4K videos were severely stuck when playing

Hi. I played 4K videos (Win10, PsychoPy v3.0), but both 4K videos at 60 FPS or 30 FPS were severely frozen, like one frame being stuck for several seconds.

These 4K videos can be smoothly played using other players. So, the computer processor is affordable.

I’m wondering if there is something to do with the version or it just can not do it yet.


Running PsychoPy v2021.2.3 on win10, I can reproduce this issue when using MovieStim3. Using the VlcMovieStim class to playback the video seems much better; maybe try using it (and PsychoPy 2021.2.3) instead.

I only have 1920x1080 monitor’s, so tested by having the 4k video displayed at 1920x1080. Tested by running a modified version of the psychopy\psychopy\demos\coder\stimuli\VlcMovieStim.py Coder demo.

Thank you sol!

I tried VlcMovieStim.py, with PsychoPy v2021.2.3 on Win10, I checked the pip list of python 3.6.6 (which is the version of PsychoPy installed), and vlc package is there. I also downloaded VLC media player as the same 64 bit as python to the PsychoPy path again (before that I had installed VLC in other path). But I ran the *.py and received an error:

File “E:\psychopy\lib\site-packages\psychopy\visual\vlcmoviestim.py”, line 1200, in
AttributeError: module ‘vlc’ has no attribute ‘CallbackDecorators’

Have no idea about this. May be you meet this too? Thank you again!

I do not get that error when using the 2021.2.3 standalone; perhaps something else is installed on my system that is making it work.

Others have reported a similar issue, and this one suggests a solution.

Can you let us know if this fixes the issue for you as well?

Thank you

Yes! This solution is the key to my problem! I can play 4K/30fps videos smoothly now, but 60 fps one is stuck as well, but far better than before. I think it’s due to the processor instead.

Anyway, thank you very much!