Problems connecting to the input pins of GMFBridge Sink Filter - c++-cli

Question

I am experiencing a strange problem when trying to use the GMFBridge filter with the output of an Euresys UxH264 card.
I am trying to integrate this card into our solution, that relies on GMFBridge to handle the ability of continuous capture to multiple files, performing muxing and file-splitting without having to stop the capture graph.
This card captures video and audio from analog inputs. It provides a DirectShow filter exposing both a raw stream of the video input and a hardware-encoded H.264 stream. The audio stream is provided as an uncompressed stream only.
When I attempt to directly connect any of the output pins of the Euresys source filters to the input pins of the GMFBridge Sink, they get rejected, with the code VFW_E_NO_ALLOCATOR. (In the past I have successfully connected both H.264 and raw audio streams to the bridge).
Grasping at straws, I plugged in a pair of SampleGrabber filters between the Euresys card filters and the bridge sink filter, and -just like that- the connections between sample grabbers and sink were accepted.
However, I am not getting any packets on the other side of the bridge (the muxing graph). I inspected the running capture graph with GraphStudioNext and somehow the sample grabbers appear detached from my graph, even though I got successful confirmations when I connected them to the source filter!.
Here's the source code creating the graph.
void EuresysSourceBox::BuildGraph() {
HRESULT hRes;
CComPtr<IGraphBuilder> pGraph;
COM_CALL(pGraph.CoCreateInstance(CLSID_FilterGraph));
#ifdef REGISTER_IN_ROT
_rotEntry1 = FilterTools::RegisterGraphInROT(IntPtr(pGraph), "euresys graph");
#endif
// [*Video Source*]
String^ filterName = "Ux H.264 Visual Source";
Guid category = _GUIDToGuid((GUID)AM_KSCATEGORY_CAPTURE);
FilterMonikerList^ videoSourceList = FilterTools::GetFilterMonikersByName(category, filterName);
CComPtr<IBaseFilter> pVideoSource;
int monikerIndex = config->BoardIndex; // a filter instance will be retrieved for every installed board
clr_scoped_ptr<CComPtr<IMoniker>>^ ppVideoSourceMoniker = videoSourceList[monikerIndex];
COM_CALL((*ppVideoSourceMoniker->get())->BindToObject(NULL, NULL, IID_IBaseFilter, (void**)&pVideoSource));
COM_CALL(pGraph->AddFilter(pVideoSource, L"VideoSource"));
// [Video Source]
//
// [*Audio Source*]
filterName = "Ux H.264 Audio Encoder";
FilterMonikerList^ audioSourceList = FilterTools::GetFilterMonikersByName(category, filterName);
CComPtr<IBaseFilter> pAudioSource;
clr_scoped_ptr<CComPtr<IMoniker>>^ ppAudioSourceMoniker = audioSourceList[monikerIndex];
COM_CALL((*ppAudioSourceMoniker->get())->BindToObject(NULL, NULL, IID_IBaseFilter, (void**)&pAudioSource));
COM_CALL(pGraph->AddFilter(pAudioSource, L"AudioSource"));
CComPtr<IPin> pVideoCompressedOutPin(FilterTools::GetPin(pVideoSource, "Encoded"));
CComPtr<IPin> pAudioOutPin(FilterTools::GetPin(pAudioSource, "Audio"));
CComPtr<IBaseFilter> pSampleGrabber;
COM_CALL(pSampleGrabber.CoCreateInstance(CLSID_SampleGrabber));
COM_CALL(pGraph->AddFilter(pSampleGrabber, L"SampleGrabber"));
CComPtr<IPin> pSampleGrabberInPin(FilterTools::GetPin(pSampleGrabber, "Input"));
COM_CALL(pGraph->ConnectDirect(pVideoCompressedOutPin, pSampleGrabberInPin, NULL)); // DOES NOT FAIL!!
CComPtr<IBaseFilter> pSampleGrabber2;
COM_CALL(pSampleGrabber2.CoCreateInstance(CLSID_SampleGrabber));
COM_CALL(pGraph->AddFilter(pSampleGrabber2, L"SampleGrabber2"));
CComPtr<IPin> pSampleGrabber2InPin(FilterTools::GetPin(pSampleGrabber2, "Input"));
COM_CALL(pGraph->ConnectDirect(pAudioOutPin, pSampleGrabber2InPin, NULL)); // DOES NOT FAIL!!
// [Video Source]---
// |-->[*Bridge Sink*]
// [Audio Source]---
CComPtr<IPin> pSampleGrabberOutPin(FilterTools::GetPin(pSampleGrabber, "Output"));
CComPtr<IPin> pSampleGrabber2OutPin(FilterTools::GetPin(pSampleGrabber2, "Output"));
CreateGraphBridge(
IntPtr(pGraph),
IntPtr(pSampleGrabberOutPin),
IntPtr(pSampleGrabber2OutPin)
);
// Root graph to parent object
_ppCaptureGraph.reset(new CComPtr<IGraphBuilder>(pGraph));
}
COM_CALL is my HRESULT checking macro, it will raise a managed exception if the result is other than S_OK. So the connection between pins succeeded, but here is how the graph looks disjointed when it is running:
So, I have three questions:
1) What could VFW_E_NO_ALLOCATOR mean in this instance? (the source filter can be successfully connected to other components such as LAV Video decoder or ffdshow video decoder).
2) Is there a known workaround to circumvent the VFW_E_NO_ALLOCATOR problem?
3) Is it possible that a filter gets disconnected at runtime as it seems to be happening in my case?

Answer 1

I found a reference by Geraint Davies giving a reason as to why the GMFBridge sink filter may be rejecting the connection.
It looks as though the parser is insisting on using its own allocator
-- this is common with parsers where the output samples are merely pointers into the input samples. However, the bridge cannot implement
suspend mode without using its own allocator, so a copy is required.
With this information, I decided to create an ultra simple CTransformFilter filter that simply accepts the allocator offered by the bridge and copies to the output sample whatever comes in from the input sample. I am not 100% sure that what I did was right, but it is working now. I could successfully plug-in the Euresys card as part of my capture infrastructure.
For reference, if anyone experiences something similar, here is the code of the filter I created:
class SampleCopyGeneratorFilter : public CTransformFilter {
protected:
HRESULT CheckInputType(const CMediaType* mtIn) override { return S_OK; }
HRESULT GetMediaType(int iPosition, CMediaType* pMediaType) override;
HRESULT CheckTransform(const CMediaType *mtIn, const CMediaType *mtOut) override { return S_OK; }
HRESULT DecideBufferSize(IMemAllocator *pAlloc, ALLOCATOR_PROPERTIES *pProp) override;
HRESULT Transform(IMediaSample *pSource, IMediaSample *pDest) override;
public:
SampleCopyGeneratorFilter();
};
//--------------------------------------------------------------------------------------------------------------------
SampleCopyGeneratorFilter::SampleCopyGeneratorFilter()
: CTransformFilter(NAME("SampleCopyGeneratorFilter"), NULL, GUID_NULL)
{
}
HRESULT SampleCopyGeneratorFilter::GetMediaType(int iPosition, CMediaType* pMediaType) {
HRESULT hRes;
ASSERT(m_pInput->IsConnected());
if( iPosition < 0 )
return E_INVALIDARG;
CComPtr<IPin> connectedTo;
COM_CALL(m_pInput->ConnectedTo(&connectedTo));
CComPtr<IEnumMediaTypes> pMTEnumerator;
COM_CALL(connectedTo->EnumMediaTypes(&pMTEnumerator));
AM_MEDIA_TYPE* pIteratedMediaType;
for( int i = 0; i <= iPosition; i++ ) {
if( pMTEnumerator->Next(1, &pIteratedMediaType, NULL) != S_OK )
return VFW_S_NO_MORE_ITEMS;
if( i == iPosition )
*pMediaType = *pIteratedMediaType;
DeleteMediaType(pIteratedMediaType);
}
return S_OK;
}
HRESULT SampleCopyGeneratorFilter::DecideBufferSize(IMemAllocator *pAlloc, ALLOCATOR_PROPERTIES *pProp) {
HRESULT hRes;
AM_MEDIA_TYPE mt;
COM_CALL(m_pInput->ConnectionMediaType(&mt));
try {
BITMAPINFOHEADER* pBMI = HEADER(mt.pbFormat);
pProp->cbBuffer = DIBSIZE(*pBMI); // format is compressed, uncompressed size should be enough
if( !pProp->cbAlign )
pProp->cbAlign = 1;
pProp->cbPrefix = 0;
pProp->cBuffers = 4;
ALLOCATOR_PROPERTIES actualProperties;
COM_CALL(pAlloc->SetProperties(pProp, &actualProperties));
if( pProp->cbBuffer > actualProperties.cbBuffer )
return E_FAIL;
return S_OK;
} finally{
FreeMediaType(mt);
}
}
HRESULT SampleCopyGeneratorFilter::Transform(IMediaSample *pSource, IMediaSample *pDest) {
HRESULT hRes;
BYTE* pBufferIn;
BYTE* pBufferOut;
long destSize = pDest->GetSize();
long dataLen = pSource->GetActualDataLength();
if( dataLen > destSize )
return VFW_E_BUFFER_OVERFLOW;
COM_CALL(pSource->GetPointer(&pBufferIn));
COM_CALL(pDest->GetPointer(&pBufferOut));
memcpy(pBufferOut, pBufferIn, dataLen);
pDest->SetActualDataLength(dataLen);
pDest->SetSyncPoint(pSource->IsSyncPoint() == S_OK);
return S_OK;
}
Here is how I inserted the filter in the capture graph:
CComPtr<IPin> pAACEncoderOutPin(FilterTools::GetPin(pAACEncoder, "XForm Out"));
CComPtr<IPin> pVideoSourceCompressedOutPin(FilterTools::GetPin(pVideoSource, "Encoded"));
CComPtr<IBaseFilter> pSampleCopier;
pSampleCopier = new SampleCopyGeneratorFilter();
COM_CALL(pGraph->AddFilter(pSampleCopier, L"SampleCopier"));
CComPtr<IPin> pSampleCopierInPin(FilterTools::GetPin(pSampleCopier, "XForm In"));
COM_CALL(pGraph->ConnectDirect(pVideoSourceCompressedOutPin, pSampleCopierInPin, NULL));
CComPtr<IPin> pSampleCopierOutPin(FilterTools::GetPin(pSampleCopier, "XForm Out"));
CreateGraphBridge(
IntPtr(pGraph),
IntPtr(pSampleCopierOutPin),
IntPtr(pAACEncoderOutPin)
);
Now, I still have no idea why inserting the sample grabber instead did not work and resulted in detached graphs. I corroborated this quirk by examining the graphs with Graphedit Plus too. If anyone can offer me an explanation, I would be very grateful indeed.