CODEWITHSUNDEEP
c++directshowavcapturedevice
s_om
s_om

Reputation: 681

Duplicate names detected for capture devices

I am using some capture devices for my application, which keep getting detected with the same name by my code which I have written following the link : https://learn.microsoft.com/en-us/windows/win32/directshow/using-the-system-device-enumerator

Here's my version of the code :

std::string CSDirectShow::GetCaptureDevice()
{
    const char* funcName = "CSDirectShow::GetCaptureDevice()";
    HRESULT     hr = S_OK;
    std::string devices = "";
    CComPtr< ICreateDevEnum > pDevEnum;
    if (FAILED(hr = pDevEnum.CoCreateInstance(CLSID_SystemDeviceEnum, NULL, CLSCTX_INPROC)))
    {
        TraceMsg("%s: couldn't create system device enumerator (0x%x)", funcName, hr);
        return "";
    }

    CComPtr< IEnumMoniker > pClassEnum;
    if (FAILED(hr = pDevEnum->CreateClassEnumerator(CLSID_VideoInputDeviceCategory, &pClassEnum, 0)))
    {
        TraceMsg("%s: CreateClassEnumerator(CLSID_VideoInputDeviceCategory) failed (0x%x)", funcName, hr);
        return "";
    }

    if (!pClassEnum)
    {
        TraceMsg("%s: no video capture device detected", funcName);
        return "";
    }
    ULONG cFetched = 0;
    std::wstring device;
    bool found = 0;
    int counter = 0;
    while (1)
    {
        CComPtr< IMoniker > pMoniker;
        if ((hr = pClassEnum->Next(1, &pMoniker, &cFetched)) != S_OK)
        {
            break;
        }
        CComPtr<IPropertyBag> pPropBag;
        hr = pMoniker->BindToStorage(0, 0, IID_IPropertyBag, (void**)& pPropBag);
        if (FAILED(hr))
        {
            continue;
        }
        // retrieve the filter's friendly name
        _variant_t varName;
        hr = pPropBag->Read(L"FriendlyName", &varName, 0);
        //hr = pPropBag->Read(L"DevicePath", &varName, 0);
        if (SUCCEEDED(hr))
        {
            _bstr_t val(varName.bstrVal);
            device = (wchar_t*)val;
        }
        if (!device.empty()) {
            std::string devicename(device.begin(), device.end());
            //devicename += "_" + to_string(counter);
            devices += devicename.c_str();
            counter += 1;
        }
        else
        {
            break;
        }
        devices += ";";

    }

    return devices;
}

I am using two Cam Link capture devices, both of whom are returned as 'Cam Link 4K' in my devices value that I am returning.

Can someone please tell me if there's an error in the code due to which the names get duplicated?

Upvotes: 0

Views: 103

Answers (1)

Roman Ryltsov
Roman Ryltsov

Reputation: 69642

Duplicate names can happen, there is no API limit or design to make it impossible. In most cases it is a question to the hardware driver which fails to assign distinct names in the case of multiple devices.

Upvotes: 2

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