We are using Matlab with Psychtoolbox to present pictures and record time to click to the next picture. We are also running Camtasia on the same machine to record both the screen, and the user interaction. We get a PTB Error Synchronization Failure.

The Camtasia is started first, Matlab second. The actual Matlab output is as follows:

PTB-INFO: This is Psychtoolbox-3 for Apple OS X, under Matlab 64-Bit (Version 3.0.11 - Build date: Apr  6 2014).
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: Deficient Apple OS/X 10.7 or later detected: Would use fragile CoreVideo timestamping as fallback,
PTB-INFO: if beamposition timestamping would not work. Will try to use beamposition timestamping if possible.
PTB-INFO: Installation of the PsychtoolboxKernelDriver is strongly recommended if you care about precise visual
PTB-INFO: onset timestamping or timing. See 'help PsychtoolboxKernelDriver' for installation instructions.
PTB-INFO: However, if you use a Intel graphics card then don't bother, as the driver is no longer useful on such a card.

PTB-INFO: OpenGL-Renderer is ATI Technologies Inc. :: AMD Radeon HD 6750M OpenGL Engine :: 2.1 ATI-7.32.12
PTB-INFO: Renderer has 1024 MB of VRAM and a maximum 1012 MB of texture memory.
PTB-INFO: VBL startline = 900 , VBL Endline = -1
PTB-INFO: Beamposition queries unsupported on this system. Will try to use kernel-level vbl interrupts as fallback.
PTB-INFO: Measured monitor refresh interval from VBLsync = 19.208361 ms [52.060661 Hz]. (259 valid samples taken, stddev=5.993061 ms.)
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 KidGoalSF_3 (line 66)
    win = Screen('OpenWindow', screen);

>>

Answer 1

[Walter Roberson]

You might not be able to actually solve the problems.

You can get a little further by reading "help PsychtoolboxKernelDriver" and installing and enabling the kernel driver shown there.

You are using ATI graphics, which I do not see much about as I browse around looking at this issue. Intel graphics is consistently said to be broken at the hardware level in the discussions. NVIDIA graphics is indicated as working very intermittently with Yosemite. (My system happens to have both.)

You can read through https://github.com/Psychtoolbox-3/Psychtoolbox-3/issues/214 which has contributions from the developer. Retina display is discussed as a challenge but not necessarily a write-off.

The most consistent workaround appears to have to do with connecting an external display, even if you do not display anything on it. (I do not have an external display to test with, not unless my house-mate allows me to try on a Mac Mini.)

[Walter Roberson]

That does not appear to have any relevance to getting psychtoolbox working. It should go into a new question. That question should make clear whether you are taking the Fourier with respect to space or time.

[Rehan]

ok, Sorry for that. I have made new question,i want wrt time. http://www.mathworks.com/matlabcentral/answers/252930-fourier-transform-of-a-pattern-with-black-and-white-stripes