PTB beta release 2012-1-7 (SVN Revision 2423)


For details, please review the detailed change log.

All systems:

  • Bugfixes.

  • Screen(‘AsyncFlipXXX’) functions greatly improved. Now much more convenient and child-proof to use. Now allow use of almost all Screen() drawing functions in parallel to a pending async-flip – for enhanced parallelism. New implemenation can be disabled via a ‘ConserveVRAM’ preference setting. Associated tests AsyncFlipTest, MultiWindowLockStepTest demonstrate usage and performance.

  • Screen GPU rendertime measurements improved. Now more flexible (Screen(‘GetWindowInfo’, …) infotypes 5 and 6) Can start/stop/start… measurement multiple times per frame for fine-grained benchmarking.

  • Handling of window geometry in stereo modes and special display modes, e.g., Bits+/DataPixx Color++/C48 mode improved.

  • Screen now enables fast offscreen window support by default on GPUs which support it –> More efficient, flexible, robust Offscreen window support. So far this was an opt-in, now it is an opt-out via a new ‘ConserveVRAM’ setting.

  • Some improvements to video capture engine.

  • moglmorpher() can now dynamically delete meshes as well, not only add new ones.

  • PsychRTBox driver now should work with latest RTBox models & firmware, although untested.

  • Some demos refined.


A new workaround for OS/X 10.7 Lions broken vblank irq timestamping is in place. We fall back to CoreVideo display link timestamping. This doesn’t work well at all on 10.4 Tiger, which is why it gets only enabled on 10.7+ systems. All older systems use our proven and robust vblank irq timestamping. Or the even more robust and precise beamposition timestamping if it is supported by the OS or by use of the PsychtoolboxKernelDriver.


  • IOPort / PsychRTBox / CMUBox response button box drivers can now auto-enable low-latency mode on FTDI usb-serial ports, no need for user setup anymore.

  • Random improvements, also in documentation.

  • Most important: As part of an improved installer, the new function PsychLinuxSetup now configures the system (pending the users permission) for root-less operation: Psychtoolbox can use realtime-scheduling, beamposition timestamping, special GPU features, various optimizations, and access to special research hardware, e.g., the products from CRS and VPixx without the need to run Matlab or Octave as root user via “sudo”. This should remove quite a bit of headaches and increase system security considerably.