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我正在引用下面的文檔部分「用於捕獲屏幕的Windows媒體API」來捕獲屏幕，原始代碼工作正常。當我添加額外的功能（我只是添加了幾行來使它從默認音頻設備記錄），它在下面的行失敗（我調試，看起來像COM層失敗？），任何提示？我發佈了原始源代碼和修改後的源代碼。無法使用Windows媒體編碼器設置默認音頻設備
「如果（FAILED（HR = pSrcGrp-> put_Profile（variant_t（pProfile））））」
http://www.geocities.com/krishnapg/screencap.html
原始源代碼：
http://www.geocities.com/krishnapg/WMEncScrnCap.zip
我的已修改源代碼（我只修改函數InitEncoder）
HRESULT InitEncoder(LPCTSTR szOutputFileName)
{
HRESULT hr = E_FAIL;
CComVariant varValue;
IWMEncSourceGroupCollection* pSrcGrpCollection=NULL;
IWMEncSourceGroup* pSrcGrp=NULL;
IWMEncSource* pSrc=NULL;
IWMEncSource* paSrc=NULL;
IPropertyBag* pPropertyBag=NULL;
IWMEncVideoSource2* pSrcVid=NULL;
IWMEncAudioSource* pSrcAud=NULL;
IWMEncFile* pOutFile=NULL;
IWMEncProfile* pProfile=NULL;
if(FAILED(CoCreateInstance(CLSID_WMEncoder,NULL,CLSCTX_INPROC_SERVER,IID_IWMEncoder2,(void**)&g_pEncoder)))
{
ErrorMessage("Unable to Create Encoder Object");
return E_FAIL;
}
if(FAILED(g_pEncoder->get_SourceGroupCollection(&pSrcGrpCollection))) //Retrieve the Source Group Collection - One Application can Have many Source Groups - We need to add as many as we want
{
ErrorMessage("Unable to Get Source Group Collection");
return E_FAIL;
}
do
{
if(FAILED(hr=pSrcGrpCollection->Add(CComBSTR("SourceGroup1"),&pSrcGrp)))//Add a Source Group to the Collection - Each Source can have one video one audio source input
{
ErrorMessage("Unable to Add A Source Group to the Collection");
break;
}
if(FAILED(hr=pSrcGrp->AddSource(WMENC_VIDEO,&pSrc))) //Add a Video Source to the Group
{
ErrorMessage("Unable to Add A Source to the Source Group");
break;
}
if(FAILED(hr=pSrcGrp->AddSource(WMENC_AUDIO,&paSrc))) //Add an Audio Source to the Group
{
ErrorMessage("Unable to Add A Source to the Source Group");
break;
}
if(FAILED(hr=pSrc->QueryInterface(IID_IWMEncVideoSource2,(void**)&pSrcVid)))
{
ErrorMessage("Unable to Query interface for Video Source");
break;
}
if(FAILED(hr=paSrc->QueryInterface(IID_IWMEncAudioSource,(void**)&pSrcAud)))
{
ErrorMessage("Unable to Query interface for Audio Source");
break;
}
if(FAILED(hr=pSrcVid->SetInput(CComBSTR("ScreenCap://ScreenCapture1"))))//The Video Input Source Device - Should be "ScreenCap" Device
{
ErrorMessage("Unable to Set Video Input Source");
break;
}
if(FAILED(hr=pSrcAud->SetInput(CComBSTR("Device://Default_Audio_Device"))))//The Video Input Source Device - Should be "Default_Audio_Device" Device
{
ErrorMessage("Unable to Set Audio Input Source");
break;
}
if(FAILED(hr=pSrcVid->QueryInterface(IID_IPropertyBag,(void**)&pPropertyBag)))
{
ErrorMessage("Unable to Query Interface for Propery bag");
break;
}
varValue = CAPTURE_FULLSCREEN;
if(FAILED(hr=pPropertyBag->Write(WMSCRNCAP_ENTIRESCREEN,&varValue))) //Set Full Screen Property true/false
{
ErrorMessage("Unable to Set Capture Screen Property");
break;
}
//int nLeft, nRight, nTop, nBottom; //Set Capture Area - when not in full screen mode
// // Initialize the capture area. The size must be even.
// varValue = false;
// if (SUCCEEDED(hr))
// {
// hr = pPropertyBag->Write(WMSCRNCAP_ENTIRESCREEN, &varValue);
// }
// varValue = nLeft;
// if (SUCCEEDED(hr))
// {
// hr = pPropertyBag->Write(WMSCRNCAP_WINDOWLEFT, &varValue);
// }
// varValue = nRight;
// if (SUCCEEDED(hr))
// {
// hr = pPropertyBag->Write(WMSCRNCAP_WINDOWRIGHT, &varValue);
// }
// varValue = nTop;
// if (SUCCEEDED(hr))
// {
// hr = pPropertyBag->Write(WMSCRNCAP_WINDOWTOP, &varValue);
// }
// varValue = nBottom;
// if (SUCCEEDED(hr))
// {
// hr = pPropertyBag->Write(WMSCRNCAP_WINDOWBOTTOM, &varValue);
// }
// varValue = true;
// if (SUCCEEDED(hr))
// {
// hr = pPropertyBag->Write(WMSCRNCAP_FLASHRECT, &varValue);
// }
if(FAILED(hr=SetupScreenCaptureProfile())) //Setup the Custom Profile
{
break;
}
if(FAILED(hr=g_pProfile->QueryInterface(IID_IWMEncProfile,(void**)&pProfile)))
{
ErrorMessage("Unable to Query Interface For Profile");
break;
}
if(FAILED(hr=pSrcGrp->put_Profile(variant_t(pProfile)))) //Select the Custom Profile into the Encoder
{
ErrorMessage("Unable to Set Profile For Source Group");
break;
}
if(FAILED(hr=g_pEncoder->get_File(&pOutFile)))
{
ErrorMessage("Unable to Get Encoder Output File Object");
break;
}
if(FAILED(hr=pOutFile->put_LocalFileName(CComBSTR(szOutputFileName)))) //Set the Target Output Filename
{
ErrorMessage("Unable to Set Output File Name");
break;
}
if(FAILED(hr=g_pEncoder->PrepareToEncode(VARIANT_TRUE))) //Using Prepare optimizes startig latency
{
ErrorMessage("Unable to Prepare for Encoding");
break;
}
}while(false);
if(pProfile)
{
pProfile->Release();
pProfile=NULL;
}
if(pOutFile)
{
pOutFile->Release();
pOutFile = NULL;
}
if(pPropertyBag)
{
pPropertyBag->Release();
pPropertyBag = NULL;
}
if(pSrcVid)
{
pSrcVid->Release();
pSrcVid = NULL;
}
if(pSrc)
{
pSrc->Release();
pSrc = NULL;
}
if(pSrcGrp)
{
pSrcGrp->Release();
pSrcGrp = NULL;
}
if(pSrcGrpCollection)
{
pSrcGrpCollection->Release();
pSrcGrpCollection = NULL;
}
return hr;
}
故障代碼是非常重要的 - 在這裏不提供。配置文件參數可能不正確 - 「SetupScreenCaptureProfile」沒有顯示準確的準備。 – 2014-05-31 13:44:48