CoCreateInstance creates empty IBaseFilter for CLSID_WavDest

Question

I am trying to record .wav by using directshow framework in C++ Visual Studio 2010 project. I am following WAV file section of this guide: https://msdn.microsoft.com/en-us/library/windows/desktop/dd375005(v=vs.85).aspx

I have built WavDest.dll, added it to registry, found it in the registry, it can be added as filter in Graphedit. I had unresolved external symbol error for _CLSID_WavDest but had fixed it by including InitGuid.h in my StdAfx.h and by linking the WavDest.lib.

Now I get no errors, program doesn't crash, but I get 0 byte wav file.

Section of code:

res = AddFilterByCLSID(dshow_dev->m_pGraph, CLSID_WavDest, (IBaseFilter **)&dshow_dev->m_pWaveDest, L"WavDest");
res = AddFilterByCLSID(dshow_dev->m_pGraph, CLSID_FileWriter, (IBaseFilter **)&dshow_dev->m_pWaveWriter, L"File Writer");


res = dshow_dev->m_pWaveWriter->QueryInterface(IID_IFileSinkFilter, (void**)&dshow_dev->m_pFileSink);
res = dshow_dev->m_pFileSink->SetFileName(L"D:\\test.wav", NULL);

res = ConnectFilters(dshow_dev->m_pGraph, dshow_dev->m_pCaptureSourceAudio, dshow_dev->m_pWaveDest);
res = ConnectFilters(dshow_dev->m_pGraph, dshow_dev->m_pWaveDest, dshow_dev->m_pWaveWriter);

AddFilterByCLSID for CLSID_WavDest returns S_OK but dshow_dev->m_pWaveDest has following values: -

[CWavDestFilter]    {m_cbWavData=0x00000000 m_cbHeader=0x00000000 } CWavDestFilter

.

Therefore, ConnectFilters for m_pWaveDest returns E_Fail and no audio is recorded.

I have tried this with both Debug and Release versions of WavDest.dll registered (first Debug, then unreg Debug and reg Release).

I have checked everything other in code, graph (dshow_dev->m_pGraph) runs fine for video preview and writing AVI file (with audio).

I am sure that that I did something wrong with WavDest integration but I don't know what.

Any help is appreciated.

Answer 1

It was my mistake after all. I have replaced

assert(pResult != NULL);

in this function

// Match a pin by pin direction and connection state.
HRESULT MatchPin(IPin *pPin, PIN_DIRECTION direction, BOOL bShouldBeConnected, BOOL *pResult)
{
    assert(pResult != NULL);

    BOOL bMatch = FALSE;
    BOOL bIsConnected = FALSE;

    HRESULT hr = IsPinConnected(pPin, &bIsConnected);
    if (SUCCEEDED(hr))
    {
        if (bIsConnected == bShouldBeConnected)
        {
            hr = IsPinDirection(pPin, direction, &bMatch);
        }
    }

    if (SUCCEEDED(hr))
    {
        *pResult = bMatch;
    }
    return hr;
}

with

if(pResult == NULL);
{
    HRESULT hr = E_FAIL;
    return hr;
}