ffmpeg fail to merge two video of different orientation

[elias tsolis]

Summary of the bug:
Having two videos one horizontally and other vertically oriented.

a) trying to merge two videos of different orientation, ffmpeg fails to autorotate one of the videos and produce a lot of errors with freezed frames like "No start code is found." or "Error splitting the input into NAL units." or "Error while decoding stream #0:0: Invalid data found when processing input".

b) by rotating in metadata only video, ffmpeg fails too. ffmpeg -i v1_t.mp4 -c copy -metadata:s:v:0 "rotate=1" v1_tno.mp4

Try to encode two videos - one horizontally and another vertically oriented. Same errors - freeze frames produced by ffmpeg.
So, there is a proper way to merge two videos of different orientation without re-encoding two times with ffmpeg?

Also, there is the problem how can you know if one of these videos is "rotated" only in metadata beforehand then?

best will be ffmpeg to "autdetect" video dimensions and autorotate in accordance.

note that opened this new ticket cause i found the problem of "freezed frames ffmpeg behavior"

`ffmpeg version 5.1.3-1 Copyright (c) 2000-2022 the FFmpeg developers
built with gcc 12 (Debian 12.2.0-14)`