Create IMFByteStream from byte array - c++

Question

I am trying to adapt a method that originally took a URL from Microsoft's MediaFoundation audio playback sample to instead take a source from a const char* array. Problem is, CreateObjectFromByteStream requires an IMFByteStream, not a const char*. How can I get what I need?
// Create a media source from a byte stream
HRESULT CreateMediaSource(const byte *data, IMFMediaSource **ppSource)
{
MF_OBJECT_TYPE ObjectType = MF_OBJECT_INVALID;
IMFSourceResolver* pSourceResolver = NULL;
IUnknown* pSource = NULL;
// Create the source resolver.
HRESULT hr = MFCreateSourceResolver(&pSourceResolver);
if (FAILED(hr))
{
goto done;
}
// Use the source resolver to create the media source.
// Note: For simplicity this sample uses the synchronous method to create
// the media source. However, creating a media source can take a noticeable
// amount of time, especially for a network source. For a more responsive
// UI, use the asynchronous BeginCreateObjectFromURL method.
hr = pSourceResolver->CreateObjectFromByteStream(data,
NULL, // URL of the source.
MF_RESOLUTION_MEDIASOURCE | MF_BYTESTREAM_CONTENT_TYPE, // Create a source object.
NULL, // Optional property store.
&ObjectType, // Receives the created object type.
&pSource // Receives a pointer to the media source.
);
if (FAILED(hr))
{
goto done;
}
// Get the IMFMediaSource interface from the media source.
hr = pSource->QueryInterface(IID_PPV_ARGS(ppSource));
done:
SafeRelease(&pSourceResolver);
SafeRelease(&pSource);
return hr;
}

Answer 1

I found easiest way to do this to just create tempfile and write *data there. Ugly hack, but worked good enough for me and if needed it can easily replaced by custom inmemory IMFByteStream implementation.
So code would be something like this:
Byte data[] = {'a','b','c','d','e','f'};
HRESULT hr = S_OK;
hr = MFStartup(MF_VERSION);
IMFByteStream *stream = NULL;
hr = MFCreateTempFile(
MF_ACCESSMODE_READWRITE,
MF_OPENMODE_DELETE_IF_EXIST,
MF_FILEFLAGS_NONE,
&stream
);
ULONG wroteBytes = 0;
stream->Write(data, sizeof(data), &wroteBytes);
stream->SetCurrentPosition(0);
// make sure that wroteBytes is equal with data length

Answer 2

You can use MFCreateMFByteStreamOnStream() to create an IMFByteStream from an IStream and you can create and IStream from a byte array using SHCreateMemStream(). The documentation at the time of writing is at https://learn.microsoft.com/en-us/windows/win32/api/mfidl/nf-mfidl-mfcreatemfbytestreamonstream and https://learn.microsoft.com/en-us/windows/win32/api/shlwapi/nf-shlwapi-shcreatememstream
Here's a quick example:
// Generate a byte array
int sample_size = 0x100;
BYTE* sample_bytes = (BYTE*)malloc(sample_size)
// Create the IStream from the byte array
IStream* pstm = SHCreateMemStream(sample_bytes, sample_size);
// Create the IMFByteStream from the IStream
IMFByteStream* pibs = NULL;
MFCreateMFByteStreamOnStream(pstm, &pibs);
// Clean up time
if (pibs)
pibs->Close();
if (pstm)
pstm->Release();
if (sample_bytes)
free(sample_bytes)
Having an IStream interface but not a byte array interface seems to be a frequent occurrence in the Microsoft API. Thankfully creating an IStream is easy.