Exploiting Hardware Features

  • Article

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 DDVIDEOPORTCAPS structure. You retrieve the capabilities of a machine's video-port hardware by calling the IDDVideoPortContainer::EnumVideoPorts method.

To exploit these features for playback, you use the IDirectDrawVideoPort::StartVideo method, which uses a DDVIDEOPORTINFO structure 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.

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