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Like other types of surfaces, you can create overlay flipping chains. After creating a flipping chain of overlays, call the IDirectDrawSurface5::Flipmethod to flip between them. For more information, see Flipping Surfaces.
Software decoders displaying video with overlay surfaces can use the DDFLIP_ODD and DDFLIP_EVEN flags when calling the Flipmethod to use features that reduce motion artifacts. If the driver supports odd-even flipping, the DDCAPS2_CANFLIPODDEVEN flag will be set in the DDCAPSstructure after retrieving driver capabilities. If DDCAPS2_CANFLIPODDEVEN is set, you can include the DDOVER_BOB flag when calling the IDirectDrawSurface5::UpdateOverlaymethod to inform the driver that you want it to use the "Bob" algorithm to minimize motion artifacts. Later, when you call Flipwith the DDFLIP_ODD or DDFLIP_EVEN flag, the driver will automatically adjust the overlay source rectangle to compensate for jittering artifacts.
If the driver doesn't set the DDCAPS2_CANFLIPODDEVEN flag when you retrieve hardware capabilities, UpdateOverlaywill fail if you specify the DDOVER_BOB flag.
For more information about the Bob algorithm, see Solutions to Common Video Artifacts.
Last updated on Tuesday, May 18, 2004