Windows Media Foundation枚舉音頻設備

我使用Microsoft MSDN提供的教程來枚舉音頻設備。Windows Media Foundation枚舉音頻設備

這是枚舉代碼：

HRESULT CreateAudioDeviceSource(IMFMediaSource **ppSource) 
{ 
    *ppSource = NULL; 

    IMFMediaSource *pSource = NULL; 
    IMFAttributes *pAttributes = NULL; 
    IMFActivate **ppDevices = NULL; 

    // Create an attribute store to specify the enumeration parameters. 
    HRESULT hr = MFCreateAttributes(&pAttributes, 1); 
    if (FAILED(hr)) 
    { 
     goto done; 
    } 

    // Source type: audio capture devices 
    hr = pAttributes->SetGUID(
     MF_DEVSOURCE_ATTRIBUTE_SOURCE_TYPE, 
     MF_DEVSOURCE_ATTRIBUTE_SOURCE_TYPE_AUDCAP_GUID 
     ); 
    if (FAILED(hr)) 
    { 
     goto done; 
    } 

    // Enumerate devices. 
    UINT32 count; 
    hr = MFEnumDeviceSources(pAttributes, &ppDevices, &count); 

    std::cout << count; 



    if (FAILED(hr)) 
    { 
     std::cout << "Enum Failed"; 
     goto done; 
    } 

    if (count == 0) 
    { 
     std::cout << "empty"; 
     hr = E_FAIL; 
     goto done; 
    } 

    // Create the media source object. 
    hr = ppDevices[0]->ActivateObject(IID_PPV_ARGS(&pSource)); 
    if (FAILED(hr)) 
    { 
     goto done; 
    } 


    *ppSource = pSource; 
    (*ppSource)->AddRef(); 

done: 
    SafeRelease(&pAttributes); 

    for (DWORD i = 0; i < count; i++) 
    { 
     SafeRelease(&ppDevices[i]); 
    } 
    CoTaskMemFree(ppDevices); 
    SafeRelease(&pSource); 
    return hr; 
}

但我沒能調用函數枚舉設備。我收到消息「Enum Failed」。所以我不知道問題發生的原因。

請非常感謝！

參考：適用於Windows媒體基金會https://msdn.microsoft.com/en-us/library/dd317912(v=vs.85).aspx

來源

2017-02-28 bcuzit

我想你應該用['MFStartup']（https://msdn.microsoft.com/en-us/library/windows/desktop/ms702238）和'MFShutdown'調用將本教程片段包圍起來。如果你報告失敗，你還應該包括'hr'代碼的值。 –

我會嘗試你的建議。非常感謝。 – bcuzit

示例代碼枚舉音頻設備，該設備捕捉struct

struct CaptureDeviceParam 
{ 
    /// <summary> 
    /// The array of devices. 
    /// </summary> 
    IMFActivate **ppDevices; 
    /// <summary> 
    /// Device count. 
    /// </summary> 
    UINT32  count; 
    /// <summary> 
    /// Device selection. 
    /// </summary> 
    UINT32  selection; 
};

而且enum設備的方法。

 /// <summary> 
     /// Get the audio capture devices. 
     /// </summary> 
     /// <param name="param">The capture device param.</param> 
     void MediaCapture::GetAudioCaptureDevices(CaptureDeviceParam *param) 
     { 
      HRESULT hr = S_OK; 
      IMFAttributes *pAttributes = NULL; 

      // Initialize an attribute store to specify enumeration parameters. 
      hr = MFCreateAttributes(&pAttributes, 1); 

      // Ask for source type = audio capture devices 
      if (SUCCEEDED(hr)) 
      { 
       // Set the device attribute. 
       hr = pAttributes->SetGUID(
        MF_DEVSOURCE_ATTRIBUTE_SOURCE_TYPE, 
        MF_DEVSOURCE_ATTRIBUTE_SOURCE_TYPE_AUDCAP_GUID 
       ); 
      } 

      // Enumerate devices. 
      if (SUCCEEDED(hr)) 
      { 
       // Enumerate the device list. 
       hr = MFEnumDeviceSources(pAttributes, &(*param).ppDevices, &(*param).count); 
      } 

      // Safe release. 
      SafeRelease(&pAttributes); 
     }

GetAudioCaptureDevices是在「MediaCapture」類的靜態方法，它可以在任何時間被調用。

來源

2017-03-05 00:27:02

Windows Media Foundation枚舉音頻設備

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