Rotating MP4 video WITHOUT re-encoding possible?

[pstein]

Assume I have a MP4 video.
Can I rotate it by 90 deg WITHOUT re-encoding?

[eumagga0x2a]

In future builds off the ffmpeg4x branch: yes.

[eumagga0x2a]

Assuming you use Windows, a 64 bits version thereof, you may want to try r190118 from https://avidemux.org/nightly/win64/

Of course, the new "Rotate video" setting in the MP4 muxer adds only a hint for video players to the metadata. The video stream as such remains unmodified.