Videos Freezing in Pavlovia

URL of experiment: Pavlovia

Hello, I am relatively new to PsychoPy and Pavlovia and have been attempting to create an experiment with video stimuli to run on Pavlovia. I have been using the PsychoPy builder. Specifically, in my experiment a fixation cross is shown, a 3-12 second video is played, and then keyboard response options appear. There are approximately 40 videos.

The problem is that some videos will not play; they freeze just as they start and stay that way until response options appear. I have isolated the problem to videos over 6 seconds. Everything 6 seconds and below seems fine, but 7 seconds and up freeze. I tried adding in a 10s static component to help load the stimuli (both with and without fixation cross), but this did not work as intended. Specifically, although the static component appeared when I ran the experiment on my local computer, it will not run when I pilot my task on Pavlovia! I’ve run out of troubleshooting ideas for my video playback problem and for getting the static component to work.

So my questions are: (a) How do I get all of my videos to play (including longer ones)? and (b) How do I get the static component to work on Pavlovia (assuming this might help pre-load stimuli)?


Hey Trevor,
how long is the first video that appears and did you put your stimuli in a loop? I assume that pre-loading is done before the experiment so this might not be a problem. It could, however, be that your first video sets sort of a cut-off point for all subsequent videos i.e. if it’s a loop, given that the first video is 6 sec long, all other will stop playing at this timestamp. This problem is known to appear with sound components. If you are not sure, try changing the order in which your stimuli appears and see what happens.

Thanks for the suggestion! I tried reordering the stimuli in variety of ways and found several things:

(1) Somehow, I was mistaken about long videos not working… it appears the short ones are actually the problem (cannot revert files to double-check, unfortunately). This is in ways more puzzling and wouldn’t seem fixable by adding buffer time.

(2) When all trials are included, regardless of ordering, no videos under 7 seconds play and all videos 7 seconds and longer play.

(3) When I exclude videos over 7 seconds, then shorter videos will play; however, only the first video in the sequence will play. For example, Video1(6s) - Plays, Video2(6s) - Doesn’t, Video3(4s) - Doesn’t, and Video4(4s) - Doesn’t.

Anyway, any further thoughts or troubleshooting ideas are appreciated!

Hi @Trevor_Williams - did you find a solution to this? I am also having issues with videos freezing in Pavlovia and am wondering if you found a fix!

Hi, I’m also experiencing freezing while trying to play short videos on Pavlovia.

I created a minimal demo in which three videos are played. The first video plays as expected, but the second (sometimes) and the third (almost always) video freeze.

I thought maybe they freeze because I am presenting the same clip each time. I tried to reset the video (myVideo.reset(), see also that thread) inside the Begin Routine tab and stop it in the End Routine tab, but in my case, it did not seem to have any effect.

The current version of the demo presents three different videos, or to be more precise, three identical videos with different names (e.g. testVid1.mp4, testVid3.mp4 etc.). The videos were converted with the VLC Player following the tutorial under Media formats suitable for online studies.

I’m sure there must be an easy solution that I can’t see at the moment… Any ideas or recommendations would be highly appreciated :slight_smile: