Negotiating an allocator between Directshow filters fails - directshow

Question

I'm developing a custom Directshow source filter to provide decompressed video data to a rendering filter. I've used the PushSource sample provided by the Directshow SDK as a basis for my filter. I'm attempting to connect this to a VideoMixingRenderer9 filter.
When creating the graph I'm calling ConnectDirect():
HRESULT hr = mp_graph_builder->ConnectDirect(OutPin, InPin, &mediaType);
but during this call, calling SetProperties on the downstream filters allocator (in DecideBufferSize()), fails with D3DERR_INVALIDCALL (0x8876086c):
ALLOCATOR_PROPERTIES actual;
memset(&actual,0,sizeof(actual));
hr = pAlloc->SetProperties(pRequest, &actual);
If I let it try to use my allocator (the one provided by CBaseOutputPin) when setting the allocator on the downstream filter, this fails with E_FAIL (in CBaseOutputPin::DecideAllocator)
hr = pPin->NotifyAllocator(*ppAlloc, FALSE);
Any help would be much appreciated!
Thanks.
EDIT:
This is the media type provided by GetMediaType
VIDEOINFOHEADER *pvi = (VIDEOINFOHEADER*)pMediaType->AllocFormatBuffer(sizeof(VIDEOINFOHEADER));
if (pvi == 0)
return(E_OUTOFMEMORY);
ZeroMemory(pvi, pMediaType->cbFormat);
pvi->AvgTimePerFrame = m_rtFrameLength;
pMediaType->formattype = FORMAT_VideoInfo;
pMediaType->majortype = MEDIATYPE_Video;
pMediaType->subtype = MEDIASUBTYPE_RGB24;
pMediaType->bTemporalCompression = FALSE;
pMediaType->bFixedSizeSamples = TRUE;
pMediaType->formattype = FORMAT_VideoInfo;
pvi->bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
pvi->bmiHeader.biWidth = (640 / 128 + 1) * 128;
pvi->bmiHeader.biHeight = -480; // negative so top down..
pvi->bmiHeader.biPlanes = 1;
pvi->bmiHeader.biBitCount = 24;
pvi->bmiHeader.biCompression = NULL; // ok if rgb else use MAKEFOURCC(...)
pvi->bmiHeader.biSizeImage = GetBitmapSize(&pvi->bmiHeader);
pvi->bmiHeader.biClrImportant = 0;
pvi->bmiHeader.biClrUsed = 0; //Use max colour depth
pvi->bmiHeader.biXPelsPerMeter = 0;
pvi->bmiHeader.biYPelsPerMeter = 0;
SetRectEmpty(&(pvi->rcSource));
SetRectEmpty(&(pvi->rcTarget));
pvi->rcSource.bottom = 480;
pvi->rcSource.right = 640;
pvi->rcTarget.bottom = 480;
pvi->rcTarget.right = 640;
pMediaType->SetType(&MEDIATYPE_Video);
pMediaType->SetFormatType(&FORMAT_VideoInfo);
pMediaType->SetTemporalCompression(FALSE);
const GUID SubTypeGUID = GetBitmapSubtype(&pvi->bmiHeader);
pMediaType->SetSubtype(&SubTypeGUID);
pMediaType->SetSampleSize(pvi->bmiHeader.biSizeImage);
and DecideBufferSize where pAlloc->SetProperties is called
HRESULT CPushPinBitmap::DecideBufferSize(IMemAllocator *pAlloc, ALLOCATOR_PROPERTIES *pRequest) {
HRESULT hr;
CAutoLock cAutoLock(CBasePin::m_pLock);
CheckPointer(pAlloc, E_POINTER);
CheckPointer(pRequest, E_POINTER);
if (pRequest->cBuffers == 0) {
pRequest->cBuffers = 2;
}
pRequest->cbBuffer = 480 * ( (640 / 128 + 1) * 128 ) * 3;
ALLOCATOR_PROPERTIES actual;
memset(&actual,0,sizeof(actual));
hr = pAlloc->SetProperties(pRequest, &actual);
if (FAILED(hr)) {
return hr;
}
if (actual.cbBuffer < pRequest->cbBuffer) {
return E_FAIL;
}
return S_OK;
}
The constants are only temporary!

Answer 1

There is no way you can use your own allocator with VMR/EVR filters. They just insist on their own, which in turn is backed on DirectDraw/Direct3D surfaces.
To connect directly to VMR/EVR filters you need a different strategy. The allocator is always theirs. You need to support extended strides. See Handling Format Changes from the Video Renderer.