How the ffmpeg backend finds its binaries and what it passes them.
An absolute path to ffmpeg, or null to read FILMSTRIP_FFMPEG from the environment and then search PATH.
ffmpeg
FILMSTRIP_FFMPEG
PATH
Arguments appended to every encode, immediately before the output file. An escape hatch, and the thing that makes an edit non-portable: nothing here is understood by any other backend, so an edit that needs it renders differently everywhere else.
An absolute path to ffprobe, or null to resolve it the same way from FILMSTRIP_FFPROBE, then PATH, then beside whichever ffmpeg was found.
ffprobe
FILMSTRIP_FFPROBE
How many threads to allow, or null to let ffmpeg decide.