=====Interrogating the audio mixer=====

//by Richard Russell, June 2010//\\ \\ **Note: On Windows Vista and Windows 7 each running application has its own independent audio mixer. The code listed here will work correctly, but the mixer interrogated is that for the specific application.**\\ \\  The article [[/Controlling%20the%20audio%20mixer|Controlling the audio mixer]] explains how to control the volume of Wave, Synth and CD outputs and the level of CD, Microphone and Line inputs (and often several others) using the **FN_mixerset** routine. The **FN_mixerget** function listed at the end of this article allows you to interrogate the settings of the various mixer controls. The function should be called using code similar to the following:

<code bb4w>
        setting% = FN_mixerget(Dest%, Source%, Control%)
</code>

The routine returns the current setting of the control (typically 0-65535 for Volume).\\ \\  The parameters are as follows:

  * **"Dest%"** - The destination for the control, which will generally be either the **Speaker Output** (= **4**) or the **Recording Input** (= **7**).
  * **"Source%"** - The audio source for the control, for example the **Line Input** (= **&1002**), **Microphone** (= **&1003**), **Synthesizer** (= **&1004**), **CD** (= **&1005**) or **Wave Output** (= **&1008**).
  * **"Control%"** - The control type, which will generally be **Volume** (= **&50030001**).

For other possible values consult the Microsoft documentation.\\ \\  So for example to interrogate the **Microphone recording level** you could use code like this:

<code bb4w>
        miclevel% = FN_mixerget(7, &1003, &50030001)
</code>

To read the **CD Player output volume**:

<code bb4w>
        cdvolume% = FN_mixerget(4, &1005, &50030001)
</code>

To read a **Master Volume** setting (which does not have a specific source) set the **"Source%"** parameter to zero. So to discover the **Master speaker volume** you could do:

<code bb4w>
        master% = FN_mixerget(4, 0, &50030001)
</code>

Finally here is the code for **FN_mixerget** itself:

<code bb4w>
        DEF FN_mixerget(dest%, source%, ctrl%)
        LOCAL hmx%, res%, ndevs%, dev%, src%, level%, MixerLine{}

        MIXER_OBJECTFMIXER = 0
        MIXER_GETLINEINFOF_SOURCE = 1
        MIXER_GETLINEINFOF_COMPONENTTYPE = 3

        DIM MixerLine{cbStruct%, dwDestination%, dwSource%, dwLineID%, fdwLine%, \
        \             dwUser%, dwComponentType%, cChannels%, cConnections%, \
        \             cControls%, szShortName&(15), szName&(63), Target{dwType%, \
        \             dwDeviceID%, wMid{l&, h&}, wPid{l&, h&}, vDriverVersion%, \
        \             szPname&(31)}}

        SYS "mixerGetNumDevs" TO ndevs%
        IF ndevs%=0 ERROR 100, "No audio mixer devices"

        level% = -1
        FOR dev% = ndevs%-1 TO 0 STEP -1
          SYS "mixerOpen", ^hmx%, dev%, 0, 0, MIXER_OBJECTFMIXER TO res%
          IF res% ERROR 100, "mixerOpen failed"

          MixerLine.cbStruct% = DIM(MixerLine{})
          MixerLine.dwComponentType% = dest%
          SYS "mixerGetLineInfo", hmx%, MixerLine{}, \
          \                       MIXER_GETLINEINFOF_COMPONENTTYPE TO res%
          IF res% ERROR 100, "mixerGetLineInfo (destination) failed"

          IF source% = 0 THEN
            level% = FN_controlget(hmx%, MixerLine.dwLineID%, ctrl%)
          ELSE
            FOR src% = 0 TO MixerLine.cConnections%-1
              MixerLine.cbStruct% = DIM(MixerLine{})
              MixerLine.dwSource% = src%
              SYS "mixerGetLineInfo", hmx%, MixerLine{}, \
              \                       MIXER_GETLINEINFOF_SOURCE TO res%
              IF res% ERROR 100, "mixerGetLineInfo (source) failed"

              IF MixerLine.dwComponentType% = source% THEN
                level% = FN_controlget(hmx%, MixerLine.dwLineID%, ctrl%)
              ENDIF
            NEXT src%
          ENDIF

          SYS "mixerClose", hmx%
        NEXT dev%
        = level%

        DEF FN_controlget(hmx%, id%, ctrl%)
        LOCAL res%, MixerLineControls{}, MixerControl{}
        LOCAL MixerControlDetails{}, MixerControlDetailsData{}

        MIXER_GETLINECONTROLSF_ONEBYTYPE = 2
        MIXER_GETCONTROLDETAILSF_VALUE = 0

        DIM MixerLineControls{cbStruct%, dwLineID%, dwControl%, cControls%, \
        \                     cbmxctrl%, pamxctrl%}

        DIM MixerControl{cbStruct%, dwControlID%, dwControlType%, fdwControl%, \
        \                cMultipleItems%, szShortName&(15), szName&(63), \
        \                lMinimum%, lMaximum%, dwReserved%(9)}

        DIM MixerControlDetails{cbStruct%, dwControlID%, cChannels%, hwndOwner%, \
        \                       cbDetails%, paDetails%}

        DIM MixerControlDetailsData{dwValue%}

        MixerLineControls.cbStruct% = DIM(MixerLineControls{})
        MixerLineControls.dwLineID% = id%
        MixerLineControls.dwControl% = ctrl%
        MixerLineControls.cControls% = 1
        MixerLineControls.cbmxctrl% = DIM(MixerControl{})
        MixerLineControls.pamxctrl% = MixerControl{}

        SYS "mixerGetLineControls", hmx%, MixerLineControls{}, \
        \                           MIXER_GETLINECONTROLSF_ONEBYTYPE TO res%
        IF res% ERROR 100, "mixerGetLineControls failed"

        MixerControlDetails.cbStruct% = DIM(MixerControlDetails{})
        MixerControlDetails.dwControlID% = MixerControl.dwControlID%
        MixerControlDetails.cChannels% = 1
        MixerControlDetails.cbDetails% = DIM(MixerControlDetailsData{})
        MixerControlDetails.paDetails% = MixerControlDetailsData{}

        SYS "mixerGetControlDetails", hmx%, MixerControlDetails{}, \
        \                             MIXER_GETCONTROLDETAILSF_VALUE TO res%
        IF res% ERROR 100, "mixerGetControlDetails failed"

        = MixerControlDetailsData.dwValue%
</code>