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video files in experiment - experiment freezes

edited June 2016 in OpenSesame


I am relatively new to OpenSesame and I am very enthousiastic about it!

At the moment I am designing an experiment containing large video files. I use the media_player_vlc item. Because of the amount of video files, I didn't use the file pool but left them in the experiment folder.

The problem is that after 5 or 6 videos, the image gets distorted or gets stuck and the sound keeps playing. After a while, the whole experiment freezes.

I already changed the back-end from legacy to xpyriment and back. In legacy performance was a bit better, but in the end the same problem occurred. Do you have any idea what I could do to solve this problem?




  • edited 8:04AM

    Hi Imke,

    This seems to be a memory problem. How you might best solve this depends on how you've structured the experiment so far. For example, do you use large videos of which you only use a part? Do you try to load all videos at once, or do you load just one video from the pool folder every iteration through a trial sequence?



  • edited June 2016

    Hi Josh,

    Thank you for your response.
    The experiment looks like this (see image). Both loops consist of 15 movies. So I guess now I load one video from the pool folder every iteration, right?
    Could it be a solution to make more loops, each containing a smaller amount of movies?



  • edited 8:04AM

    Hi Imke,

    It is known that OpenSesame's video handling capabilities are currently limited (we're working on it), but the vlc plugin is known to be quite stable when it works. Did you check if your video files do play correctly in a stand alone video player (probably you did, but I'm asking any way). You could also try to convert the video files to a different format using VLC: or a different program like handbrake:

    Alternatively, you could try using one of the other video player implementations for OpenSesame, such as or (which is pretty new, and still in a test stage, so it might be buggy). Installing these plugins may be quite difficult though, so if you want to give it a try and can't figure it out yourself, let us know.

    Hopefully one of these suggestions help you out!

  • edited 8:04AM


    Yes, I checked, they play perfectly in a stand alone video player:)

    What format would actually be best for the vlc plugin? Currently the videos are .mov files.

    Tomorrow I will try to run the experiment on another computer, to see whether that makes a difference and otherwise I will try to install one of the other video player implementations, thanks for the links!

  • edited 8:04AM

    I ran the experiment on another computer and it works! Thanks for your comments.

  • edited 8:04AM

    Great to hear Imke. We'll keep our eyes open for other reports on this problem, but for now we'll regard it as a system-specific issue.

  • Hi, I have problems with the video. I created an experiment that involved watching a movie and it worked very well. Now, running the experiment with version 3.8 of opensesesme the video icon has disappeared and the video freezing. How can I do? Thanks

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