[FFmpeg-user] want to introduce some option

[a b]

for example: -tmp [file location] or absence of output file.
meaning: edit in place
cases of use: we need change something in source file but don't want anything new, in our filesystem, - change color mapping, video/audio codecs changes.
expected usage: ffmpeg -i source_file encoding_options [-tmp]
e.g.: r/o source_file -> some_actions_from_cmd reflected on temp file -> delete source -> mv temp file to source filename
and ofcourse highly warn to user about power/media/free_space contitional risks.
example: ffmpeg -i test.mkv -c:v pass -c:a aac [-tmp]
result: test.mkv with reencoded soundtrack 
benefits: more easily batch processing. in case when /tmp is mounted on ramfs/tmpfs - engage in performance with speed you cpu/ssd/hdd, in this sequence.
thanks to all