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//但这种方法并不能抓取有的播放器的图像,这是因为播放器显示页面时采用了hardware overlay (硬件加速), 3 b+ q% M. ^8 \8 ?$ @//你需要在“显示” 设置里面禁用该功能。或者有时你会发现,你多开一个播放器窗口,后面的就可以抓屏了,因为 0 P. ]5 [9 J( o# I( H//overlay 技术的硬件支持有限,后面的不能再用这个技术了。有的人说编程hook 了DirectDraw的相应函数可以禁用 1 Q) S) L5 S6 {# z6 {9 q
//这个功能。有的抓屏软件也可以做到,不知道人家是怎么做的。 & Q3 F4 c! e% b$ ~& S8 K. o" D / t' g; N \+ O: L, b//下面是些参考资料: * X" K: ^: I7 C& Z
//Video Renderer (VR)是接收RGB/YUV裸数据,然后在显示器上显示的Filter。 $ e' Z i$ {4 L8 n: _( g# g//为提高计算机画图性能,根据你计算机显卡的能力,VR会优先使用DirectDraw以及Overlay表面; 7 o% C( k, a e- r9 i//如果这些特性得不到显卡的支持,VR会使用GDI函数进行画图 6 \! c! h5 E X/ H//Video Mixing Renderer Filter 7 (VMR-7), 8 [$ o, C* d0 G% X2 g' `
//可以这么说,VMR是Windows平台上新一代的Video Renderer。 # @' R8 b1 |. | u' I 1 X! E: e8 e$ G4 \+ R7 c//视频覆盖(Video Overlay) 或者说是hardware overlay 是早期的技术, 现在好像是VMR-7 , VMR-9 了 @# L( D+ _; f/ k) I4 @3 ]( t* l2 Q' c% {8 U$ o) P
// % O2 `$ b/ F) O//One consequence of hardware overlay use is that a screenshot program (for example, 7 V9 j) J2 l$ g& c, W4 s
//the one automatically built into Windows that activates when the PrtSc key is pressed) 8 a/ @# f) p8 ]2 V" u$ K//often does not capture the content appearing in the hardware overlay window. Rather, . \( H1 z& _# M; {* x$ Q) z* m6 E//a blank region containing only the special mask color is captured. This is because the & G6 f3 l) I' T$ w9 N8 F% j6 R
//screen capture routine doesn't consider the special video memory regions dedicated to ' |5 i2 E% l. W# s2 z& V
//overlays - it simply captures the shared main screen as rendered by the software's graphical # r2 f5 q5 r3 s
//subsystem. Some Digital Rights Management schemes use hardware overlay to display & B* Z& L N; n
//protected content on the screen, taking advantage of this quirk to prevent the copying of ) U' m, G2 w* f7 [. b) U! f
//protected documents by way of screen capture[citation needed]. Disabling the support for 3 e- B) V8 J, Q& C, j//overlays causes the normally overlay using software to fallback to the shared memory, ! ]/ i& y8 j! z: f
//enabling screenshots. - P2 y4 j) _) Z' v5 A4 {- ^; J8 u; ]: r6 D( r( {8 ~# t
//Starting with Windows Vista's enhanced graphics capabilities, the basic concept % n2 _0 ]# c2 F( P' T# k, z//of hardware overlays is replaced by full hardware compositing for every application window 1 e7 I R. |+ k/ G$ ?3 `8 b# G//running on the system, not just movie players or games, through the Desktop Window Manager. 2 g3 e' S: _! h' p( F2 d//Mac OS X has been using hardware compositing since Quartz Extreme was introduced in Mac OS X 10.2. $ d, k; }- N, k. y
//To improve performance, each program draws to its own independent memory buffer instead of to a 1 B$ ^$ L9 K1 u3 Y. t7 P
//slow graphical subsystem. (In Windows Vista, each hardware overlay is more correctly known as 8 V. c: C9 |; x, `2 c
//a Direct3D surface). Then, the system's GPU assembles each of the windows into a single 2 l% P/ \ e3 }8 D" y3 l3 G//display screen in real time. With enhanced GPUs on the market capable of stunning 3D 7 k" m3 @9 g6 {7 M1 `//graphics as a consequence of the video game industry, impressive motion, scaling, ; B( B" u' Y7 t+ D. M" S) B. e//and lighting effects can be applied to normal 2D windows by the operating system. & u# W9 f( ^* p# m, B. L/ s/ U; B1 a
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//步骤1双击“控制面板”中的“显示”图标,或在桌面空白位置单击右键,选择“属性”,打开显示属性设置窗口。选择“设置”选项卡,并单击窗口中的“高级”按钮,打开高级属性设置窗口。 ; x, p% q5 Q/ M; \# l. x//步骤2 在高级属性设置窗口中选择“疑难解答”选项卡,拖动“硬件加速”滑块至“无”,单击“确定”退出。 ) t# C2 [" q9 N1 h2 `
//步骤3 在视频播放软件比如RealOne中拖拉滑杆至需要截取的画面,按PrintScreen键截取屏幕界面。 7 V* i1 ?$ p* N9 |9 |/ H& U
//步骤4 打开“开始”/“程序”/“附件”/“画图”,单击“编辑”/“粘贴”将截取后存储于剪贴板的屏幕截图粘贴到画图程序中,可以看到,已经可以成功截取视频图像,不过,较之启用硬件加速功能,此时的视频图像质量会有一定程度的损失