windows DirectShow：网络摄像头预览和图像捕获
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原文地址: http://stackoverflow.com/questions/7550643/
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DirectShow: webcam preview and image capture
提问by Darkhydro
After looking at a very similar question and seeing almost identical code, I've decided to ask this question separately. I want to show a video preview of the webcam's video stream to the default window DirectShow uses, and I also want the ability to "take a picture" of the video stream at any given moment.
在查看了一个非常相似的问题并看到几乎相同的代码后，我决定单独提出这个问题。我想在 DirectShow 使用的默认窗口中显示网络摄像头视频流的视频预览，并且我还希望能够在任何给定时刻对视频流“拍照”。
I started with the DirectShow examples on MSDN, as well as the AMCap sample code, and have something I believe should should the preview part, but does not. I've found no examples of grabbing an image from the video stream except using SampleGrabber, which is deprecated and therefore I am trying not to use it.
我从 MSDN 上的 DirectShow 示例以及 AMCap 示例代码开始，我认为预览部分应该有一些东西，但没有。除了使用已弃用的 SampleGrabber 之外，我没有发现从视频流中抓取图像的示例，因此我尽量不使用它。
Below is my code, line for line. Note that most of the code in EnumerateCameras is commented out. That code would've been for attaching to another window, which I don't want to do. In the MSDN documentation, it explicitly states that the VMR_7 creates its own window to display the video stream. I get no errors in my app, but this window never appears.
下面是我的代码，一行一行。请注意，EnumerateCameras 中的大部分代码都被注释掉了。该代码将用于附加到另一个窗口，我不想这样做。在 MSDN 文档中，它明确指出 VMR_7 创建自己的窗口来显示视频流。我的应用程序中没有任何错误，但此窗口从未出现。
My question then is this: What am I doing wrong? Alternatively, if you know of a simple example of what I am trying to do, link me to it. AMCap is not a simple example, for reference.
那么我的问题是：我做错了什么？或者，如果您知道我正在尝试做的一个简单示例，请将我链接到它。AMCap 不是一个简单的例子，供参考。
NOTE: InitalizeVMR is for running in windowless state, which is my ultimate goal (integrating into a DirectX game). For now, however, i just want it to run in the simplest mode possible.
注意：InitalizeVMR 用于在无窗口状态下运行，这是我的最终目标（集成到 DirectX 游戏中）。但是，就目前而言，我只希望它以最简单的模式运行。
EDIT: The first portion of this question, that is previewing the camera stream, is solved. I am now just looking for an alternative to the deprecated SampleGrabber class so I can snap a photo at any moment and save it to a file.
编辑：这个问题的第一部分，即预览相机流，已解决。我现在只是在寻找已弃用的 SampleGrabber 类的替代品，这样我就可以随时拍摄照片并将其保存到文件中。
EDIT: After looking for almost an hour on google, the general concensus seems to be that you HAVE to use ISampleGrabber. Please let me know if you find anything different.
编辑：在谷歌上找了将近一个小时后，普遍的共识似乎是你必须使用 ISampleGrabber。如果您发现任何不同之处，请告诉我。
Testing code (main.cpp):
测试代码（main.cpp）：
CWebcam* camera = new CWebcam();
HRESULT hr = CoInitializeEx(NULL, COINIT_MULTITHREADED);
MessageBox(NULL, L"text", L"caption", NULL);
if (SUCCEEDED(hr))
{
camera->Create();
camera->EnumerateCameras();
camera->StartCamera();
}
int d;
cin >> d;
Webcam.cpp:
网络摄像头.cpp：
#include "Webcam.h"
CWebcam::CWebcam() {
HRESULT hr = CoInitializeEx(NULL, COINIT_MULTITHREADED);
//m_pTexInst = nullptr;
//m_pTexRes = nullptr;
}
CWebcam::~CWebcam() {
CoUninitialize();
m_pDeviceMonikers->Release();
m_pMediaController->Release();
}
BOOL CWebcam::Create() {
InitCaptureGraphBuilder(&m_pFilterGraph, &m_pCaptureGraph);
hr = m_pFilterGraph->QueryInterface(IID_IMediaControl, (void **)&m_pMediaController);
return TRUE;
}
void CWebcam::Destroy() {
}
void CWebcam::EnumerateCameras() {
HRESULT hr = EnumerateDevices(CLSID_VideoInputDeviceCategory, &m_pDeviceMonikers);
if (SUCCEEDED(hr))
{
//DisplayDeviceInformation(m_pDeviceMonikers);
//m_pDeviceMonikers->Release();
IMoniker *pMoniker = NULL;
if(m_pDeviceMonikers->Next(1, &pMoniker, NULL) == S_OK)
{
hr = pMoniker->BindToObject(0, 0, IID_IBaseFilter, (void**)&m_pCameraFilter);
if (SUCCEEDED(hr))
{
hr = m_pFilterGraph->AddFilter(m_pCameraFilter, L"Capture Filter");
}
}
// connect the output pin to the video renderer
if(SUCCEEDED(hr))
{
hr = m_pCaptureGraph->RenderStream(&PIN_CATEGORY_PREVIEW, &MEDIATYPE_Video,
m_pCameraFilter, NULL, NULL);
}
//InitializeVMR(hwnd, m_pFilterGraph, &m_pVMRControl, 1, FALSE);
//get the video window that will be displayed from the filter graph
IVideoWindow *pVideoWindow = NULL;
hr = m_pFilterGraph->QueryInterface(IID_IVideoWindow, (void **)&pVideoWindow);
/*if(hr != NOERROR)
{
printf("This graph cannot preview properly");
}
else
{
//get the video stream configurations
hr = m_pCaptureGraph->FindInterface(&PIN_CATEGORY_CAPTURE,
&MEDIATYPE_Video, m_pCameraFilter,
IID_IAMStreamConfig, (void **)&m_pVideoStreamConfig);
//Find out if this is a DV stream
AM_MEDIA_TYPE *pMediaTypeDV;
//fake window handle
HWND window = NULL;
if(m_pVideoStreamConfig && SUCCEEDED(m_pVideoStreamConfig->GetFormat(&pMediaTypeDV)))
{
if(pMediaTypeDV->formattype == FORMAT_DvInfo)
{
// in this case we want to set the size of the parent window to that of
// current DV resolution.
// We get that resolution from the IVideoWindow.
IBasicVideo* pBasivVideo;
// If we got here, gcap.pVW is not NULL
//ASSERT(pVideoWindow != NULL);
hr = pVideoWindow->QueryInterface(IID_IBasicVideo, (void**)&pBasivVideo);
/*if(SUCCEEDED(hr))
{
HRESULT hr1, hr2;
long lWidth, lHeight;
hr1 = pBasivVideo->get_VideoHeight(&lHeight);
hr2 = pBasivVideo->get_VideoWidth(&lWidth);
if(SUCCEEDED(hr1) && SUCCEEDED(hr2))
{
ResizeWindow(lWidth, abs(lHeight));
}
}
}
}
RECT rc;
pVideoWindow->put_Owner((OAHWND)window); // We own the window now
pVideoWindow->put_WindowStyle(WS_CHILD); // you are now a child
GetClientRect(window, &rc);
pVideoWindow->SetWindowPosition(0, 0, rc.right, rc.bottom); // be this big
pVideoWindow->put_Visible(OATRUE);
}*/
}
}
BOOL CWebcam::StartCamera() {
if(m_bIsStreaming == FALSE)
{
m_bIsStreaming = TRUE;
hr = m_pMediaController->Run();
if(FAILED(hr))
{
// stop parts that ran
m_pMediaController->Stop();
return FALSE;
}
return TRUE;
}
return FALSE;
}
void CWebcam::EndCamera() {
if(m_bIsStreaming)
{
hr = m_pMediaController->Stop();
m_bIsStreaming = FALSE;
//invalidate client rect as well so that it must redraw
}
}
BOOL CWebcam::CaptureToTexture() {
return TRUE;
}
HRESULT CWebcam::InitCaptureGraphBuilder(
IGraphBuilder **ppGraph, // Receives the pointer.
ICaptureGraphBuilder2 **ppBuild // Receives the pointer.
)
{
if (!ppGraph || !ppBuild)
{
return E_POINTER;
}
IGraphBuilder *pGraph = NULL;
ICaptureGraphBuilder2 *pBuild = NULL;
// Create the Capture Graph Builder.
HRESULT hr = CoCreateInstance(CLSID_CaptureGraphBuilder2, NULL,
CLSCTX_INPROC_SERVER, IID_ICaptureGraphBuilder2, (void**)&pBuild );
if (SUCCEEDED(hr))
{
// Create the Filter Graph Manager.
hr = CoCreateInstance(CLSID_FilterGraph, 0, CLSCTX_INPROC_SERVER,
IID_IGraphBuilder, (void**)&pGraph);
if (SUCCEEDED(hr))
{
// Initialize the Capture Graph Builder.
pBuild->SetFiltergraph(pGraph);
// Return both interface pointers to the caller.
*ppBuild = pBuild;
*ppGraph = pGraph; // The caller must release both interfaces.
return S_OK;
}
else
{
pBuild->Release();
}
}
return hr; // Failed
}
HRESULT CWebcam::EnumerateDevices(REFGUID category, IEnumMoniker **ppEnum)
{
// Create the System Device Enumerator.
ICreateDevEnum *pSystemDeviceEnumerator;
HRESULT hr = CoCreateInstance(CLSID_SystemDeviceEnum, NULL,
CLSCTX_INPROC_SERVER, IID_PPV_ARGS(&pSystemDeviceEnumerator));
if (SUCCEEDED(hr))
{
// Create an enumerator for the category.
hr = pSystemDeviceEnumerator->CreateClassEnumerator(category, ppEnum, 0);
if (hr == S_FALSE)
{
hr = VFW_E_NOT_FOUND; // The category is empty. Treat as an error.
}
pSystemDeviceEnumerator->Release();
}
return hr;
}
void CWebcam::DisplayDeviceInformation(IEnumMoniker *pEnum)
{
IMoniker *pMoniker = NULL;
int counter = 0;
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("%d: %S\n", counter, 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("%d: WaveIn ID: %d\n", counter, var.lVal);
VariantClear(&var);
}
hr = pPropBag->Read(L"DevicePath", &var, 0);
if (SUCCEEDED(hr))
{
// The device path is not intended for display.
printf("%d: Device path: %S\n", counter, var.bstrVal);
VariantClear(&var);
}
pPropBag->Release();
pMoniker->Release();
counter++;
}
}
HRESULT CWebcam::InitializeVMR(
HWND hwndApp, // Application window.
IGraphBuilder* pFG, // Pointer to the Filter Graph Manager.
IVMRWindowlessControl** ppWc, // Receives the interface.
DWORD dwNumStreams, // Number of streams to use.
BOOL fBlendAppImage // Are we alpha-blending a bitmap?
)
{
IBaseFilter* pVmr = NULL;
IVMRWindowlessControl* pWc = NULL;
*ppWc = NULL;
// Create the VMR and add it to the filter graph.
HRESULT hr = CoCreateInstance(CLSID_VideoMixingRenderer, NULL,
CLSCTX_INPROC, IID_IBaseFilter, (void**)&pVmr);
if (FAILED(hr))
{
return hr;
}
hr = pFG->AddFilter(pVmr, L"Video Mixing Renderer");
if (FAILED(hr))
{
pVmr->Release();
return hr;
}
// Set the rendering mode and number of streams.
IVMRFilterConfig* pConfig;
hr = pVmr->QueryInterface(IID_IVMRFilterConfig, (void**)&pConfig);
if (SUCCEEDED(hr))
{
pConfig->SetRenderingMode(VMRMode_Windowless);
// Set the VMR-7 to mixing mode if you want more than one video
// stream, or you want to mix a static bitmap over the video.
// (The VMR-9 defaults to mixing mode with four inputs.)
if (dwNumStreams > 1 || fBlendAppImage)
{
pConfig->SetNumberOfStreams(dwNumStreams);
}
pConfig->Release();
hr = pVmr->QueryInterface(IID_IVMRWindowlessControl, (void**)&pWc);
if (SUCCEEDED(hr))
{
pWc->SetVideoClippingWindow(hwndApp);
*ppWc = pWc; // The caller must release this interface.
}
}
pVmr->Release();
// Now the VMR can be connected to other filters.
return hr;
}
采纳答案by Roman R.
In windowless mode VMR would not create separate window. Since you started initialization for widnowless mode, you have to follow SetVideoClippingWindow with IVMRWindowlessControl::SetVideoPosition call to provide position within the window, see VMR Windowless Mode on MSDN.
在无窗口模式下，VMR 不会创建单独的窗口。由于您开始初始化无窗口模式，您必须遵循 SetVideoClippingWindow 和 IVMRWindowlessControl::SetVideoPosition 调用来提供窗口内的位置，请参阅MSDN 上的 VMR 无窗口模式。
Another sample code snippet for you: http://www.assembla.com/code/roatl-utilities/subversion/nodes/trunk/FullScreenWindowlessVmrSample01/MainDialog.h#ln188
另一个示例代码片段：http: //www.assembla.com/code/roatl-utilities/subversion/nodes/trunk/FullScreenWindowlessVmrSample01/MainDialog.h#ln188
