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POc++ builder: convert video to png-snapshots with directshow
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12006656
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12019279
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2012-08-17T13:21:25.987
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2012-08-18T20:47:54.147
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2012-08-18T20:47:54.147
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Thanks to your help I was able to search for the right words to use directshow a bit better. I found a tutorial how to use the SampleGrabber-object here: <a href="http://msdn.microsoft.com/en-us/library/windows/desktop/dd407288%28v=vs.85%29.aspx" rel="nofollow">http://msdn.microsoft.com/en-us/library/windows/desktop/dd407288%28v=vs.85%29.aspx</a> I could implement it and modified it a bit so it isn't just saving the first frame, but every Frame to a PNG. For that I use corona. However, I just guessed something around and don't quite know which buffers are containing my data and in which form. So, I have basically 3 questions: Am I using SavePNG right? the resulting Images are upside-down! Can I replace the BaseFilter for the video with one that is connected to a camera? Contains pBuffer my Imagedata so I can get rgb-byte-informations by simply type pBuffer[123]? I'm using embarcadero's C++-Builder (XE2 16). Here is the code I found at the website, a bit modified (error-handling removed for better view. after each hr=... there is a Failed-check): <pre><code>void __fastcall TForm1::btn_kameraClick(TObject *Sender) { HRESULT hr = S_OK; IGraphBuilder *pGraph = NULL; IMediaControl *pControl = NULL; IMediaEventEx *pEvent = NULL; IBaseFilter *pGrabberF = NULL; ISampleGrabber *pGrabber = NULL; IBaseFilter *pSourceF = NULL; IEnumPins *pEnum = NULL; IPin *pPin = NULL; IBaseFilter *pNullF = NULL; BYTE *pBuffer = NULL; hr = CoCreateInstance(CLSID_FilterGraph, NULL,CLSCTX_INPROC_SERVER,IID_PPV_ARGS(&pGraph)); hr = pGraph->QueryInterface(IID_PPV_ARGS(&pControl)); hr = pGraph->QueryInterface(IID_PPV_ARGS(&pEvent)); hr = CoCreateInstance(CLSID_SampleGrabber, NULL, CLSCTX_INPROC_SERVER,IID_PPV_ARGS(&pGrabberF)); hr = pGraph->AddFilter(pGrabberF, L"Sample Grabber"); hr = pGrabberF->QueryInterface(IID_PPV_ARGS(&pGrabber)); AM_MEDIA_TYPE mt; ZeroMemory(&mt, sizeof(mt)); mt.majortype = MEDIATYPE_Video; mt.subtype = MEDIASUBTYPE_RGB24; hr = pGrabber->SetMediaType(&mt); hr = pGraph->AddSourceFilter(L"C:/Users/Julian/Desktop/homogenität/1,1x_2,7y.mpg", L"Source", &pSourceF); hr = pSourceF->EnumPins(&pEnum); while (S_OK == pEnum->Next(1, &pPin, NULL)) { hr = ConnectFilters(pGraph, pPin, pGrabberF); SafeRelease(&pPin); if (SUCCEEDED(hr))break; } hr = CoCreateInstance(CLSID_NullRenderer, NULL, CLSCTX_INPROC_SERVER,IID_PPV_ARGS(&pNullF)); hr = pGraph->AddFilter(pNullF, L"Null Filter"); hr = ConnectFilters(pGraph, pGrabberF, pNullF); hr = pGrabber->SetOneShot(TRUE); hr = pGrabber->SetBufferSamples(TRUE); long evCode=0; long cbBuffer=0; hr = pControl->Run(); hr = pEvent->WaitForCompletion(INFINITE, &evCode); hr = pGrabber->GetCurrentBuffer(&cbBuffer, NULL); pBuffer = (BYTE*)CoTaskMemAlloc(cbBuffer); hr = pGrabber->GetConnectedMediaType(&mt); CComQIPtr< IMediaSeeking, &IID_IMediaSeeking > pSeeking( pGraph ); // for(int i=0;i<10;i++){ bool hui=true;int i=0; while(hui){ REFERENCE_TIME Start = i * UNITS; hr = pSeeking->SetPositions( &Start, AM_SEEKING_AbsolutePositioning,NULL, AM_SEEKING_NoPositioning ); // Sleep(10); hr = pEvent->WaitForCompletion(INFINITE,&evCode); if(hr!=0)hui=false; hr = pGrabber->GetCurrentBuffer(&cbBuffer, (long*)pBuffer); if ((mt.formattype == FORMAT_VideoInfo) &&(mt.cbFormat >= sizeof(VIDEOINFOHEADER)) &&(mt.pbFormat != NULL)) { VIDEOINFOHEADER *pVih = (VIDEOINFOHEADER*)mt.pbFormat; // hr = WriteBitmap(("hui"+(String)i+".bmp").c_str(), &pVih->bmiHeader, mt.cbFormat - SIZE_PREHEADER, pBuffer, cbBuffer); hr = SavePNG(i,pBuffer, pVih->bmiHeader.biWidth, pVih->bmiHeader.biHeight); } else hr = VFW_E_INVALIDMEDIATYPE; i++; } FreeMediaType(mt); done: CoTaskMemFree(pBuffer); SafeRelease(&pPin); SafeRelease(&pEnum); SafeRelease(&pNullF); SafeRelease(&pSourceF); SafeRelease(&pGrabber); SafeRelease(&pGrabberF); SafeRelease(&pControl); SafeRelease(&pEvent); SafeRelease(&pGraph); } bool SavePNG(int i, Byte* m_pImageData,long m_Width,long m_Height) { // Make sure there is image data if (!m_pImageData) return false; stringstream FilePath; FilePath << "hui"<< i<<".png"; // Create a corona image corona::Image* pImage = corona::CreateImage(m_Width, m_Height, corona::PF_R8G8B8, m_pImageData); // Make sure the image was created if (!pImage) return false; // Save the image to a PNG file corona::SaveImage(FilePath.str().c_str(), corona::FF_PNG, pImage); // Delete the corona image delete pImage; // Nothing went wrong return true; } </code></pre> I hope I have done nothing horribly wrong... I really tried to research everything^^ Does somebody knows about my 3 questions above? I you found something really wrong here, I would also appreciate for you to tell me, so I can fix and improve. Regards, Julian
Tags
<directshow><c++builder><video-capture><corona><samplegrabber>
Title
c++ builder: convert video to png-snapshots with directshow
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PostAcceptedAnswerId
1. PO
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1. This table or related slice is empty.
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1. PTQuestion
UserLastEditorUserId
1. USJulian
UserOwnerUserId
1. USJulian
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1. PO
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