custom MFT in windows phone app

Question

I need to create a custom MFT because it's the only way to get raw frames in YUV format on windows phone 8.1 (Runtime, no silverlight).

I know it's not easy but I don't have any other choice.

I'm trying to learn for the example of GrayscaleTransform: https://code.msdn.microsoft.com/windowsapps/Media-Capture-Sample-adf87622

But I don't really understand how does it work. The only thing I see which has a reference on the C++ Grayscale in the Application is :

_mediaCaptureMgr.AddEffectAsync(Windows.Media.Capture.MediaStreamType.Photo,"GrayscaleTransform.GrayscaleEffect", null);

There isn't any instance of the Grayscale created, or any called to any methods. So, I'm wondering how does is work ?

Thanks,

Sebastien

Answer 1

The MediaCapture sample registers GrayscaleTransform.GrayscaleEffect in its Pakage.appxmanifest, line 35:

<Extension Category="windows.activatableClass.inProcessServer">
  <InProcessServer>
    <Path>GrayscaleTransform.dll</Path>
    <ActivatableClass ActivatableClassId="GrayscaleTransform.GrayscaleEffect" ThreadingModel="both" />
  </InProcessServer>
</Extension>

This lets the MediaCapture object find the added effect and add it to the media pipeline.

An app can also register MFTs with the MediaExtensionManager class.

Answer 2

I think you are asking where can you find the Grayscale cpp file itself. In the solution explorer you can find it under MediaExtensions/MFExtensions/GrayscaleTransform/GrayscaleTransform.Shared/

There you will see Grayscale.cpp and all of its functions. Hopefully viewing those will help.