Why does Overlay work this way?

Dark Shikari · 16th July 2007, 08:53

Today I was watching a video on Stage6 and alt-tabbed to an OpenOffice Impress presentation I was making. The background of the slide was a dark blue-black gradiant... and interestingly enough, there was a slice of it that was see-through. Of course, I quickly realized that particular color was used as the "overlay color" by the graphics card, and the Stage6 video was playing using the overlay renderer.

Now, why does it work this way? Who decided that 00000F would be the color that is transparent to overlays?

(Of course, I've always loved overlay mode, as it means I can draw on videos as they play...)

check · 16th July 2007, 11:29

The colour chosen for the colour key is actually video card/driver dependant. Some ATI cards use a hot pink, and most (all?) nvidia setups use pure black. As to why, I'm afraid I don't have any idea

. If nobody else here knows, I would suggest going over to bug phaeron @ virtualdub.org

foxyshadis · 16th July 2007, 14:25

Drivers have defaults, but most applications override them, it seems. For more than you probably want to know, see: http://www.virtualdub.org/blog/pivot/entry.php?id=91

16th July 2007, 08:53	#1 \| Link
Dark Shikari x264 developer Join Date: Sep 2005 Posts: 8,666	Why does Overlay work this way? Today I was watching a video on Stage6 and alt-tabbed to an OpenOffice Impress presentation I was making. The background of the slide was a dark blue-black gradiant... and interestingly enough, there was a slice of it that was see-through. Of course, I quickly realized that particular color was used as the "overlay color" by the graphics card, and the Stage6 video was playing using the overlay renderer. Now, why does it work this way? Who decided that 00000F would be the color that is transparent to overlays? (Of course, I've always loved overlay mode, as it means I can draw on videos as they play...)

16th July 2007, 11:29	#2 \| Link
check phjbdpcrjlj2sb3h Join Date: Sep 2005 Location: Western Australia Posts: 1,691	The colour chosen for the colour key is actually video card/driver dependant. Some ATI cards use a hot pink, and most (all?) nvidia setups use pure black. As to why, I'm afraid I don't have any idea . If nobody else here knows, I would suggest going over to bug phaeron @ virtualdub.org __________________ CCCP \| MeWiki \| techouse's x264 builds \| Kovensky's mplayer builds

16th July 2007, 14:25	#3 \| Link
foxyshadis Angel of Night Join Date: Nov 2004 Location: Tangled in the silks Posts: 9,559	Drivers have defaults, but most applications override them, it seems. For more than you probably want to know, see: http://www.virtualdub.org/blog/pivot/entry.php?id=91