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Custom Media Sink for Use with Media Foundation Topologies and WinRT/WRL MediaCapture

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26 Dec 2015CPOL1 min read 33.4K   408   5   10
Custom Media Sink for use with Media Foundation Topologies and WinRT/WRL MediaCapture

Introduction

WinRT and WRL introduce the requirement that most Media Foundation interfaces can no longer be directly created. If one wants to record audio or video through a sink, the only way to do so is with quite literally hundreds to thousands of lines of code in a custom sink. This prototype will get someone started towards achieving that with greater ease. Native C++ and C++/CX compatible. This is also compatible with non-WinRT/non-WRL uses since custom sinks could also be used prior to Windows 8 but generally shortcut interfaces were used.

Background

Knowledge of WinRT, WRL, C++, C++/CX, MediaCapture, Media Foundation, ATL and COM are recommended.

Using the Code

The block of code here is for all scenarios including non-WinRT/non-WRL cases where it is bound as an output node of a topology.

C++
#ifdef _WINRT_DLL
#ifdef __cplusplus_winrt
Windows::Media::MediaProperties::VideoEncodingProperties^ vidProps;
Windows::Media::MediaProperties::AudioEncodingProperties^ audProps;
Windows::Media::MediaProperties::MediaEncodingProfile^ medEncProf = 
        ref new Windows::Media::MediaProperties::MediaEncodingProfile;
medEncProf->Video = vidProps;
medEncProf->Audio = audProps;
//set any properties to pass to the Custom Sink in a PropertySet as a best practice
Windows::Foundation::Collections::IPropertySet^ pSet = 
        ref new Windows::Foundation::Collections::PropertySet();
Windows::Media::Capture::MediaCapture^ medCap;
HRESULT hr = medCap->StartPreviewToCustomSinkAsync(medEncProf, 
    ref new Platform::String(RuntimeClass_TimeStamp_WebCamSecExtensions_MediaSink), pSet);
//when finished
hr = medCap->StopPreviewAsync();
#else
ABI::Windows::Media::Capture::IMediaCapture* medCap;
ABI::Windows::Media::MediaProperties::IVideoEncodingProperties* vidProps;
ABI::Windows::Media::MediaProperties::IAudioEncodingProperties* audProps;
ABI::Windows::Foundation::IAsyncAction** pAction;
HRESULT hr;
Microsoft::WRL::ComPtr<ABI::Windows::Media::Capture::IMediaCaptureVideoPreview> imedPrevCap;
if (pAction == nullptr) return E_POINTER;
hr = medCap->QueryInterface<ABI::Windows::Media::Capture::IMediaCaptureVideoPreview>(&imedPrevCap);
if (FAILED(hr)) return hr;
Microsoft::WRL::ComPtr<IActivationFactory> objFactory;
hr = Windows::Foundation::GetActivationFactory(Microsoft::WRL::Wrappers::HStringReference
    (RuntimeClass_Windows_Media_MediaProperties_MediaEncodingProfile).Get(), objFactory.ReleaseAndGetAddressOf());
if (FAILED(hr)) return hr;
Microsoft::WRL::ComPtr<IInspectable> medEncProf;
hr = objFactory->ActivateInstance(medEncProf.ReleaseAndGetAddressOf());
if (FAILED(hr)) return hr;
Microsoft::WRL::ComPtr<ABI::Windows::Media::MediaProperties::IMediaEncodingProfile> encProps;
hr = medEncProf.As<ABI::Windows::Media::MediaProperties::IMediaEncodingProfile>(&encProps);
if (FAILED(hr)) return hr;
hr = encProps->put_Video(vidProps);
if (FAILED(hr)) return hr;
//if audio desired must also set an audio sink stream
hr = encProps->put_Audio(audProps);
if (FAILED(hr)) return hr;
hr = Windows::Foundation::GetActivationFactory(Microsoft::WRL::Wrappers::HStringReference
    (RuntimeClass_Windows_Foundation_Collections_PropertySet).Get(), objFactory.ReleaseAndGetAddressOf());
if (FAILED(hr)) return hr;
Microsoft::WRL::ComPtr<IInspectable> pSet;
hr = objFactory->ActivateInstance(pSet.GetAddressOf());
if (FAILED(hr)) return hr;
Microsoft::WRL::ComPtr<ABI::Windows::Foundation::Collections::IPropertySet> pProps;
hr = pSet.As(&pProps);
if (FAILED(hr)) return hr;
Microsoft::WRL::ComPtr<ABI::Windows::Foundation::Collections::IMap<HSTRING, IInspectable *>> spSetting;
hr = pSet.As(&spSetting);
if (FAILED(hr)) return hr;
hr = Windows::Foundation::GetActivationFactory(Microsoft::WRL::Wrappers::HStringReference
    (RuntimeClass_Windows_Foundation_PropertyValue).Get(), objFactory.ReleaseAndGetAddressOf());
if (FAILED(hr)) return hr;
Microsoft::WRL::ComPtr<ABI::Windows::Foundation::IPropertyValueStatics> spPropVal;
hr = objFactory.As(&spPropVal);
if (FAILED(hr)) return hr;
hr = imedPrevCap->StartPreviewToCustomSinkIdAsync(encProps.Get(), Microsoft::WRL::Wrappers::HStringReference
    (RuntimeClass_TimeStamp_WebCamSecExtensions_MediaSink).Get(), pProps.Get(), pAction);
//when finished
hr = imedPrevCap->StopPreviewAsync(pAction);
#endif
#else
CComPtr<IMFTopologyNode> pNode; // Create the node.
HRESULT hr = MFCreateTopologyNode(MF_TOPOLOGY_OUTPUT_NODE, &pNode);
if (SUCCEEDED(hr)) {
CComPtr<IMFMediaSink> pSink;
hr = TimeStamp::WebCamSecExtensions::MediaSink::CreateInstance<IMFMediaSink>(&pSink);
if (FAILED(hr)) return hr;
CComPtr<IMFAttributes> pAttr;
hr = pSink->QueryInterface(&pAttr);
if (FAILED(hr)) return hr;
CComPtr<IMFMediaTypeHandler> pHandler; hr = pSD->GetMediaTypeHandler(&pHandler);
if (FAILED(hr)) return hr;
CComPtr<IMFMediaType> pMediaType;
hr = pHandler->GetCurrentMediaType(&pMediaType);
if (FAILED(hr)) return hr;
hr = pAttr->SetUnknown(MF_MEDIASINK_PREFERREDTYPE, pMediaType.Detach());
if (FAILED(hr)) return hr;
hr = pNode->SetObject(pSink);
}
#endif

Points of Interest

Passing parameters is done through a PropertyBag in WinRT/WRL yet through the IMFAttribute interface in non-WinRT/non-WRL code which can be found through IUnknown QueryInterface on the Custom Sink object.

An object of type ICustomSinkCallback must be passed and the interface implemented to utilize the features including initialization, cleanup, property change notification, preparing for samples and sample processing.

When initializing the custom sink, if planning to reuse the MediaCapture object, then be sure to pass the activation name to StartPreviewToCustomSinkAsync and not an instance of a CustomSink object. There is a bug in the MediaCapture library which causes it to become in a bad state if not using the activation ID which is present in Windows 8 and Windows 8.1.

The code is compatible with Visual Studio 2012/2013/2015 and Windows 8/8.1/10.

History

  • Initial version

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


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Comments and Discussions

 
QuestionMy Previous Post Pin
Eitan Barazani31-Oct-14 6:11
Eitan Barazani31-Oct-14 6:11 
QuestionReading RAW video stream from a Windows Phone/Tablet camera (in WinRT) Pin
Eitan Barazani29-Oct-14 9:25
Eitan Barazani29-Oct-14 9:25 
AnswerRe: Reading RAW video stream from a Windows Phone/Tablet camera (in WinRT) Pin
Gregory Morse29-Oct-14 10:34
Gregory Morse29-Oct-14 10:34 
GeneralRe: Reading RAW video stream from a Windows Phone/Tablet camera (in WinRT) Pin
Eitan Barazani29-Oct-14 11:25
Eitan Barazani29-Oct-14 11:25 
QuestionIs FTM a must have? Pin
zxli6-Jun-14 19:12
zxli6-Jun-14 19:12 
AnswerRe: Is FTM a must have? Pin
Gregory Morse8-Jun-14 0:18
Gregory Morse8-Jun-14 0:18 
QuestionIs this something I would need given my requirement? Pin
Steven123456789026-May-14 8:56
Steven123456789026-May-14 8:56 
AnswerRe: Is this something I would need given my requirement? Pin
Gregory Morse26-May-14 12:47
Gregory Morse26-May-14 12:47 
QuestionThis is really helpful... Pin
zxli20-May-14 13:13
zxli20-May-14 13:13 
AnswerRe: This is really helpful... Pin
Gregory Morse20-May-14 16:07
Gregory Morse20-May-14 16:07 
I would but it is a side point though. I disassembled the library and spent an hour or two studying it and I noticed that on the different code paths one would never reinitialized the MediaCapture object when a CustomSink was passed in directly. Hope Microsoft will add the line of code or whatever else is necessary at some point to fix it.

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