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对于小摄像头的驱动有几种方法,通过使用DirectShow来驱动摄像头灵活性比较好,有简单的方法也有比较复杂但更有效的方法,本文只介绍简单方法,希望与大家交流!
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; z+ g4 C# `" q; Y- R用DirectShow来使用摄像头,一般要求摄像头的驱动是WDM格式的,当然,一些比较老的驱动格式DirectShow也可支持。DirectShow通过图形过滤管理器(Filter Graph Manager)来与上层应用程序和下层的驱动进行联系。DirectShow通过一种叫作捕获过滤器(Capture Filter)的东东来支持对摄像头的捕获,一个捕获过滤器有多个插口(pin),其中的预览(preview)插口可用来进行显示祯图象。 + O0 L( b: c. }
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DirectShow通过几个COM接口来对视频捕获的全过程进行控制,其中IGraphBuilder 用于建立过滤器,ICaptureGraphBuilder2用于与下层的驱动程序建立联系,IVideoWindow,IMediaControl,IMediaEventEx分别对整个过程的视频窗口,播放过程和事件响应进行控制, * I6 ?2 X( d2 }; k7 {
% s, h( b8 N% A1 X+ f7 r下面是例程:
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/ R& a! ^- }$ \# z Y1 ]( [1 hCComQIPtr<IVideoWindow> m_pVW; & i$ {; w8 f B1 M
CComQIPtr<IMediaControl> m_pMC;
8 z3 F* H9 h6 f0 Z' u+ y* PCComQIPtr<IMediaEventEx> m_pME; : K6 V- t$ `2 E; E0 F7 ~+ V: `
CComPtr<IGraphBuilder> m_pGraph; " _, r/ O: e+ y5 ?* R& k+ T
CComPtr<ICaptureGraphBuilder2> m_pCapture;
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i5 }( F. ~2 o, @6 tDWORD m_dwGraphRegister; ( V3 L( I; T" C. s
0 h0 I2 ?3 J" ]( R' Obool bInit(HWND hWnd) 7 c0 M( U3 H# Q m/ N4 p" Q
{
/ A: }9 E. y3 THRESULT hr;
" u) O/ U) }" s" W& O) y2 a" ^0 X//获得接口
; H( s* }: \! P, x9 t* S+ thr=CoCreateInstance (CLSID_FilterGraph, NULL, CLSCTX_INPROC,
4 ^; Y4 e: H8 ]& d- ]: [, jIID_IGraphBuilder, (void **) &m_pGraph);
! L D% c2 e: x% U9 i9 Nif (FAILED(hr))
2 V5 O' Q" E4 V5 i9 Z: ~return false;
# m2 |# b. `# \& \" ~. Bhr=CoCreateInstance (CLSID_CaptureGraphBuilder2 , NULL, CLSCTX_INPROC,
# O) v: y% ~/ ? E, xIID_ICaptureGraphBuilder2, (void **) &m_pCapture);
, y5 C* C- J" I' rif (FAILED(hr)) ) L+ P. a r8 V( H7 s. t
return false;
& Q7 `, d1 b2 d: I" Z1 Jm_pMC=m_pGraph; ( c: O# e9 x! `4 Z8 a; i
m_pVW=m_pGraph; 1 G. l. V0 r$ g5 Q0 L' @# x
m_pME=m_pGraph; 1 O! L6 s6 ]4 h& p5 e9 \4 p4 ~
//取得消息
2 M* i7 u& d4 \! a1 xm_pME->SetNotifyWindow((OAHWND)(m_hWnd=hWnd), WM_GRAPHNOTIFY, 0); + X7 D5 o- W9 i4 _
//将过滤和捕获进行连接 9 ]8 {6 {- A+ {: z) {$ Y$ z, J
m_pCapture->SetFiltergraph(m_pGraph);
% E: N" V% a' ?5 b: b//设备联接 " N/ Y9 K( V8 P8 L+ J
//枚举设备
' t& W5 [ n, I+ W3 MCComPtr <ICreateDevEnum> pCde=NULL; ' h# b! T" j' m" s: t
CComPtr <IEnumMoniker> pEm=NULL; 1 L7 j2 }9 J: {* K9 H2 e
hr=CoCreateInstance (CLSID_SystemDeviceEnum, NULL, CLSCTX_INPROC,
" J6 Z; [4 B! oIID_ICreateDevEnum, (void **) &pCde); ; s% |/ r. O1 i4 l
if (FAILED(hr)) ; b m5 k- v; [
return false;
, n1 H: j ?( b6 ]' o) E( JpCde->CreateClassEnumerator(CLSID_VideoInputDeviceCategory
7 b- `$ I! W: O. }; n2 V' L2 P& y ], &pEm, 0);
! ?0 V" x$ A, m2 b1 y2 c+ tif(pEm==NULL) 2 z3 T9 k6 q S9 e# q9 L
return false; 6 P. g5 ]/ h8 h; Z& O
CComPtr <Imoniker> pM=NULL;
4 Y# Y0 k0 W, O3 G2 F! M- |ULONG cFetched; 6 |/ v6 D! S/ F% [/ T) f! k
CComPtr<IBaseFilter> pBf=NULL;
8 Q p/ j9 e1 }: [) b8 b: u2 J) ]if(pEm->Next(1,&pM,&cFetched)==S_OK)
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6 K: }% L% L) w6 c' \5 ]pM->BindToObject(0,0,IID_IBaseFilter, (void**)&pBf); ) D, A# H7 n+ G, c* j. y2 _
pM.Release(); $ O8 D0 J9 G- x" t8 b; M
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else 7 p. o6 E3 A2 o* U5 a# b
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return false;
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; o _/ K" Z, k8 x7 C3 o4 v//将设备添加到graph ! |9 P9 C9 r- z' p! l# ^" W5 E
hr = m_pGraph->AddFilter(pBf, L"Video Capture");
/ ?$ G" O4 y; q# O" oif (FAILED(hr)) - |* T6 `6 ^" z4 T: q
return false;
! \: O0 u; K& Z- ]$ Z//连接一个源插口 1 Y2 a0 D8 \* G2 B8 U# [) V! O
hr=m_pCapture->RenderStream(& IN_CATEGORY_PREVIEW,&MEDIATYPE_Video
6 s" I( R |7 r9 A R- D) N,pBf,NULL,NULL); + f3 K/ F% E3 `
if (FAILED(hr)) . `$ i; l& B# C3 N& I
return false; : e" L1 f8 _, S7 e4 [) I
pBf.Release(); # g9 x9 ?7 K; ?$ x9 D) ]
//设定视频窗口
: P8 {7 @' {0 E. T& D/ v//设定视频窗口为主窗口的一个子窗口 3 T7 B7 f) X2 T' p3 Z
hr=m_pVW->put_Owner((OAHWND)hWnd);
, w2 o/ _' w* M- B u: zif (FAILED(hr)) / D7 M5 I. i% L2 J
return false; 2 t# ^/ x/ u. K4 u
//设定窗口样式
) m# S, ^% f- W/ P. Y0 d4 Ym_pVW->put_WindowStyle(WS_CHILD | WS_CLIPCHILDREN); 9 B3 b0 p6 G9 l' Z5 o, T2 x5 {
if (FAILED(hr)) 1 e- }/ f, G- h3 q5 e; G. [: q
return false; ! y [9 ?2 U9 F9 ^4 h0 G4 C5 s! R+ u
//设定窗口大小
- b$ h; D8 ]. S0 v1 Q9 h1 D* F. dCrect rectClient;
( p! H5 P! [* j- q3 ^4 Y2 k0 ]GetClientRect(hWnd,rectClient);
* T) A! T7 n: L, k/ Km_pVW->SetWindowPosition(0, 0, 320, 240); ! s- t& c& j# l7 \! T. w
//设定可视
8 B+ v% j1 F1 ~! [hr=m_pVW->put_Visible(OATRUE); # u& K' u. q. Z6 Y9 T
if (FAILED(hr))
0 \& z- l& C3 H M9 O) Hreturn false; 9 R! {. D% i: H4 O: F* n5 u" T6 V& Q
//将对象加入到运行对象列表中 2 [( W5 i7 A |! R, _6 P% G
CComPtr<IRunningObjectTable> pROT;
" W8 z# ?8 d% J9 R5 p2 P, H. j$ LGetRunningObjectTable(0,&pROT); % d$ V* L$ I7 L
WCHAR c[128];
( ? T( M( Q7 q2 t# FwsprintfW(c, L"FilterGraph %08x pid %08x\0", (DWORD_PTR)m_pGraph.p,
Q) b* G7 p! N0 M$ u- T- _GetCurrentProcessId()); " o6 x7 Z w7 |+ X, f* I$ J
hr = CreateItemMoniker(L"!",c,&pM); + [ x/ F' ~/ G
if (FAILED(hr)) # ]2 T5 Z! ~, T7 h
return false; ; D3 ~6 j( R, J- L% b6 l+ i: L9 S
hr = pROT->Register(ROTFLAGS_REGISTRATIONKEEPSALIVE,m_pGraph,
; R7 k- X3 P3 X/ K2 lpM,&m_dwGraphRegister); 9 p+ z1 h0 \8 S1 I
pM.Release(); / Z, Y0 ]$ I# H4 g- A; s; ~
return false;
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