Movie lagging issue

OS : Win 7/Win10
PsychoPy version : 2021.1.4
**Standard Standalone? ** : Yes
What are you trying to achieve?:
We designed a simple naturalistic experiment that show a video in MRI scanner.

What did you try to make it work?:
By using the Movie component in Builder, we showed a 5 minutes video (.mp4) after recieving the trigger (‘s’). To let the video be preloaded at the beginning, the constant path was set in ‘Movie file’. The layout is (2,2) ‘size’ with norm ‘spatial units’

What specifically went wrong when you tried that?:
The video was played with instabe fps and obvious lagging. We tried several ways:

  1. We used different resolutions for the video, leading to different file sizes (~700MB in 1080p, ~500MB in 720p). The smaller file could reduce the lagging in certain degree, but it’s still there.
  2. We used default size of video, thich is occupied just 1/3 screen. The lagging seems disappeared.
  3. If we put the movie trial in a loop and use variable path defined in a condition file, the video would be loaded at the beginning of the loop and played with no lagging. But it causes another issue that loading time (2-6 sconds) could mess up the start timing of scans.
  4. When we using the latest version (2022.2.4) on MacOS, it seems no lagging issues.

I’m wondering what is the reason caused this situation and if there is some way to fix it.
Thanks very much for any ideas on this!