Best DirectShow way to capture image from web cam preview ? SampleGrabber is deprecated

Question

I have developed DirectShow C++ app which successfully previews web cam view into provided window. Now I want to capture image from this live web cam preview. I have used gr

Answer 1

Listed on Microsoft's website is an example of how to capture a frame using IVMRWindowlessControl9::GetCurrentImage ... Here's one way of doing it:

IBaseFilter*            vmr9ptr; // I'm assuming that you got this pointer already
IVMRWindowlessControl9* controlPtr = NULL;

vmr9ptr->QueryInterface(IID_IVMRWindowlessControl9, (void**)controlPtr);
assert ( controlPtr != NULL );

// Get the current frame
BYTE*   lpDib = NULL;
hr = controlPtr->GetCurrentImage(&lpDib);

// If everything is okay, we can create a BMP
if (SUCCEEDED(hr))
{
    BITMAPINFOHEADER*   pBMIH = (BITMAPINFOHEADER*) lpDib;
    DWORD               bufSize = pBMIH->biSizeImage;

    // Let's create a bmp
    BITMAPFILEHEADER    bmpHdr;
    BITMAPINFOHEADER    bmpInfo;
    size_t              hdrSize     = sizeof(bmpHdr);
    size_t              infSize     = sizeof(bmpInfo);

    memset(&bmpHdr, 0, hdrSize);
    bmpHdr.bfType                   = ('M' << 8) | 'B';
    bmpHdr.bfOffBits                = static_cast(hdrSize + infSize);
    bmpHdr.bfSize                   = bmpHdr.bfOffBits + bufSize;

    // Builder the bit map info.
    memset(&bmpInfo, 0, infSize);
    bmpInfo.biSize                  = static_cast(infSize);
    bmpInfo.biWidth                 = pBMIH->biWidth;
    bmpInfo.biHeight                = pBMIH->biHeight;
    bmpInfo.biPlanes                = pBMIH->biPlanes;
    bmpInfo.biBitCount              = pBMIH->biBitCount;

    // boost::shared_arrays are awesome!
    boost::shared_array buf(new BYTE[bmpHdr.bfSize]);//(lpDib);
    memcpy(buf.get(),                       &bmpHdr,    hdrSize); // copy the header
    memcpy(buf.get() + hdrSize,             &bmpInfo,   infSize); // now copy the info block
    memcpy(buf.get() + bmpHdr.bfOffBits,    lpDib,      bufSize);

    // Do something with your image data ... seriously...
    CoTaskMemFree(lpDib);

} // All done!