使用dshow捕获摄像头图像

#include "stdafx.h"
#include <DShow.h>
#include <Guiddef.h>
#include <strmif.h>

#define CHECK_HR(s) if (FAILED(s)) {return 1;}
#define SAFE_RELEASE(p)     do { if ((p)) { (p)->Release(); (p) = NULL; } } while(0)

LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam);

#pragma comment(lib, "Dxguid.lib")
#pragma comment(lib, "Strmiids.lib")

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow)
{
CoInitialize(NULL);
int nRes = 0;

WNDCLASSEX wcex;

wcex.cbSize = sizeof(WNDCLASSEX);
wcex.style = CS_HREDRAW | CS_VREDRAW;
wcex.lpfnWndProc = WndProc;
wcex.cbClsExtra = 0;
wcex.cbWndExtra = 0;
wcex.hInstance = hInstance;
wcex.hIcon = LoadIcon(hInstance, MAKEINTRESOURCE(IDI_APPLICATION));
wcex.hCursor = LoadCursor(NULL, IDC_ARROW);
wcex.hbrBackground = (HBRUSH)(COLOR_WINDOW + 1);
wcex.lpszMenuName = NULL;
wcex.lpszClassName = _T("dshow capture");
wcex.hIconSm = LoadIcon(wcex.hInstance, MAKEINTRESOURCE(IDI_APPLICATION));

if (!RegisterClassEx(&wcex))
{
MessageBox(NULL, _T("Call to RegisterClassEx failed!"), _T("Win32 Guided Tour"), NULL);

return 1;
}

HWND m_hWnd = ::CreateWindowA("STATIC", "ds_video_preview", WS_POPUP, 100, 100, 500, 500, NULL, NULL, NULL, NULL);
ShowWindow(m_hWnd, nCmdShow);
UpdateWindow(m_hWnd);

if (m_hWnd == NULL)
{
nRes = 11;
}

//----------------------用dshow获取摄像头---start--------------------------

IGraphBuilder         *m_pGraph;//filter总图表管理器
ICaptureGraphBuilder2 *m_pBuild;//捕获图表管理器
IVideoWindow          *m_pVidWin;//窗口接口
HRESULT hr = CoCreateInstance(CLSID_FilterGraph, NULL, CLSCTX_INPROC_SERVER, IID_IGraphBuilder, (void**)&m_pGraph);
CHECK_HR(1);
hr = CoCreateInstance(CLSID_CaptureGraphBuilder2, NULL, CLSCTX_INPROC_SERVER, IID_ICaptureGraphBuilder2, (void**)&m_pBuild);
CHECK_HR(2);
hr = m_pBuild->SetFiltergraph(m_pGraph);//给捕获图表管理器指定一个可用的图表管理器来进行使用
CHECK_HR(3);
hr = m_pGraph->QueryInterface(IID_IVideoWindow, (void **)&m_pVidWin);//通过此函数来查询某个组件是否支持某个特定的接口,如果支持就返回这些接口的指针
CHECK_HR(4);

ICreateDevEnum *pDevEnum = NULL;
IEnumMoniker *pClsEnum = NULL;
IMoniker *pMoniker = NULL;
//创建设备枚举COM对象
hr = CoCreateInstance(CLSID_SystemDeviceEnum, NULL, CLSCTX_INPROC, IID_ICreateDevEnum, (void **)&pDevEnum);
CHECK_HR(5);
//创建视频采集设备枚举COM对象
hr = pDevEnum->CreateClassEnumerator(CLSID_VideoInputDeviceCategory, &pClsEnum, 0);
CHECK_HR(6);

int i = 0;
while (i <= 0)
{
hr = pClsEnum->Next(1, &pMoniker, NULL);
++i;
}
CHECK_HR(7);

IBaseFilter           *m_pSrc;
hr = pMoniker->BindToObject(0, 0, IID_IBaseFilter, (void **)&m_pSrc);//就是这句获得Filter
CHECK_HR(8);

SAFE_RELEASE(pMoniker);
SAFE_RELEASE(pClsEnum);
SAFE_RELEASE(pDevEnum);

//将设备添加到filter管理器graph
hr = m_pGraph->AddFilter(m_pSrc, L"Video Capture");
CHECK_HR(9);

hr = m_pBuild->RenderStream(&PIN_CATEGORY_PREVIEW, &MEDIATYPE_Video, m_pSrc, NULL, NULL);
CHECK_HR(10);

m_pVidWin->put_Owner((OAHWND)m_hWnd);
m_pVidWin->SetWindowPosition(100, 100, 400, 300);
m_pVidWin->put_WindowStyle(WS_CHILD | WS_CLIPSIBLINGS);

//IMediaControl接口,用来控制流媒体在Filter Graph中的流动,例如流媒体的启动和停止
IMediaControl         *m_pMediaControl;
hr = m_pGraph->QueryInterface(IID_IMediaControl, (void **)&m_pMediaControl);
CHECK_HR(12);

hr = m_pMediaControl->Run();

//----------------------用dshow获取摄像头---end--------------------------

MSG msg;
while (GetMessage(&msg, NULL, 0, 0))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
return (int)msg.wParam;

}

LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
PAINTSTRUCT ps;
HDC hdc;
TCHAR greeting[] = _T("Hello, World!");

switch (message)
{
case WM_PAINT:
hdc = BeginPaint(hWnd, &ps);
TextOut(hdc, 5, 5, greeting, _tcslen(greeting));
EndPaint(hWnd, &ps);
break;
case WM_DESTROY:
PostQuitMessage(0);
break;
default:
return DefWindowProc(hWnd, message, wParam, lParam);
break;
}

return 0;
}