How to mute microphone in Windows 7 with C/C++?

Question

I made a program to mute microphone using WinAPI and it seems to work perfectly in Windows XP but doesn't do a thing in Windows 7. Is it possible to control microphone volume or mute with WinAPI in Windows 7?

void setVolume(DWORD volume) {
HMIXER mixer;

if (mixerOpen(&mixer, 0, 0, 0, 0) != MMSYSERR_NOERROR) {
    MessageBoxW(NULL, L"Error: mixerOpen()", NULL, MB_ICONHAND);
    return;
}

// Get the line info
MIXERCAPS mixcaps;
MIXERLINE mixerLine;
mixerGetDevCaps(0, &mixcaps, sizeof(MIXERCAPS));
mixerLine.cbStruct = sizeof(MIXERLINE);
mixerLine.dwComponentType = MIXERLINE_COMPONENTTYPE_DST_WAVEIN;
mixerLine.dwSource = 0;
mixerLine.dwDestination = 0;

if (mixerGetLineInfo(reinterpret_cast<HMIXEROBJ>(mixer), &mixerLine, MIXER_GETLINEINFOF_SOURCE)
    != MMSYSERR_NOERROR) {
        MessageBoxW(NULL, L"Error: mixerGetLineInfo()", NULL, MB_ICONHAND);
        return;
}

// Get control for mixerline
MIXERCONTROL mixerCtrl;
MIXERLINECONTROLS mixerLineCtrl;

mixerLineCtrl.cbStruct = sizeof(MIXERLINECONTROLS);
mixerLineCtrl.dwLineID = mixerLine.dwLineID;
mixerLineCtrl.dwControlType = MIXERCONTROL_CONTROLTYPE_VOLUME;
mixerLineCtrl.cControls = 1;
mixerLineCtrl.pamxctrl = &mixerCtrl;
mixerLineCtrl.cbmxctrl = sizeof(MIXERCONTROL);
mixerLineCtrl.cControls = 5;

if (mixerGetLineControls(reinterpret_cast<HMIXEROBJ>(mixer), &mixerLineCtrl, MIXER_GETLINECONTROLSF_ONEBYTYPE)
    != MMSYSERR_NOERROR) {
        MessageBoxW(NULL, L"Error: mixerGetLineControls()", NULL, MB_ICONHAND);
        return;
}

// Volume..
MIXERCONTROLDETAILS mixerCtrlDetails;
MIXERCONTROLDETAILS_UNSIGNED mixerCtrlDetailsUnsigned;

mixerCtrlDetailsUnsigned.dwValue = volume;
mixerCtrlDetails.dwControlID = mixerCtrl.dwControlID;
mixerCtrlDetails.cbStruct = sizeof(MIXERCONTROLDETAILS);
mixerCtrlDetails.cMultipleItems = 0;
mixerCtrlDetails.paDetails = &mixerCtrlDetailsUnsigned;
mixerCtrlDetails.cbDetails = sizeof(MIXERCONTROLDETAILS_UNSIGNED);
mixerCtrlDetails.cChannels = 1;

if (mixerSetControlDetails(reinterpret_cast<HMIXEROBJ>(mixer), &mixerCtrlDetails, MIXER_OBJECTF_HMIXER | MIXER_GETCONTROLDETAILSF_VALUE)
    != MMSYSERR_NOERROR) {
        MessageBoxW(NULL, L"Error: mixerSetControlDetails()", NULL, MB_ICONHAND);
        return;
}

mixerClose(mixer);
}

Answer 1

You need to use the new audio APIs introduced by Windows Vista.

Here is an example.

*EDIT: Visual Studio 2015 (C++):

Usange:

// To 100%
ConsoleApplication3.exe -f 1

// To  0%
ConsoleApplication3.exe -f 0

// To 50%
ConsoleApplication3.exe -f 0.50

Code:

#include "stdafx.h"
#include <stdio.h>
#include <windows.h>
#include <mmdeviceapi.h>
#include <endpointvolume.h>

void Usage()
{
    printf("Usage: \n");
    printf(" SetVolume [Reports the current volume]\n");
    printf(" SetVolume -d <new volume in decibels> [Sets the current default render device volume to the new volume]\n");
    printf(" SetVolume -f <new volume as an amplitude scalar> [Sets the current default render device volume to the new volume]\n");

}
int _tmain(int argc, _TCHAR* argv[])
{
    HRESULT hr;
    bool decibels = false;
    bool scalar = false;
    double newVolume;
    if (argc != 3 && argc != 1)
    {
        Usage();
        return -1;
    }
    if (argc == 3)
    {
        if (argv[1][0] == '-')
        {
            if (argv[1][1] == 'f')
            {
                scalar = true;
            }
            else if (argv[1][1] == 'd')
            {
                decibels = true;
            }
        }
        else
        {
            Usage();
            return -1;
        }

        newVolume = _tstof(argv[2]);
    }

    // -------------------------
    CoInitialize(NULL);
    IMMDeviceEnumerator *deviceEnumerator = NULL;
    hr = CoCreateInstance(__uuidof(MMDeviceEnumerator), NULL, CLSCTX_INPROC_SERVER, __uuidof(IMMDeviceEnumerator), (LPVOID *)&deviceEnumerator);
    IMMDevice *defaultDevice = NULL;

    hr = deviceEnumerator->GetDefaultAudioEndpoint(eRender, eConsole, &defaultDevice);
    deviceEnumerator->Release();
    deviceEnumerator = NULL;

    IAudioEndpointVolume *endpointVolume = NULL;
    hr = defaultDevice->Activate(__uuidof(IAudioEndpointVolume), CLSCTX_INPROC_SERVER, NULL, (LPVOID *)&endpointVolume);
    defaultDevice->Release();
    defaultDevice = NULL;

    // -------------------------
    float currentVolume = 0;
    endpointVolume->GetMasterVolumeLevel(&currentVolume);
    printf("Current volume in dB is: %f\n", currentVolume);

    hr = endpointVolume->GetMasterVolumeLevelScalar(&currentVolume);
    printf("Current volume as a scalar is: %f\n", currentVolume);
    if (decibels)
    {
        hr = endpointVolume->SetMasterVolumeLevel((float)newVolume, NULL);
    }
    else if (scalar)
    {
        hr = endpointVolume->SetMasterVolumeLevelScalar((float)newVolume, NULL);
    }
    endpointVolume->Release();

    CoUninitialize();
    return 0;
}