[FFmpeg-user] Merge files with different rotations

[Mark Filipak]

On 03/30/2020 05:25 AM, Gabriele Greco wrote:
> Hi guys,
> 
> Just wondering if there is a way to merge multiple files without re
> encoding using the concat format (-f concat) when one or more of the files
> are recorded with a mobile device using an upside/down orientation (rotate
> metadata to 180).
> 
> If it's not possible, as i guess, there is a way to set the rotate metadata
> not at file level but to handle it from a certain offset in the file so
> that after the result file of the concat operation could then be used to
> encode a video with a proper rotation for the whole length

Questions:
Are the "multiple files" a fixed number of files or variable?
Is the "upside/down orientation" something you want to do (or undo) or is it just what you have and 
want?
If the files are merged, should they paneled or should they simply overlay each other?