如何获取在Windows上的视频捕获设备(网络摄像头)的列表? (C ++) [英] How to get a list of video capture devices (web cameras) on windows? (C++)

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问题描述

所以我们有一个简单的C ++ win32控制台应用程序。我们所需要的是打印网络摄像头和其他视频捕获设备的列表。我们想尽可能多地使用windows apis - 毕竟,我们想要的是打印出aa列表 - 不要飞到月球!)如何做这样的事情?



我自己的财产:
我发现这个官方msdn示例,但我仍然没有得到如何输出设备列表到屏幕上=((对不起 - 我是新的C ++)



...一些更多...



在一个最简单的ms示例中,找到了

  HRESULT OnInitDialog(HWND hwnd,ChooseDeviceParam * pParam)
{
HRESULT hr = S_OK;

HWND hList = GetDlgItem(hwnd,IDC_DEVICE_LIST);

//显示设备列表

(DWORD i = 0; i {
WCHAR * szFriendlyName = NULL;

hr = pParam-> ppDevices [i] - > GetAllocatedString(
MF_DEVSOURCE_ATTRIBUTE_FRIENDLY_NAME,
& szFriendlyName,
NULL
);

if(FAILED(hr))
{
break;
}

int index = ListBox_AddString(hList,szFriendlyName);

ListBox_SetItemData(hList,index,i);

CoTaskMemFree(szFriendlyName);
}

看起来像它应该做的工作,但我不知道如何包括进入简单的命令行应用程序,以便输出数据...






b


解决方案

从显示的示例中,将以下代码复制到dev.c.然后打开所有SDK变量设置的命令行。在命令行链接到ole32.lib和oleaut32.lib。然后会显示所有设备。



cl dev.c ole32.lib oleaut32.lib



dev .exe将在命令行上给出列表。

  #include< windows.h> 
#include< dshow.h>

#pragma comment(lib,strmiids)

HRESULT EnumerateDevices(REFGUID category,IEnumMoniker ** ppEnum)
{
//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))
{
//为类别创建一个枚举器。
hr = pDevEnum-> CreateClassEnumerator(category,ppEnum,0);
if(hr == S_FALSE)
{
hr = VFW_E_NOT_FOUND; //类别为空。视为错误。
}
pDevEnum-> Release();
}
return hr;
}


void DisplayDeviceInformation(IEnumMoniker * pEnum)
{
IMoniker * pMoniker = NULL;

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

VARIANT var;
VariantInit(& var);

//获取描述或友好名称。
hr = pPropBag-> Read(LDescription,& var,0);
if(FAILED(hr))
{
hr = pPropBag-> Read(LFriendlyName,& var,0);
}
if(SUCCEEDED(hr))
{
printf(%S \\\
,var.bstrVal);
VariantClear(& var);
}

hr = pPropBag-> Write(LFriendlyName,& var);

// WaveInID仅适用于音频捕获设备。
hr = pPropBag-> Read(LWaveInID,& var,0);
if(SUCCEEDED(hr))
{
printf(WaveIn ID:%d\\\
,var.lVal);
VariantClear(& var);
}

hr = pPropBag-> Read(LDevicePath,& var,0);
if(SUCCEEDED(hr))
{
//设备路径不用于显示。
printf(设备路径:%S \\\
,var.bstrVal);
VariantClear(& var);
}

pPropBag->发布();
pMoniker-> Release();
}
}

void main()
{
HRESULT hr = CoInitializeEx(NULL,COINIT_MULTITHREADED);
if(SUCCEEDED(hr))
{
IEnumMoniker * pEnum;

hr = EnumerateDevices(CLSID_VideoInputDeviceCategory,& pEnum);
if(SUCCEEDED(hr))
{
DisplayDeviceInformation(pEnum);
pEnum-> Release();
}
hr = EnumerateDevices(CLSID_AudioInputDeviceCategory,& pEnum);
if(SUCCEEDED(hr))
{
DisplayDeviceInformation(pEnum);
pEnum-> Release();
}
CoUninitialize();
}
}


So we have a simple C++ win32 console app. All we want is to print list of web cameras and other video capture devices that are avaliable. We want to use windows apis as much as possible - no external libs - after all - all we want is to print out a a list - not to fly onto the moon!) How to do such thing?

My own reserch: I found this official msdn sample but I still do not get how to output device list onto screen=( (sorry - I am new to C++)

... some more reserch...

In one of simpliest ms samples on topic found this

HRESULT OnInitDialog(HWND hwnd, ChooseDeviceParam *pParam)
{
    HRESULT hr = S_OK;

    HWND hList = GetDlgItem(hwnd, IDC_DEVICE_LIST);

    // Display a list of the devices.

    for (DWORD i = 0; i < pParam->count; i++)
    {
        WCHAR *szFriendlyName = NULL;

        hr = pParam->ppDevices[i]->GetAllocatedString(
            MF_DEVSOURCE_ATTRIBUTE_FRIENDLY_NAME,
            &szFriendlyName,
            NULL
            );

        if (FAILED(hr))
        {
            break;
        }

        int index = ListBox_AddString(hList, szFriendlyName);

        ListBox_SetItemData(hList, index, i);

        CoTaskMemFree(szFriendlyName);
    }

looks like it should do the job but I do not get how to include this into simple command line app so to output data...


also from this series:

解决方案

From the examples shown, copy the following code into dev.c. Then open the command line with all the SDK variables set. At the command line link to ole32.lib and oleaut32.lib. It will then show you all the devices.

cl dev.c ole32.lib oleaut32.lib

dev.exe will give out the list on the command line.

#include <windows.h>
#include <dshow.h>

#pragma comment(lib, "strmiids")

HRESULT EnumerateDevices(REFGUID category, IEnumMoniker **ppEnum)
{
    // Create the System Device Enumerator.
    ICreateDevEnum *pDevEnum;
    HRESULT hr = CoCreateInstance(CLSID_SystemDeviceEnum, NULL,  
        CLSCTX_INPROC_SERVER, IID_PPV_ARGS(&pDevEnum));

    if (SUCCEEDED(hr))
    {
        // Create an enumerator for the category.
        hr = pDevEnum->CreateClassEnumerator(category, ppEnum, 0);
        if (hr == S_FALSE)
        {
            hr = VFW_E_NOT_FOUND;  // The category is empty. Treat as an error.
        }
        pDevEnum->Release();
    }
    return hr;
}


void DisplayDeviceInformation(IEnumMoniker *pEnum)
{
    IMoniker *pMoniker = NULL;

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

        VARIANT var;
        VariantInit(&var);

        // Get description or friendly name.
        hr = pPropBag->Read(L"Description", &var, 0);
        if (FAILED(hr))
        {
            hr = pPropBag->Read(L"FriendlyName", &var, 0);
        }
        if (SUCCEEDED(hr))
        {
            printf("%S\n", var.bstrVal);
            VariantClear(&var); 
        }

        hr = pPropBag->Write(L"FriendlyName", &var);

        // WaveInID applies only to audio capture devices.
        hr = pPropBag->Read(L"WaveInID", &var, 0);
        if (SUCCEEDED(hr))
        {
            printf("WaveIn ID: %d\n", var.lVal);
            VariantClear(&var); 
        }

        hr = pPropBag->Read(L"DevicePath", &var, 0);
        if (SUCCEEDED(hr))
        {
            // The device path is not intended for display.
            printf("Device path: %S\n", var.bstrVal);
            VariantClear(&var); 
        }

        pPropBag->Release();
        pMoniker->Release();
    }
}

void main()
{
    HRESULT hr = CoInitializeEx(NULL, COINIT_MULTITHREADED);
    if (SUCCEEDED(hr))
    {
        IEnumMoniker *pEnum;

        hr = EnumerateDevices(CLSID_VideoInputDeviceCategory, &pEnum);
        if (SUCCEEDED(hr))
        {
            DisplayDeviceInformation(pEnum);
            pEnum->Release();
        }
        hr = EnumerateDevices(CLSID_AudioInputDeviceCategory, &pEnum);
        if (SUCCEEDED(hr))
        {
            DisplayDeviceInformation(pEnum);
            pEnum->Release();
        }
        CoUninitialize();
    }
}

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