NOWWORKINGON

https://ffmpeg.org/

ffmpeg is een suite van tools en libraries
bvb
- html5 video af te spelen in een browser
- codec
- screenrecoding , etc

TODO seach PKS for ffmpeg , i have used it several times

ffmpeg --help

rotate video

$INPUTVIDEO='input.mp4'
$OUTPUTVIDEO='output.mp4'
ffmpeg -i $INPUTVIDEO -metadata:s:v rotate="-90" -codec copy $OUTPUTVIDEO

#or 
ffmpeg -i 2017-09-21.mp4 -metadata:s:v rotate="-90" -codec copy 2017-09-21-rotated.mp4

use 270 for the oposite direction
This just writes right metadata.
If your videoplayer does not support it, or you’ll open ‘converted’ video with OpenCV – you will see no difference.

If you want to actually change the orientation of the pixel matrix you can use the transpose filter.
But it will be incredibly slower than just modifying the metadata.

=> did not work