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I am trying to run code in Matlab that uses the Psychtoolbox and OpenGL. The commands that throw the error described below are:

    PsychJavaTrouble
    AssertOpenGL

Here are my specs:

    OS: Ubuntu 14.04 LTS, 64bit        
    Processor: Intel Core i5-2450M CPT @ 2.50GHz x 4
    Graphics: Intel Sandybridge Mobile
    Matlab Version: Matlab 64-Bit (Version 3.0.11 - Build date: Apr  6 2014)
    Psychophysics version installed: 3
    Installation methodology: 
      1. sudo apt-get install psychtoolbox in Terminal
      2. updated it via UpdatePsychToolbox command in Matlab console

Here is the error message:

    PsychJavaTrouble: Will now try to add the PsychJava folder to Matlabs dynamic 
      classpath...
    Warning: "/home/lillian/Desktop/Matlab/Mona_Lisa/Psychtoolbox/PsychJava" is already 
    specified on static java path. 
    > In javaclasspath>local_validate_dynamic_path at 285
      In javaclasspath>local_javapath at 182
      In javaclasspath at 119
      In javaaddpath at 71
      In PsychJavaTrouble at 86
      In ReverseCorrelationFaces at 2 
    PsychJavaTrouble: Added PsychJava folder to dynamic class path. Psychtoolbox Java 
    commands should work now!
    PTB-INFO: Display ':0' : X-Screen 0 : Assigning primary output as 0 with RandR-CRTC 
    0 and GPU-CRTC 0.
    PTB-INFO: This is Psychtoolbox-3 for GNU/Linux X11, under Matlab 64-Bit (Version 
    3.0.11 - Build date: Apr  6 2014).
    PTB-INFO: No low-level controllable GPU on screenId 0. Beamposition timestamping and 
      other special functions disabled.
    PTB-INFO: Failed to enable realtime-scheduling [Operation not permitted]!
    PTB-DEBUG:PsychOSGetSwapCompletionTimestamp: Invalid return values ust = 0, msc = 0 
      from call with success return code (sbc = 304)! Failing with rc = -2.
    PTB-DEBUG:PsychOSGetSwapCompletionTimestamp: This likely means a driver bug or 
      malfunction, or that timestamping support has been disabled by the user in the 
      driver!
    PTB-INFO: OpenGL-Renderer is Intel Open Source Technology Center :: Mesa DRI 
      Intel(R) Sandybridge Mobile  :: 3.0 Mesa 10.1.3
    PTB-INFO: VBL startline = 768 , VBL Endline = -1
    PTB-INFO: Will try to use OS-Builtin OpenML sync control support for accurate Flip 
      timestamping.
    PTB-INFO: Measured monitor refresh interval from VBLsync = 16.685075 ms [59.933804 
      Hz]. (297 valid samples taken, stddev=0.310528 ms.)
    PTB-INFO: Reported monitor refresh interval from operating system = 16.646968 ms 
      [60.070999 Hz].
    PTB-INFO: Small deviations between reported values are normal and no reason to 
      worry.
    WARNING: Couldn't compute a reliable estimate of monitor refresh interval! Trouble 
    with VBL syncing?!?
    ----- ! PTB - ERROR: SYNCHRONIZATION FAILURE ! ----
    One or more internal checks (see Warnings above) indicate that synchronization
    of Psychtoolbox to the vertical retrace (VBL) is not working on your setup.

    This will seriously impair proper stimulus presentation and stimulus presentation 
    timing!
    Please read 'help SyncTrouble' for information about how to solve or work-around the  
    problem.
    You can force Psychtoolbox to continue, despite the severe problems, by adding the 
    command
    Screen('Preference', 'SkipSyncTests', 1); at the top of your script, if you really 
    know what you are doing.
    Error using Screen
    See error message printed above.

    Error in ReverseCorrelationFaces (line 81)
    window=Screen('OpenWindow', windowNum);

What am I missing? A package? Is my hardware not okay? I can't figure this error out.

Vadim Kotov
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lrthistlethwaite
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  • Have you done what the error message suggests? – Schorsch Jul 05 '14 at 03:18
  • Skipping the sync tests causing MAJOR software failure and I have to force shut down the entire OS because it freezes. It is not good to skip the syncs. Other than this, I don't see any instructions. Also, the first line of the file I call adds all the psychtoolbox directories to the path. – lrthistlethwaite Jul 05 '14 at 04:53

1 Answers1

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So.. buried deep inside the DownloadPsychtoolbox.m file found here (see installation instructions here), is the instruction that apparently Psychtoolbox requires a special SDK. Super annoying. I will never use this toolbox again because it's so much drama to use. But this is what was missing that was causing the Screen call to fail

Missing SDK download link: http://docs.gstreamer.com/display/GstSDK/Installing+on+Windows

lrthistlethwaite
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