how to Rotate a 3gp video without re-encoding
Rotate without re-encoding

You can add rotation metadata:

ffmpeg -i input.3gp -c copy -metadata:s:v rotate=90 output.3gp



-c copy will enable stream copy mode, so it will just re-mux instead of re-encode.
Player and device support for the rotate metadata may vary, so your player or device may not actually rotate the video. If that is the case you may have to manually rotate within the player, or re-encode.


Rotate with re-encoding

When re-encoding ffmpeg will automatically rotate the video. The rotate metadata/sidedata will not be copied from the input (which is a good thing).

ffmpeg -i input output


If it doesn't work for you then your build is too old. Refer to the FFmpeg Download page.