如何使用DirectShow捕捉RGB中的實時相機幀

我正在通過DirectShow實現實時視頻捕捉以進行實時處理和顯示。（增強現實應用程序）。如何使用DirectShow捕捉RGB中的實時相機幀

我可以很容易地訪問像素，但似乎我無法讓SampleGrabber提供RGB數據。該設備（在VMware中運行iSight的VC++ Express）僅報告MEDIASUBTYPE_YUY2。

經過廣泛的谷歌搜索之後，我仍然無法弄清楚DirectShow是否應該爲這類事情提供內置的色彩空間轉換。有些網站報告說沒有YUV < - > RGB轉換內置，others報告，您只需調用ISampleGrabber上的SetMediaType和RGB子類型。

任何意見，非常感謝，我瘋了這一個。代碼如下。請注意，

代碼工作，但它不提供RGB數據

我知道，我可以實現我自己的轉換過濾器，但是這是不可行的，因爲我不得不預見所有可能的設備格式，這是一個比較小的項目

// Playback 
IGraphBuilder *pGraphBuilder = NULL; 
ICaptureGraphBuilder2 *pCaptureGraphBuilder2 = NULL; 
IMediaControl *pMediaControl = NULL; 
IBaseFilter *pDeviceFilter = NULL; 
IAMStreamConfig *pStreamConfig = NULL; 
BYTE *videoCaps = NULL; 
AM_MEDIA_TYPE **mediaTypeArray = NULL; 

// Device selection 
ICreateDevEnum *pCreateDevEnum = NULL; 
IEnumMoniker *pEnumMoniker = NULL; 
IMoniker *pMoniker = NULL; 
ULONG nFetched = 0; 

HRESULT hr = CoInitializeEx(NULL, COINIT_MULTITHREADED); 

// Create CreateDevEnum to list device 
hr = CoCreateInstance(CLSID_SystemDeviceEnum, NULL, CLSCTX_INPROC_SERVER, IID_ICreateDevEnum, (PVOID *)&pCreateDevEnum); 
if (FAILED(hr)) goto ReleaseDataAndFail; 

// Create EnumMoniker to list devices 
hr = pCreateDevEnum->CreateClassEnumerator(CLSID_VideoInputDeviceCategory, &pEnumMoniker, 0); 
if (FAILED(hr)) goto ReleaseDataAndFail; 

pEnumMoniker->Reset(); 

// Find desired device 
while (pEnumMoniker->Next(1, &pMoniker, &nFetched) == S_OK) 
{ 
    IPropertyBag *pPropertyBag; 
    TCHAR devname[256]; 

    // bind to IPropertyBag 
    hr = pMoniker->BindToStorage(0, 0, IID_IPropertyBag, (void **)&pPropertyBag); 

    if (FAILED(hr)) 
    { 
    pMoniker->Release(); 
    continue; 
    } 

    VARIANT varName; 
    VariantInit(&varName); 
    HRESULT hr = pPropertyBag->Read(L"DevicePath", &varName, 0); 

    if (FAILED(hr)) 
    { 
    pMoniker->Release(); 
    pPropertyBag->Release(); 
    continue; 
    } 

    char devicePath[DeviceInfo::STRING_LENGTH_MAX] = ""; 

    wcstombs(devicePath, varName.bstrVal, DeviceInfo::STRING_LENGTH_MAX); 

    if (strcmp(devicePath, deviceId) == 0) 
    { 
    // Bind Moniker to Filter 
    pMoniker->BindToObject(0, 0, IID_IBaseFilter, (void**)&pDeviceFilter); 

    break; 
    } 

    pMoniker->Release(); 
    pPropertyBag->Release(); 
} 

if (pDeviceFilter == NULL) goto ReleaseDataAndFail; 

// Create sample grabber 
IBaseFilter *pGrabberF = NULL; 
hr = CoCreateInstance(CLSID_SampleGrabber, NULL, CLSCTX_INPROC_SERVER, IID_IBaseFilter, (void**)&pGrabberF); 
if (FAILED(hr)) goto ReleaseDataAndFail; 

hr = pGrabberF->QueryInterface(IID_ISampleGrabber, (void**)&pGrabber); 
if (FAILED(hr)) goto ReleaseDataAndFail; 

// Create FilterGraph 
hr = CoCreateInstance(CLSID_FilterGraph, 
NULL, 
CLSCTX_INPROC, 
IID_IGraphBuilder, 
(LPVOID *)&pGraphBuilder); 
if (FAILED(hr)) goto ReleaseDataAndFail; 

// create CaptureGraphBuilder2 
hr = CoCreateInstance(CLSID_CaptureGraphBuilder2, NULL, CLSCTX_INPROC, IID_ICaptureGraphBuilder2, (LPVOID *)&pCaptureGraphBuilder2); 
if (FAILED(hr)) goto ReleaseDataAndFail; 

// set FilterGraph 
hr = pCaptureGraphBuilder2->SetFiltergraph(pGraphBuilder); 
if (FAILED(hr)) goto ReleaseDataAndFail; 

// get MediaControl interface 
hr = pGraphBuilder->QueryInterface(IID_IMediaControl, (LPVOID *)&pMediaControl); 
if (FAILED(hr)) goto ReleaseDataAndFail; 

// Add filters 
hr = pGraphBuilder->AddFilter(pDeviceFilter, L"Device Filter"); 
if (FAILED(hr)) goto ReleaseDataAndFail; 

hr = pGraphBuilder->AddFilter(pGrabberF, L"Sample Grabber"); 
if (FAILED(hr)) goto ReleaseDataAndFail; 

// Set sampe grabber options 
AM_MEDIA_TYPE mt; 
ZeroMemory(&mt, sizeof(AM_MEDIA_TYPE)); 
mt.majortype = MEDIATYPE_Video; 
mt.subtype = MEDIASUBTYPE_RGB32; 
hr = pGrabber->SetMediaType(&mt); 
if (FAILED(hr)) goto ReleaseDataAndFail; 

hr = pGrabber->SetOneShot(FALSE); 
if (FAILED(hr)) goto ReleaseDataAndFail; 

hr = pGrabber->SetBufferSamples(TRUE); 
if (FAILED(hr)) goto ReleaseDataAndFail; 

// Get stream config interface 
hr = pCaptureGraphBuilder2->FindInterface(NULL, &MEDIATYPE_Video, pDeviceFilter, IID_IAMStreamConfig, (void **)&pStreamConfig); 
if (FAILED(hr)) goto ReleaseDataAndFail; 

int streamCapsCount = 0, capsSize, bestFit = -1, bestFitPixelDiff = 1000000000, desiredPixelCount = _width * _height, 
bestFitWidth = 0, bestFitHeight = 0; 

float desiredAspectRatio = (float)_width/(float)_height; 

hr = pStreamConfig->GetNumberOfCapabilities(&streamCapsCount, &capsSize); 
if (FAILED(hr)) goto ReleaseDataAndFail; 

videoCaps = (BYTE *)malloc(capsSize * streamCapsCount); 
mediaTypeArray = (AM_MEDIA_TYPE **)malloc(sizeof(AM_MEDIA_TYPE *) * streamCapsCount); 

for (int i = 0; i < streamCapsCount; i++) 
{ 
    hr = pStreamConfig->GetStreamCaps(i, &mediaTypeArray[i], videoCaps + capsSize * i); 
    if (FAILED(hr)) continue; 

    VIDEO_STREAM_CONFIG_CAPS *currentVideoCaps = (VIDEO_STREAM_CONFIG_CAPS *)(videoCaps + capsSize * i); 

    int closestWidth = MAX(currentVideoCaps->MinOutputSize.cx, MIN(currentVideoCaps->MaxOutputSize.cx, width)); 
    int closestHeight = MAX(currentVideoCaps->MinOutputSize.cy, MIN(currentVideoCaps->MaxOutputSize.cy, height)); 

    int pixelDiff = ABS(desiredPixelCount - closestWidth * closestHeight); 

    if (pixelDiff < bestFitPixelDiff && ABS(desiredAspectRatio - (float)closestWidth/(float)closestHeight) < 0.1f) 
    { 
    bestFit = i; 
    bestFitPixelDiff = pixelDiff; 
    bestFitWidth = closestWidth; 
    bestFitHeight = closestHeight; 
    } 
} 

if (bestFit == -1) goto ReleaseDataAndFail; 

AM_MEDIA_TYPE *mediaType; 
hr = pStreamConfig->GetFormat(&mediaType); 
if (FAILED(hr)) goto ReleaseDataAndFail; 

VIDEOINFOHEADER *videoInfoHeader = (VIDEOINFOHEADER *)mediaType->pbFormat; 
videoInfoHeader->bmiHeader.biWidth = bestFitWidth; 
videoInfoHeader->bmiHeader.biHeight = bestFitHeight; 
//mediaType->subtype = MEDIASUBTYPE_RGB32; 
hr = pStreamConfig->SetFormat(mediaType); 
if (FAILED(hr)) goto ReleaseDataAndFail; 

pStreamConfig->Release(); 
pStreamConfig = NULL; 

free(videoCaps); 
videoCaps = NULL; 
free(mediaTypeArray); 
mediaTypeArray = NULL; 

// Connect pins 
IPin *pDeviceOut = NULL, *pGrabberIn = NULL; 

if (FindPin(pDeviceFilter, PINDIR_OUTPUT, 0, &pDeviceOut) && FindPin(pGrabberF, PINDIR_INPUT, 0, &pGrabberIn)) 
{ 
    hr = pGraphBuilder->Connect(pDeviceOut, pGrabberIn); 
    if (FAILED(hr)) goto ReleaseDataAndFail; 
} 
else 
{ 
    goto ReleaseDataAndFail; 
} 

// start playing 
hr = pMediaControl->Run(); 
if (FAILED(hr)) goto ReleaseDataAndFail; 

hr = pGrabber->GetConnectedMediaType(&mt); 

// Set dimensions 
width = bestFitWidth; 
height = bestFitHeight; 
_width = bestFitWidth; 
_height = bestFitHeight; 

// Allocate pixel buffer 
pPixelBuffer = (unsigned *)malloc(width * height * 4); 

// Release objects 
pGraphBuilder->Release(); 
pGraphBuilder = NULL; 
pEnumMoniker->Release(); 
pEnumMoniker = NULL; 
pCreateDevEnum->Release(); 
pCreateDevEnum = NULL; 

return true;

來源

2009-12-01 Simplex

股票色彩空間轉換器不支持YUY2到RGB轉換。但是，有許多應用程序和設備可以安裝某種類型的轉換器，如果這種轉換器已正確註冊，則dshow會自動使用它。這就是爲什麼有些人報告說它是正常的。（當然有些設備提供RGB，所以在這些情況下不需要轉換）。

您可以從YUV Transform (at the bottom of the page)下載免費的YUV轉換濾鏡「yuvxfm」。將它註冊到您的系統上，它應該允許以任何合理的RGB或YUV格式進行捕獲。

來源

2009-12-02 09:06:12

非常感謝您的豐富迴應。我嘗試在設備和採樣器之間添加一個yuvxfm濾波器，該濾波器可以工作。但是，我也發現，如果它也沒有工作。我試着取消註冊yuvxfm並直接從設備到rgb採樣卡。我不知道爲什麼它以前沒有工作。我正在運行幾乎全新安裝的XP SP3。在Windows 7上也嘗試過，這也適用。那麼YUY2到RGB的轉換髮生在哪裏？我可以依靠這個嗎？ – Simplex 2009-12-02 19:02:08

是的。它的AviDecompressor支持YUY2 FourCC。有關提供的過濾器列表，請參閱http://msdn.microsoft.com/en-us/library/dd375464%28v=VS.85%29.aspx。 – Christopher 2010-06-08 07:34:18

AviDecompressor是Video for Windows編解碼器的封裝器。您可能安裝了可以進行YUY2轉換的VfW編解碼器，但這將取決於系統。在某些系統上，Avi Decompressor包裝過濾器可能沒有YUY2支持。 – 2010-06-08 20:47:36

如何使用DirectShow捕捉RGB中的實時相機幀

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