如何获得directshow网络摄像头视频流的宽度和高度

Question

我发现了一些代码,可以让我访问网络摄像头的原始像素数据.但是我需要知道图像的宽度,高度,像素格式,最好是数据步幅(音高,内存填充或任何你想要调用它),如果它不是每个像素的宽度*字节之外的东西

#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();
    //AM_MEDIA_TYPE* info;
    //smp->GetMediaType(&info);
    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 ); 
    }
};

如果你可以告诉我如何让这个东西不渲染一个窗口但仍让我访问图像数据,那么奖励积分.

Answer 1

那太难看了.请不要这样做.插入一个类似于样本采集器的传递过滤器(因为我回复了同一主题的其他帖子).将样本抓取器连接到空渲染器可以在不渲染图像的情况下以干净,安全的方式获取位.

要获得进步,您需要通过ISampleGrabber或IPin :: ConnectionMediaType获取媒体类型.格式块将是VIDEOINFOHEADER或VIDEOINFOHEADER2(检查格式GUID).bitmapinfo标头biWidth和biHeight定义位图尺寸(因此是步幅).如果RECT不为空,则定义位图内的相关图像区域.

触摸这篇文章后,我现在要洗手了.