官方文档：https://docs.microsoft.com/zh-cn/windows/win32/directshow/directshow

创建CLR类库项目（CSharpDirectShow），编写托管的DirectShow类库，右键项目属性–>链接器–> 输入–>附加依赖项；添加静态库文件Strmiids.lib和Quartz.lib；

定义头文件CSharpDirectShow.h，包含头文件dshow.h，定义如下方法：

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#pragma once

#include <dshow.h>

using namespace System;
using namespace System::Runtime::InteropServices;

public ref class DirectShow
{
public:
    /// <summary>
    /// 在当前线程上初始化COM库，并将并发模型标识为单线程单元（STA）
    /// </summary>
    /// <returns></returns>
    static Boolean ComInit();
    /// <summary>
    /// 关闭当前线程上的COM库，卸载该线程加载的所有DLL，释放该线程维护的所有其他资源，并强制关闭该线程上的所有RPC连接
    /// </summary>
    static void ComUinit();
    /// <summary>
    /// 获取视频输入设备
    /// </summary>
    /// <param name="devices"></param>
    /// <returns></returns>
    static Int32 GetVideoInputDevices([Out]array<VideoInputDsDevice^>^% devices);
    /// <summary>
    /// 获取音频输入设备
    /// </summary>
    /// <param name="device"></param>
    /// <returns></returns>
    static Int32 GetAudioInputDevices([Out]array<AudioInputDsDevice^>^% device);
};

其中，初始化COM库只能在STA线程调用，控制台程序直接调用会返回失败，在Winform和WPF等应用程序应该在第一次使用时初始化COM库；
当前线程初始化COM库和关闭COM库：

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Boolean DirectShow::ComInit()
{
    HRESULT hr = CoInitialize(NULL);
    return hr == S_OK || hr == S_FALSE;
}

void DirectShow::ComUinit()
{
    CoUninitialize();
}

一、枚举视频输入设备，参考：https://docs.microsoft.com/zh-cn/windows/win32/directshow/selecting-a-capture-device

1、创建视频输入设备的枚举器IEnumMoniker

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HRESULT DirectShow::EnumerateDevices(REFGUID category, IEnumMoniker** ppEnum)
{
    // 创建系统设备枚举器
    ICreateDevEnum* pDevEnum;
    HRESULT hr = CoCreateInstance(CLSID_SystemDeviceEnum, NULL, CLSCTX_INPROC_SERVER, IID_PPV_ARGS(&pDevEnum));

    if (SUCCEEDED(hr))
    {
        // 为类别创建枚举数.
        hr = pDevEnum->CreateClassEnumerator(category, ppEnum, 0);

        if (hr == S_FALSE)
            hr = VFW_E_NOT_FOUND;  // 类别是空的，视为错误

        pDevEnum->Release();
    }
    return hr;
}

Int32 DirectShow::GetVideoInputDevices([Out]array<VideoInputDsDevice^>^% devices)
{
    devices = nullptr;

    IEnumMoniker* pEnum;
    HRESULT hr = EnumerateDevices(CLSID_VideoInputDeviceCategory, &pEnum);        // 创建视频输入设备枚举器

    if (FAILED(hr))
        return hr;

    hr = EnumerateVideoInputDevices(pEnum, devices);    // 枚举视频输入设备
    pEnum->Release();
    return hr;
}

2、调用IEnumMoniker::Next()方法枚举设备，调用IPropertyBag::Read方法读取设备属性，以获取设备的友好名称和设备标识字符串：

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HRESULT DirectShow::EnumerateVideoInputDevices(IEnumMoniker* pEnum, [Out]array<VideoInputDsDevice^>^% devices)
{
    HRESULT hr = S_FALSE;
    devices = nullptr;
    List<VideoInputDsDevice^>^ list = gcnew List<VideoInputDsDevice^>();

    IMoniker* pMoniker;
    while (pEnum->Next(1, &pMoniker, NULL) == S_OK)
    {
        IPropertyBag* pPropBag;
        hr = pMoniker->BindToStorage(0, 0, IID_PPV_ARGS(&pPropBag));
        if (FAILED(hr))
        {
            pMoniker->Release();
            continue;
        }

        VideoInputDsDevice^ device = gcnew VideoInputDsDevice();

        VARIANT var;
        VariantInit(&var);

        // 获取设备友好名
        hr = pPropBag->Read(L"FriendlyName", &var, 0);

        if (FAILED(hr))
            hr = pPropBag->Read(L"Description", &var, 0);

        if (SUCCEEDED(hr))
        {
            device->FriendlyName = System::String(var.bstrVal).ToString();
            VariantClear(&var);
        }

        // 获取设备Moniker名
        LPOLESTR pOleDisplayName = reinterpret_cast<LPOLESTR>(CoTaskMemAlloc(MAX_MONIKER_NAME_LENGTH * 2));
        hr = pMoniker->GetDisplayName(NULL, NULL, &pOleDisplayName);

        if (SUCCEEDED(hr))
        {
            device->MonikerName = System::String(pOleDisplayName).ToString();
            array<VideoParams^>^ params;
            hr = EnumerateVideoParams(pMoniker, params);    // 枚举设备的采集参数
            if (SUCCEEDED(hr))
                device->Params = params;
        }

        CoTaskMemFree(pOleDisplayName);

        list->Add(device);
        pPropBag->Release();
        pMoniker->Release();
    }

    devices = list->ToArray();
    return S_OK;
}

3、枚举视频输入设备的采集参数：

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HRESULT DirectShow::EnumerateVideoParams(IMoniker* pMoniker, [Out]array<VideoParams^>^% params)
{
    params = nullptr;
    IBaseFilter* pFilter;
    HRESULT    hr = pMoniker->BindToObject(NULL, NULL, IID_IBaseFilter, (void**)&pFilter);

    if (FAILED(hr))
        return hr;

    IEnumPins* pinEnum;
    hr = pFilter->EnumPins(&pinEnum);

    if (FAILED(hr)) {
        pFilter->Release();
        return hr;
    }

    List<VideoParams^>^ list = gcnew List<VideoParams^>();
    IPin* pPins;
    while (pinEnum->Next(1, &pPins, NULL) == S_OK)
    {
        PIN_INFO pinInfo;
        hr = pPins->QueryPinInfo(&pinInfo);

        if (FAILED(hr) || pinInfo.dir != PINDIR_OUTPUT)
        {
            pPins->Release();
            continue;
        }

        IEnumMediaTypes* mtEnum;
        hr = pPins->EnumMediaTypes(&mtEnum);

        if (FAILED(hr))
        {
            pPins->Release();
            continue;
        }

        AM_MEDIA_TYPE* mt;
        while (mtEnum->Next(1, &mt, NULL) == S_OK)
        {
            VideoParams^ param = nullptr;
            if (mt->formattype == FORMAT_VideoInfo)
            {
                VIDEOINFOHEADER* pVih = reinterpret_cast<VIDEOINFOHEADER*>(mt->pbFormat);
                param = gcnew VideoParams();
                param->FrameWidth = pVih->bmiHeader.biWidth;
                param->FrameHeight = pVih->bmiHeader.biHeight;
                param->AverageFrameRate = pVih->AvgTimePerFrame == 0 ? 0 : 10000000 / pVih->AvgTimePerFrame;
            }
            else if (mt->formattype == FORMAT_VideoInfo2) {
                VIDEOINFOHEADER2* pVih = reinterpret_cast<VIDEOINFOHEADER2*>(mt->pbFormat);
                param = gcnew VideoParams();
                param->FrameWidth = pVih->bmiHeader.biWidth;
                param->FrameHeight = pVih->bmiHeader.biHeight;
                param->AverageFrameRate = pVih->AvgTimePerFrame == 0 ? 0 : 10000000 / pVih->AvgTimePerFrame;
            }

            if (param && param->AverageFrameRate > 1)
            {
                Boolean isExit = false;
                for each (VideoParams ^ item in list)
                {
                    if (item->FrameWidth == param->FrameWidth && item->FrameHeight == param->FrameHeight && item->AverageFrameRate == param->AverageFrameRate)
                    {
                        isExit = true;
                        break;
                    }
                }
                if (!isExit)
                    list->Add(param);
            }
        }
        pPins->Release();
    }

    pFilter->Release();

    params = list->ToArray();
    return S_OK;
}

调用代码及结果：

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var ret = DirectShow.GetVideoInputDevices (out VideoInputDsDevice[] videoInputDevices);

if (ret == 0) {
    Console.WriteLine ("视频输入设备：");

    foreach (var videoInputDevice in videoInputDevices) {
        Console.WriteLine ($"{videoInputDevice.FriendlyName}\t{videoInputDevice.MonikerName}");

        if (videoInputDevice.Params.Length > 0) {
            Console.WriteLine ("像素宽度\t像素高度\t1秒平均帧数");

            foreach (var param in videoInputDevice.Params) {
                Console.WriteLine ($"{param.FrameWidth}\t{param.FrameHeight}\t{param.AverageFrameRate}");
            }
        }

        Console.WriteLine ();
    }
}

二、枚举音频输入设备，参考https://docs.microsoft.com/zh-cn/windows/win32/directshow/selecting-a-capture-device ，过程和视频一样：

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ret = DirectShow.GetAudioInputDevices (out AudioInputDsDevice[] audioInputDevices);

if (ret == 0) {
    Console.WriteLine ("音频输入设备：");

    foreach (var audioInputDevice in audioInputDevices) {
        Console.WriteLine ($"{audioInputDevice.FriendlyName}\t{audioInputDevice.MonikerName}");

        if (audioInputDevice.Params.Length > 0) {
            Console.WriteLine ("音频格式\t通道数\t采样速率\t块对齐\t位数");

            foreach (var param in audioInputDevice.Params) {
                Console.WriteLine ($"{param.Format}\t{param.Channels}\t{param.SampleRate}\t{param.BlockAlign}\t{param.BitsPerSample}");
            }
        }

        Console.WriteLine ();
    }
}

官方文档：https://docs.microsoft.com/zh-cn/windows/win32/directshow/directshow
参考链接：https://www.cnblogs.com/pumbaa/p/14255725.html
参考代码：https://github.com/LowPlayer/CameraCapture