Why would this happen?

ingeborgdot

Golden Member
Jan 12, 2005
1,349
27
91
Someone had me come and look at their projector that was connected to the computer because it wasn't working right. I got it to work on the pj but this next thing I have never had happen before. The screen was there and so were the icons and cursor. I brought up the dvd player and it came up. On the computer screen the movie was playing but it was not playing on the screen. You could see the screen of the player but nothing was playing in he box. It was black. What is this???????>
 

GotGoose

Member
Feb 25, 2006
41
0
0
This has happened to me before in the same exact way (projector shows screen but not video). Can anyone enlighten us?
 

xtknight

Elite Member
Oct 15, 2004
12,974
0
71
Most video players use overlay, which only exists on the primary surface (generally a PC monitor). There are ways around this. I believe there's a cloning mode for overlay somewhere in the video driver's options, or some video software lets you choose a different rendering mode (GDI (desktop) or VMR (DirectX)).

The way it works is that the software fills the screen with a color and gives the video card a rectangle of that area. The GPU proceeds to replace everything filled with that color with the actual video itself. That color will show up on the projector but it will not be filled with video. The keying color could have been anything...it's typically black, blue, or purple.