网上流传很广的CCaptureVideo类有一些小问题，而且使用起来也不是特别方便。为了方便开发人员使用directshow的方便功能，我又重新封装了一下，代码也改了一些，修正了原有的bug，这个版本我相信是稍加修改就可以作为商业代码使用的，让它支持多次摄像头的打开，关闭，以及开始数据采集和关闭数据采集。本来可以把那些没必要的静态成员都放到类里面去的，但是考虑到大家对网上的那个CCaptureVideo类比较熟悉，不想破坏了大家的兴致，所以保留原有CCaptureVideo的全局变量。现将该类的代码贴出来，希望能够对想做摄像头应用软件开发的开发人员有用。
CCaptureVideo类的头文件：
#pragma once
#endif // _MSC_VER > 1000
#include <atlbase.h>
#include <windows.h>
#include <dshow.h>
#include <Qedit.h> // ISampleGrabberCB
#ifndef SAFE_RELEASE
#define SAFE_RELEASE( x ) \
if ( NULL != x ) \
{ \
x->Release( ); \
x = NULL; \
}
#endif
class CVdoFrameHandler {
public:
virtual void VdoFrameData(double dblSampleTime, BYTE * pBuffer, long lBufferSize) = 0 ;
};
class CSampleGrabberCB : public ISampleGrabberCB
{
public:
long lWidth ;
long lHeight ;
CVdoFrameHandler * frame_handler ;
BOOL bGrabVideo ;
public:
CSampleGrabberCB(){
lWidth = 0 ;
lHeight = 0 ;
bGrabVideo = FALSE ;
frame_handler = NULL ;
}
STDMETHODIMP_(ULONG) AddRef() { return 2; }
STDMETHODIMP_(ULONG) Release() { return 1; }
STDMETHODIMP QueryInterface(REFIID riid, void ** ppv) {
if( riid == IID_ISampleGrabberCB || riid == IID_IUnknown ){
*ppv = (void *) static_cast<ISampleGrabberCB*> ( this );
return NOERROR;
}
return E_NOINTERFACE;
}
STDMETHODIMP SampleCB( double SampleTime, IMediaSample * pSample ) {
return 0;
}
STDMETHODIMP BufferCB( double dblSampleTime, BYTE * pBuffer, long lBufferSize ){
if (!pBuffer) return E_POINTER;
if(bGrabVideo && frame_handler) frame_handler->VdoFrameData(dblSampleTime, pBuffer, lBufferSize) ;
return 0;
}
};
class CCaptureVideo : public CWnd
{
friend class CSampleGrabberCB;
public:
void GrabVideoFrames(BOOL bGrabVideoFrames, CVdoFrameHandler * frame_handler);
HRESULT Open(int iDeviceID,HWND hWnd);
HRESULT Close();
int EnumDevices(HWND hList);
CCaptureVideo();
virtual ~CCaptureVideo();
protected:
HWND m_hWnd;
IGraphBuilder * m_pGB;
ICaptureGraphBuilder2* m_pCapture;
IBaseFilter* m_pBF;
IMediaControl* m_pMC;
IVideoWindow* m_pVW;
ISampleGrabber* m_pGrabber;
protected:
void FreeMediaType(AM_MEDIA_TYPE& mt);
bool BindFilter(int deviceId, IBaseFilter **pFilter);
void ResizeVideoWindow();
HRESULT SetupVideoWindow();
HRESULT InitCaptureGraphBuilder();
};
CCaptrureVideo类的源文件：
#include "stdafx.h"
#include "CaptureVideo.h"
#ifdef _DEBUG
#undef THIS_FILE
static char THIS_FILE[]=__FILE__;
#define new DEBUG_NEW
#endif
CSampleGrabberCB mCB;
//////////////////////////////////////////////////////////////////////
// Construction/Destruction
//////////////////////////////////////////////////////////////////////
CCaptureVideo::CCaptureVideo()
{
//COM Library Intialization
if(FAILED(CoInitialize(NULL))) /*, COINIT_APARTMENTTHREADED)))*/
{
AfxMessageBox("CCaptureVideo CoInitialize Failed!\r\n");
return;
}
m_hWnd = NULL;
m_pVW = NULL;
m_pMC = NULL;
m_pGB = NULL;
m_pBF = NULL;
m_pGrabber = NULL;
m_pCapture = NULL;
}
CCaptureVideo::~CCaptureVideo()
{
// Stop media playback
// Stop media playback
if(m_pMC)m_pMC->StopWhenReady();
if(m_pVW){
m_pVW->put_Visible(OAFALSE);
m_pVW->put_Owner(NULL);
}
SAFE_RELEASE(m_pMC);
SAFE_RELEASE(m_pVW);
SAFE_RELEASE(m_pGB);
SAFE_RELEASE(m_pBF);
SAFE_RELEASE(m_pGrabber);
SAFE_RELEASE(m_pCapture);
CoUninitialize() ;
}
int CCaptureVideo::EnumDevices(HWND hList)
{
if (!hList)
return -1;
int id = 0;
//枚举视频扑捉设备
ICreateDevEnum *pCreateDevEnum;
HRESULT hr = CoCreateInstance(CLSID_SystemDeviceEnum, NULL, CLSCTX_INPROC_SERVER,IID_ICreateDevEnum, (void**)&pCreateDevEnum);
if (hr != NOERROR)return -1;
CComPtr<IEnumMoniker> pEm;
hr = pCreateDevEnum->CreateClassEnumerator(CLSID_VideoInputDeviceCategory,&pEm, 0);
if (hr != NOERROR)return -1;
pEm->Reset();
ULONG cFetched;
IMoniker *pM;
while(hr = pEm->Next(1, &pM, &cFetched), hr==S_OK) {
IPropertyBag *pBag;
hr = pM->BindToStorage(0, 0, IID_IPropertyBag, (void **)&pBag);
if(SUCCEEDED(hr)) {
VARIANT var;
var.vt = VT_BSTR;
hr = pBag->Read(L"FriendlyName", &var, NULL);
if (hr == NOERROR) {
TCHAR str[2048];
id++;
WideCharToMultiByte(CP_ACP,0,var.bstrVal, -1, str, 2048, NULL, NULL);
::SendMessage(hList, CB_ADDSTRING, 0,(LPARAM)str);
SysFreeString(var.bstrVal);
}
pBag->Release();
}
pM->Release();
}
return id;
}
HRESULT CCaptureVideo::Close()
{
// Stop media playback
if(m_pMC)m_pMC->StopWhenReady();
if(m_pVW){
m_pVW->put_Visible(OAFALSE);
m_pVW->put_Owner(NULL);
}
SAFE_RELEASE(m_pMC);
SAFE_RELEASE(m_pVW);
SAFE_RELEASE(m_pGB);
SAFE_RELEASE(m_pBF);
SAFE_RELEASE(m_pGrabber);
SAFE_RELEASE(m_pCapture);
return S_OK ;
}
HRESULT CCaptureVideo::Open(int iDeviceID, HWND hWnd)
{
HRESULT hr;
hr = InitCaptureGraphBuilder();
if (FAILED(hr)){
AfxMessageBox("Failed to get video interfaces!");
return hr;
}
// Bind Device Filter. We know the device because the id was passed in
if(!BindFilter(iDeviceID, &m_pBF))return S_FALSE;
hr = m_pGB->AddFilter(m_pBF, L"Capture Filter");
// hr = m_pCapture->RenderStream(&PIN_CATEGORY_PREVIEW, &MEDIATYPE_Video,
// m_pBF, NULL, NULL);
// create a sample grabber
hr = CoCreateInstance( CLSID_SampleGrabber, NULL, CLSCTX_INPROC_SERVER, IID_ISampleGrabber, (void**)&m_pGrabber );
if(FAILED(hr)){
AfxMessageBox("Fail to create SampleGrabber, maybe qedit.dll is not registered?");
return hr;
}
CComQIPtr< IBaseFilter, &IID_IBaseFilter > pGrabBase( m_pGrabber );
//设置视频格式
AM_MEDIA_TYPE mt;
ZeroMemory(&mt, sizeof(AM_MEDIA_TYPE));
mt.majortype = MEDIATYPE_Video;
mt.subtype = MEDIASUBTYPE_RGB24; // MEDIASUBTYPE_RGB24 ;
hr = m_pGrabber->SetMediaType(&mt);
if( FAILED( hr ) ){
AfxMessageBox("Fail to set media type!");
return hr;
}
hr = m_pGB->AddFilter( pGrabBase, L"Grabber" );
if( FAILED( hr ) ){
AfxMessageBox("Fail to put sample grabber in graph");
return hr;
}
// try to render preview/capture pin
hr = m_pCapture->RenderStream(&PIN_CATEGORY_PREVIEW, &MEDIATYPE_Video,m_pBF,pGrabBase,NULL);
if( FAILED( hr ) )
hr = m_pCapture->RenderStream(&PIN_CATEGORY_CAPTURE, &MEDIATYPE_Video,m_pBF,pGrabBase,NULL);
if( FAILED( hr ) ){
AfxMessageBox("Can't build the graph");
return hr;
}
hr = m_pGrabber->GetConnectedMediaType( &mt );
if ( FAILED( hr) ){
AfxMessageBox("Failt to read the connected media type");
return hr;
}
VIDEOINFOHEADER * vih = (VIDEOINFOHEADER*) mt.pbFormat;
mCB.lWidth = vih->bmiHeader.biWidth;
mCB.lHeight = vih->bmiHeader.biHeight;
mCB.bGrabVideo = FALSE ;
mCB.frame_handler = NULL ;
FreeMediaType(mt);
hr = m_pGrabber->SetBufferSamples( FALSE );
hr = m_pGrabber->SetOneShot( FALSE );
hr = m_pGrabber->SetCallback( &mCB, 1 );
//设置视频捕捉窗口
m_hWnd = hWnd ;
SetupVideoWindow();
hr = m_pMC->Run();//开始视频捕捉
if(FAILED(hr)){AfxMessageBox("Couldn't run the graph!");return hr;}
return S_OK;
}
bool CCaptureVideo::BindFilter(int deviceId, IBaseFilter **pFilter)
{
if (deviceId < 0)
return false;
// enumerate all video capture devices
CComPtr<ICreateDevEnum> pCreateDevEnum;
HRESULT hr = CoCreateInstance(CLSID_SystemDeviceEnum, NULL, CLSCTX_INPROC_SERVER,
IID_ICreateDevEnum, (void**)&pCreateDevEnum);
if (hr != NOERROR)
{
return false;
}
CComPtr<IEnumMoniker> pEm;
hr = pCreateDevEnum->CreateClassEnumerator(CLSID_VideoInputDeviceCategory,&pEm, 0);
if (hr != NOERROR)
{
return false;
}
pEm->Reset();
ULONG cFetched;
IMoniker *pM;
int index = 0;
while(hr = pEm->Next(1, &pM, &cFetched), hr==S_OK, index <= deviceId)
{
IPropertyBag *pBag;
hr = pM->BindToStorage(0, 0, IID_IPropertyBag, (void **)&pBag);
if(SUCCEEDED(hr))
{
VARIANT var;
var.vt = VT_BSTR;
hr = pBag->Read(L"FriendlyName", &var, NULL);
if (hr == NOERROR)
{
if (index == deviceId)
{
pM->BindToObject(0, 0, IID_IBaseFilter, (void**)pFilter);
}
SysFreeString(var.bstrVal);
}
pBag->Release();
}
pM->Release();
index++;
}
return true;
}
HRESULT CCaptureVideo::InitCaptureGraphBuilder()
{
HRESULT hr;
// 创建IGraphBuilder接口
hr=CoCreateInstance(CLSID_FilterGraph, NULL, CLSCTX_INPROC_SERVER, IID_IGraphBuilder, (void **)&m_pGB);
// 创建ICaptureGraphBuilder2接口
hr = CoCreateInstance (CLSID_CaptureGraphBuilder2 , NULL, CLSCTX_INPROC,
IID_ICaptureGraphBuilder2, (void **) &m_pCapture);
if (FAILED(hr))return hr;
m_pCapture->SetFiltergraph(m_pGB);
hr = m_pGB->QueryInterface(IID_IMediaControl, (void **)&m_pMC);
if (FAILED(hr))return hr;
hr = m_pGB->QueryInterface(IID_IVideoWindow, (LPVOID *) &m_pVW);
if (FAILED(hr))return hr;
return hr;
}
HRESULT CCaptureVideo::SetupVideoWindow()
{
HRESULT hr;
hr = m_pVW->put_Owner((OAHWND)m_hWnd);
if (FAILED(hr))return hr;
hr = m_pVW->put_WindowStyle(WS_CHILD | WS_CLIPCHILDREN);
if (FAILED(hr))return hr;
ResizeVideoWindow();
hr = m_pVW->put_Visible(OATRUE);
return hr;
}
void CCaptureVideo::ResizeVideoWindow()
{
if (m_pVW){
//让图像充满整个窗口
CRect rc;
::GetClientRect(m_hWnd,&rc);
m_pVW->SetWindowPosition(0, 0, rc.right, rc.bottom);
}
}
void CCaptureVideo::FreeMediaType(AM_MEDIA_TYPE& mt)
{
if (mt.cbFormat != 0) {
CoTaskMemFree((PVOID)mt.pbFormat);
// Strictly unnecessary but tidier
mt.cbFormat = 0;
mt.pbFormat = NULL;
}
if (mt.pUnk != NULL) {
mt.pUnk->Release();
mt.pUnk = NULL;
}
}
void CCaptureVideo::GrabVideoFrames(BOOL bGrabVideoFrames, CVdoFrameHandler * frame_handler)
{
mCB.frame_handler = frame_handler ;
mCB.bGrabVideo = bGrabVideoFrames ;
}
在这里，声明了一个CVdoFrameHandler的纯虚基类，里面有一个纯虚函数，用户使用的时候，只要继承这个类，然后重载这个纯虚函数，就可以自动采集视频图像了。
首先：
class CMyClass : pulic CVdoFrameHandler {
...
public:
// 重载它，这里的pBuffer指针里面放的就是BGR24的的采集结果，lBufferSize就是pBuffer长度
void VdoFrameData(double dblSampleTime, BYTE * pBuffer, long lBufferSize) ;
public:
CCaptureVideo m_cap_vdo; // 这个就是视频采集的类的对象了
};
采集的顺序：
HWND hWnd = m_cam_scr.GetSafeHwnd() ;
// 这个m_cam_scr是一个CStatic的对象，只要是个hWnd就行，
// directshow要在上面绘制出全屏的摄像头数据预览的
打开摄像头：
m_cap_vdo.Open(0, hWnd) ;
开始视频采集：
m_cap_vdo.GrabVideoFrames(TRUE, this) ;
此时就会周期性的自动的调用上面重载的VdoFrameData函数了，然后再编码发送，呵呵，就没问题了。
停止视频采集：
m_cap_vdo.GrabVideoFrames(FALSE, NULL) ;
关闭摄像头：
m_cap_vdo.Close() ;
最后，需要说明的是上述程序需要安装directx 9b的sdk，然后加入对应的lib：
strmiids.lib Quartz.lib winmm.lib dsound.lib dxguid.lib
我顺便也把directsound的lib给加上了。
如果只使用视频的话，大家用的时候也可以去掉。 | 
