## DDVIDEOPORTCAPS

The DDVIDEOPORTCAPS structure describes the capabilities and alignment restrictions of a video port. This structure is used with the IDDVideoPortContainer::EnumVideoPorts method.

typedef struct _DDVIDEOPORTCAPS {

DWORD dwSize; // Size of the DDVIDEOPORTCAPS structure

DWORD dwFlags; // Indicates which fields contain data

DWORD dwMaxWidth; // Max width of the video port field

DWORD dwMaxVBIWidth; // Max width of the VBI data

DWORD dwMaxHeight; // Max height of the video port field

DWORD dwVideoPortID; // Video port ID (0 - (dwMaxVideoPorts -1))

DWORD dwCaps; // Video port capabilities

DWORD dwFX; // More video port capabilities

DWORD dwNumAutoFlipSurfaces; // Number of autoflippable surfaces

DWORD dwAlignVideoPortBoundary; // Byte restriction of placement within the surface

DWORD dwAlignVideoPortPrescaleWidth; // Byte restriction of width after prescaling

DWORD dwAlignVideoPortCropBoundary; // Byte restriction of left cropping

DWORD dwAlignVideoPortCropWidth; // Byte restriction of cropping width

DWORD dwPreshrinkXStep; // Width can be shrunk in steps of 1/x

DWORD dwPreshrinkYStep; // Height can be shrunk in steps of 1/x

DWORD dwNumVBIAutoFlipSurfaces; // Number of VBI autoflippable surfaces

DWORD dwReserved1; // Reserved for future use

DWORD dwReserved2; // Reserved for future use

} DDVIDEOPORTCAPS, *LPDDVIDEOPORTCAPS;

##### Members

dwSize
  Size of the structure, in bytes. This must be initialized before use.
dwFlags
  Flag values indicating the fields that contain valid data. The following flags are defined.

  DDVD_WIDTH | The dwMaxWidth member is valid.
  DDVPD_HEIGHT | The dwMaxHeight member is valid.
  DDVPD_ID | The dwVideoPortID member is valid.
  DDVPD_CAPS | The dwCaps member is valid.
  DDVPD_FX | The dwFX member is valid.
  DDVPD_AUTOFLIP | The dwNumAutoFlipSurfaces member is valid.
  DDVPD_ALIGN | The dwAlignVideoPortBoundary, dwAlignVideoPortPrescaleWidth,dwAlignVideoPortCropBoundary, and dwAlignVideoPortCropWidth are valid.

dwMaxWidth
  Maximum width of the video port field.
dwMaxVBIWidth
  Maximum width of the VBI data.
dwMaxHeight
  Maximum height of the video port field.
dwVideoPortID
  Zero based index identifying the video port.
dwCaps
  Video port capabilities.

  DDVPCAPS_AUTOFLIP | Flip can be performed automatically to avoid tearing when a VREF occurs. If the data is being interleaved in memory, it will flip on every other VREF.
  DDVPCAPS_INTERLACED | Supports interlaced video.
  DDVPCAPS_NONINTERLACED | Supports non-interlaced video.
  DDVPCAPS_READBACKFIELD | Supports the IDirectDrawVideoPort::GetFieldPolarity method.
  DDVPCAPS_READBACKLINE | Supports the IDirectDrawVideoPort::GetVideoLine method.
  DDVPCAPS_SHAREABLE | Supports two genlocked video streams that share the video port, where one stream uses the even fields and the other uses the odd fields. Separate parameters (including address, scaling, cropping, etc.) are maintained for both fields.
  DDVPCAPS_SKIPEVENFIELDS | Even fields of video can be automatically discarded.
  DDVPCAPS_SKIPODDFIELDS | Odd fields of video can be automatically discarded.
  DDVPCAPS_SYNCMASTER | Can drive the graphics sync (refresh rate) based on the video port sync.
  DDVPCAPS_SYSTEMMEMORY | Capable of writing to surfaces created in system memory.
  DDVPCAPS_VBISURFACE | Data within the VBI can be written to a different surface.
  DDVPCAPS_COLORCONTROL | Can perform color control operations on incoming data before writing to the frame buffer.
  DDVPCAPS_OVERSAMPLEDVBI | Can accept VBI data in a different format or width than the regular video data.

dwFX
  Additional video port capabilities.

  DDVPFX_CROPTOPDATA | Limited cropping is available to crop VBI data.
  DDVPFX_CROPX | Incoming data can be cropped in the x direction before it is written to the surface.
  DDVPFX_CROPY | Incoming data can be cropped in the y direction before it is written to the surface.
  DDVPFX_INTERLEAVE | Supports interleaving interlaced fields in memory.
  DDVPFX_MIRRORLEFTRIGHT | Supports mirroring left to right as the video data is written into the frame buffer.
  DDVPFX_MIRRORUPDOWN | Supports mirroring top to bottom as the video data is written into the frame buffer.
  DDVPFX_PRESHRINKX | Data can be arbitrarily shrunk in the x direction before it is written to the surface.
  DDVPFX_PRESHRINKY | Data can be arbitrarily shrunk in the y direction before it is written to the surface.
  DDVPFX_PRESHRINKXB | Data can be binary shrunk (1/2, 1/4, 1/8, etc.) in the x direction before it is written to the surface.
  DDVPFX_PRESHRINKYB | Data can be binary shrunk (1/2, 1/4, 1/8, etc.) in the y direction before it is written to the surface.
  DDVPCAPS_PRESHRINKXS | Data can be shrunk in the x direction by increments of 1/x, where x is specified in the dwShrinkXStep member.
  DDVPCAPS_PRESHRINKYS | Data can be shrunk in the y direction by increments of 1/y, where y is specified in the dwShrinkYStep
  DDVPFX_PRESTRETCHX | Data can be arbitrarily stretched in the x direction before it is written to the surface.
  DDVPFX_PRESTRETCHY | Data can be arbitrarily stretched in the y direction before it is written to the surface.
  DDVPFX_PRESTRETCHXN | Data can be integer stretched in the x direction before it is written to the surface. (1x, 2x, 3x, etc.)
  DDVPFX_PRESTRETCHYN | Data can be integer stretched in the y direction before it is written to the surface. (1x, 2x, 3x, etc.)
  DDVPFX_VBICONVERT | Data within the VBI can be converted independently of the remaining video data.
  DDVPFX_VBINOSCALE | Scaling can be disabled for data within the VBI.
  DDVPFX_IGNOREVBIXCROP | The video port can ignore the left and right cropping coordinates when cropping oversampled VBI data.

dwNumAutoFlipSurfaces
  Number of autoflippable surfaces supported by the video port.
dwAlignVideoPortBoundary
  Byte restriction of placement within the surface.
dwAlignVideoPortPrescaleWidth
  Byte restriction of width after prescaling.
dwAlignVideoPortCropBoundary
  Byte restriction of left cropping.
dwAlignVideoPortCropWidth
  Byte restriction of cropping width.
dwPreshrinkXStep
  Width can be shrunk in the x direction in steps of 1/dwPreshrinkXStep.
dwPreshrinkYStep
  Height can be shrunk in the y direction in steps of 1/dwPreshrinkYStep.
dwNumVBIAutoFlipSurfaces
  Number of autoflipping surfaces capable of receiving data transmitted during the vertical blanking interval (VBI) independent from the remainder of the video stream. When constructing the autoflip chain, the number of VBI surfaces must equal the number of surfaces receiving the remainder of the video data.
dwReserved1 and dwReserved2
  Reserved; set to zero.