# sync test

**URL:** <https://psychtoolbox.discourse.group/t/sync-test/98>\
**Category:** Uncategorized\
**Created:** [June 7, 2017, 3:00pm UTC](https://psychtoolbox.discourse.group/t/sync-test/98 "2017-06-07T15:00:27Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Allen\_Ingling](https://avatars.discourse-cdn.com/v4/letter/a/a183cd/32.png) [@Allen\_Ingling](https://psychtoolbox.discourse.group/u/Allen_Ingling)\
**Post date:** [June 7, 2017, 3:00pm UTC](https://psychtoolbox.discourse.group/t/sync-test/98/1 "2017-06-07T15:00:27Z")

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Dear All, I am testing a new set up on linux. The output of VBLSyncTest doesn't look very nice, but after I run the command   
Screen('Preference', 'SuppressAllWarnings', 1);   
the figures VBLSyncTest generates look very nice. My question if whether disabling warnings and comments actually improves syncing or just causes VBLSyncTest not to measure correctly.  
thanks  
Pablo

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**Author:** ![cabalangofeld](https://avatars.discourse-cdn.com/v4/letter/c/f17d59/32.png) [@cabalangofeld](https://psychtoolbox.discourse.group/u/cabalangofeld)\
**Post date:** [June 7, 2017, 6:26pm UTC](https://psychtoolbox.discourse.group/t/sync-test/98/2 "2017-06-07T18:26:29Z")

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Hi Mario, thanks a lot for your response.  
  
When I ran this line   
VBLSyncTest(1000, 0, 0.6, 0, 0, 1, 0)  
the output is   
  
\*\*\*\*  
PTB-WARNING: Flip for window 10 didn't use pageflipping for flip. Visual presentation timing and timestamps are likely unreliable!  
PTB-WARNING: Something is misconfigured on your system, otherwise pageflipping would have been used by the graphics driver for reliable timing.  
PTB-WARNING: Read the Linux specific section of 'help SyncTrouble' for some common causes and fixes for this problem.  
  
INFO: PTB's Screen('Flip', 10) command seems to have missed the requested stimulus presentation deadline  
INFO: a total of 10 times out of a total of 1005 flips during this session.  
  
INFO: This number is fairly accurate (and indicative of real timing problems in your own code or your system)  
INFO: if you provided requested stimulus onset times with the 'when' argument of Screen('Flip', window [, when]);  
INFO: If you called Screen('Flip', window); without the 'when' argument, this count is more of a ''mild'' indicator  
INFO: of timing behaviour than a hard reliable measurement. Large numbers may indicate problems and should at least  
INFO: deserve your closer attention. Cfe. 'help SyncTrouble', the FAQ section at [www.psychtoolbox.org](http://www.psychtoolbox.org) and the  
INFO: examples in the PDF presentation in PsychDocumentation/ Psychtoolbox3-Slides.pdf for more info and timing tips.  
  
PTB missed 73 out of 1000 stimulus presentation deadlines.  
One missed deadline is ok and an artifact of the measurement.  
PTB completed 0 stimulus presentations before the requested target time.  
Have a look at the plots for more details...   
\*\*\*\*  
  
but after running Screen('Preference', 'SuppressAllWarnings', 1) or Screen('Preference', 'Verbosity', 0)   

the line VBLSyncTest(1000, 0, 0.6, 0, 0, 1, 0) gives   

   
\*\*\*  
The refresh interval reported by the operating system is 11.76471 ms.  
Measured refresh interval, as reported by "GetFlipInterval" is 11.78714 ms. (nsamples = 0, stddev = 0.00000 ms)  
  
  
PTB missed 1 out of 1000 stimulus presentation deadlines.  
One missed deadline is ok and an artifact of the measurement.  
PTB completed 0 stimulus presentations before the requested target time.  
Have a look at the plots for more details...  
\*\*\*  
  
The computer: AMD A8-7600 Radeon R7, 4G RAM, running Linux Mint, Matlab R2016a  
  
opengl info gives  
 Version: '3.0 Mesa 10.1.3'  
 Vendor: 'X.Org'  
 Renderer: 'Gallium 0.4 on AMD KAVERI'  
 MaxTextureSize: 16384  
 Visual: 'Visual 0x21d, (RGBA 32 bits (8 8 8 8), Z depth 16 bits, Hardware acceleration, D…'  
 Software: 'false'  
 HardwareSupportLevel: 'full'  
 SupportsGraphicsSmoothing: 1  
 SupportsDepthPeelTransparency: 1  
 SupportsAlignVertexCenters: 1  
 Extensions: {188x1 cell}  
 MaxFrameBufferSize: 16384  
  
  

Thanks  

Pablo  
  
  
  

  
  

  

2017-06-07 15:04 GMT-03:00 [mario.kleiner@...](mailto:mario.kleiner@...) [PSYCHTOOLBOX] \<[PSYCHTOOLBOX@yahoogroups.com](mailto:PSYCHTOOLBOX@yahoogroups.com)\>:  

> > XX---In [PSYCHTOOLBOX@yahoogroups.com](mailto:PSYCHTOOLBOX@yahoogroups.com), \<cabalangofeld@...\> wrote :
> > 
> >   
> > 
> > Dear All, I am testing a new set up on linux. The output of VBLSyncTest doesn't look very nice, but after I run the command   
> > Screen('Preference', 'SuppressAllWarnings', 1);   
> > the figures VBLSyncTest generates look very nice. My question if whether disabling warnings and comments actually improves syncing or just causes VBLSyncTest not to measure correctly.  
> > thanks  
> > Pablo  
> >   
> > 
> > -\> Neither. Be more specific. Post the full PTB output that "doesn't look very nice"? That could mean anything. What's the hardware/software setup, graphics card etc.?
> > 
> > -mario