[Windows] Beating Hardware Overlays

[Tanoro]

Ever wanted to make a screenshot or screen capture of a video on your computer and it resulted in nothing but a black screen with no video image in it? If so, then you've been victimized by the infamous "hardware overlay" effect.

What is a Hardware Overlay?
Well, a hardware overlay is a feature produced by the video card on your computer to help improve system performance for displaying videos. When your video card communicates with the graphics subsystem of your operating system (i.e. Windows), it essentially sets aside an amount of video memory for your operating system to use. This is where all of your windows, displays, and most applications are displayed on your monitor. Most computer operations stay within these bounds.

Now, when you want to play a video (an application that requires your video card to redraw your display several times per second), your media player typically attempts to improve system performance by requesting additional memory from the video card that is outside of what Windows uses (out of bounds). Because the video memory for the overlay lies outside of Window's reach, you can't capture it with a simple screen grab like everything that is within Window's portion of video memory. In short, the videos you watch on your computer are not being displayed in the media player window at all. The video is actually being displayed on your monitor at a hardware level (kinda like the control box that appears when you adjust your monitor).

You've probably noticed that when you try to paste a screenshot that you captured from the media player, the video shows up (probably off-center) in the area of color that you pasted! However, when you close the video player, the picture you pasted becomes black and you can never get the video's image to show up there. That is no glitch. There is a logical reason for this. When the media player requests the additional memory from the video card, it also defines a specific color called the "chroma key." This color is used as a mask to help the video card determine where on your monitor to display the video. It is usually an off black color. You guessed it! That black color that you got when you pasted the empty media player window into MS Paint was actually the chroma key! That's why you can see the video in the Paint window while it is displaying the chroma key color. The video card thinks Paint is the media player!

How to beat the overlay?
If you want to take a screen shot or screen capture of a video, but the overlay is stopping you, you'll be very happy to know there are a few ways to beat it. First, you can set your media player not to use overlays. In Windows Media Player, you do this by following Tools => Options => Performance => Advanced. There are two checkboxes here to turn overlays on or off. One is for DVDs and the other is for everything else.

You can also set Windows not to allow hardware overlays. For Windows XP, right click on your desktop and click Properties => Settings => Advanced => Troubleshoot and move the slider all the way to the left. This will stop all overlays, system-wide. By the way, I recommend you place these settings back after you've got your screenshots. Overlays do help improve video performance, hence their purpose!

There are also some online media players that display videos in an overlay and some of these may even continue to use overlays even if you set Windows not to use them. What do you do then? Here's a neat little trick! Most video cards can only handle ONE hardware overlay at a time. So if you turn your overlays on (turn them back on in both Windows and your media player), open a video on your computer, pause that video, and THEN navigate to the online player you want to copy from, the online player is left with only two options: it can either error because your overlay is already being used by your media player or (more likely) it will just display the video without the overlay. If the online media player displays the video without the overlay, then screen grab all you want because it's free game now!

I hope this tutorial was helpful. Have fun!

[hola]

nice job

[BBarash]

Great to read +rep.

[Tanoro]

Thanks, guys! Incidentally, I was able to use my 3rd method up there to capture an anime episode from Toonami Jetstream. Their online player uses a persistant overlay and remains even if you turn it off in Windows. So I opened my media player before going to Jetstream. That occupied my overlay plane, so Jetstream had no choice but to display the video in a format I could capture.

It's fun being sneaky! XD