我正在尝试使用 IAMStreamConfig，但无论我把
int iCount = 0, iSize = 0;
hr = pConfig->GetNumberOfCapabilities(&iCount, &iSize);
// Check the size to make sure we pass in the correct structure.
if (iSize == sizeof(VIDEO_STREAM_CONFIG_CAPS))
{
// Use the video capabilities structure.
for (int iFormat = 0; iFormat < iCount; iFormat++)
{
VIDEO_STREAM_CONFIG_CAPS scc;
AM_MEDIA_TYPE *pmtConfig;
hr = pConfig->GetStreamCaps(iFormat, &pmtConfig, (BYTE*)&scc);
if (SUCCEEDED(hr))
{
/* Examine the format, and possibly use it. */
cout << scc.CropAlignX << endl;
cout << scc.CropAlignY << endl;
// Delete the media type when you are done.
DeleteMediaType(pmtConfig);
}
}
在我的代码中找到 CropAlignX 和 CropAlignY。它编译，但我得到一个异常并且程序崩溃。这就是我的代码的样子，有人可以告诉我需要在哪里插入该代码以使其工作吗？
int main(int argc, char **argv)
{
// Intialise COM
hr = CoInitializeEx(NULL, COINIT_MULTITHREADED);
if (hr != S_OK)
exit_message("Could not initialise COM", 7);
hr = CoCreateInstance(CLSID_FilterGraph, NULL, CLSCTX_INPROC_SERVER, IID_IGraphBuilder,
(void**)&pGraph);
if (hr != S_OK)
exit_message("Could not create filter graph", 8);
hr = CoCreateInstance(CLSID_CaptureGraphBuilder2, NULL, CLSCTX_INPROC_SERVER, IID_ICaptureGraphBuilder2,
(void **)&pBuilder);
if (hr != S_OK)
exit_message("Could not create capture graph builder", 9);
hr = pBuilder->SetFiltergraph(pGraph);
if (hr != S_OK)
exit_message("Could not attach capture graph builder to graph", 10);
hr = CoCreateInstance(CLSID_SystemDeviceEnum, NULL, CLSCTX_INPROC_SERVER, IID_PPV_ARGS(&pDevEnum));
if (hr != S_OK)
exit_message("Could not create system device enumerator", 11);
// Video input device enumerator
hr = pDevEnum->CreateClassEnumerator(CLSID_VideoInputDeviceCategory, &pEnum, 0);
if (hr != S_OK)
exit_message("No video devices found", 12);
VARIANT var;
n = 0;
while(1)
{
// Access next device
hr = pEnum->Next(1, &pMoniker, NULL);
if (hr == S_OK)
{
n++; // increment device count
}
else
{
if (device_number == 0)
{
fprintf(stderr,
"Video capture device %s not found\n",
device_name);
}
else
{
fprintf(stderr,
"Video capture device %d not found\n",
device_number);
}
exit_message("", 14);
}
else if (n >= device_number) break;
}
hr = pMoniker->BindToStorage(0, 0, IID_PPV_ARGS(&pPropBag));
VariantInit(&var);
hr = pPropBag->Read(L"FriendlyName", &var, 0);
VariantClear(&var);
hr = pMoniker->BindToObject(0, 0, IID_IBaseFilter, (void**)&pCap);
if (hr != S_OK) exit_message("Could not create capture filter", 16);
hr = pGraph->AddFilter(pCap, L"Capture Filter");
if (hr != S_OK) exit_message("Could not add capture filter to graph", 17);
hr = CoCreateInstance(CLSID_SampleGrabber, NULL,CLSCTX_INPROC_SERVER, IID_IBaseFilter,
(void**)&pSampleGrabberFilter);
if (hr != S_OK)
exit_message("Could not create Sample Grabber filter", 18);
hr = pSampleGrabberFilter->QueryInterface(IID_ISampleGrabber, (void**)&pSampleGrabber);
if (hr != S_OK)
exit_message("Could not get ISampleGrabber interface to sample grabber filter", 19);
hr = pSampleGrabber->SetBufferSamples(TRUE);
if (hr != S_OK)
exit_message("Could not enable sample buffering in the sample grabber", 20);
AM_MEDIA_TYPE mt;
ZeroMemory(&mt, sizeof(AM_MEDIA_TYPE));
mt.majortype = MEDIATYPE_Video;
mt.subtype = MEDIASUBTYPE_RGB24;
hr = pSampleGrabber->SetMediaType((_AMMediaType *)&mt);
if (hr != S_OK)
exit_message("Could not set media type in sample grabber", 21);
//////////////// IID_IAMStreamConfig ////////////////////////////////////////////////////
hr = pBuilder->FindInterface(&PIN_CATEGORY_PREVIEW, 0, pCap, IID_IAMStreamConfig, (void**)&pConfig);
hr = pGraph->AddFilter(pSampleGrabberFilter, L"SampleGrab");
if (hr != S_OK)
exit_message("Could not add Sample Grabber to filter graph", 22);
hr = CoCreateInstance(CLSID_NullRenderer, NULL, CLSCTX_INPROC_SERVER, IID_IBaseFilter,
(void**)&pNullRenderer);
if (hr != S_OK)
exit_message("Could not create Null Renderer filter", 23);
/*
hr = pBuilder->RenderStream(&PIN_CATEGORY_PREVIEW, &MEDIATYPE_Video,
pCap, NULL, NULL);
if (hr != S_OK && hr != VFW_S_NOPREVIEWPIN)
exit_message("Could not render preview video stream", 26);
*/
hr = pGraph->AddFilter(pNullRenderer, L"NullRender");
if (hr != S_OK)
exit_message("Could not add Null Renderer to filter graph", 24);
hr = pBuilder->RenderStream(&PIN_CATEGORY_CAPTURE, &MEDIATYPE_Video,
pCap, pSampleGrabberFilter, pNullRenderer);
if (hr != S_OK)
exit_message("Could not render capture video stream", 25);
hr = pGraph->QueryInterface(IID_IMediaControl, (void**)&pMediaControl);
if (hr != S_OK) exit_message("Could not get media control interface", 27);
while(1)
{
hr = pMediaControl->Run();
// Hopefully, the return value was S_OK or S_FALSE
if (hr == S_OK) break; // graph is now running
if (hr == S_FALSE) continue; // graph still preparing to run
fprintf(stderr, "Error: %u\n", hr);
exit_message("Could not run filter graph", 28);
}
long buffer_size = 0;
while(true)
{
if ( (cvWaitKey(10) & 255) == 27 ) break;
while(1)
{
hr = pSampleGrabber->GetCurrentBuffer(&buffer_size, NULL);
if (hr == S_OK && buffer_size != 0) break;
if (hr != S_OK && hr != VFW_E_WRONG_STATE)
exit_message("Could not get buffer size", 29);
}
pBuffer = new char[buffer_size];
if (!pBuffer)
exit_message("Could not allocate data buffer for image", 30);
hr = pSampleGrabber->GetCurrentBuffer(&buffer_size, (long*)pBuffer);
if (hr != S_OK)
exit_message("Could not get buffer data from sample grabber", 31);
hr = pSampleGrabber->GetConnectedMediaType((_AMMediaType *)&mt);
if (hr != S_OK)
exit_message("Could not get media type", 32);
VIDEOINFOHEADER *pVih = NULL;
if ((mt.formattype == FORMAT_VideoInfo) && (mt.cbFormat >= sizeof(VIDEOINFOHEADER)) && (mt.pbFormat != NULL))
{
pVih = (VIDEOINFOHEADER*)mt.pbFormat;
long cbBitmapInfoSize = mt.cbFormat - SIZE_PREHEADER;
BITMAPFILEHEADER bfh;
ZeroMemory(&bfh, sizeof(bfh));
bfh.bfType = 'MB'; // Little-endian for "BM".
bfh.bfSize = sizeof(bfh) + buffer_size + cbBitmapInfoSize;
bfh.bfOffBits = sizeof(BITMAPFILEHEADER) + cbBitmapInfoSize;
..Blah blah..
编辑：附加调用堆栈