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DDVIDEOPORTBANDWIDTH

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This structure describes the bandwidth characteristics of an overlay surface when used with a particular video port and pixel format configuration. This structure is used with the IDirectDrawVideoPort::GetBandwidthInfo method.

typedef struct _DDVIDEOPORTBANDWIDTH {
  DWORD dwSize;
  DWORD dwCaps;
  DWORD dwOverlay;
  DWORD dwColorkey;
  DWORD dwYInterpolate;
  DWORD dwYInterpAndColorkey;
  DWORD dwReserved1;
  DWORD dwReserved2;
} DDVIDEOPORTBANDWIDTH, *LPDDVIDEOPORTBANDWIDTH;

Members

  • dwSize
    Size of this structure, in bytes. This member must be initialized before use.
  • dwCaps
    Flag values specifying device dependency. The following table shows the possible flags.
    Flag Description
    DDVPBCAPS_DESTINATION This device's capabilities are described in terms of the overlay's minimum stretch factor. Bandwidth information provided for this device refers to the destination overlay size.
    DDVPBCAPS_SOURCE This device's capabilities are described in terms of the required source overlay size. Bandwidth information provided for this device refers to the source overlay size.
  • dwOverlay
    Stretch factor or overlay source size at which an overlay is supported multiplied by 1000. For example, 1.3 = 1300, or 0.75 = 750.
  • dwColorkey
    Stretch factor or overlay source size at which an overlay with color keying is supported multiplied by 1000. For example, 1.3 (1300), or 0.75 (750).
  • dwYInterpolate
    Stretch factor or overlay source size at which an overlay with y-axis interpolation is supported multiplied by 1000. For example, 1.3 (1300), or 0.75 (750).
  • dwYInterpAndColorkey
    Stretch factor or overlay source size at which an overlay with y-axis interpolation and color keying is supported multiplied by 1000. For example, 1.3 (1300), or 0.75 (750).
  • dwReserved1 and dwReserved2
    Reserved; set to zero.

Remarks

When DDVPBCAPS_DESTINATION is specified, the stretch factors described in the other members describe the minimum stretch factor required to display an overlay with the dimensions given when calling the GetBandwidthInfo method. Stretch factor values under 1000 mean that the video port is capable of shrinking an overlay when displayed, and values over 1000 mean that the overlay must be stretched larger than their source to be displayed.

When DDVPBCAPS_SOURCE is specified, the stretch factors described in the other members describe how much you must shrink the overlay source so it can be displayed. In this case, the best possible value is 1000, meaning that no shrinking is required. Smaller values tell you that the source rectangle you specified when calling GetBandwidthInfo was too large. For example, if the stretch factor is 750 and you specified 320 pixels for the dwWidth parameter, then you will not be able to display the overlay at that size. To display the overlay successfully, you must use a source rectangle 240 pixels wide.

Requirements

OS Versions: Windows CE 2.12 and later. Version 2.12 requires DXPAK 1.0 or later.
Header: Dvp.h.

 Last updated on Thursday, April 08, 2004

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