Video Stimuli Recommended Format

Online experiments
1

Description of the problem:
Hi,

I am intending to use Pavlovia for my experiment. The study contains about 200 video stimuli. I have tested a mini experiment with only 5 videos. Everything seemed to be working. However, when I added more videos (n = 20), the experiment kept crashing/the page froze at the end of the first video/or the screen went blank as soon as I started the experiment.

I believe the culprit is my videos which are very large (~10-15MB each).

I have made these videos in Blender and I have some time to re-render them again. However, before re-rendering them, I want to make sure, what is the best file format/size for Pavlovia to use video stimuli? Like, what is the most compatible codec (H.264, QT, …), video format (AVI, FFmpeg), …?

Thank you so much.
Asal

1 Like
2

How many videos does each participant need? Could you just download the files you need for each participant?

3

Unfortunately, each participant needs around 120 files.
I managed to downsize the videos from 15MB to 1.3MB by changing the output quality from “lossless” to “mediuam quality”.

Hopefully, Pavlovia will be happy with me now.

4

Using Pavlovia for online experimentation, I have found the best cross-browser compatibility is achieved by using H.264 encoded MP4 with AAC audio encoding.

2 Likes
5

Thank you so much. I will get back to y’all if that didn’t work.

6

Thank you! I am able to run 160 MP4 files with H.264 codec without crashing Pavlovia. Each video is about 1-2.5MB.