ffmpeg -report option
I've seen the following ffmpeg option "-report" that could be interesting for debugging purpose:
‘-report’
Dump full command line and console output to a file named program-YYYYMMDD-HHMMSS.log in the current directory.
This file can be useful for bug reports.
It also implies -loglevel verbose.
Note: setting the environment variable FFREPORT to any value has the same effect.