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The DirectDraw modes are entirely replaced by the Direct3D mode. We strongly recommend to use the Direct3D mode instead of the DirectDraw modes. |
The video image is digitized straight in the visible area of the VGA card. In this mode the highest image refresh rate and fast live image display are possible. It is not possible to overlay images in this mode, as the image data is immediately overwritten by the next image. Unlike many other frame grabber cards, dialog boxes and other windows can be placed over the live image without affecting it. To achieve this, clipping lists are transferred to the board on a second DMA channel and those areas of the video image are left out while displaying.
Mode = IS_SET_DM_DIRECTDRAW | IS_SET_DM_ALLOW_PRIMARY
Fig. 38: DirectDraw primary surface mode
