How to get a SourceReader to decompress frames and send them to a Direct3D9 texture?

I am trying to get a MediaFoundation SourceReader to read an H.264 video file, and render the frames to some Direct3D textures so I can them render them as I wish with Direct3D.

I'm using SharpDX, but the principles are of course the same as native code.

As I understand it, the general data flow should be like this:

1. A SourceReader reads and decodes the video using SourceReader.ReadSample()
2. A VideoProcessor (from IDirect3DDeviceManager9) transfers the frame to a Direct3D9 surface using VideoProcessor.VideoProcessBlt()
3. My Direct3D9 renderer uses the surface to render the frame however I want onto the screen

If this is how it's supposed to work, I've pretty much have it figured out, and almost running.

I was able to decode frames from H.264 to X8R8G8B8 by setting EnableVideoProcessing when I created my SourceReader:

MediaFactory.CreateAttributes(mediaAttributes, 0);
mediaAttributes.Set(SourceReaderAttributeKeys.EnableVideoProcessing, 1);
MediaFactory.CreateSourceReaderFromURL(url, mediaAttributes, SourceReader);

And by setting the media type subtype to the X8R8G8B8 GUID for the video stream:

VideoSubType = currentMediaType.Get<Guid>(MediaTypeAttributeKeys.Subtype);
UnpackLong(currentMediaType.Get(MediaTypeAttributeKeys.FrameSize), out VideoWidth, out VideoHeight);
UnpackLong(currentMediaType.Get(MediaTypeAttributeKeys.FrameRate), out VideoFrameRateNumerator, out VideoFrameRateDenominator);
VideoInterlaceMode = (VideoInterlaceMode)(uint)(currentMediaType.Get(MediaTypeAttributeKeys.InterlaceMode));

MediaFactory.CreateMediaType(outputMediaType);
outputMediaType.Set(MediaTypeAttributeKeys.MajorType, MediaTypeGuids.Video);
outputMediaType.Set(MediaTypeAttributeKeys.Subtype, VideoSubType);
outputMediaType.Set(MediaTypeAttributeKeys.FrameSize.Guid, PackLong(VideoWidth, VideoHeight));
outputMediaType.Set(MediaTypeAttributeKeys.FrameRate.Guid, PackLong(VideoFrameRateNumerator, VideoFrameRateDenominator));
outputMediaType.Set(MediaTypeAttributeKeys.InterlaceMode.Guid, VideoInterlaceMode);
outputMediaType.Set(MediaTypeAttributeKeys.PixelAspectRatio.Guid, PackLong(1, 1));

SourceReader.SetCurrentMediaType(streamIndex, outputMediaType);

Later, when I call ReadSample(), I am getting video and audio samples, so I think the decoding process is working fine.

However, in order to get VideoProcessor-compatible frames, I need to create my SourceReader, setting the D3DManager on the media attributes, and also make sure DXVA is not disabled:

mediaAttributes.Set(SourceReaderAttributeKeys.D3DManager, VideoConnector.GetManager());
mediaAttributes.Set(SourceReaderAttributeKeys.DisableDxva, 0);

The problem is that CreateSourceReaderFromURL fails (0x80070057) when I set both EnableVideoProcessing and D3DManager. This is implied by the D3DManager reference:

You would not set this attribute if [...] you are getting compressed video from the source reader. In that case, the source reader does not create a decoder.

Supposing I could decode the frames later (perhaps with a VideoDecoder?), I tried removing EnableVideoProcessing and just leave D3DManager and DisableDxva, but in that case, it's ReadSample that fails (0xC00D36B4) even before I get a chance to use the data in the sample.

So how am I supposed to read, decode and send my frames to the Direct3D surface?

Please take a look at the MFCaptureToFile sample project in the SDK, there it configures the source reader to output the frames in the desired format. The method ConfigureSourceReader() does that.