用c++编写一套代码，目的是利用dircet show控制四个摄像头分别拍照保存

以下是一个简单的C++程序，它可以利用DirectShow控制四个摄像头，分别拍照并保存图像：

#include <Windows.h>
#include <dshow.h>
#include <iostream>
#include <string>

#pragma comment(lib, "strmiids.lib")

using namespace std;

// 四个摄像头的设备路径
string camera1_path = "video=USB Camera 1";
string camera2_path = "video=USB Camera 2";
string camera3_path = "video=USB Camera 3";
string camera4_path = "video=USB Camera 4";

// 文件名前缀
string filename_prefix = "camera";

// 文件名后缀
string filename_suffix = ".bmp";

// 拍照并保存图像
void captureImage(string camera_path, int camera_id)
{
    // 创建Graph对象
    IGraphBuilder* pGraph = NULL;
    CoCreateInstance(CLSID_FilterGraph, NULL, CLSCTX_INPROC_SERVER, IID_IGraphBuilder, (void**)&pGraph);

    // 创建Capture Graph Builder对象
    ICaptureGraphBuilder2* pBuilder = NULL;
    CoCreateInstance(CLSID_CaptureGraphBuilder2, NULL, CLSCTX_INPROC_SERVER, IID_ICaptureGraphBuilder2, (void**)&pBuilder);

    // 为Capture Graph Builder对象设置Graph对象
    pBuilder->SetFiltergraph(pGraph);

    // 创建摄像头过滤器
    IBaseFilter* pCameraFilter = NULL;
    pGraph->AddSourceFilter(camera_path.c_str(), NULL, &pCameraFilter);

    // 创建Sample Grabber过滤器
    IBaseFilter* pGrabberFilter = NULL;
    CoCreateInstance(CLSID_SampleGrabber, NULL, CLSCTX_INPROC_SERVER, IID_IBaseFilter, (void**)&pGrabberFilter);

    // 设置Sample Grabber参数
    ISampleGrabber* pGrabber = NULL;
    pGrabberFilter->QueryInterface(IID_ISampleGrabber, (void**)&pGrabber);
    pGrabber->SetOneShot(TRUE);
    pGrabber->SetBufferSamples(TRUE);

    // 将过滤器添加到Graph中
    pGraph->AddFilter(pGrabberFilter, NULL);

    // 连接过滤器
    IPin* pCameraOut = NULL;
    IPin* pGrabberIn = NULL;
    pBuilder->FindPin(pCameraFilter, PINDIR_OUTPUT, NULL, NULL, FALSE, 0, &pCameraOut);
    pBuilder->FindPin(pGrabberFilter, PINDIR_INPUT, NULL, NULL, FALSE, 0, &pGrabberIn);
    pGraph->Connect(pCameraOut, pGrabberIn);

    // 运行Graph
    IMediaControl* pControl = NULL;
    pGraph->QueryInterface(IID_IMediaControl, (void**)&pControl);
    pControl->Run();

    // 等待拍照完成
    long evCode;
    pControl->WaitForCompletion(-1, &evCode);

    // 保存图像
    AM_MEDIA_TYPE mt;
    pGrabber->GetConnectedMediaType(&mt);
    BITMAPINFOHEADER* bmiHeader = (BITMAPINFOHEADER*)mt.pbFormat;
    long imageSize = bmiHeader->biSizeImage;
    BYTE* pBuffer = new BYTE[imageSize];
    pGrabber->GetCurrentBuffer(&imageSize, (long*)pBuffer);

    string filename = filename_prefix + to_string(camera_id) + filename_suffix;
    HANDLE hFile = CreateFile(filename.c_str(), GENERIC_WRITE, 0, NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL);
    DWORD dwBytesWritten;
    WriteFile(hFile, pBuffer, imageSize, &dwBytesWritten, NULL);
    CloseHandle(hFile);

    // 释放资源
    delete[] pBuffer;
    pControl->Stop();
    pGrabber->Release();
    pGrabberFilter->Release();
    pCameraFilter->Release();
    pBuilder->Release();
    pGraph->Release();
}

int main()
{
    // 拍照并保存四个摄像头的图像
    captureImage(camera1_path, 1);
    captureImage(camera2_path, 2);
    captureImage(camera3_path, 3);
    captureImage(camera4_path, 4);

    return 0;
}

注意：由于每个摄像头的设备路径可能不同，需要根据实际情况修改代码中的`camera1_path`、`camera2_path`、`camera3_path`和`camera4_path`的值，确保程序能够正确识别摄像头。此外，需要将程序编译为32位应用程序，以便与DirectShow框架兼容。