如何使用C++控制麦克风增强/ AGC

我终于想出了怎么做。我在上面的示例代码中省略了代码的一些重要部分。

为了帮助那些有同样困境的人，这是解决方案。要编译，只需将 MessageBox 语句替换为 printf。

这里重要的一点是，在枚举部分时，一定要知道它是输入还是输出。否则，您将永远找不到所需的零件。此示例查找电子捕获终结点的可用部分。

这是我的消息来源：http://social.msdn.microsoft.com/Forums/windowsdesktop/en-US/9741bae1-c330-4802-9860-2fd202dba797/enumeration-of-available-levels-for-a-specific-installed-sound-card?forum=windowspro-audiodevelopment

如果您在编译时遇到问题，请告诉我。

#include <windows.h>
#include <stdio.h>
#include <mmdeviceapi.h>
#include <devicetopology.h>
HRESULT WalkTreeBackwardsFromPart(IPart *pPart, int iTabLevel = 0);
HRESULT DisplayVolume(IAudioVolumeLevel *pVolume, int iTabLevel);
HRESULT DisplayMute(IAudioMute *pMute, int iTabLevel);
void Tab(int iTabLevel);
int __cdecl main(void) {
HRESULT hr = CoInitialize(NULL);
if (FAILED(hr)) {
    printf("Failed CoInitializeEx: hr = 0x%08xn", hr);
    return __LINE__;
}
// get default render endpoint
IMMDeviceEnumerator *pEnum = NULL;
hr = CoCreateInstance(
    __uuidof(MMDeviceEnumerator), NULL, CLSCTX_ALL, __uuidof(IMMDeviceEnumerator),
    (void**)&pEnum
);
if (FAILED(hr)) {
    printf("Couldn't get device enumerator: hr = 0x%08xn", hr);
    CoUninitialize();
    return __LINE__;
}
IMMDevice *pDevice = NULL;
hr = pEnum->GetDefaultAudioEndpoint(eCapture, eConsole, &pDevice);
if (FAILED(hr)) {
    printf("Couldn't get default capture device: hr = 0x%08xn", hr);
    pEnum->Release();
    CoUninitialize();
    return __LINE__;
}
pEnum->Release();
// get device topology object for that endpoint
IDeviceTopology *pDT = NULL;
hr = pDevice->Activate(__uuidof(IDeviceTopology), CLSCTX_ALL, NULL, (void**)&pDT);
if (FAILED(hr)) {
    printf("Couldn't get device topology object: hr = 0x%08xn", hr);
    pDevice->Release();
    CoUninitialize();
    return __LINE__;
}
pDevice->Release();
// get the single connector for that endpoint
IConnector *pConnEndpoint = NULL;
hr = pDT->GetConnector(0, &pConnEndpoint);
if (FAILED(hr)) {
    printf("Couldn't get the connector on the endpoint: hr = 0x%08xn", hr);
    pDT->Release();
    CoUninitialize();
    return __LINE__;
}
pDT->Release();
// get the connector on the device that is
// connected to
// the connector on the endpoint
IConnector *pConnDevice = NULL;
hr = pConnEndpoint->GetConnectedTo(&pConnDevice);
if (FAILED(hr)) {
    printf("Couldn't get the connector on the device: hr = 0x%08xn", hr);
    pConnEndpoint->Release();
    CoUninitialize();
    return __LINE__;
}
pConnEndpoint->Release();
// QI on the device's connector for IPart
IPart *pPart = NULL;
hr = pConnDevice->QueryInterface(__uuidof(IPart), (void**)&pPart);
if (FAILED(hr)) {
    printf("Couldn't get the part: hr = 0x%08xn", hr);
    pConnDevice->Release();
    CoUninitialize();
    return __LINE__;
}
pConnDevice->Release();
// all the real work is done in this function
hr = WalkTreeBackwardsFromPart(pPart);
if (FAILED(hr)) {
    printf("Couldn't walk the tree: hr = 0x%08xn", hr);
    pPart->Release();
    CoUninitialize();
    return __LINE__;
}
pPart->Release();
CoUninitialize();
system("pause");
return 0;
}
HRESULT WalkTreeBackwardsFromPart(IPart *pPart) {
HRESULT hr = S_OK;
LPWSTR pwszPartName = NULL;
hr = pPart->GetName(&pwszPartName);
if (FAILED(hr)) {
    printf("Could not get part name: hr = 0x%08x", hr);
    return hr;
}
printf("Part name: %wsn", *pwszPartName ? pwszPartName : L"(Unnamed)");
CoTaskMemFree(pwszPartName);

// Check AGC settings
const IID IID_IAudioAutoGainControl = __uuidof(IAudioAutoGainControl);
IAudioAutoGainControl *aGCcontrol = NULL;
hr = pPart->Activate(CLSCTX_ALL, IID_IAudioAutoGainControl, (void**)&aGCcontrol);
if (E_NOINTERFACE == hr) {
      printf("NO AGC CONTROLn");
    // not a Microphone node
} else if (FAILED(hr)) {
    printf("Unexpected failure trying to activate IAudioAutoGainControl : hr = 0x%08xn", hr);
    return hr;
} else {
    // it's an AGC node...
    printf("HAS AGC CONTROL");
    aGCcontrol->SetEnabled(1, NULL);   //Activate it
    if (FAILED(hr)) {
        printf("AGC Failed: hr = 0x%08x", hr);
        aGCcontrol->Release();
        return hr;
    }
    aGCcontrol->Release();
}
// get the list of incoming parts
IPartsList *pOutgoingParts = NULL;
hr = pPart->EnumPartsOutgoing(&pOutgoingParts);
if (E_NOTFOUND == hr) {
    // not an error... we've just reached the end of the path
    MessageBox("No incoming parts at this partn", MB_OK);
}
if (FAILED(hr)) {
    MessageBox("Couldn't enum outgoing parts", MB_OK);
}
UINT nParts = 0;
hr = pOutgoingParts->GetCount(&nParts);
if (FAILED(hr)) {
    MessageBox("Couldn't get count of outgoing parts", MB_OK);
    pOutgoingParts->Release();
    return hr;
}
// walk the tree on each incoming part recursively
for (UINT n = 0; n < nParts; n++) {
    IPart *pOutgoingPart = NULL;
    hr = pOutgoingParts->GetPart(n, &pOutgoingPart);
    if (FAILED(hr)) {
        MessageBox("Couldn't get part ", MB_OK);
        pOutgoingParts->Release();
        return hr;
    }
    hr = WalkTreeBackwardsFromPart(pOutgoingPart);
    if (FAILED(hr)) {
        MessageBox("Couldn't walk tree on part", MB_OK);
        pOutgoingPart->Release();
        pOutgoingParts->Release();
        return hr;
    }
    pOutgoingPart->Release();
}
pOutgoingParts->Release();
return S_OK;

}