DirectShow编程实现摄像头视频捕捉

1、DirectShow编程实现摄像头视频捕捉前言DirectShow是微软公司提供的一套在Windows平台上进行流媒体处理的开发包，与DirectX开发包一起发布。 DirectShow为多媒体流的捕捉和回放提供了强有力的支持。用DirectShow开发应用程序，我们可以很方便地从支持WDM驱动模型的采集卡上捕获数据，并且进行相应的后期处理乃至存储到文件中。DirectShow是基于COM的，为了编写DirectShow应用程序，需要了解COM客户程序编写的基础知识。Directshow提供了大量的接口，但在编程中发现还是不够方便，如果能构建一个视频捕捉类把常用的一些动作封装起来，那么就更方便

2、了。编程思路# W+ K9 7 M( u' z5 U2 P2 g为了更加容易建立视频捕捉应用程序，DirectShow提供了一个叫做Capture Graph Builder的对象，Capture Graph Builder提供IcaptureGraphBuilder2接口，该接口可以建立和控制Capture Graph。建立视频捕捉程序，必须首先获取并初始化IcaptureGraphBuilder2接口，然后选择一个适当的视频捕捉设备。选择好设备后，为该设备创建Capture filter，然后调用AddFilter把Capture filter添加到Filter Graph。如果仅

3、仅希望用摄像头来进行实时监控的话，只需要在上面的基础上调用ICaptureGraphBuilder2:RenderStream就可以了：ICaptureGraphBuilder2 *pBuild; / Capture Graph Builder$ N/ |3 v% Z- R. E# m/省略初始化部分代码IBaseFilter *pCap; / Video capture filter.: p# y! D s; # v+ Q/省略初始化和添加到Filter Graph部分代码pBuild->RenderStream(&PIN_CATEGORY_PREVIEW, &MEDI

4、ATYPE_Video, pCap, NULL, NULL);DirectShow提供了一个捕捉静态图像的方法：使用Sample Grabber filter。依次按照以下三个步骤就可以了：: g; ?) m: X& : L# v第一步, 定义一个类实现Sample Grabber的回调接口IsampleGrabberCB：: V& ' u' w. G5 x n: Nclass CSampleGrabberCB : public ISampleGrabberCB k* a$ K2 s+ y" R5 c O1 /在后面提供的类中具体完成CSampleGr

5、abberCB mCB;第二步、调用RenderStream依次把Still pin、Sample Grabber和系统默认Renderer Filter连接起来。! N Q7 c/ O5 g/ ?, c" p第三步、配置Sample Grabber以捕获数据。0 U3 a3 L' H0 X视频捕捉类CCaptureVideo的具体实现/ CCaptureVideo视频捕捉类头文件+ 8 e2 - a) n3 a" r& Y# /#if!defined(AFX_CAPTUREVIDEO_H_F5345AA4_A39F_4B07_B843_3D87C4287A

6、A0_INCLUDED_)( 7 C! Y6 e# k$ H! l" o/ B#define AFX_CAPTUREVIDEO_H_F5345AA4_A39F_4B07_B843_3D87C4287AA0_INCLUDED_* q5 q1 K8 G: n/ CaptureVideo.h : header file/#if _MSC_VER > 1000#pragma once8 T5 E! a2 ' s: w' p#endif / _MSC_VER > 1000; P" f) U8 ) m& b% : #include <atlba

7、se.h>( R5 n1 ! A# p, g* j8 2 K/ K#include <windows.h>1 t* # u1 s: K7 E; L7 K! P#include <dshow.h>#ifndef SAFE_RELEASE#define SAFE_RELEASE( x ) & W! C9 K- L& Kif ( NULL != x ) + r4 n% s% Z- X; e" Q x->Release( ); x = NULL; ; Y# S/ u F6 # t( e2 W#endif& g& j$ Y $

8、 _2 w M2 T& kclass CSampleGrabberCB;class CCaptureVideo : public CWnd& d; d" E* d4 H" j0 Hfriend class CSampleGrabberCB;public:, C& * 2 H+ v4 # void GrabOneFrame(BOOL bGrab);HRESULT Init(int iDeviceID,HWND hWnd);* : Q% * & z7 rint EnumDevices(HWND hList);CCaptureVideo();vir

9、tual CCaptureVideo();private:5 d, n& g g) S a J9 M- V- HWND m_hWnd;, R! x( 1 h8 + |$ jIGraphBuilder *m_pGB;ICaptureGraphBuilder2* m_pCapture;1 p4 s, q0 2 S1 H) n% r7 q" PIBaseFilter* m_pBF;IMediaControl* m_pMC;IVideoWindow* m_pVW;CComPtr<ISampleGrabber> m_pGrabber;protected:void FreeM

10、ediaType(AM_MEDIA_TYPE& mt);+ k& H, y* W2 1 U: Xbool BindFilter(int deviceId, IBaseFilter *pFilter);void ResizeVideoWindow();3 ; v) ; _) C& G; - ) WHRESULT SetupVideoWindow();' S ; & X6 m. h# l% F5 KHRESULT InitCaptureGraphBuilder();& x+ L, r; J* M. o; F2 # a;#endif/!defined(

11、AFX_CAPTUREVIDEO_H_F5345AA4_A39F_4B07_B843_3D87C4287AA0_INCLUDED_)3 J7 S! A+ Y- Q' a1 E# N/-/ CCaptureVideo视频捕捉类实现文件CaptureVideo.cpp3 h) b7 q5 _1 j3 , v/ F; i7 /-/ CaptureVideo.cpp: implementation of the CCaptureVideo class.0 $ S% D, D e* u$ # . A3 T/" o( o7 S) S' M#include "stdafx

12、.h"' 2 P* _9 Q3 l! 6 X6 g3 #include "CaptureVideo.h" b! a, t: ) S) _#ifdef _DEBUG: |" r- 0 G$ b7 C#undef THIS_FILE2 7 N% p$ ! w- static char THIS_FILE=_FILE_;#define new DEBUG_NEW6 y3 s* o7 E: p) Z) P% l$ d* U( |' i#endif- K/ r7 l2 * |0 M2 T; NBOOL bOneShot=FALSE;/全局变量4 ,

13、 _1 5 s" z3 s- X7 uclass CSampleGrabberCB : public ISampleGrabberCB9 n" A7 Y- I4 P4 Q: X gpublic:long lWidth;long lHeight;$ r7 q+ i) P8 ? t4 e& fTCHAR m_szFileNameMAX_PATH;/ 位图文件名称CSampleGrabberCB( )* x4 N7 K- Y3 Z0 n6 ustrcpy(m_szFileName, "c:donaldo.bmp");STDMETHODIMP_(ULON

14、G) AddRef() return 2; STDMETHODIMP_(ULONG) Release() return 1; STDMETHODIMP QueryInterface(REFIID riid, void * ppv)if( riid = IID_ISampleGrabberCB | riid = IID_IUnknown )1 : V' C8 F2 u9 f% d5 |& N/ E*ppv = (void *) static_cast<ISampleGrabberCB*> ( this );" h4 E1 C7 i. V; U0 C9 are

15、turn NOERROR;& ( j0 c" L0 x+ P" J! s+ o1 w# return E_NOINTERFACE;' N1 t- F8 W! r* l2 p2 7 b' 7 _5 o" R/ a! u8 P% v# nSTDMETHODIMP SampleCB( double SampleTime, IMediaSample * pSample )" e, U" Z2 d _+ e) l, ereturn 0; w* z) ! Y- J2 M0 b. a; o! c5 P9 # c0 LSTDMETHOD

16、IMP BufferCB( double dblSampleTime, BYTE * pBuffer, long lBufferSize ). C1 P/ , 4 w. q7 A' 7 p5 dif( !bOneShot )return 0;if (!pBuffer)return E_POINTER;SaveBitmap(pBuffer, lBufferSize);& g8 e; 4 q7 O4 i2 wbOneShot = FALSE;2 i$ , S! B6 G: B4 _! J! greturn 0;$ j7 Q. f% & a5 w4 u( m* V4 /创建位

17、图文件BOOL SaveBitmap(BYTE * pBuffer, long lBufferSize )HANDLE hf = CreateFile( U& L4 6 U: U# X. V5 wm_szFileName, GENERIC_WRITE, FILE_SHARE_READ, NULL,: e1 B- I# E/ ?5 oCREATE_ALWAYS, NULL, NULL );0 ' I0 l0 C8 I" Bif( hf = INVALID_HANDLE_VALUE )return 0;. j) X6 Y' J! T9 c/ L( H/ 写文件头,

18、 h# h# S% W( r" gBITMAPFILEHEADER bfh;memset( &bfh, 0, sizeof( bfh ) );- A8 Y4 i6 E0 L' 4 y4 _/ _3 obfh.bfType = MB;! V' N6 T2 # Abfh.bfSize = sizeof( bfh ) + lBufferSize + sizeof( BITMAPINFOHEADER );& R2 V2 R' 6 Q' x J4 ; Fbfh.bfOffBits = sizeof( BITMAPINFOHEADER ) + si

19、zeof( BITMAPFILEHEADER );DWORD dwWritten = 0; U+ k0 A7 ( K9 aWriteFile( hf, &bfh, sizeof( bfh ), &dwWritten, NULL );/ 写位图格式BITMAPINFOHEADER bih;memset( &bih, 0, sizeof( bih ) );( P& Z! B% D3 v6 s5 1 I7 ?2 hbih.biSize = sizeof( bih );bih.biWidth = lWidth;8 E$ W6 x- O) r( + $ 4 Wbih.bi

20、Height = lHeight;* & F& O) F# c% l7 ebih.biPlanes = 1;bih.biBitCount = 24;WriteFile( hf, &bih, sizeof( bih ), &dwWritten, NULL );/ 写位图数据$ _ L7 V$ j, |9 xWriteFile( hf, pBuffer, lBufferSize, &dwWritten, NULL );/ ( R2 D' T, I W* s; ZCloseHandle( hf );return 0;' M( F9 e"

21、; 2 d2 ?, x. r3 R! q( 2 L;+ c( D; d2 x5 h6 v; F8 ICSampleGrabberCB mCB;/ q# K( i4 U4 l/ ) ?/ Construction/Destruction/* S/ X g7 K6 R0 q; CCaptureVideo:CCaptureVideo()1 ( i3 D. k7 P' n9 a/COM Library Intializationif(FAILED(CoInitialize(NULL) /*, COINIT_APARTMENTTHREADED)*/ * R- g& r0 ?4 t( Af

22、xMessageBox("CoInitialize Failed!rn");* z- g7 8 O+ A* T8 A, U! j. : w: w$ p3 return;* ?" P4 L, p5 u1 K! b$ Y G* n5 t! 0 Bm_hWnd = NULL;/ q/ O# n$ k+ t0 Nm_pVW = NULL;* k, ?3 X+ c7 b$ S9 f8 2 v& y5 o$ m_pMC = NULL;1 0 / j$ w3 R7 Zm_pGB = NULL;m_pCapture = NULL;2 / i8 h a6 s. k( t5

23、p6 K& O$ x, i% b% rCCaptureVideo:CCaptureVideo()8 h+ D) K) u. S' z6 W/ Stop media playbackif(m_pMC)m_pMC->Stop();8 F/ k6 S5 j6 c# 8 hif(m_pVW)m_pVW->put_Visible(OAFALSE);m_pVW->put_Owner(NULL);: " r! p$ n* SAFE_RELEASE(m_pCapture);/ U; V1 m. D* C$ ) B. B% z* K+ wSAFE_RELEASE(m_

24、pMC);, b0 T; ; Z" S$ O# ) FSAFE_RELEASE(m_pGB);SAFE_RELEASE(m_pBF);( 4 G2 e- A5 s9 a( B8 L1 sCoUninitialize( );int CCaptureVideo:EnumDevices(HWND hList) N' * W$ ?) * i, M6 # J* s0 & if (!hList)2 7 t' U: a9 C) V6 n+ n! Greturn -1; ?6 X' f3 V1 O1 Y9 g$ 1 Q dint id = 0;' B# G:

25、p. V, # x: . H6 q* A ' s7 2 % F* 7 R- U/枚举视频扑捉设备ICreateDevEnum *pCreateDevEnum;HRESULT hr = CoCreateInstance(CLSID_SystemDeviceEnum, NULL, CLSCTX_INPROC_SERVER,IID_ICreateDevEnum, (void*)&pCreateDevEnum);- n7 m; _$ s8 D0 p" Gif (hr != NOERROR)return -1;CComPtr<IEnumMoniker> pEm;hr

26、 = pCreateDevEnum->CreateClassEnumerator(CLSID_VideoInputDeviceCategory,&pEm, 0);if (hr != NOERROR)return -1;pEm->Reset();ULONG cFetched;' J% # 4 Q$ o1 d# ?IMoniker *pM;! o2 % a0 a3 e9 Cwhile(hr = pEm->Next(1, &pM, &cFetched), hr=S_OK), z5 |; 4 j, U0 fIPropertyBag *pBag;$ 5

27、S: q: d, O% Phr = pM->BindToStorage(0, 0, IID_IPropertyBag, (void *)&pBag);if(SUCCEEDED(hr). w% ?) Q7 f/ c* LVARIANT var;+ d: W# y4 B1 E1 r$ m, S, q% O, cvar.vt = VT_BSTR;hr = pBag->Read(L"FriendlyName", &var, NULL);if (hr = NOERROR) b7 & r& U: 9 u# g2 QTCHAR str2048;

28、! b7 T0 z& J$ M* C& K- t3 Eid+;WideCharToMultiByte(CP_ACP,0,var.bstrVal, -1, str, 2048, NULL, NULL);:SendMessage(hList, CB_ADDSTRING, 0,(LPARAM)str);SysFreeString(var.bstrVal);0 |& q2 |/ k0 % Y( k+ ' W! r% 0 Y1 pBag->Release();% C6 N# z; e5 N+ . q$ H+ ypM->Release();) / o$ T% M

29、. f4 * h- u% 1 e+ F2 O7 h2 g- I' H) |return id;3 d, ) ?. z: c z, X2 D- l* c. iHRESULT CCaptureVideo:Init(int iDeviceID, HWND hWnd) R3 V* : M Y& _! V: H9 _HRESULT hr;hr = InitCaptureGraphBuilder();if (FAILED(hr)" $ J: | b; gAfxMessageBox("Failed to get video interfaces!");+ P;

30、x! + g6 j, Z9 return hr;, P4 Y: ?0 O" B' / Bind Device Filter. We know the device because the id was passed inif(!BindFilter(iDeviceID, &m_pBF)return S_FALSE;) v5 M/ % p, 0 rhr = m_pGB->AddFilter(m_pBF, L"Capture Filter");/ hr = m_pCapture->RenderStream(&PIN_CATEGORY

31、_PREVIEW, &MEDIATYPE_Video,9 : u1 |- P* 4 C' L0 / m_pBF, NULL, NULL);2 h3 N2 H* B- o% P( v( T/ create a sample grabberhr = m_pGrabber.CoCreateInstance( CLSID_SampleGrabber );+ v$ r8 p2 D! + V, V2 y' Qif( !m_pGrabber )% |) L" N$ J* rAfxMessageBox("Fail to create SampleGrabber, m

32、aybe qedit.dll is not registered?");return hr;3 e4 T. l4 t. B7 ( ?" oCComQIPtr< IBaseFilter, &IID_IBaseFilter > pGrabBase( m_pGrabber );: K$ p2 m* K9 D! $ E) M/设置视频格式: d3 N. H h5 E6 d3 R* U2 aAM_MEDIA_TYPE mt;8 l7 _0 y* P& m$ TZeroMemory(&mt, sizeof(AM_MEDIA_TYPE);+ '

33、 q( s! M& o: f% N% M8 w3 Ymt.majortype = MEDIATYPE_Video;mt.subtype = MEDIASUBTYPE_RGB24; y1 G q3 7 p9 s4 d' E- qhr = m_pGrabber->SetMediaType(&mt);/ v8 H5 ( Z! C# w! kif( FAILED( hr ) )# i- t8 G1 t# j- s3 l* ZAfxMessageBox("Fail to set media type!");return hr; m7 C+ q( ; g;

34、 b6 Rhr = m_pGB->AddFilter( pGrabBase, L"Grabber" );" # & p1 A6 f: O! v; if( FAILED( hr ) )AfxMessageBox("Fail to put sample grabber in graph");4 v* 9 Q7 z" % 9 Ireturn hr;% _: v. s2 F# T, u% / try to render preview/capture pin 0 x O6 d6 Y) Z4 U* W$ b c; Chr = m_

35、pCapture->RenderStream(&PIN_CATEGORY_PREVIEW, &MEDIATYPE_Video,m_pBF,pGrabBase,NULL);+ 9 : u" Z7 q8 p0 Fif( FAILED( hr ) )hr = m_pCapture->RenderStream(&PIN_CATEGORY_CAPTURE, &MEDIATYPE_Video,m_pBF,pGrabBase,NULL);. d1 ? x: k4 l2 x; mif( FAILED( hr ) )AfxMessageBox("C

36、ant build the graph");* 5 w) L) E; g4 ! nreturn hr;7 Q' J. a8 h" * yhr = m_pGrabber->GetConnectedMediaType( &mt );8 d t: i; K" d. E- H# | Bif ( FAILED( hr) )AfxMessageBox("Failt to read the connected media type");return hr;7 A$ P+ z8 e: ?% & lVIDEOINFOHEADER *

37、 vih = (VIDEOINFOHEADER*) mt.pbFormat;mCB.lWidth = vih->bmiHeader.biWidth;1 |- D. S/ ) q; n) j" n" G9 p8 mCB.lHeight = vih->bmiHeader.biHeight;FreeMediaType(mt);9 u0 V( r; " O$ C) P# Phr = m_pGrabber->SetBufferSamples( FALSE );hr = m_pGrabber->SetOneShot( FALSE );- s! N6 L

38、& z! z+ p! Vhr = m_pGrabber->SetCallback( &mCB, 1 );1 X( G( G8 ?. L/设置视频捕捉窗口+ Z3 ) U: U! D& v9 Gm_hWnd = hWnd ;SetupVideoWindow();hr = m_pMC->Run();/开始视频捕捉if(FAILED(hr)AfxMessageBox("Couldnt run the graph!");return hr;7 + R6 Z0 S3 D6 z8 C* l% x4 O7 Wreturn S_OK;* d' B

39、) Q' r: r Ebool CCaptureVideo:BindFilter(int deviceId, IBaseFilter *pFilter): D. w( Q& . if (deviceId < 0)! W" |, G' g$ O5 N1 J, % return false;4 * $ e* k5 J) u' T# j! n8 k) V( _ P3 f/ J& I/ enumerate all video capture devicesCComPtr<ICreateDevEnum> pCreateDevEnum;H

40、RESULT hr = CoCreateInstance(CLSID_SystemDeviceEnum, NULL, CLSCTX_INPROC_SERVER,IID_ICreateDevEnum, (void*)&pCreateDevEnum);if (hr != NOERROR)return false;1 Y, Z) p; ) m ?CComPtr<IEnumMoniker> pEm;hr = pCreateDevEnum->CreateClassEnumerator(CLSID_VideoInputDeviceCategory,&pEm, 0);if

41、(hr != NOERROR)/ m5 v8 b! l5 G0 N- J" Z1 p w% v greturn false;. W& e2 n, f5 Z7 : H1 MpEm->Reset();4 X- G, l* W- n4 I W+ B/ l; f2 c0 IULONG cFetched;% / W& s7 W( C9 C0 W4 h: ! B* AIMoniker *pM;. C2 k+ ?! j- d7 H- j) E2 % P/ sint index = 0;while(hr = pEm->Next(1, &pM, &cFetc

42、hed), hr=S_OK, index <= deviceId)1 w$ Y. G' _( d6 _. ; GIPropertyBag *pBag;! 8 W6 E6 o4 x6 a2 i- Lhr = pM->BindToStorage(0, 0, IID_IPropertyBag, (void *)&pBag);/ d. N- v1 t9 y, if(SUCCEEDED(hr)# x2 l( C: T1 s7 i0 % ; e$ G- C: dVARIANT var;var.vt = VT_BSTR;hr = pBag->Read(L"Frie

43、ndlyName", &var, NULL);if (hr = NOERROR)5 S5 : A8 & e6 Q$ r0 7 |9 if (index = deviceId)! t5 p8 _. k3 G4 q8 T0 d! v( m! s) y! opM->BindToObject(0, 0, IID_IBaseFilter, (void*)pFilter);SysFreeString(var.bstrVal);* i, Z& l( D U$ y" F" pBag->Release();pM->Release();- q

44、# a# n3 t+ j& M5 Cindex+;- p) j7 q+ 3 Z5 m' M. S! W3 f8 I$ y: L2 Z6 C0 freturn true;) e1 |2 . L" c8 i6 8 H$ QHRESULT CCaptureVideo:InitCaptureGraphBuilder()6 P! . e5 C; F; F' M$ R8 / X$ ( D* r8 p8 f* jHRESULT hr; p/ u7 o4 , i! U) P& + h' f" u" y/ 创建IGraphBuilder接口$

45、 z; R; a5 K$ q; T( x hr=CoCreateInstance(CLSID_FilterGraph, NULL, CLSCTX_INPROC_SERVER, IID_IGraphBuilder, (void *)&m_pGB);/ 创建ICaptureGraphBuilder2接口- 5 v$ Y' M2 # ehr = CoCreateInstance (CLSID_CaptureGraphBuilder2 , NULL, CLSCTX_INPROC,: ; 6 j: H* l) v. n7 X; 6 g0 jIID_ICaptureGraphBuilder

46、2, (void *) &m_pCapture);if (FAILED(hr)return hr;+ u6 m* O+ fm_pCapture->SetFiltergraph(m_pGB);3 B1 # o c4 U* m! E; Rhr = m_pGB->QueryInterface(IID_IMediaControl, (void *)&m_pMC);if (FAILED(hr)return hr;/ G# 9 g8 h5 B0 t1 H7 h+ Ohr = m_pGB->QueryInterface(IID_IVideoWindow, (LPVOID *

47、) &m_pVW);$ I1 H, j" a- C8 g5 |if (FAILED(hr)return hr; c1 S: S! W3 8 O, lreturn hr;HRESULT CCaptureVideo:SetupVideoWindow()HRESULT hr;hr = m_pVW->put_Owner(OAHWND)m_hWnd);if (FAILED(hr)return hr;& a 3 W, g* - f0 Ihr = m_pVW->put_WindowStyle(WS_CHILD | WS_CLIPCHILDREN);if (FAILED(

48、hr)return hr;0 S- , ?; H. Y/ p% O) JResizeVideoWindow();, e8 f: $ : v, t* J5 p A8 hr = m_pVW->put_Visible(OATRUE);# c: a+ 3 I4 H; G5 areturn hr;: a G, b2 J4 T: J4 D0 j; c1 q; xvoid CCaptureVideo:ResizeVideoWindow()$ P7 g9 s# v/ q! w) M$ bif (m_pVW). B; ; & g: e# h3 E3 G9 L% o/让图像充满整个窗口CRect r

49、c;4 O7 o7 g- A% E! Q. b:GetClientRect(m_hWnd,&rc);$ a, ?6 ?5 k; # Y% Z& Q0 K/ nm_pVW->SetWindowPosition(0, 0, rc.right, rc.bottom);" r6 K6 x1 q- E5 V) jvoid CCaptureVideo:GrabOneFrame(BOOL bGrab)2 1 x8 v. R, W$ |+ d0 U5 i0 nbOneShot = bGrab;void CCaptureVideo:FreeMediaType(AM_MEDIA_TYPE& mt), ( A8 l5 a0 H5 b$ S2 s& h9 wif (mt.cbFormat != 0) " A: k! T h0 C) RCoTaskMemFree(PVOID)mt.pbFormat);+ B& E( W7 9 |4 C4 s/ Strictly unnecessary but tidiermt.cbFormat = 0;mt.pbFormat = NULL;)