|Microsoft DirectX 9.0|
The UseScanLine method determines whether the renderer should check the current scan line when drawing a video.
HRESULT UseScanLine( long UseScanLine );
Long integer value that specifies whether or not to use the scan line information. Set to OATRUE to use scan line information or OAFALSE to ignore it.
Returns E_INVALIDARG if the argument is invalid or S_OK otherwise.
If you blit an image to the video memory while the monitor's scan line is scanning over a visible portion of the screen, the complete image will be a composite of the old and new images. This composite is known as a torn video image. You can avoid torn images by waiting until the previous image is complete before blitting the new image. Some video cards can retrieve the scan line's current position; if this information is available, you can have DirectShow try to reduce