How to multiplex audio streams by using Media Foundation in a Store app.

Question

Dear all,

    As you know, the MFTEnumEx function is unsupported in the Windows Store Apps. As a result, I can not enumerate the existing MFTs. Is there any other way to get the Multiplexer? If no, how to write such a custom Multiplexer? Any reference is help. Thank you.

Answer 1

Hello,

It is certainly possible to write a custom multiplexer. The streams on an MFT are not represented as distinct COM objects. Instead, each stream has a designated stream identifier, and the methods in the IMFTransform interface take stream identifiers as input parameters. Override IMFTransform::GetStreamIDs  to return your particular pattern of inputs and outputs.

IMFTransform::GetStreamIDs

http://msdn.microsoft.com/en-us/library/windows/desktop/ms693988(v=vs.85).aspx

I hope this helps,

James

---

Windows SDK Technologies - Microsoft Developer Services - http://blogs.msdn.com/mediasdkstuff/

Answer 2

Dear James,

I'm afraid I made a mistake. What I want to do is to merge two videos. The last 3 seconds of the first video and the first 3 seconds of the second video will be played at the same time. So I should mix the audio streams and apply a crossfade effect on video sterams. The topology may be like this:

audio stream1

                     \

                       audio mixer(MFT)

                      /                       \

audio stream2                             \

                                                    target file

video stream1                             /

                     \                         /

                      crossfade MFT

                     /

video stream2

Is this right? Is there a built-in audio-mixer MFT can be retrieved in Windows Store App.

Answer 3

Hi Aragorn,

Sorry to bother you.

I'm doing the same thing right now. And I have the same question. Did you get the solution?

Thank you.