Apply MFPKEY_ASFMEDIASINK_AUTOADJUST_BITRATE to IMFSinkWriter - c++

Question

Currently I'm creating WMV file with Windows Media Foundation SDK using the method (Transcode API) in following article: https://learn.microsoft.com/en-us/windows/desktop/medfound/tutorial--using-the-sink-writer-to-encode-video
What I noticed is if I don't set MFPKEY_ASFMEDIASINK_AUTOADJUST_BITRATE, output WMV file may be corrupted (show up as terrible artifacts during playback) when coded WMV file over the specified bitrate.
According to following article, the flag needs to set to IMFASFContentInfo:
https://learn.microsoft.com/en-us/windows/desktop/medfound/mfpkey-asfmediasink-autoadjust-bitrate-property
So I tried following way:
IMFSinkWriter* pSinkWriter = NULL;
//initialize sink writer with MFCreateSinkWriterFromURL
...
IMFASFContentInfo* pContentInfo = NULL;
pSinkWriter->GetServiceForStream((DWORD)MF_SINK_WRITER_MEDIASINK, GUID_NULL, __uuidof(IMFASFContentInfo), (LPVOID*)&pContentInfo);
IPropertyStore* pPropStore = NULL;
pContentInfo->GetEncodingConfigurationPropertyStore(0, &pPropStore);
PROPVARIANT var;
PropVariantInit(&var);
var.vt = VT_BOOL;
var.boolVal = VARIANT_TRUE;
pPropStore->SetValue(MFPKEY_ASFMEDIASINK_AUTOADJUST_BITRATE, var);
PropVariantClear(&var);
//Add Video stream and BeginWriting, then start passing samples
...
But, the settings does not seem to be applied to muxer, and I still see obvious artifacts of corrupted stream.
What I guess is since MFCreateSinkWriterFromURL will create MediaSink and underlying IMFASFMultiplexer internally, however MFASF_MULTIPLEXER_AUTOADJUST_BITRATE needs to be set during creating IMFASFMultiplexer, so settings the flag after SinkWriter is created is too late.
If I don't use Transcode API, and create IMFASFWriter by myself, I think I can set MFASF_MULTIPLEXER_AUTOADJUST_BITRATE during creating IMFASFWriter manually but since I already have a working code besides settings this flag by using Transcode API, if possible I want to keep current way.
If anybody has any clue/solution/workaround, please let me know.

Answer 1

You should be able to query for IPropertyStore of to the ASF File Sink from the Sink Writer directly using GetServiceForStream and specifying MF_SINK_WRITER_MEDIASINK like this:
pSinkWriter->GetServiceForStream(MF_SINK_WRITER_MEDIASINK, GUID_NULL, IID_PPV_ARGS(&pPropertyStore));
where pPropertyStore points to an IPropertyStore.
After that you should set the MFPKEY_ASFMEDIASINK_AUTOADJUST_BITRATE property as explained here