Ik deed het met het "avconv" commando bijvoorbeeld :
avconv -i VID_20150814_102550.3gp -vf "transpose=1" out.mp4
Dit roteert 90 graden met klok mee (clockwise) en de output wordt out.mp4
Zie de manpage. Hieruit:
transpose
Transpose rows with columns in the input video and optionally flip it.
It accepts a parameter representing an integer, which can assume the
values:
0 Rotate by 90 degrees counterclockwise and vertically flip
(default), that is:
L.R L.l
. . -> . .
l.r R.r
1 Rotate by 90 degrees clockwise, that is:
L.R l.L
. . -> . .
l.r r.R
2 Rotate by 90 degrees counterclockwise, that is:
L.R R.r
. . -> . .
3 Rotate by 90 degrees clockwise and vertically flip, that is:
L.R r.R
. . -> . .
l.r l.L