Windows Media Foundation 录制音频

I'm using the windows media foundation api to enumerate both my microphones and available cameras, which both work.

这是我的枚举代码:

class deviceInput {
public:
    deviceInput( REFGUID source );
    ~deviceInput();

    int listDevices(bool refresh = false);
    IMFActivate *getDevice(unsigned int deviceId);
    const WCHAR *getDeviceName(unsigned int deviceId);

private:
    void Clear();
    HRESULT EnumerateDevices();

    UINT32      m_count;
    IMFActivate **m_devices;
    REFGUID     m_source;
};

deviceInput::deviceInput( REFGUID source )
    : m_devices( NULL )
    , m_count( 0 )
    , m_source( source )
{   }

deviceInput::~deviceInput()
{
    Clear();
}

int deviceInput::listDevices(bool refresh)
{
    if ( refresh || !m_devices ) {
        if ( FAILED(this->EnumerateDevices()) ) return -1;
    }
    return m_count;
}

IMFActivate *deviceInput::getDevice(unsigned int deviceId)
{
    if ( deviceId >= m_count ) return NULL;

    IMFActivate *device = m_devices[deviceId];
    device->AddRef();

    return device;
}

const WCHAR *deviceInput::getDeviceName(unsigned int deviceId)
{
    if ( deviceId >= m_count ) return NULL;

    HRESULT hr = S_OK;
    WCHAR *devName = NULL;
    UINT32 length;

    hr = m_devices[deviceId]->GetAllocatedString( MF_DEVSOURCE_ATTRIBUTE_FRIENDLY_NAME, &devName, &length );
    if ( FAILED(hr) ) return NULL;

    return devName;
}

void deviceInput::Clear()
{
    if ( m_devices ) {
        for (UINT32 i = 0; i < m_count; i++) SafeRelease( &m_devices[i] );
        CoTaskMemFree( m_devices );
    }
    m_devices = NULL;
    m_count = 0;
}

HRESULT deviceInput::EnumerateDevices()
{
    HRESULT hr = S_OK;
    IMFAttributes *pAttributes = NULL;

    Clear();

    hr = MFCreateAttributes(&pAttributes, 1);
    if ( SUCCEEDED(hr) ) hr = pAttributes->SetGUID( MF_DEVSOURCE_ATTRIBUTE_SOURCE_TYPE, m_source );
    if ( SUCCEEDED(hr) ) hr = MFEnumDeviceSources( pAttributes, &m_devices, &m_count );

    SafeRelease( &pAttributes );

    return hr;
}

要抓取音频或相机捕获设备，我指定 MF_DEVSOURCE_ATTRIBUTE_SOURCE_TYPE_AUDCAP_GUID 或 MF_DEVSOURCE_ATTRIBUTE_SOURCE_TYPE_VIDCAP_GUID 没有问题，我可以抓取设备的名称，以及IMF 激活.我有将网络摄像头录制到输出视频文件的代码，但是，我很难弄清楚如何将音频录制到文件中.我的印象是我需要使用 IMFSinkWriter，但我找不到任何使用音频捕获 IMFActivate 和 IMFSinkWriter 的示例.

// http://msdn.microsoft.com/en-us/library/windows/desktop/dd388085(v=vs.85).aspx
HRESULT CreateAggregateMediaSource(IMFMediaSource *videoSource,
                                   IMFMediaSource *audioSource,
                                   IMFMediaSource **aggregateSource)
{
    *aggregateSource = nullptr;
    IMFCollection *pCollection = nullptr;

    HRESULT hr = ::MFCreateCollection(&pCollection);

    if (S_OK == hr)
        hr = pCollection->AddElement(videoSource);

    if (S_OK == hr)
        hr = pCollection->AddElement(audioSource);

    if (S_OK == hr)
        hr = ::MFCreateAggregateSource(pCollection, aggregateSource);

    SafeRelease(&pCollection);
    return hr;
}

HRESULT        hr                  = S_OK;
IMFMediaType  *videoInputType      = nullptr;
IMFMediaType  *videoOutputType     = nullptr;
DWORD          videoOutStreamIndex = 0u;
DWORD          audioOutStreamIndex = 0u;
IMFSinkWriter *writer              = nullptr;

// [other create and configure writer]

if (S_OK == hr))
    hr = writer->AddStream(videoOutputType, &videoOutStreamIndex);    

// [more configuration code]

if (S_OK == hr)
    hr = writer->AddStream(audioOutputType, &audioOutStreamIndex);