERLINE structure is strictly bound to the MIDI output device detailed in the remaining members of the Target structure member of the MIXERLINE structure.
MIXERLINE_TARGETTYPE_UNDEFINED	The audio line described by the MIXERLINE structure is not strictly bound to a defined media type. All remaining Target structure members of the MIXERLINE structure should be ignored. An application cannot use the MIXERLINE_TARGETTYPE_UNDEFINED target type when calling the mixerGetLineInfo function with the MIXER_GETLINEINFOF_TARGETTYPE flag.
MIXERLINE_TARGETTYPE_WAVEIN	The audio line described by the MIXERLINE structure is strictly bound to the waveform-audio input device detailed in the remaining members of the Target structure member of the MIXERLINE structure.
MIXERLINE_TARGETTYPE_WAVEOUT	The audio line described by the MIXERLINE structure is strictly bound to the waveform-audio output device detailed in the remaining members of the Target structure member of the MIXERLINE structure.

Target.dwDeviceID

Current device identifier of the target media device when the dwType member is a target type other than MIXERLINE_TARGETTYPE_UNDEFINED. This identifier is identical to the current media device index of the associated media device. When calling the mixerGetLineInfo function with the MIXER_GETLINEINFOF_TARGETTYPE flag, this member is ignored on input and will be returned to the caller by the audio mixer manager.

Target.wMid

Manufacturer identifier of the target media device when the dwType member is a target type other than MIXERLINE_TARGETTYPE_UNDEFINED. This identifier is identical to the wMid member of the device-capabilities structure for the associated media. Manufacturer identifiers are defined in Manufacturer and Product Identifiers.

Target.wPid

Product identifier of the target media device when the dwType member is a target type other than MIXERLINE_TARGETTYPE_UNDEFINED. This identifier is identical to the wPid member of the device-capabilities structure for the associated media. Product identifiers are defined in Manufacturer and Product Identifiers.

Target.vDriverVersion

Driver version of the target media device when the dwType member is a target type other than MIXERLINE_TARGETTYPE_UNDEFINED. This version is identical to the vDriverVersion member of the device-capabilities structure for the associated media.

Target.szPname[MAXPNAMELEN]

Product name of the target media device when the dwType member is a target type other than MIXERLINE_TARGETTYPE_UNDEFINED. This name is identical to the szPname member of the device-capabilities structure for the associated media.

Remarks

Note

The mmeapi.h header defines MIXERLINE 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]
Header	mmeapi.h

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MIXERLINEA structure (mmeapi.h)

Syntax

Members

Remarks

Requirements

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