How to use WASPAI Capture in Metro style apps

Question

Since the WASAPI is surpported in Metro style apps, I tried it:

Platform::String^ id = Windows::Media::Devices::MediaDevice::GetDefaultAudioCaptureId( Windows::Media::Devices::AudioDeviceRole::Console );

Microsoft::WRL::ComPtr<IAudioClient> pAudioClient = NULL;

ActivateAudioInterface( id->Data(), __uuidof( IAudioClient ), (void**)&pAudioClient );

WAVEFORMATEX *pDeviceFormat = NULL;

pAudioClient->GetMixFormat( &pDeviceFormat );

All of above are success !

HRESULT hr = pAudioClient->Initialize( AUDCLNT_SHAREMODE_SHARED, AUDCLNT_STREAMFLAGS_EVENTCALLBACK, 0, 0,  pDeviceFormat  , NULL);

BUT,   ***  IAudioClient::Initialize ***    failed!!!!     the Error code is ( E_ACCESSDENIED 0x80070005 ).

BUT, if I check the "Microphone" in Package.appxmanifest -- Capabilities , the Error is 0x8000FFFF.

Help me please !

Answer 1

I do not see in your code where you are initializing COM.  Are you doing this?

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Jeff Sanders (MSFT)

Answer 2

What a Strange thing! I create a new project, and check the "Microphone" in Capabilities. And now it does not return error, but it hangs in method IAudioClient::Initialize. When I stop debugging, a dialog, which askes whether to allow using the Mricophone, flashes on the screen. How can I make that dialog appear in the beginning.

Answer 3

I do not see in your code where you are initializing COM.  Are you doing this?

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Jeff Sanders (MSFT)

Hi Jeff, I has the same question, can I send you a demo? It's my email: linyehui#live.com

Answer 4

If you are still having this issue please let me know and I will do what I can to help.

-James

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

Answer 5

I need help here. Is the above code for windows 8? They are not compiling for me.

Answer 6

Well now, I can compile the code. But IAudioClient->initialize hangs too. I don't see the dialog to ask for permission to use the microphone either.

Answer 7

I figured the IAudioClient->initialize issue. Except checking the "Microphone" in Capabilities, you also need to set the permission in system settings. Start the application (comment out the hanging part of the code, just run the blank application), choose settings charm to set the permission for microphone. go back to code to uncomment the initialize code, run the application again. It should work now.

Answer 8

Just following up on this thread now that I am back in the office. Do you have everything you need? Was your previous post a good solution for you?

-James

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

Answer 9

Yes, James. This problem is resolved. But I have another issue which I am still waiting for reply. Please see my thread here:

http://social.msdn.microsoft.com/Forums/bs-Cyrl-BA/winappswithcsharp/thread/34b081ba-0c4c-49f4-8353-c915b2e26cc3

Answer 10

I replied on the referenced thread.

-James

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

Answer 11

Great, this has helped!

I have another question, concerning IAudioClient->Initialize, although it seems to work for now. The WASAPI documentation states:

Note  In Windows 8 Consumer Preview, the first use of IAudioClient to access the audio device should be on the STA thread. Calls from an MTA thread may result in undefined behavior.

But C++ threads are MTA by default and this doesn't seem to work:

using namespace Windows::Foundation;
using namespace Platform;

[Threading(ThreadingModel=ThreadingModel::STA] 
public ref class MySTAClass
{
};

Intellisense declares Error: Attributes are not allowed here.

Answer 12

Make sure it is initialized and used on the main UI thread if you are using XAML in C++.

-James

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

Answer 13

Hi,

Following several threads on how to use WASAPI in Metro Style Apps, I still have many issues understanding how it works:

What is "ActivateAudioInterface" ? never found it in MSDN except forums, and can't make it work either.

Thanks,
~Jerome

Answer 14

Jerome,

This is now:

ActivateAudioInterfaceAsync

Best Wishes - Eric

Answer 15

Jerome & Community,

The API has not been indexed by the MSDN index server. The documentation can be found here:

ActivateAudioInterfaceAsync function

http://msdn.microsoft.com/en-us/library/windows/desktop/jj128298(v=vs.85).aspx

-James

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

Answer 16

For Jerome & Community.  Pay special attention to the remarks section for ActivateAudioInterfaceAsync it should save you a lot of time.