This answer is simply a summary of the comments provided by LordNeckbeard. ffmpeg -i input.mp4 -c copy -metadata:s:v:0 rotate=0 output.mp4

My iphone had marked the video as portrait for the entire video.

I started recording video in portrait mode, realized my mistake and immediately turn my phone to landscape to continue recording. Set rotation to 270°: exiftool -rotation=270 FILE.mp4Īdd 90° to existing rotation value: exiftool '-rotation<$' FILE.mp4 In case your video contains stereo audio, this is obviously not switched, so in case you want the sound to match with video rotation (180°), you need to switch the left and right channels. In the two rows before it the rotation matrix is stored In between there should be an sign (HEX 40) Some rows above (for my files mostly 9, sometimes 12) you should see trak. khd

Open mp4 with hex editor and search for vide to find the metadata of the video track metadata) rotation, I couldn't find a solution, so I grabbed a hex editor (eg HxD) and analyzed the rotated video files. exiftool can read the rotation matrix and rotation flag, and since version 10.89 also write it as described below. FFmpeg and similar programs change the metadata even with the -map_metadata option.

Ffmpeg rotate video without re encoding