DirectShow Memory Leak - c++

Question

I'm experiencing an important memory leak in a camera application that uses an EVR (Enhanced Video Renderer). The leak happens when I prepare, run, stop and unprepare a graph several times (several MB every cycle, depending on the video resolution).
I simplified the code as much as I could; you can download it from here:
https://daptech.box.com/s/6csm91vhcawiw18u42kq
The graph has a video capture filter, a SampleGrabber filter and a renderer. When connecting, it creates an AVI Decompressor filter to complete the graph.
Here are some excerpts...
Declarations:
CComPtr<IGraphBuilder> pGraphBuilder;
CComPtr<IBaseFilter> pSource; // The capture device filter
CComPtr<IBaseFilter> pSampleGrabberFilter; // Filter to capture data that flows through the graph
CComPtr<IBaseFilter> pRenderer; // EVR
Graph preparation (validation removed):
hr = m_p->pGraphBuilder.CoCreateInstance(CLSID_FilterGraph, NULL, CLSCTX_INPROC);
hr = m_p->pSampleGrabberFilter.CoCreateInstance(CLSID_SampleGrabber, NULL, CLSCTX_INPROC);
CComQIPtr<ISampleGrabber, &IID_ISampleGrabber> pSampleGrabber(m_p->pSampleGrabberFilter);
hr = pSampleGrabber->SetBufferSamples(FALSE); // Don't copy image data for better performances
// Setup the callback
hr = pSampleGrabber->SetCallback(&m_p->cb, 1); // 0: SampleCB() is called, so that we directly access the buffer. 1: BufferCB() is called. The doc states that the function always makes a copy of the data.
CComPtr<IPin> pSampleGrabberInputPin( FindPin(m_p->pSampleGrabberFilter, PINDIR_INPUT, NULL) );
CComPtr<IPin> pSampleGrabberOutputPin( FindPin(m_p->pSampleGrabberFilter, PINDIR_OUTPUT, NULL) );
hr = m_p->pGraphBuilder->AddFilter(m_p->pSampleGrabberFilter, L"SampleGrabber");
hr = FindVideoCaptureDevice(m_p->pSource, (unsigned)iCameraIndex);
CComPtr<IPin> pSourceOutputPin( FindPin(m_p->pSource, PINDIR_OUTPUT, L"CAPTURE") );
hr = m_p->pGraphBuilder->AddFilter(m_p->pSource, L"Camera");
hr = m_p->pRenderer.CoCreateInstance(CLSID_EnhancedVideoRenderer, NULL, CLSCTX_INPROC);
hr = m_p->pGraphBuilder->AddFilter(m_p->pRenderer, L"Renderer");
hr = ConfigEVR(m_p->pRenderer, m_staticPreview.m_hWnd, uWidth, uHeight);
CComPtr<IPin> pRendererInputPin( FindPin(m_p->pRenderer, PINDIR_INPUT, NULL) );
// Now select the format:
if (!SelectFormat(pSourceOutputPin, uWidth, uHeight, bCompression))
{ MessageBox(L"No appropriate format found.\n"); return; }
// Connection:
hr = m_p->pGraphBuilder->Connect(pSourceOutputPin, pSampleGrabberInputPin);
hr = m_p->pGraphBuilder->Connect(pSampleGrabberOutputPin, pRendererInputPin);
This function is called to "unprepare" the graph:
void FreeDirectShowGraph()
{
if (pSource) DisconnectDownstream(pSource);
RemoveAndRelease(pRenderer);
RemoveAndRelease(pSampleGrabberFilter);
RemoveAndRelease(pSource);
if (pGraphBuilder) pGraphBuilder.Release();
}
Any clue would be appreciated!