Decode Mp3 in c++/cx (Universal app)

Question

I'm new to C++/CX so the scenario is next:

I have a universal app windows 8.1 with c#, so I'd like to decode an mp3 from c#. Well I know that I can Use SharpDx, but I just not what to use it, my idea is really simple: using c++/cx and media foundation to decode mp3, and return a stream to c# so for example

from c#

Stream stream = GetMp3Stream("some.mp3"); //a custom method in c#
var audioEng = new AudioEng();   //c++/cx class
var streamOut = audioEng.DecodeMp3(stream);

so my problems are:

1. I dunno how using stream in c++/cx
2. I dunno how decode mp3 in c++/cx

I have found some example in cpp using ComPtr but I'd like to use c++/cx not c++

Answer 1

What do you mean by decoding an MP3?

Depending on what you mean there are several audio API you can use. Take a look at the MediaElement, WASAPI, and XAudio2.

Answer 2

Sorry, yes you right, well

I mean transform to raw audio to MediaPlayer object via stream, because between raw audio and mediaplayer I'd like to apply some filters, well I'd like to use MediaPlayer because I want to use BackgroundMediaPlayer, to achive background player in windows phone 8.1, since in the last release support decoding.

So I should use MediaFoundation (supported now in wp8.1 http://msdn.microsoft.com/en-us/library/windows/apps/dn632424.aspx), to decode mp3 with decoding class in windows api.

thanks again

Answer 3

Hello,

Media Foundation allows you to write plug-ins to transform the audio (i.e. DSP). These plug-ins must be written in C++. Currently we do not support audio or video transforms directly from C#. There are a number of reasons for this but nondeterministic finalization is at the top of the list.

You can use the MediaElement (C#) to play the audio and add your plug-in (C++) to the underlying MF topology using AddAudioEffect.

MediaElement.AddAudioEffect

http://msdn.microsoft.com/en-us/library/windows/apps/windows.ui.xaml.controls.mediaelement.addaudioeffect.aspx

Writing a Custom MFT

http://msdn.microsoft.com/en-us/library/windows/desktop/dd940441(v=vs.85).aspx

I hope this helps,

James

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