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Video-port hardware often supports special features for adjusting color, shrinking or zooming images, handling VBI data, or skipping fields. The HAL provides information about these features by using flags in the DDVIDEOPORTCAPSstructure. You retrieve the capabilities of a machine's video-port hardware by calling the IDDVideoPortContainer::EnumVideoPortsmethod.
To exploit these features for playback, you use the IDirectDrawVideoPort::StartVideomethod, which uses a DDVIDEOPORTINFOstructure to request that hardware features be used to modify image data before placing it in the frame buffer or for display. By setting values and flags in this structure, you can specify the source rectangle used with the overlay surface, indicate cropping regions, request hardware scaling, and set pixel formats.
DirectDrawVideoPort objects do not emulate video-port hardware services.
Last updated on Tuesday, May 18, 2004