Manage the volume of other applications

Question

I am trying to create an application that manages the volume of another process using the Windows 7 audio API.

What I'm looking for is ISimpleAudioVolume for the session used by another process.

I tried using IAudioSessionEnumerator , but it will give me only IAudioSessionControl2 sessions. Using IAudioSessionControl, I was able to receive notifications when I change the volume through sndvol, but do not change it myself.

I also tried using GetSimpleAudioVolume () from IAudioSessionManager, but it will only give me sessions in the current process.

How do you do this? This should be possible since sndvol does this.

Answer 1

There is a MSDN forum question and a blog post about this very issue. Hope this helps.

Answer 2

According to Larry Osterman

"There is no publicly documented mechanism to accomplish what you are trying to do."

Answer 3

Here is an example of muting another process using the Core Audio API.

#include <windows.h>
#include <iostream>
#include <mmdeviceapi.h>
#include <endpointvolume.h>
#include <Audiopolicy.h>
#include <comdef.h>
#include <comip.h>

#define CHECK_HR(hr)   \
    if(FAILED(hr)) {    \
        std::cout << "error" << std::endl;   \
        return 0;   \
                }
_COM_SMARTPTR_TYPEDEF(IMMDevice, __uuidof(IMMDevice));
_COM_SMARTPTR_TYPEDEF(IMMDeviceEnumerator, __uuidof(IMMDeviceEnumerator));
_COM_SMARTPTR_TYPEDEF(IAudioSessionManager2, __uuidof(IAudioSessionManager2));
_COM_SMARTPTR_TYPEDEF(IAudioSessionManager2, __uuidof(IAudioSessionManager2));
_COM_SMARTPTR_TYPEDEF(IAudioSessionEnumerator, __uuidof(IAudioSessionEnumerator));
_COM_SMARTPTR_TYPEDEF(IAudioSessionControl2, __uuidof(IAudioSessionControl2));
_COM_SMARTPTR_TYPEDEF(IAudioSessionControl, __uuidof(IAudioSessionControl));
_COM_SMARTPTR_TYPEDEF(ISimpleAudioVolume, __uuidof(ISimpleAudioVolume));

IAudioSessionManager2Ptr CreateSessionManager()
{
    HRESULT hr = S_OK;

    IMMDevicePtr pDevice;
    IMMDeviceEnumeratorPtr pEnumerator;
    IAudioSessionManager2Ptr pSessionManager;


    // Create the device enumerator.
    CHECK_HR(hr = CoCreateInstance(
        __uuidof(MMDeviceEnumerator),
        NULL, CLSCTX_ALL,
        __uuidof(IMMDeviceEnumerator),
        (void**)&pEnumerator));

    // Get the default audio device.
    CHECK_HR(hr = pEnumerator->GetDefaultAudioEndpoint(
        eRender, eConsole, &pDevice));

    // Get the session manager.
    CHECK_HR(hr = pDevice->Activate(
        __uuidof(IAudioSessionManager2), CLSCTX_ALL,
        NULL, (void**)&pSessionManager));

    return pSessionManager;
}

bool MuteProcess(DWORD processId) {

    IAudioSessionManager2Ptr mgr = CreateSessionManager();
    if (!mgr) {
        return false;
    }
    IAudioSessionEnumeratorPtr enumerator;
    if (SUCCEEDED(mgr->GetSessionEnumerator(&enumerator))) {
        int sessionCount;
        if (SUCCEEDED(enumerator->GetCount(&sessionCount))) {
            for (int i = 0; i < sessionCount; i++) {
                IAudioSessionControlPtr control;
                if (SUCCEEDED(enumerator->GetSession(i, &control))) {
                    IAudioSessionControl2Ptr control2;
                    if (SUCCEEDED(control->QueryInterface(__uuidof(IAudioSessionControl2), (void**)&control2))) {
                        DWORD foundProcessId;
                        if (SUCCEEDED(control2->GetProcessId(&foundProcessId))) {
                            if (foundProcessId == processId) {
                                ISimpleAudioVolumePtr volume;
                                if (SUCCEEDED(control2->QueryInterface(_uuidof(ISimpleAudioVolume), (void**)&volume))) {
                                    if (SUCCEEDED(volume->SetMute(TRUE, 0))) {
                                        return true;
                                    }
                                }
                            }
                        }

                    }

                }
            }
        }
    }
    return false;
}

int _tmain(int argc, _TCHAR* argv[]){
    CoInitialize(NULL);
    DWORD processId = 11944;
    MuteProcess(processId);

    return 0;
}