I noticed that julia is using its own version of ffmpeg, not the one my system has installed.
For testing, I removed that version (by deleting the ffmpeg file from .julia/artifacts…) and at least the test code you provided works now.
(I cannot play the video, but I have the same issue with any video I create with ffmpeg and pix_fmt rgb24)
When using the code from the tutorial using “record” I get this error now:
ERROR: LoadError: IOError: could not spawn `/home/ben/.julia/artifacts/7f40eeb66d90d3026ae5fb68761c263b57adb840/bin/ffmpeg -loglevel quiet -i '/tmp/jl_OF6ZyS/##video#264.mkv' -crf 20 -c:v libx264 -preset slow -r 30 -profile:v high422 -pix_fmt yuv420p -c:a libvo_aacenc -b:a 128k -y /tmp/jl_SAsXCJ/out.mp4`: no such file or directory (ENOENT)
which is not very surprising, since I removed it, I was hoping it would default to my system ffmpeg automatically.
I have something to work with now at least, trying to find out why the version that comes from julia does not seem to work on my system.