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| rjg |
| Posted: Jan 23 2012, 02:25 PM |
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Newbie
Group: Members
Posts: 3
Member No.: 34101
Joined: 23-January 12
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Just to add to the Windows 7 issue that I'm aware of (http://forums.virtualdub.org/index.php?act...=ST&f=2&t=20652) - I'm using *Windows XP* and I'm having this issue. I upgraded my graphics card and also the graphics card driver. It's a nVidia GTX 260. Like Windows 7, I can only capture the mouse cursor when trying to use the OpenGL capture mode.
Could it be that nVidia are now being lazy and have dropped the OpenGL mode that VirtualDub needs to use? Or is something else going on here...
Regardless it's a bummer for me as I can't capture my entire screen smoothly without excessive CPU usage even on a Core2 Quad.
If I can somehow assist with debugging this, let me know!
Cheers. |
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| phaeron |
| Posted: Jan 24 2012, 12:09 AM |
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Virtualdub Developer
Group: Administrator
Posts: 7773
Member No.: 61
Joined: 30-July 02
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Yeah, it probably broke in the latest set of NVIDIA drivers. Problem is, that mode relies on some stretch interpretations of some pretty obscure parts of the OpenGL standard that weren't supported by everyone to begin with and aren't likely used in that way anywhere else. Works a treat on some cards and drivers, just doesn't on others. Video drivers have never been about 100% correctness -- they're far too complex for that -- but best bang for the buck.
That having been said, it's possible that changing some setting in the driver may revive the function, possibly multi-monitor support.
Sadly, not much that can be done until Windows 8 arrives.
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| rjg |
| Posted: Jan 24 2012, 09:02 AM |
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Newbie
Group: Members
Posts: 3
Member No.: 34101
Joined: 23-January 12
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Thanks for the reply phaeron. I feared it might be something like that - I'll have a play around with my existing driver and see if I can convince it to work. As it stands I already use it in multi-monitor mode, but I'll play around with some other settings.
Failing that I'll downgrade my drivers until it works (if it works!). I'm no hardcore gamer, I play Half-Life 1 based mods online still, so I doubt I'll miss any features!
I'm assuming any attempt for me to contact nVidia about it will be a waste of time? |
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| rjg |
| Posted: Jan 24 2012, 10:05 AM |
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Newbie
Group: Members
Posts: 3
Member No.: 34101
Joined: 23-January 12
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I went as far as 260.99 from 2010 and gave up.
What's the technical name of the OpenGL mode that VirtualDub exploits? I want to do some further research on it... |
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| phaeron |
| Posted: Feb 4 2012, 09:34 PM |
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Virtualdub Developer
Group: Administrator
Posts: 7773
Member No.: 61
Joined: 30-July 02
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It pertains to the definition of the OpenGL front buffer. In OpenGL, the front buffer is defined as being mapped to the screen through a window ownership test defined by the windowing system. This test is only mentioned for writes to the framebuffer, so reads in theory are unchecked and capture everything within the bounds. The procedure therefore is to select the front buffer as the active framebuffer and then use glCopyTexSubImage2D() to copy it into a texture.
There are two problems with this scenario. The first is that it relies on the GL implementation working properly, which is definitely not always the case. I encountered a couple of video cards that inexplicably required buffer swaps before this worked. The second is that it requires that the front buffer to be directly mapped to the screen. This isn't guaranteed, and in fact in WDDM (Vista and up) it is explicitly defined as being an intermediate buffer, which prevents this trick from working.
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