Currently known problems and limitations

Here are some current problems and limitations of Expyriment you should be aware of. Where possible, we include suggestions on how to deal with or work around the issue.

MPEG-1 video playback only

At the moment, only MPEG-1 video files can be played back.

This is a limitation of the underlying video system of Pygame. On the long run, we are planning to move to a different Python video package.

However, ffmpeg can be used to convert videos into the supported format:

ffmpeg -i <inputfile> -vcodec mpeg1video -acodec libmp3lame -intra -qscale 2  <outputfile.mpg>

The -qscale option is the quality setting. It can take values from 1 to 31. 1 is the best quality, but big file size. 31 is the worst quality, but small file size. Play around with this setting to get a good balance between quality and file size.

No native 3D stimuli

Right now Expyriment only offers static 2D visual stimuli.

While PyOpenGL can be used direclty to create dynamic 3D stimuli, we are planning to add a dedicated 3D stimulus class in the future, to facilitate the creation of 3D stimuli.

No support for multiple monitors

It is not possible to run Expyriment in fullscreen mode on a specific monitor, since the underlying Pygame package is not aware of multiple monitors.

If the additional monitors are set to extend the desktop, then Expyriment will treat everything as one big display (spanned over all monitors).

If you simply want to run an experiment on a different monitor (e.g. an external monitor on a laptop), we suggest to set the additional monitor to clone the primary one.