由于在使用 c++ 和 opencv 时难以更改相机的分辨率，我不得不为我的眼动追踪软件更改为 directshow。
Directshow 对我来说是新的，而且很难理解一切。但我发现这个很好的例子非常适合捕捉和查看网络摄像头。
http://www.codeproject.com/Articles/12869/Real-time-video-image-processing-frame-grabber-usi
我正在使用不需要 directShow SDK 的版本。（但示例中使用的仍然是directshow，对吗？？）
#include <windows.h>
#include <dshow.h>
#pragma comment(lib,"Strmiids.lib")
#define DsHook(a,b,c) if (!c##_) { INT_PTR* p=b+*(INT_PTR**)a; VirtualProtect(&c##_,4,PAGE_EXECUTE_READWRITE,&no);\
*(INT_PTR*)&c##_=*p; VirtualProtect(p, 4,PAGE_EXECUTE_READWRITE,&no); *p=(INT_PTR)c; }
// Here you get image video data in buf / len. Process it before calling Receive_ because renderer dealocates it.
HRESULT ( __stdcall * Receive_ ) ( void* inst, IMediaSample *smp ) ;
HRESULT __stdcall Receive ( void* inst, IMediaSample *smp ) {
BYTE* buf; smp->GetPointer(&buf); DWORD len = smp->GetActualDataLength();
HRESULT ret = Receive_ ( inst, smp );
return ret;
}
int WINAPI WinMain(HINSTANCE inst,HINSTANCE prev,LPSTR cmd,int show){
HRESULT hr = CoInitialize(0); MSG msg={0}; DWORD no;
IGraphBuilder* graph= 0; hr = CoCreateInstance( CLSID_FilterGraph, 0, CLSCTX_INPROC,IID_IGraphBuilder, (void **)&graph );
IMediaControl* ctrl = 0; hr = graph->QueryInterface( IID_IMediaControl, (void **)&ctrl );
ICreateDevEnum* devs = 0; hr = CoCreateInstance (CLSID_SystemDeviceEnum, 0, CLSCTX_INPROC, IID_ICreateDevEnum, (void **) &devs);
IEnumMoniker* cams = 0; hr = devs?devs->CreateClassEnumerator (CLSID_VideoInputDeviceCategory, &cams, 0):0;
IMoniker* mon = 0; hr = cams->Next (1,&mon,0); // get first found capture device (webcam?)
IBaseFilter* cam = 0; hr = mon->BindToObject(0,0,IID_IBaseFilter, (void**)&cam);
hr = graph->AddFilter(cam, L"Capture Source"); // add web cam to graph as source
IEnumPins* pins = 0; hr = cam?cam->EnumPins(&pins):0; // we need output pin to autogenerate rest of the graph
IPin* pin = 0; hr = pins?pins->Next(1,&pin, 0):0; // via graph->Render
hr = graph->Render(pin); // graph builder now builds whole filter chain including MJPG decompression on some webcams
IEnumFilters* fil = 0; hr = graph->EnumFilters(&fil); // from all newly added filters
IBaseFilter* rnd = 0; hr = fil->Next(1,&rnd,0); // we find last one (renderer)
hr = rnd->EnumPins(&pins); // because data we are intersted in are pumped to renderers input pin
hr = pins->Next(1,&pin, 0); // via Receive member of IMemInputPin interface
IMemInputPin* mem = 0; hr = pin->QueryInterface(IID_IMemInputPin,(void**)&mem);
DsHook(mem,6,Receive); // so we redirect it to our own proc to grab image data
hr = ctrl->Run();
while ( GetMessage( &msg, 0, 0, 0 ) ) {
TranslateMessage( &msg );
DispatchMessage( &msg );
}
};
对于来自 cam 的每个新帧，都会调用 HRESULT Receive 方法。评论说 buf 包含数据。但我有 3 个问题/问题。
我不能包含 opencv 库。我在 Visual Studio 中创建了一个新项目，并添加了与我一直包含的相同的属性表。与早期项目的唯一区别是我现在创建了一个完全空的项目，之前我创建了一个 win32 应用程序。如何将opencv添加到directshow项目中？
上面的例子。来自 buf。这是一个指向数据的指针。如何将其输入到 iplImage/Mat 中以用于 opencv calc？
有没有办法不显示来自网络摄像头的图像（我只需要在帧上执行一些算法，我猜删除带有结果的窗口可能会给我更多的分析算法能力？！）
谢谢！