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MIXERCONTROL structure

The MIXERCONTROL structure describes the state and metrics of a single control for an audio line.

Syntax


typedef struct {
  DWORD cbStruct;
  DWORD dwControlID;
  DWORD dwControlType;
  DWORD fdwControl;
  DWORD cMultipleItems;
  TCHAR szShortName[MIXER_SHORT_NAME_CHARS];
  TCHAR szName[MIXER_LONG_NAME_CHARS];
  union {
    struct {
      LONG lMinimum;
      LONG lMaximum;
    };
    struct {
      DWORD dwMinimum;
      DWORD dwMaximum;
    };
    DWORD  dwReserved[6];
  } Bounds;
  union {
    DWORD cSteps;
    DWORD cbCustomData;
    DWORD dwReserved[6];
  } Metrics;
} MIXERCONTROL, *PMIXERCONTROL, FAR *PMIXERCONTROL;

Members

cbStruct

Size, in bytes, of the MIXERCONTROL structure.

dwControlID

Audio mixer-defined identifier that uniquely refers to the control described by the MIXERCONTROL structure. This identifier can be in any format supported by the mixer device. An application should use this identifier only as an abstract handle. No two controls for a single mixer device can ever have the same control identifier.

dwControlType

Class of the control for which the identifier is specified in dwControlID. An application must use this information to display the appropriate control for input from the user. An application can also display tailored graphics based on the control class or search for a particular control class on a specific line. If an application does not know about a control class, this control must be ignored. There are eight control class classifications, each with one or more standard control types:

NameDescriptions
MIXERCONTROL_CT_CLASS_CUSTOM

MIXERCONTROL_CONTROLTYPE_CUSTOM

MIXERCONTROL_CT_CLASS_FADER

MIXERCONTROL_CONTROLTYPE_BASS MIXERCONTROL_CONTROLTYPE_EQUALIZER MIXERCONTROL_CONTROLTYPE_FADER MIXERCONTROL_CONTROLTYPE_TREBLE MIXERCONTROL_CONTROLTYPE_VOLUME

MIXERCONTROL_CT_CLASS_LIST

MIXERCONTROL_CONTROLTYPE_MIXER MIXERCONTROL_CONTROLTYPE_MULTIPLESELECT MIXERCONTROL_CONTROLTYPE_MUX MIXERCONTROL_CONTROLTYPE_SINGLESELECT

MIXERCONTROL_CT_CLASS_METER

MIXERCONTROL_CONTROLTYPE_BOOLEANMETER MIXERCONTROL_CONTROLTYPE_PEAKMETER MIXERCONTROL_CONTROLTYPE_SIGNEDMETER MIXERCONTROL_CONTROLTYPE_UNSIGNEDMETER

MIXERCONTROL_CT_CLASS_NUMBER

MIXERCONTROL_CONTROLTYPE_DECIBELS MIXERCONTROL_CONTROLTYPE_PERCENT MIXERCONTROL_CONTROLTYPE_SIGNED MIXERCONTROL_CONTROLTYPE_UNSIGNED

MIXERCONTROL_CT_CLASS_SLIDER

MIXERCONTROL_CONTROLTYPE_PAN MIXERCONTROL_CONTROLTYPE_QSOUNDPAN MIXERCONTROL_CONTROLTYPE_SLIDER

MIXERCONTROL_CT_CLASS_SWITCH

MIXERCONTROL_CONTROLTYPE_BOOLEAN MIXERCONTROL_CONTROLTYPE_BUTTON MIXERCONTROL_CONTROLTYPE_LOUDNESS MIXERCONTROL_CONTROLTYPE_MONO MIXERCONTROL_CONTROLTYPE_MUTE MIXERCONTROL_CONTROLTYPE_ONOFF MIXERCONTROL_CONTROLTYPE_STEREOENH

MIXERCONTROL_CT_CLASS_TIME

MIXERCONTROL_CONTROLTYPE_MICROTIME MIXERCONTROL_CONTROLTYPE_MILLITIME

 

fdwControl

Status and support flags for the audio line control. The following values are defined:

NameDescription
MIXERCONTROL_CONTROLF_DISABLED

The control is disabled, perhaps due to other settings for the mixer hardware, and cannot be used. An application can read current settings from a disabled control, but it cannot apply settings.

MIXERCONTROL_CONTROLF_MULTIPLE

The control has two or more settings per channel. An equalizer, for example, requires this flag because each frequency band can be set to a different value. An equalizer that affects both channels of a stereo line in a uniform fashion will also specify the MIXERCONTROL_CONTROLF_UNIFORM flag.

MIXERCONTROL_CONTROLF_UNIFORM

The control acts on all channels of a multichannel line in a uniform fashion. For example, a control that mutes both channels of a stereo line would set this flag. Most MIXERCONTROL_CONTROLTYPE_MUX and MIXERCONTROL_CONTROLTYPE_MIXER controls also specify the MIXERCONTROL_CONTROLF_UNIFORM flag.

 

cMultipleItems

Number of items per channel that make up a MIXERCONTROL_CONTROLF_MULTIPLE control. This number is always two or greater for multiple-item controls. If the control is not a multiple-item control, do not use this member; it will be zero.

szShortName

Short string that describes the audio line control specified by dwControlID. This description should be appropriate to use as a concise label for the control.

szName

String that describes the audio line control specified by dwControlID. This description should be appropriate to use as a complete description for the control.

Bounds

Union of boundary types.

lMinimum

Minimum signed value for a control that has a signed boundary nature. This member cannot be used in conjunction with dwMinimum.

lMaximum

Maximum signed value for a control that has a signed boundary nature. This member cannot be used in conjunction with dwMaximum.

dwMinimum

Minimum unsigned value for a control that has an unsigned boundary nature. This member cannot be used in conjunction with lMinimum.

dwMaximum

Maximum unsigned value for a control that has an unsigned boundary nature. This member cannot be used in conjunction with lMaximum.

dwReserved

Reserved; do not use.

Metrics

Union of boundary metrics.

cSteps

Number of discrete ranges within the union specified for a control specified by the Bounds member. This member overlaps with the other members of the Metrics structure member and cannot be used in conjunction with those members.

cbCustomData

Size, in bytes, required to contain the state of a custom control class. This member is appropriate only for the MIXERCONTROL_CONTROLTYPE_CUSTOM control class.

dwReserved

Reserved; do not use.

Requirements

Minimum supported client

Windows 2000 Professional [desktop apps only]

Minimum supported server

Windows 2000 Server [desktop apps only]

Header

Mmsystem.h (include Windows.h)

See also

Audio Mixers
Audio Mixer Structures
mixerGetLineControls
MIXERLINECONTROLS
Audio Mixers

 

 

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