Capturing an Image From a Still Image Pin (Windows Embedded CE 6.0)
1/6/2010
Some cameras can produce a still image separate from the capture stream, and often the still image is of higher quality than the images produced by the capture stream. The camera may have a button that acts as a hardware trigger, or it may support software triggering. A camera that supports still images will expose a still image pin, which is pin category PIN_CATEGORY_STILL (see Pin Property Set).
To trigger the still pin, use the IAMVideoControl::SetMode method when the graph is running, as shown in the following code.
pControl->Run(); // Run the graph.
IAMVideoControl *pAMVidControl = NULL;
hr = pCap->QueryInterface(IID_IAMVideoControl, (void**)&pAMVidControl);
if (SUCCEEDED(hr))
{
// Find the still pin.
IPin *pPin = 0;
hr = pBuild->FindPin(pCap, PINDIR_OUTPUT, &PIN_CATEGORY_STILL, 0,
FALSE, 0, &pPin);
if (SUCCEEDED(hr))
{
hr = pAMVidControl->SetMode(pPin, VideoControlFlag_Trigger);
pPin->Release();
}
pAMVidControl->Release();
}
Query the capture filter for an IAMVideoControl interface. If the interface is supported, get a pointer to the still pin's IPin Interface by calling the ICaptureGraphBuilder2::FindPin method, as shown in the previous example.
Note
Depending on the camera, you might need to render the capture pin (PIN_CATEGORY_CAPTURE) before the still pin will connect.