We are running an experiment showing short 5 second video clips and recording ratings about each clip for 5 seconds. While testing on a new Windows 10 laptop (to be used for running the experiment), the following warning was issued:
PTB-WARNING: Startup test of beamposition queries for high precision timestamping detected problems on your graphics card + driver combo.
PTB-WARNING: Some of the queries fail even outside the vertical blank interval, so no effective workaround for this driver bug exists.
PTB-WARNING: This renders beamposition queries pretty useless -- Disabling high precision timestamping for now.
PTB-WARNING: Please report this message with a description of your graphics card, operating system and video driver to
PTB-WARNING: the Psychtoolbox forum. Maybe the gathered information allows for some work-around in
PTB-WARNING: future PTB releases to get high precision timestamping back on your setup.
PTB-WARNING: Couldn't determine end-line of vertical blanking interval for your display! Trouble with beamposition queries?!?
PTB-WARNING: Detected end-line is 2160, which is either lower or more than 1.250000 times higher than vbl startline 1707 --> Out of sane range!
PTB-INFO: OpenGL-Renderer is NVIDIA Corporation :: Quadro M620/PCIe/SSE2 :: 4.6.0 NVIDIA 432.13
PTB-INFO: VBL startline = 1707 , VBL Endline = 2160
PTB-INFO: Beamposition queries unsupported or defective on this system. Using basic timestamping as fallback.
PTB-INFO: Timestamps returned by Screen('Flip') will be therefore less robust and accurate.
PTB-INFO: Measured monitor refresh interval from VBLsync = 16.676020 ms [59.966347 Hz]. (50 valid samples taken, stddev=0.464644 ms.)
PTB-INFO: Reported monitor refresh interval from operating system = 16.666667 ms [60.000000 Hz].
This is with Matlab Version:
‘9.7.0.1296695 (R2019b) Update 4’ on Windows 10
I wasn’t able to find a post addressing this exact issue. Is this simply an issue of the hardware in this laptop? Any information/suggestions on this warning would be very helpful.
Yes, your hardware is the problem, because against our hardware recommendations, you got yourself an NVidia Optimus laptop. From:
"This device has no display connectivity, as it is not designed to have monitors connected to it. Rather it is intended for use in laptop/notebooks and will use the output of the host mobile device. "
This means that visual timing will be completely and unfixably broken under Windows-10 with your NVidia. Here are your options:
Disable the NVidia gpu for use with Matlab. I think right-clicking on the Matlab icon -> context menu -> Properties -> will lead you to some checkbox or setting somewhere that allows to use the integrated graphics only for Matlab. Or follow these instructions for selecting “Power saving” instead of “high performance”:
Then you’ll only use Intel integrated graphics, with substantially reduced performance, and either get reasonable visual timing, or if your Intel graphics driver is buggy (which many versions are with many Intel chips on Windows) still broken timing -> Upgrade/Downgrade the Intel driver and hope for the best.
The better solution is to upgrade to Linux, e.g., Ubuntu 18.04.4 LTS at this point. Do not ask it to install proprietary drivers if it proposes to do so – during install or at runtime, but use the standard open-source drivers. Intel graphics will be used by default, with reduced performance but usually well working timing. If you needed more performance you could try to utilize the NVidia with the nouveau open-source graphics driver --> “help HybridGraphics”, may need setup with our XOrgConfCreator script. This may or may not give extra performance, depending if your Nvidia gpu is old enough (good!) or recent (bad!).
In general i advise against NVidia gpu’s at this point, unless you have very good reasons to use them. Especially on Linux you won’t be able to take advantage of certain improvements over Windows with modern NVidia gpu’s. We generally also advise against hybrid graphics laptops, because they are mostly broken wrt. visual timing on Windows, and on Linux it depends on the specific hardware configuration if it works very well or not so much. In any case they are less plug & play and more fiddly to set up for visual stimulation.