求教direct show摄像头视频提取问题

Question

出学directshow，用它做了个小程序，可以实现摄像头视频提取，可在windows界面播放。好像可以设置图像的祯率，请教各位，directshow中提供接口设置输出影像分辨率的大小了吗？如果可行，怎么设置呢？多谢各位指点

Answer 1

使用IVideoWindow来设置。
CComQIPtr< IVideoWindow, &IID_IVideoWindow > pWindow
pWindow->put_Left( 0 );
pWindow->put_Top( 0 );
pWindow->put_Width(xxwide);
pWindow->put_Height(xxhigh);

Answer 2

调出属性页进行设置
用DXshow的例子AMCAP的代码            else if(id - MENU_DIALOG0 == gcap.iVCapCapturePinDialogPos)
            {
                // You can change this pin's output format in these dialogs.
                // If the capture pin is already connected to somebody who's 
                // fussy about the connection type, that may prevent using 
                // this dialog(!) because the filter it's connected to might not
                // allow reconnecting to a new format. (EG: you switch from RGB
                // to some compressed type, and need to pull in a decoder)
                // I need to tear down the graph downstream of the
                // capture filter before bringing up these dialogs.
                // In any case, the graph must be STOPPED when calling them.
                if(gcap.fWantPreview)
                    StopPreview();  // make sure graph is stopped                // The capture pin that we are trying to set the format on is connected if
                // one of these variable is set to TRUE. The pin should be disconnected 
                // for the dialog to work properly.
                if(gcap.fCaptureGraphBuilt || gcap.fPreviewGraphBuilt)
                {
                    DbgLog((LOG_TRACE,1,TEXT("Tear down graph for dialog")));
                    TearDownGraph();    // graph could prevent dialog working
                }                IAMStreamConfig *pSC;
                hr = gcap.pBuilder->FindInterface(&PIN_CATEGORY_CAPTURE,
                    &MEDIATYPE_Interleaved, gcap.pVCap,
                    IID_IAMStreamConfig, (void **)&pSC);                if(hr != NOERROR)
                    hr = gcap.pBuilder->FindInterface(&PIN_CATEGORY_CAPTURE,
                        &MEDIATYPE_Video, gcap.pVCap,
                        IID_IAMStreamConfig, (void **)&pSC);                ISpecifyPropertyPages *pSpec;
                CAUUID cauuid;                hr = pSC->QueryInterface(IID_ISpecifyPropertyPages,
                    (void **)&pSpec);                if(hr == S_OK)
                {
                    hr = pSpec->GetPages(&cauuid);
                    hr = OleCreatePropertyFrame(ghwndApp, 30, 30, NULL, 1,
                        (IUnknown **)&pSC, cauuid.cElems,
                        (GUID *)cauuid.pElems, 0, 0, NULL);                    // !!! What if changing output formats couldn't reconnect
                    // and the graph is broken?  Shouldn't be possible...                    if(gcap.pVSC)
                    {
                        AM_MEDIA_TYPE *pmt;
                        // get format being used NOW
                        hr = gcap.pVSC->GetFormat(&pmt);                        // DV capture does not use a VIDEOINFOHEADER
                        if(hr == NOERROR)
                        {
                            if(pmt->formattype == FORMAT_VideoInfo)
                            {
                                // resize our window to the new capture size
                                ResizeWindow(HEADER(pmt->pbFormat)->biWidth,
                                    abs(HEADER(pmt->pbFormat)->biHeight));
                            }
                            DeleteMediaType(pmt);
                        }
                    }                    CoTaskMemFree(cauuid.pElems);
                    pSpec->Release();
                }                pSC->Release();
                if(gcap.fWantPreview)
                {
                    BuildPreviewGraph();
                    StartPreview();
                }
            }
            else if(id - MENU_DIALOG0 == gcap.iVCapPreviewPinDialogPos)
            {
                // this dialog may not work if the preview pin is connected
                // already, because the downstream filter may reject a format
                // change, so we better kill the graph. (EG: We switch from 
                // capturing RGB to some compressed fmt, and need to pull in
                // a decompressor)
                if(gcap.fWantPreview)
                {
                    StopPreview();
                    TearDownGraph();
                }                IAMStreamConfig *pSC;                // This dialog changes the preview format, so it might affect
                // the format being drawn.  Our app's window size is taken
                // from the size of the capture pin's video, not the preview
                // pin, so changing that here won't have any effect. All in all,
                // this probably won't be a terribly useful dialog in this app.
                hr = gcap.pBuilder->FindInterface(&PIN_CATEGORY_PREVIEW,
                                                  &MEDIATYPE_Interleaved, gcap.pVCap,
                                                  IID_IAMStreamConfig, (void **)&pSC);
                if (hr != NOERROR)
                {
                    hr = gcap.pBuilder->FindInterface(&PIN_CATEGORY_PREVIEW,
                        &MEDIATYPE_Video, gcap.pVCap,
                        IID_IAMStreamConfig, (void **)&pSC);
                }                ISpecifyPropertyPages *pSpec;
                CAUUID cauuid;                hr = pSC->QueryInterface(IID_ISpecifyPropertyPages,
                    (void **)&pSpec);

                if(hr == S_OK)
                {
                    hr = pSpec->GetPages(&cauuid);                    hr = OleCreatePropertyFrame(ghwndApp, 30, 30, NULL, 1,
                        (IUnknown **)&pSC, cauuid.cElems,
                        (GUID *)cauuid.pElems, 0, 0, NULL);                    CoTaskMemFree(cauuid.pElems);
                    pSpec->Release();
                }                pSC->Release();
                if(gcap.fWantPreview)
                {
                    BuildPreviewGraph();
                    StartPreview();
                }
            }

Answer 3

1.定义IAMStreamConfig InterfaceIAMStreamConfig *pConfig;2.初始化IAMStreamConfig Interfacehr = pBuild->FindInterface(&PIN_CATEGORY_CAPTURE,&MEDIATYPE_Interleaved,pCap,IID_IAMStreamConfig,(void **)&pConfig);// 这pBuild是一个ICaptureGraphBuilder2 Interface.  if( hr != NOERROR )
  {
   hr = pBuild->FindInterface(&PIN_CATEGORY_CAPTURE,&MEDIATYPE_Video,pCap,IID_IAMStreamConfig,(void **)&pConfig);
   if(hr == NOERROR)
    AfxMessageBox("load config filter succeed!");
   else
   {
    AfxMessageBox("load config filter failed!");
    return;
   }
  }3.设置参数(取原来的参数,修改想要改变的部分)AM_MEDIA_TYPE * mmt;pConfig->GetFormat(&mmt);    //取得默认参数VIDEOINFOHEADER * vvih = (VIDEOINFOHEADER*) mmt->pbFormat;AM_MEDIA_TYPE * pmt = mmt;VIDEOINFOHEADER * pvih = (VIDEOINFOHEADER*) pmt->pbFormat;pvih->bmiHeader.biHeight=288;  //修改采集视频的高为288
pvih->bmiHeader.biWidth=352;   //修改采集视频的宽为352pmt->pbFormat = (unsigned char *) pvih;pConfig->SetFormat(pmt);   //重新设置参数这样,DirectShow采集的视频的Data Flow被设置为宽为352,高为288..