Synchronizing and loading large resource folder (with videos) online

Hey everyone:

I’m about to run an experiment with a large number of videos so my total resource file is large (~1GB). It takes about 10-15 min to load all the resources in the U.S., and with a vpn (I’m now in China) it could take more than an hour. I wonder if there is a way to compress the videos without losing quality (currently my video is already low in resolution) so that my subjects can load the resources faster (ideally within 5 min). Or is there special strategy to live with large resource folder without video compression? Thanks in advance!

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I’ve got a tip on how to reduce the size of the videos, which could also help in ensuring that they play without problems on various browsers. See this guide: Media formats suitable for online studies — PsychoPy v2021.1

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Thanks! I’ll have a look.

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Hello! There are a few possible options here (heads up that dynamic loading of resources should be available in the new release!) but as another possible solution would it be appropriate so consider embedding videos from, Youtube, OSF or vimeo? There is a demo of how to do that in the brooks template from @wakecarter PsychoPy Online Demos

oops it’s here Embedded YouTube video success story

I realised that I hadn’t actually added the Brookes template to my list of online demos – but it’s there now.


my bad I assumed this was where it was! thanks for adding!

Hi Becca–thanks for sharing. I have a quick question: Will updating to a new Psychopy version cause some problem to the old program (like some of the code need to be modified…)? I’m hesitating whether to download the newest version.

Understandable concern, and I cannot promise it won’t (you are right to have hesitance over beta releases). Before making any suggestions there- could you tell us more about your study? e.g. do you want the videos to autoplay - so how long is each video? it will be easier to suggest if embedding a html is more appropriate/possible!


The experiment includes two parts. In the first part I will present subjects with sequences of short videos (1~6s, video will autoplay and the duration is defined is the condition file). Subjects will simply move mouse on the slider to report emotion ratings on the videos throughout each sequence (I have some code modified from wakefield’s interactive slider). In the second part their memory for the movies will be tested–screenshots of videos from a same studied sequence will be displayed on the screen and subjects will be asked to sort the screenshots to the original sequence order by dragging and dropping (code modified from the online Drag&Drop demo).

Here is the URL: I’m testing it now there might be minor issue. Thank you so much!

Do the videos need to autoplay? or can participant press play on each video?

The videos need to autoplay because I want to record their continuous emotion ratings on movies in a sequence.

OK in that case if embedding was the route taken you couldn’t stream from drive or OSF (which leaves youtube, but I am worried about ads in youtube Delay in playing videos and problems with Youtube embedding or vimeo (which I haven’t used) @wakecarter do you know if you can autoplay from vimeo?

The alternative at the moment would be to wait until there is something more workable in the release

I found the answer in my Qualtrics Primer slides.

Set privacy to private link. Copy embed code.

Paste the URL and format it to look like this:
<iframe src="" width="640" height="360" frameborder="0" allow="autoplay; fullscreen" allowfullscreen></iframe>


Amazing thank you!

Hi Thomas–Thanks for your suggestion on video compression. I believe I followed all the steps in the guide but after I converted all the videos, some videos could not be played. I got the following error. Do you have any idea what might cause this error? Thank you!

I’m not sure why this happened based on this info, but I’ve got some tips regardless:

  1. Try converting them again, perhaps one of the settings was incorrect after all.
  2. Check what the codec is. In VLC player, when you try to play the video, go to Tools → Media Information → Codec
  3. You could share one of the videos with me, then I can try? (you could upload it to wetransfer and send me a link in a PM for instance)