Display Control Interface DDK
  
PSS ID Number: Q120260
Article last modified on 06-20-1995
 
1.00
 
WINDOWS
 

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The information in this article applies to:
 
 - Microsoft Windows Display Control Interface (DCI) Driver Developer
   Kit version 1.0, for Windows version 3.1
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Product Description
===================
 
The Display Control Interface (DCI) for the Microsoft Windows operating
system is a driver-level software interface that provides access to display
devices while maintaining compatibility with Windows GDI. DCI works with
Windows 95 and Windows 3.1.
 
NOTE: A newer version of the DCI spec will be provided to address the
Windows 95 aspects and implementation.
 
DCI provides a device-independent way for Windows subsystem software, such
as 3-D graphics packages, games interface packages, or digital video
codecs, to access display device-dependent features. In the case of digital
video codecs, additional support is provided so that any codec that already
supports the ICM_DECOMPRESSEX message as specified by the Video for Windows
Installable Codec Interface automatically takes advantage of DCI
capabilities, if these capabilities are available.
 
DCI works with a wide variety of display hardware, ranging from simple
SVGAs to advanced hardware implementations containing clipping, stretching,
and non-RGB color format support. The interface is designed so that DCI
clients can request the capabilities of the underlying hardware, then use
the capabilities as required. Cards that use chipsets that don't support
access to the frame buffer by the host are not supported by the DCI
Specification.
 
DCI provides access to the following display device-dependent benefits:
 
 - Improved video playback quality through access to YUV color
   formats
 - Improved graphics and video quality through access to
   image-stretching hardware
 - Support for double-buffered graphics
 - Simultaneous access to standard and enhanced display device
   memory areas
 - Smooth rendering of 3-D graphics
 - Graphics overlaid on video in a window
 
The interface is not designed to provide access to software running on
coprocessors that require display capabilities; typically these designs
feature hardware-specific interfaces from the coprocessor to the display,
so no Windows-based software is used to put pixels on the display. For
example, video coprocessors, such as the Intel i750 processor or MPEG
decompression processors, typically provide, their own hardware-specific
drivers. If these coprocessors pass data back to Windows subsystem
software, then DCI may be used.
 
Windows NT Considerations
=========================
 
DCI support under the Windows NT operating system is not addressed by this
document. DCI relies on the ability to directly access and draw on display
memory. Windows NT display memory is not exposed the same way as Windows
3.1. A special solution is being worked on.
 
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Copyright Microsoft Corporation 1995.
