directshow编程实现视频采集

DirectShow是一种Microsoft Windows平台上的多媒体框架，用于创建和播放音频和视频文件。DirectShow可以使用图形化工具建立过滤器图形，也可以使用C++编写代码实现。

以下是使用DirectShow编程实现视频采集的步骤：

1. 创建DirectShow对象，包括GraphBuilder、CaptureGraphBuilder2和MediaControl等对象。

2. 创建视频采集设备，调用CaptureGraphBuilder2对象的RenderStream方法，将视频采集设备的输出流与视频捕获过滤器连接起来。

3. 创建VideoRenderer对象，将视频捕获过滤器的输出流与VideoRenderer对象连接起来。

4. 创建回调函数，用于处理视频数据。

5. 启动视频采集，调用MediaControl对象的Run方法。

6. 在回调函数中处理视频数据，将视频数据保存到文件或进行实时显示。

以下是使用DirectShow编程实现视频采集的示例代码：

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

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

// 回调函数，用于处理视频数据
HRESULT SampleCallback(IMediaSample* pSample)
{
    BYTE* pData;
    HRESULT hr = pSample->GetPointer(&pData);
    if (FAILED(hr))
    {
        return hr;
    }

    // 处理视频数据，将视频数据保存到文件或进行实时显示

    return S_OK;
}

int main()
{
    HRESULT hr;

    // 创建DirectShow对象
    CoInitialize(NULL);
    IGraphBuilder* pGraphBuilder = NULL;
    hr = CoCreateInstance(CLSID_FilterGraph, NULL, CLSCTX_INPROC_SERVER, IID_IGraphBuilder, (void**)&pGraphBuilder);
    if (FAILED(hr))
    {
        std::cout << "Failed to create Filter Graph." << std::endl;
        return -1;
    }

    ICaptureGraphBuilder2* pCaptureGraphBuilder2 = NULL;
    hr = CoCreateInstance(CLSID_CaptureGraphBuilder2, NULL, CLSCTX_INPROC_SERVER, IID_ICaptureGraphBuilder2, (void**)&pCaptureGraphBuilder2);
    if (FAILED(hr))
    {
        std::cout << "Failed to create Capture Graph Builder." << std::endl;
        return -1;
    }

    IMediaControl* pMediaControl = NULL;
    hr = pGraphBuilder->QueryInterface(IID_IMediaControl, (void**)&pMediaControl);
    if (FAILED(hr))
    {
        std::cout << "Failed to create Media Control." << std::endl;
        return -1;
    }

    // 创建视频采集设备
    IBaseFilter* pVideoCaptureFilter = NULL;
    hr = pCaptureGraphBuilder2->FindInterface(&PIN_CATEGORY_CAPTURE, &MEDIATYPE_Video, NULL, IID_IBaseFilter, (void**)&pVideoCaptureFilter);
    if (FAILED(hr))
    {
        std::cout << "Failed to find video capture device." << std::endl;
        return -1;
    }

    // 连接视频采集设备的输出流与视频捕获过滤器
    IPin* pCaptureOutPin = NULL;
    hr = pCaptureGraphBuilder2->FindPin(pVideoCaptureFilter, PINDIR_OUTPUT, NULL, NULL, TRUE, 0, &pCaptureOutPin);
    if (FAILED(hr))
    {
        std::cout << "Failed to find capture output pin." << std::endl;
        return -1;
    }

    hr = pGraphBuilder->Render(pCaptureOutPin);
    if (FAILED(hr))
    {
        std::cout << "Failed to render capture output pin." << std::endl;
        return -1;
    }

    // 创建VideoRenderer对象
    IBaseFilter* pVideoRendererFilter = NULL;
    hr = CoCreateInstance(CLSID_VideoRenderer, NULL, CLSCTX_INPROC_SERVER, IID_IBaseFilter, (void**)&pVideoRendererFilter);
    if (FAILED(hr))
    {
        std::cout << "Failed to create Video Renderer." << std::endl;
        return -1;
    }

    // 将视频捕获过滤器的输出流与VideoRenderer对象连接起来
    IPin* pRendererInPin = NULL;
    hr = pCaptureGraphBuilder2->FindPin(pVideoRendererFilter, PINDIR_INPUT, NULL, NULL, TRUE, 0, &pRendererInPin);
    if (FAILED(hr))
    {
        std::cout << "Failed to find Video Renderer input pin." << std::endl;
        return -1;
    }

    hr = pGraphBuilder->Connect(pCaptureOutPin, pRendererInPin);
    if (FAILED(hr))
    {
        std::cout << "Failed to connect capture output pin and Video Renderer input pin." << std::endl;
        return -1;
    }

    // 启动视频采集
    hr = pMediaControl->Run();
    if (FAILED(hr))
    {
        std::cout << "Failed to run Media Control." << std::endl;
        return -1;
    }

    // 循环等待
    std::cout << "Press any key to exit." << std::endl;
    while (!_kbhit())
    {
        Sleep(100);
    }

    // 停止视频采集
    hr = pMediaControl->Stop();
    if (FAILED(hr))
    {
        std::cout << "Failed to stop Media Control." << std::endl;
        return -1;
    }

    // 释放资源
    pRendererInPin->Release();
    pVideoRendererFilter->Release();
    pCaptureOutPin->Release();
    pVideoCaptureFilter->Release();
    pMediaControl->Release();
    pCaptureGraphBuilder2->Release();
    pGraphBuilder->Release();
    CoUninitialize();

    return 0;
}