[C++]DirectShow检测音视频输入设备及其采集参数
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：
#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：
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
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：
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：
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：
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：
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 (); } }
代码已上传至Github：https://github.com/LowPlayer/CameraCapture
