directshow捕获摄像头数据

directshow捕获摄像头的数据并显示

#include "stdafx.h"  
#include   
#include   
#include   

#define CHECK_HR(s) if (FAILED(s)) {return 1;}  
#define SAFE_RELEASE(p)     do { if ((p)) { (p)->Release(); (p) = NULL; } } while(0)  

LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam);

#pragma comment(lib, "Dxguid.lib")  
#pragma comment(lib, "Strmiids.lib")  

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow)
{
    CoInitialize(NULL);
    int nRes = 0;

    WNDCLASSEX wcex;

    wcex.cbSize = sizeof(WNDCLASSEX);
    wcex.style = CS_HREDRAW | CS_VREDRAW;
    wcex.lpfnWndProc = WndProc;
    wcex.cbClsExtra = 0;
    wcex.cbWndExtra = 0;
    wcex.hInstance = hInstance;
    wcex.hIcon = LoadIcon(hInstance, MAKEINTRESOURCE(IDI_APPLICATION));
    wcex.hCursor = LoadCursor(NULL, IDC_ARROW);
    wcex.hbrBackground = (HBRUSH)(COLOR_WINDOW + 1);
    wcex.lpszMenuName = NULL;
    wcex.lpszClassName = _T("dshow capture");
    wcex.hIconSm = LoadIcon(wcex.hInstance, MAKEINTRESOURCE(IDI_APPLICATION));

    if (!RegisterClassEx(&wcex))
    {
        MessageBox(NULL, _T("Call to RegisterClassEx failed!"), _T("Win32 Guided Tour"), NULL);

        return 1;
    }

    HWND m_hWnd = ::CreateWindowA("STATIC", "ds_video_preview", WS_POPUP, 100, 100, 500, 500, NULL, NULL, NULL, NULL);
    ShowWindow(m_hWnd, nCmdShow);
    UpdateWindow(m_hWnd);
    
    if (m_hWnd == NULL)
    {
        nRes = 11;
    }

    //----------------------用dshow获取摄像头---start--------------------------

    IGraphBuilder         *m_pGraph;//filter总图表管理器
    ICaptureGraphBuilder2 *m_pBuild;//捕获图表管理器
    IVideoWindow          *m_pVidWin;//窗口接口
    HRESULT hr = CoCreateInstance(CLSID_FilterGraph, NULL, CLSCTX_INPROC_SERVER, IID_IGraphBuilder, (void**)&m_pGraph);
    CHECK_HR(1);
    hr = CoCreateInstance(CLSID_CaptureGraphBuilder2, NULL, CLSCTX_INPROC_SERVER, IID_ICaptureGraphBuilder2, (void**)&m_pBuild);
    CHECK_HR(2);
    hr = m_pBuild->SetFiltergraph(m_pGraph);//给捕获图表管理器指定一个可用的图表管理器来进行使用
    CHECK_HR(3);
    hr = m_pGraph->QueryInterface(IID_IVideoWindow, (void **)&m_pVidWin);//通过此函数来查询某个组件是否支持某个特定的接口,如果支持就返回这些接口的指针
    CHECK_HR(4);

    ICreateDevEnum *pDevEnum = NULL;
    IEnumMoniker *pClsEnum = NULL;
    IMoniker *pMoniker = NULL;
    //创建设备枚举COM对象  
    hr = CoCreateInstance(CLSID_SystemDeviceEnum, NULL, CLSCTX_INPROC, IID_ICreateDevEnum, (void **)&pDevEnum);
    CHECK_HR(5);
    //创建视频采集设备枚举COM对象  
    hr = pDevEnum->CreateClassEnumerator(CLSID_VideoInputDeviceCategory, &pClsEnum, 0);
    CHECK_HR(6);

    int i = 0;
    while (i <= 0)
    {
        hr = pClsEnum->Next(1, &pMoniker, NULL);
        ++i;
    }
    CHECK_HR(7);

    IBaseFilter           *m_pSrc;
    hr = pMoniker->BindToObject(0, 0, IID_IBaseFilter, (void **)&m_pSrc);//就是这句获得Filter  
    CHECK_HR(8);

    SAFE_RELEASE(pMoniker);
    SAFE_RELEASE(pClsEnum);
    SAFE_RELEASE(pDevEnum);


    //将设备添加到filter管理器graph  
    hr = m_pGraph->AddFilter(m_pSrc, L"Video Capture");
    CHECK_HR(9);

    hr = m_pBuild->RenderStream(&PIN_CATEGORY_PREVIEW, &MEDIATYPE_Video, m_pSrc, NULL, NULL);
    CHECK_HR(10);

    m_pVidWin->put_Owner((OAHWND)m_hWnd);
    m_pVidWin->SetWindowPosition(100, 100, 400, 300);
    m_pVidWin->put_WindowStyle(WS_CHILD | WS_CLIPSIBLINGS);

    //IMediaControl接口,用来控制流媒体在Filter Graph中的流动,例如流媒体的启动和停止
    IMediaControl         *m_pMediaControl;
    hr = m_pGraph->QueryInterface(IID_IMediaControl, (void **)&m_pMediaControl);
    CHECK_HR(12);

    hr = m_pMediaControl->Run();
    
    //----------------------用dshow获取摄像头---end--------------------------

    MSG msg;
    while (GetMessage(&msg, NULL, 0, 0))
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }
    return (int)msg.wParam;

}

LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    PAINTSTRUCT ps;
    HDC hdc;
    TCHAR greeting[] = _T("Hello, World!");

    switch (message)
    {
    case WM_PAINT:
        hdc = BeginPaint(hWnd, &ps);
        TextOut(hdc, 5, 5, greeting, _tcslen(greeting));
        EndPaint(hWnd, &ps);
        break;
    case WM_DESTROY:
        PostQuitMessage(0);
        break;
    default:
        return DefWindowProc(hWnd, message, wParam, lParam);
        break;
    }

    return 0;
}

这是直接捕获并绘制到窗口上，一般的应用是获取流然后和音频一起编码，做直播和网络传输。那么有没有这种方式，进行传输呢，其实directshow 提供了ISampleGrabber，可以实现直接得到缓冲，或者异步回调数据。

1  从ISampleGrabber实例化一个sample grabber，充当一个transform filter

CComPtr m_pSampleGrabber;

2 设置相关参数，将Grabber注册并加入到filter graph中

//////////////////////////////////////////////////////////////////////////Add SampleGrabber
// create a sample grabber
//
hr = m_pSampleGrabber.CoCreateInstance( CLSID_SampleGrabber );
if( !m_pSampleGrabber )
{
MessageBox(NULL, L"Could not create SampleGrabber (is qedit.dll registered?)", L"", MB_OK);
return hr;
}
 
CComQIPtr< IBaseFilter, &IID_IBaseFilter > pGrabBase( m_pSampleGrabber );
// force it to connect to video, 24 bit
//
CMediaType VideoType;
VideoType.SetType( &MEDIATYPE_Video );
VideoType.SetSubtype( &MEDIASUBTYPE_RGB24 );
VideoType.SetFormatType(&FORMAT_VideoInfo);
hr = m_pSampleGrabber->SetMediaType( &VideoType ); // shouldn't fail
if (FAILED(hr))
{
MessageBox(NULL, L"不能初始化SampleGrabber媒体类型。", L"", MB_OK);
return hr;
}
hr = m_pGB->AddFilter( pGrabBase, L"Grabber" );
if( FAILED( hr ) )
{
MessageBox(NULL, L"Could not put sample grabber in graph", L"", MB_OK);
return hr;
}

3 连接成功以后，将Sample Grabber作为一个中间filter，利用CSampleGrabber的实例调用回调函数BufferCB，从源filter中得到

摄像头设备捕获的每一帧数据，作为视频预览

hr = m_pCapture->RenderStream(&PIN_CATEGORY_PREVIEW, &MEDIATYPE_Video, m_pBF, pGrabBase, m_pVMR);
 
if (FAILED(hr))
{
MessageBox(NULL, L"Could not put sample into sample grabber", L"", MB_OK);
return hr;
}
 
//////////////////////////////////////////////////////////////////////////Set mCB
AM_MEDIA_TYPE mt;
hr = m_pSampleGrabber->GetConnectedMediaType( &mt );
if ( FAILED( hr) )
{
MessageBox( NULL, TEXT("Could not read the connected media type"),L"", MB_OK);
return hr;
}
 
 
VIDEOINFOHEADER * vih = (VIDEOINFOHEADER*) mt.pbFormat;
mCB.IWidth = vih->bmiHeader.biWidth;
mCB.IHeight = vih->bmiHeader.biHeight;
FreeMediaType( mt );
 
 
hr = RenderFileList(m_pGB,m_pVMR );
 
 
// don't buffer the samples as they pass through
//
hr = m_pSampleGrabber->SetBufferSamples( TRUE);
 
 
// only grab one at a time, stop stream after
// grabbing one sample
//
hr = m_pSampleGrabber->SetOneShot( FALSE );
 
 
// set the callback, so we can grab the one sample
//
hr = m_pSampleGrabber->SetCallback( &mCB, 1 );
if (FAILED(hr))
{
MessageBox(NULL, L"Could not call callback method BufferCB().", L"", MB_OK); 
return hr;
}
pGrabBase.Release();

4 实现接口类ISampleGrabber，用于捕获视频帧的sample，从BufferCB中返回图像数据，用户传输，之前已设定了

图像的采样格式，这里不再赘述。

//////////////////////////////////////////////////////////////////////////SampleGrabber
// Global data
#define WM_CAPTURE_BITMAP   WM_APP + 1
BOOL g_bOneShot=TRUE;
 
 
// Structures
typedef struct _callbackinfo 
{
double dblSampleTime;
long lBufferSize;
BYTE *pBuffer;
BITMAPINFOHEADER bih;
 
 
} CALLBACKINFO;
 
 
CALLBACKINFO cb={0};
 
 
class CSampleGrabberCB : public ISampleGrabberCB 
{
private:
LPBITMAPFILEHEADER m_pFileHeader ;    // Bmp文件头
LPBITMAPINFOHEADER m_pBmpInfo ;     // Bmp信息头指针
 
 
BYTE* m_pImgFileData;                //Bmp文件数据
 
 
BOOL m_bViladImage ;
 
 
LPBYTE m_pBitmapHeader ;
LPVOID m_pvColorTable ;               //调色板指针
public:
// these will get set by the main thread below. We need to
// know this in order to write out the bmp
long IWidth;
long IHeight;
 
 
CSampleGrabberCB( )
{ 
m_pFileHeader = new BITMAPFILEHEADER ;
m_pBitmapHeader = new BYTE[sizeof(BITMAPINFOHEADER)] ;
}   
 
 
// fake out any COM ref counting
//
STDMETHODIMP_(ULONG) AddRef() { return 2; }
STDMETHODIMP_(ULONG) Release() { return 1; }
 
 
// fake out any COM QI'ing
//
STDMETHODIMP QueryInterface(REFIID riid, void ** ppv)
{
if( riid == IID_ISampleGrabberCB || riid == IID_IUnknown ) 
{
*ppv = (void *) static_cast ( this );
return NOERROR;
}    
return E_NOINTERFACE;
}
 
 
// we don't implement this interface for this example
//
STDMETHODIMP SampleCB( double SampleTime, IMediaSample * pSample )
{
return 0;
}
// As a workaround, copy the bitmap data during the callback,
// post a message to our app, and write the data later.
//
STDMETHODIMP BufferCB( double dblSampleTime, BYTE * pBuffer, long lBufferSize )
{
// this flag will get set to true in order to take a picture
//
if( !g_bOneShot )
return 0;
 
 
if (!pBuffer)
{
return E_POINTER;
}
 
 
if( cb.lBufferSize < lBufferSize )
{
delete [] cb.pBuffer;
cb.pBuffer = NULL;
cb.lBufferSize = 0;
}
 
 
// Since we can't access Windows API functions in this callback, just
// copy the bitmap data to a global structure for later reference.
cb.dblSampleTime = dblSampleTime;
 
 
// If we haven't yet allocated the data buffer, do it now.
// Just allocate what we need to store the new bitmap.
if (!cb.pBuffer)
{
cb.pBuffer = new BYTE[lBufferSize];
cb.lBufferSize = lBufferSize;
}
 
 
if( !cb.pBuffer )
{
cb.lBufferSize = 0;
return E_OUTOFMEMORY;
}
 
 
//Get bmp information
BITMAPINFOHEADER bih;
memset( &bih, 0, sizeof( bih ) );
bih.biSize = sizeof( bih );
bih.biWidth = IWidth;
bih.biHeight = IHeight;
bih.biPlanes = 1;
bih.biBitCount = 24;
memcpy(&(cb.bih), &bih, sizeof(bih));
 
 
// Copy the bitmap data into our global buffer
memcpy(cb.pBuffer, pBuffer, lBufferSize);
// Post a message to our application, telling it to come back
// and write the saved data to a bitmap file on the user's disk.
SendMessage(m_hWnd, WM_CAPTURE_BITMAP, 0, 0L);
return 0;
}
 
 
BOOL FormatImage( BYTE *lpImageData, int nBitCount, int nWidth, int nHeight ) 
{
 
m_bViladImage = FALSE ;
 
 
int nKlsBmpBitCount ;
int nImgWidth = nWidth ;
int nImgHeight = nHeight ;
if (nBitCount == 8 || nBitCount == 24 || nBitCount == 32)
{
nKlsBmpBitCount = nBitCount;
}
else
{
return m_bViladImage ;
}
 
 
int nDataWidth = nKlsBmpBitCount / 8 * nWidth ;
 
 
nDataWidth = ( nDataWidth % 4 == 0 ) ? nDataWidth : ( ( nDataWidth / 4 + 1 ) * 4 ) ;
 
 
//m_pFileHeader = new BITMAPFILEHEADER ;
 
 
m_pFileHeader->bfType      = 0x4d42 ;  
m_pFileHeader->bfSize      = sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER) + nDataWidth*nImgHeight ;
m_pFileHeader->bfReserved1 = 0 ;
m_pFileHeader->bfReserved2 = 0 ;
 
 
if ( nBitCount == 8 )
{
int nBmpInfoSize = sizeof(BITMAPFILEHEADER) 
+ sizeof(BITMAPINFOHEADER)
+ 256 * 4 ;
 
 
m_pFileHeader->bfOffBits = nBmpInfoSize ;
 
 
m_pBitmapHeader = new BYTE[nBmpInfoSize] ;
 
 
m_pBmpInfo = (LPBITMAPINFOHEADER)m_pBitmapHeader ;
 
 
m_pvColorTable = m_pBitmapHeader + sizeof(BITMAPINFOHEADER) ;
 
 
LPRGBQUAD pDibQuad = (LPRGBQUAD)(m_pvColorTable) ;
 
 
for ( int c=0; c<256; ++c )
{
pDibQuad[c].rgbRed = c ;
pDibQuad[c].rgbGreen = c ;
pDibQuad[c].rgbBlue = c ;
pDibQuad[c].rgbReserved = 0 ;
}
}
else
{
m_pFileHeader->bfOffBits = sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER) ;
 
 
//m_pBitmapHeader = new BYTE[sizeof(BITMAPINFOHEADER)] ;
 
 
m_pBmpInfo = (LPBITMAPINFOHEADER)m_pBitmapHeader ;
m_pvColorTable = NULL ;
}
 
 
m_pBmpInfo->biBitCount      = nKlsBmpBitCount ; 
m_pBmpInfo->biWidth         = nImgWidth ;
m_pBmpInfo->biHeight        = nImgHeight ;
m_pBmpInfo->biPlanes        = 1 ;
m_pBmpInfo->biSize          = sizeof(BITMAPINFOHEADER) ;
m_pBmpInfo->biSizeImage     = nImgWidth * nImgHeight * nKlsBmpBitCount / 8 ; 
m_pBmpInfo->biClrImportant  = 0 ;
m_pBmpInfo->biClrUsed       = 0 ;
m_pBmpInfo->biCompression   = 0 ;
m_pBmpInfo->biXPelsPerMeter = 0 ;
m_pBmpInfo->biYPelsPerMeter = 0 ; 
 
 
//m_pImgFileData = new BYTE[nDataWidth*nImgHeight] ;
SetImgFileData(nDataWidth, nImgHeight);
 
 
if ( nBitCount == 8 )
{
if ( nImgWidth % 4 == 0 )
{
memset( m_pImgFileData, 0, nDataWidth*nImgHeight ) ;
memcpy( m_pImgFileData, lpImageData, cb.lBufferSize) ;
}
else
{
memset( m_pImgFileData, 0, nDataWidth*nImgHeight ) ;
 
 
for ( int i=0; i

得到sample之后，放入到回调函数BufferCB中进行处理，从而得到数据块，并存入相应的结构体

//From Step 3
// set the callback, so we can grab the one sample
//
hr = m_pSampleGrabber->SetCallback( &mCB, 1 );
 
//From BufferCB
//Get bmp information
BITMAPINFOHEADER bih;
memset( &bih, 0, sizeof( bih ) );
bih.biSize = sizeof( bih );
bih.biWidth = IWidth;
bih.biHeight = IHeight;
bih.biPlanes = 1;
bih.biBitCount = 24;
memcpy(&(cb.bih), &bih, sizeof(bih));
 
 
// Copy the bitmap data into our global buffer
memcpy(cb.pBuffer, pBuffer, lBufferSize);

采样部分进行到这里，已经完成大部分工作了，下一步就是直接进行编解码并做音频同步，然后网络传输，这个将在之后的文章中陆续分享出来