I took some landscape videos with a GoPro and, for some reason, they're played as a portrait ones. It seems that the camera understood that it was handled in portrait and automatically did something. I want to rotate them to landscape.
I tried with some StackOverflow accepted answers like Rotate mp4 videos without re-encoding or this GitHub Gist but they give an invalid rotation or do nothing at all.
On a Mac using brew, install ffmpeg running brew install ffmpeg and then run this for every video:
ffmpeg -i input.MP4 -c copy -metadata:s:v:0 rotate=0 output.MP4
By the way, it also works for upside-down videos.