How to determine which modules needed for licensing FFmpeg as part of an app I developed an app that uses ffmpeg for some simple muxing, which I am going to sell. I contacted MPEG LA about licensing, and they said I the license I need depends on which codecs I use.

Is there any way to determine which codecs/libraries are actually being used by a particular ffmpeg command?

If not, is there any way to temporarily disable/enable options to see if they are required for a given operation?

FWIW, my operation doesn't re-encode anything. It uses c:v copy and c:a copy with a map function to re-arrange audio tracks. In some cases it converts pcm_s24be to pcm_s24le.
In general, the codecs involved in a pure muxing command are the decoders and bitstream parsers for the codecs of the streams in the input file.

Even though there's no decoding or encoding requested in a pure muxing command, ffmpeg uses the decoders to acquire the attributes of the streams in the input. These attributes are then passed on to the muxer, which will write in the header/metadata section(s) of the output file. This has to be done because the attributes of an encoded stream is stored in a form specific to that codec.