View Full Version : DFG/USB2-lt stops displaying images on screen w/ filter after random amount of time
January 27, 2010, 09:56:38
We are using the DFG/USB2-lt to display a video stream of an automatically controlled vacuum chamber. However, occasionally the image on the screen stops being updated, while this is not reproducable on our developer PCs, we have 2 machines in house displaying this behavior, which causes a desync between the perceived object position and the actual object position.
We use the 3.0 version of the imaging control lib, with a framefilter to perform deinterlacing and digital zoom.
I have narrowed down the issue somewhat, it appears to only occur if a frame filter is active, however the frame filter continues to receive, process, and dispatch data. Having the framefilter dump the incoming video stream shows that the incoming data is not static, so my guess is that the image is being processed correctly and not being displayed. The filter also resizes the video image to the size of the window. We also have an image overlay active.
We have tried to use the newest driver version (december 2009), however this has not helped.
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January 27, 2010, 10:15:24
If you have two computers, that do not show this behavior and two computers, that show this behavior, then it is interresting to know the differences between them. I guess the problem must be on the computers, that stop displaying the live video streams.
Also if there are any energy options available, you may set them to the highest values. This is to avoid the USB Controllers slowed down, if the computer does not get busy enough.
January 27, 2010, 10:51:47
The thing is, we have about a dozen computers running the different machines with identical hardware setups and OS images, and of these I know of two that freeze often (Not counting instruments at clients labs). Others freeze as well, but not as quickly.
I do not think it has anything to do with the energy options, as the filter function still receives new images, they just are not shown on screen. However I just checked and the power scheme is set to always on.
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January 27, 2010, 11:18:10
What does your filter function does? Is it a directshow filter or an IC frame filter?
January 27, 2010, 11:56:26
I believe it is an IC frame filter based on the inversion example, I am not sure as it was originally made by a different dev.
It currently scales RGB24/32 input formatted frames (768x576) down to the size of the window(between 256x256 and 512x512), using either the full frame data, or a zoom rect. At the same time it does deinterlacing by using only even/odd lines of data. It also has the option of dropping frames during a remote desktop session. Disabling all filter functionality except frame copying with cropping does not help.
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January 27, 2010, 12:38:37
It does not seem to be a problem with the frame filter. I guess, the problem is the video renderer. You may disable the hardware acceleration on the specified computers and see, what happends. Also you may update the graphic board drivers.
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January 27, 2010, 14:51:15
I'm having one computer have hardware acceleration disabled and the second is receiving driver update. Will reply with the results when they are available.
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January 27, 2010, 17:14:03
Neither option helped, and it turns out that a third PC where this has rarely occured is using an ATI card, so that should eliminate that possibility.
I also got the chance to examine a PC where the freeze had just occured, and it seems there is no painting being done in the window with the video image, when dragging a window over the video display area the portions covered are drawn in the default background color.
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January 28, 2010, 10:48:29
I suggest to create a small project, that reproduces the problem and check it on your computers. I must admit, I can only guess, what happens, since you wrote the problem occurs only on some computers.
February 2, 2010, 13:57:50
I was now told that the PC with hardware acceleration disabled no longer freezes, either that or it just randomly decided to stop freezing the last 2 days, I apologize for the conflicting information.
I am now having hardware acceleration moved up a few steps on that system to try to isolate when it starts to freeze.
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