You can use the
-report option. From the documentation:
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.
Setting the environment variable FFREPORT to any value has the same effect. If the value is a ’:’-separated key=value sequence, these options will affect the report; options values must be escaped if they contain special characters or the options delimiter ’:’ (see the “Quoting and escaping” section in the ffmpeg-utils manual). The following option is recognized:
set the file name to use for the report; %p is expanded to the name of the program, %t is expanded to a timestamp, %% is expanded to a plain %
Errors in parsing the environment variable are not fatal, and will not appear in the report.
You can set the
error to only pick up errors. Search in the documentation for 'loglevel' for more information.