DIVE Display Engine Functional Characteristics

The DIVE system-level interface abstracts the low-level device driver DIVE interface to a higher level and adds software emulation for operations that digital video CODECs were previously required to do. This system-level interface is referred to as the DIVE display engine.

The DIVE display engine consists of a single, stand-alone DLL that exports the following functions:

• Query for display capabilities
  
• Open instance
  
• Visible region specification
  
• Allocation of image data buffers
  
• Buffer-to-screen/buffer-to-buffer transfer (blitter) setup
  
• bit CLUT color palette simulation/specification
  
• Transfer buffer to image display/transfer buffer to buffer
  
• Utility functions useful for direct access, including window starting-address calculation
  
• Frame buffer acquire/deacquire
  
• VRAM bank selection (for bank-switched displays)
  
• Close instance

The display engine enables subsystem components (for example, video CODECs) and applications to either directly access the video buffer or to use the display engine screen transfer functions. If direct access is used, the using component or application is responsible for writing to the frame buffer format for the current display mode and correctly clipping the output. In addition, the component is responsible for acquiring and bank switching the display apertures. If display engine screen transfer functions are used, the display engine handles clipping, pel format and color space conversions, and any necessary hardware serialization. The input formats and their corresponding color encoding specification values are:

• CLUT 8 (256 color) - "LUT8" 
  8-bit greyscale - "GREY"
  
  RGB 16 (5-6-5, 5-5-5) - "R565", "R555", "R664"
  
  RGB 24 (R-G-B, B-G-R) - "RGB3", "BGR3"
  
  RGB 32 (R-G-B, B-G-R) - "RGB4", "BGR4"
  
  YUV 9 - DVI/Indeo three-plane color subsampled - "YUV9"
  
  YUV 422 - "Y422"
  
  YUV CCIR601 - three-plane 2x2 color subsampled (MJPEG, MPEG) - "Y2X2"
  
  YUV CCIR601 - three-plane 4x4 color subsampled - "Y4X4"

  The output formats are:

  • CLUT 8 (256 color) 
    RGB 16 (5-6-5, 5-5-5, 6-6-4)
    
    RGB 24 (R-G-B, B-G-R)
    
    RGB 32 (R-G-B-x, B-G-R-x)
    
    YUV 422 (Y-U-Y-V)

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