IDirectDrawVideo::UseOverlayStretch method (amvideo.h)

[The feature associated with this page, DirectShow, is a legacy feature. It has been superseded by MediaPlayer, IMFMediaEngine, and Audio/Video Capture in Media Foundation. Those features have been optimized for Windows 10 and Windows 11. Microsoft strongly recommends that new code use MediaPlayer, IMFMediaEngine and Audio/Video Capture in Media Foundation instead of DirectShow, when possible. Microsoft suggests that existing code that uses the legacy APIs be rewritten to use the new APIs if possible.]

The UseOverlayStretch method determines whether the renderer should check overlay stretch limitations.

Syntax

HRESULT UseOverlayStretch(
  long UseOverlayStretch
);

Parameters

UseOverlayStretch

Value specifying whether the renderer checks overlay stretching. Set to OATRUE for the renderer to check overlay stretching; otherwise, set to OAFALSE.

Return value

Returns an HRESULT value.

Remarks

Some display cards provide the use of overlay surfaces through DirectDraw. An overlay surface is a block of video memory whose contents are overlaid onto the display during the monitor's vertical refresh. DirectShow uses all available overlay surfaces where possible because they typically offer higher-quality video and very fast performance. On some display cards set to relatively high bit depths, the overlay must be displayed on the screen larger than its real size (to accommodate certain display hardware bandwidth limitations). If the overlay is not displayed large enough, certain undesirable effects can be seen on the display (sometimes described as a "fleeting shimmering" effect).

If UseOverlayStretch is set to OATRUE (on, the default), DirectShow will ensure the overlay is adequately stretched before displaying it. If it is set to OAFALSE (off), DirectShow will not check that the overlay is adequately stretched, and the user is likely to experience artifacts on the screen (although it will also guarantee that the overlay will be used if possible).

Requirements

See also

Error and Success Codes

IDirectDrawVideo Interface