VBL Sync and Beamposition Error when running PTB DualMoviesDemo

Allen_Ingling · February 15, 2017, 10:31pm

Hi All,

While troubleshooting a program of ours that works on a Windows 7 PC but not on a new Windows 10 PC I came across a strange situation where I'm not sure what to do next.

Our in-house program uses Gstreamer, PTB and Matlab... but, essentially it's very similar to DualMovieDemo. When testing the PTB DualMovieDemo in Matlab or Octave, it would fail and output either of the following 2 errors. (listed at the end)

Although, when I run the PTB test PerceptualVBLSyncTest.m and BeampositionTest.m (Found in C:\toolbox\Psyctoolbox\PsychTests\) in Octave prior to running DualMoviesDemo, DualMoviesDemo runs fine despite the output complaining about VBL sync.

Alternatively, this workaround does not work in Matlab. Interestingly enough (and I don't know if this means anything) the "tel" output from the BeampositionTest.m in Matlab was always over 1.0 (tel = 1.3296) while Octave always produced a number below 1.0.

Migrating to Octave or linux is not an option, so I'm not sure how to proceed from here. Would performing a clean installation of the video drivers help? Might an older model video card be a viable option?

Any input would be greatly appreciated.

Thanks,

Will.

Here is a copy of the output from Matlab from "Both" runs:

*********************************************************************************************************************

>> PlayDualMoviesDemo

PTB-INFO: This is Psychtoolbox-3 for Microsoft Windows, under Matlab 64-Bit (Version 3.0.13 - Build date: May 31 2016).

PTB-INFO: Support status on this operating system release: Windows version 10.0 supported and tested to some limited degree.

PTB-INFO: Type 'PsychtoolboxVersion' for more detailed version information.

PTB-INFO: Most parts of the Psychtoolbox distribution are licensed to you under terms of the MIT License, with

PTB-INFO: some restrictions. See file 'License.txt' in the Psychtoolbox root folder for the exact licensing conditions.

PTB-INFO: Will disable DWM because a regular fullscreen onscreen window is opened -> We want best timing and performance.

PTB-INFO: The detected endline of the vertical blank interval is equal or lower than the startline. This indicates

PTB-INFO: that i couldn't detect the duration of the vertical blank interval and won't be able to correct timestamps

PTB-INFO: for it. This will introduce a very small and constant offset (typically << 1 msec). Read 'help BeampositionQueries'

PTB-INFO: for how to correct this, should you really require that last few microseconds of precision.

PTB-INFO: Btw. this can also mean that your systems beamposition queries are slightly broken. It may help timing precision to

PTB-INFO: enable the beamposition workaround, as explained in 'help ConserveVRAMSettings', section 'kPsychUseBeampositionQueryWorkaround'.

PTB-INFO: OpenGL-Renderer is NVIDIA Corporation :: Quadro K2200/PCIe/SSE2 :: 4.5.0 NVIDIA 376.62

PTB-INFO: VBL startline = 1024 , VBL Endline = 1023

PTB-INFO: Measured monitor refresh interval from beamposition = 16.661379 ms [60.019043 Hz].

PTB-INFO: Will use beamposition query for accurate Flip time stamping.

PTB-INFO: Measured monitor refresh interval from VBLsync = 16.660302 ms [60.022922 Hz]. (50 valid samples taken, stddev=0.131972 ms.)

PTB-INFO: Reported monitor refresh interval from operating system = 16.666667 ms [60.000000 Hz].

PTB-INFO: Small deviations between reported values are normal and no reason to worry.

PTB-INFO: ==============================================================================================================================

PTB-INFO: WINDOWS DWM DESKTOP COMPOSITOR IS ACTIVE. On this Windows-10 or later system, Psychtoolbox can no longer reliably detect if

PTB-INFO: this will cause trouble for timing and integrity of visual stimuli or not. You might be just fine, or you could be in trouble.

PTB-INFO: Use external measurement equipment and independent procedures to verify reliability of timing if you care about proper timing.

PTB-INFO: ==============================================================================================================================

PTB-ERROR: Statechange failed with GST_STATE_CHANGE_FAILURE!

PTB-ERROR: Could not open movie file [C:\Users\stimpy2\Documents\MATLAB\DualDiscs.mov] for playback! No such moviefile with the given path and filename.

PTB-ERROR: The specific file URI of the missing movie was: file:///C:\Users\stimpy2\Documents\MATLAB\DualDiscs.mov.

PTB-ERROR: GStreamer movie playback engine reports this error:

Error from element source: GStreamer error: state change failed and some element failed to post a proper error message with the reason for the failure.

Additional debug info: gstbasesrc.c(3356): gst_base_src_start (): /GstPlayBin:ptbmovieplaybackpipeline/GstURIDecodeBin:uridecodebin0/GstFileSrc:source:

Failed to start.

PTB-ERROR: Could not open movie file [C:\Users\stimpy2\Documents\MATLAB\DualDiscs.mov] for playback! No such moviefile with the given path and filename.

PTB-ERROR: The specific file URI of the missing movie was: file:///C:\Users\stimpy2\Documents\MATLAB\DualDiscs.mov.

PTB-ERROR: GStreamer movie playback engine reports this error:

Error from element source: GStreamer error: state change failed and some element failed to post a proper error message with the reason for the failure.

Additional debug info: gstbasesrc.c(3356): gst_base_src_start (): /GstPlayBin:ptbmovieplaybackpipeline/GstURIDecodeBin:uridecodebin0/GstFileSrc:source:

Failed to start.

Error in function OpenMovie: Usage error

In OpenMovie: Opening the movie failed I. Reason given above.

*****************************************************************************************

Alternate output