如何设置摄像头捕获图像的宽高，或实时改变捕获图像流数据的宽高要求效率高

HRESULT CCaptureVideo::Init(int iDeviceID, HWND hWnd)
{
HRESULT hr;
hr = InitCaptureGraphBuilder();
if (FAILED(hr))
{
AfxMessageBox("Failed to get video interfaces!");
return hr;
}
// Bind Device Filter. We know the device because the id was passed in
if(!BindFilter(iDeviceID, &m_pBF))return S_FALSE;
hr = m_pGB->AddFilter(m_pBF, L"Capture Filter");
// hr = m_pCapture->RenderStream(&PIN_CATEGORY_PREVIEW, &MEDIATYPE_Video,
// m_pBF, NULL, NULL);
// create a sample grabber
hr = m_pGrabber.CoCreateInstance( CLSID_SampleGrabber );
if( !m_pGrabber )
{
AfxMessageBox("Fail to create SampleGrabber, maybe qedit.dll is not registered?");
return hr;
}
CComQIPtr< IBaseFilter, &IID_IBaseFilter > pGrabBase( m_pGrabber );
//设置视频格式
AM_MEDIA_TYPE mt;
ZeroMemory(&mt, sizeof(AM_MEDIA_TYPE));
mt.majortype = MEDIATYPE_Video;
mt.subtype = MEDIASUBTYPE_RGB24;
hr = m_pGrabber->SetMediaType(&mt);
if( FAILED( hr ))
{
AfxMessageBox("Fail to set media type!");
return hr;
}
hr = m_pGB->AddFilter( pGrabBase, L"Grabber" );
if( FAILED( hr ) )
{
AfxMessageBox("Fail to put sample grabber in graph");
return hr;
}
// try to render preview/capture pin
hr = m_pCapture->RenderStream(&PIN_CATEGORY_PREVIEW, &MEDIATYPE_Video,m_pBF,pGrabBase,NULL);
if( FAILED( hr ) )
hr = m_pCapture->RenderStream(&PIN_CATEGORY_CAPTURE, &MEDIATYPE_Video,m_pBF,pGrabBase,NULL);
if( FAILED( hr ) )
{
AfxMessageBox("Can't build the graph");
return hr;
}
hr = m_pGrabber->GetConnectedMediaType(&mt);
if ( FAILED( hr) )
{
AfxMessageBox("Failt to read the connected media type");
return hr;
}
VIDEOINFOHEADER * vih = (VIDEOINFOHEADER*) mt.pbFormat;
mCB.lWidth = vih->bmiHeader.biWidth;
mCB.lHeight = vih->bmiHeader.biHeight;
FreeMediaType(mt);
hr = m_pGrabber->SetBufferSamples( FALSE );
hr = m_pGrabber->SetOneShot( FALSE );
hr = m_pGrabber->SetCallback( &mCB, 1 );
//设置视频捕捉窗口
m_hWnd = hWnd ;
SetupVideoWindow();
hr = m_pMC->Run();//开始视频捕捉
if(FAILED(hr)){AfxMessageBox("Couldn't run the graph!");return hr;}
return S_OK;
}
或在流里如何改变
class CSampleGrabberCB : public ISampleGrabberCB
{
public:
long lWidth;
long lHeight;
TCHAR m_szFileName[MAX_PATH];// 位图文件名称
CSampleGrabberCB()
{
strcpy(m_szFileName, "c:\\donaldo.bmp");
}
STDMETHODIMP_(ULONG) AddRef() { return 2; }
STDMETHODIMP_(ULONG) Release() { return 1; }
STDMETHODIMP QueryInterface(REFIID riid, void ** ppv)
{
if( riid == IID_ISampleGrabberCB || riid == IID_IUnknown )
{
*ppv = (void *) static_cast<ISampleGrabberCB*> ( this );
return NOERROR;
}
return E_NOINTERFACE;
}
STDMETHODIMP SampleCB( double SampleTime, IMediaSample * pSample )
{
return 0;
}
STDMETHODIMP BufferCB( double dblSampleTime, BYTE * pBuffer, long lBufferSize )
{
if( !bOneShot)
return 0;
if(!pBuffer)return E_POINTER;
SaveBitmap(pBuffer, lBufferSize);//如何快速改变流的宽高因为要用于实际时数据传输
bOneShot = FALSE;
return 0;
}
//创建位图文件
BOOL SaveBitmap(BYTE * pBuffer, long lBufferSize )
{
HANDLE hf = CreateFile(
m_szFileName, GENERIC_WRITE, FILE_SHARE_READ, NULL,
CREATE_ALWAYS, NULL, NULL );
if( hf == INVALID_HANDLE_VALUE )
return 0;
// 写文件头
BITMAPFILEHEADER bfh;
memset( &bfh, 0, sizeof( bfh ) );
bfh.bfType = 'MB';
bfh.bfSize = sizeof( bfh ) + lBufferSize + sizeof( BITMAPINFOHEADER );
bfh.bfOffBits = sizeof( BITMAPINFOHEADER ) + sizeof( BITMAPFILEHEADER );
DWORD dwWritten = 0;
WriteFile( hf, &bfh, sizeof( bfh ), &dwWritten, NULL );
// 写位图格式
BITMAPINFOHEADER bih;
memset( &bih, 0, sizeof( bih ) );
bih.biSize = sizeof( bih );
bih.biWidth = lWidth;
bih.biHeight = lHeight;
bih.biPlanes = 1;
bih.biBitCount = 24;
WriteFile( hf, &bih, sizeof( bih ), &dwWritten, NULL );
// 写位图数据
WriteFile( hf, pBuffer, lBufferSize, &dwWritten, NULL );
CloseHandle( hf );
return 0;
}
};